Tillering Nodes Research Articles

Correlation between perennial grass productivity and landscape and climatic conditions

The yield monitoring (1998–2023) of cloverothymothy grass stands of 1 year of use within the moraine hill was carried out in order to find patterns in the influence of weather conditions on it. The grass stands were operated in the conditions of the Tver region without fertilizers in a single-cut mode on a field divided into 120 plots. Using regression analysis, we determined the influence of temporal variability of average monthly values: average daily temperatures, their amplitude, amount of precipitation and hydrothermal coefficient on the hay yield of perennial grasses. It was revealed that in total these parameters determine about 43% of the variability in grass productivity, but fluctuations in temperature amplitudes are responsible for 32% of the temporal variability of the yield. The yield of herbs is affected by the variability of growing conditions not only in time, but also in space. The negative impact on the yield of air temperature changes is observed in all parts of the landscape, except for the flat top, where productivity responds positively to the growth of the hydrothermal coefficient and negatively to the increase in air temperatures in the pre-harvest period. The following have a negative impact on product yield: temperature changes in late summer and early autumn, especially on southern slopes, which can make it difficult for plants to overwinter; thaws in March, causing the formation of an ice crust on the soil surface and damaging the tillering nodes of plants; hot days in the pre-harvest period, accelerating the ripening of grasses and reducing the intensity of biomass accumulation. February thaws, promoting the accumulation of moisture in the soil, lead to an increase in grass yield. Measures that reduce the negative impact of temperature changes on the grass harvest include: autumn mowing of young grass, snow retention in meadows, and sprinkling of grass on the hottest days of the pre-harvest period.

Effects of phosphorus application rate on distribution of 13C assimilates and spike formation in different til-lers of wheat with supplementary irrigation

To clarify the appropriate rate of phosphorus application and physiological mechanism for promoting wheat tillering and efficient utilization of phosphorus fertilizer with supplementary irrigation, we used 'Jimai 22' wheat variety as the test material, to set up three phosphorus application treatments, including low (90 kg P2O5·hm-2, P1), medium (135 kg P2O5·hm-2, P2), and high (180 kg P2O5·hm-2, P3) application rates, with no phosphorus application as the control (P0). We increased the relative soil water content of each treatment at join-ting stage and anthesis stage to 70%, and measured the area of tiller node, the content of endogenous hormones, the number of tillers in each tiller position, photosynthetic parameters, the distribution of 13C assimilates in each stem and tiller, as well as the grain yield and partial productivity of phosphate fertilizer. The results showed that compared with P0 and P1 treatments, P2 significantly increased the area of tiller node and the trans-zeatin (tZ), the photosynthetic parameters of the uppermost expanded leaves of the main stem, the total tillers per plant, and the distribution of 13C assimilates in each tiller. The number of ears per plant was increased by 0.51 and 0.36, and grain yield was increased by 40.3% and 13.2%, respectively. In P3 treatment, the number of tillers increased, but the panicles per plant, and the grain yield and phosphate fertilizer partial productivity decreased. Our results suggested that the moderate phosphorus treatment (135 kg·hm-2) under supplementary irrigation was suitable for high yield and high efficiency of wheat.

Unequal carbon and nitrogen translocation between ramets affects sexual reproductive performance of the clonal grass Leymus chinensis under nitrogen addition

Sexual reproduction is crucial for population continuity in clonal plants. The effect of nutrient translocation between ramets on sexual reproduction of clonal plants under nitrogen addition remains unclear. In this study, we focused on clonal fragments of Leymus chinensis reproductive ramets with different number of vegetative ramets connected to tillering nodes. A series of pot experiments was conducted under nitrogen addition, including 13C and 15N bidirectional labelling of vegetative ramets and reproductive ramets at the milk-ripe stage, determination of the 13C and 15N amount translocated, and assessment of the quantitative characteristics, nitrogen and carbon concentrations of reproductive ramets and vegetative ramets. Nitrogen addition promoted the translocation of 13C while inhibiting 15N between vegetative ramets and reproductive ramets. With an increase in the number of connected vegetative ramets, the 13C translocated by reproductive ramets and the 15N translocated by reproductive and vegetative ramets gradually increased. The translocation of 13C and 15N between vegetative and reproductive ramets was bidirectional and unequal. The translocated amount of 13C and 15N from reproductive ramets to vegetative ramets was always higher than that from vegetative ramets to reproductive ramets. Nitrogen addition did not prominently affect the sexual reproductive performance of L. chinensis, whereas the number of connected vegetative ramets both positively and negatively affected sexual reproductive performance. Ramet biomass is an important driver of nutrient acquisition by L. chinensis ramets. We demonstrate for the first time that unequal nutrient translocation between ramets affects sexual reproductive performance in L. chinensis. The findings contribute to an enhanced understanding of the reproductive strategies of clonal plant populations in future environments.

Effect of Mowing on Wheat Growth at Seeding Stage.

Winter wheat is used as forage at the tillering stage in many countries; however, the regrowth pattern of wheat after mowing remains unclear. In this study, the growth patterns of wheat were revealed through cytological and physiological assessments as well as transcriptome sequencing. The results of agronomic traits and paraffin sections showed that the shoot growth rate increased, but root growth was inhibited after mowing. The submicroscopic structure revealed a decrease in heterochromatin in the tillering node cell and a change in mitochondrial shape in the tillering node and secondary root. Analysis of the transcriptome showed the number of differentially expressed genes (DEGs) involved in biological processes, cellular components, and molecular functions; 2492 upregulated DEGs and 1534 downregulated DEGs were identified. The results of the experimental study showed that mowing induced expression of DEGs in the phenylpropanoid biosynthesis pathway and increased the activity of PAL and 4CL. The upregulated DEGs in the starch and sucrose metabolism pathways and related enzyme activity alterations indicated that the sugar degradation rate increased. The DEGs in the nitrogen metabolism pathway biosynthesis of the amino acids, phenylpropanoid biosynthesis metabolism, and in the TCA pathway also changed after mowing. Hormone content and related gene expression was also altered in the tillering and secondary roots after mowing. When jasmonic acid and ethylene were used to treat the wheat after mowing, the regeneration rate increased, whereas abscisic acid inhibited regrowth. This study revealed the wheat growth patterns after mowing, which could lead to a better understanding of the development of dual-purpose wheat.

Influence of autumn plant condition on cold hardiness of winter cereal crops at different sowing dates

Research on the influence of autumn plant condition as a factor affecting the cold hardiness of winter wheat, rye, and triticale was conducted at the Siberian Scientific Research Institute of Plant Growing and Breeding, a branch of the Institute of Cytology and Genetics, SB RAS, from 2018 to 2021. Morphological indicators of pre-winter plant condition in cereal crops (plant height, number of tillering shoots, and green mass) are primarily associated with the sowing date (contributing to 54.68–85.86%) and genotypic characteristics of winter crops (contributing to 3.63–22.81%). The best morphological indicators were observed with the first sowing date, which decreased by the third sowing date. Over the research period, more vigorous growth, the formation of tillering shoots, and the development of green mass were observed in winter rye compared to triticale and wheat, regardless of the sowing date. In addition to morphological changes in plants, biochemical changes were also observed (sugar content in the tillering node). The accumulation of sugars was influenced by the meteorological conditions of the year (contributing to 30.36%) and determined by the biological characteristics of the crop (contributing to 18.69%). High sugar content in the node of tillering of rye was found in 2020 - 34.3–43.4%, in wheat - 22.8–32.5%, and in triticale - 28.4–37.3%, which can be explained by excellent vegetative conditions promoting the accumulation of more sugars in the node of tillering of plants. At different sowing dates, high sugar content was observed in winter rye: in the first - 36.5%, the second - 26.8%, and the third - 31.3%. Triticale exceeded winter rye in sugar content in the second - 29.5% and third sowing date - 33.0%. Winter rye exhibited high morphological and biochemical indicators in autumn, contributing to its high cold hardiness (80–100%) at different sowing dates. A positive correlation was established with plant height and tillering coefficient (r =0.90*–0.91*), indicating increased cold hardiness with these traits. Wheat and triticale significantly lagged behind rye due to their lower resistance to extreme negative temperatures compared to rye. It was found that an increase in linear growth promotes increased cold hardiness, the formation of tillering shoots, and the amount of sugars in the node of tillering (r =0.34…0.93*) in wheat and the maximum height and number of tillering shoots (r =0.84*…0.94*) in triticale in the autumn period.

Clonal dominant grass Leymus chinensis benefits more from physiological integration in sexual reproduction than its main companions in a meadow.

The bioecological characteristics of plants determine their status and role in the community. The advantages of dominant species in the community compared with companion species in terms of physiological and ecological characteristics remain unclear. When both dominant and companion species in grassland plant communities are clonal, these plants are able to share resources within clones (physiological integration). However, it is unclear how the clonal dominant and companion species differ in the effect of their physiological integration on sexual reproduction. We chose Leymus chinensis, the dominant species of the most widespread meadow plant communities in the semiarid and arid regions of northern China, and its main companion species L. secalinus, Calamagrostis ripidula, C. pseudophragmites, and C. epigeios and conducted a series of in situ field experiments in a homogeneous environment, including the determination of the phenotypic characteristics of reproductive ramets with connected (allowing physiological integration) and disconnected (preventing integration) tillering nodes for each species, as well as 15N leaf labeling of ramet pairs at the milk-ripe stage. In the clonal populations of the five grasses, physiological integration between vegetative ramets and reproductive ramets interconnected by tillering nodes significantly increased the leaf, stem, inflorescence and ramet biomasses of reproductive ramets, and relative changes in ramet biomass were greatest in L. chinensis. 15N labeling showed that vegetative ramets supplied nutrients to reproductive ramets through tillering nodes; the amount of translocated 15N per unit of reproductive ramet biomass was highest in L. chinensis. Overall, our results indicate that in the five clonal grasses, physiological integration between functionally different ramets under tillering node connections had a significant positive effect on sexual reproduction, indicating interspecific consistency in the contribution of physiological integration to sexual reproduction between the dominant and companion species, but this positive effect was greater in the dominant species L. chinensis than in the four main companion species. Therefore, differences in the physiological integration ability between the dominant and main companion species, identified for the first time in this study, may explain, at least partly, the dominance of L. chinensis in the community.

A new winter common wheat VARIETY ‘Sultan’

Winter wheat occupies significant areas in the fields of the Republic of Tatarstan. The purpose of the current paper was to develope a new winter common wheat variety ‘Sultan’ and to identify its ability to produce not only high yields, but also grain quality in the conditions of the Republic. The study was carried out on the fields of the TatRIA, a separate structural subdivision of the FRC KazSC RAS on gray forest soil when sown on bare fallow at the optimal time for this area. The paper has presented the characteristics of the variety according to economically valuable traits during the years of study (2018–2020). The variety was developed by the method of individual selection from a hybrid population (Kazanskaya84 х Moskovskaya39) х Kazanskaya 285. According to the productivity, the new variety ‘Sultan’ has exceeded the standard variety ‘Kazanskaya 560’ by 0.75 t/ha. There has been established that the large productivity of the variety ‘Sultan’ is formed due to the density of the productive stem, large number and weight of grain per ear. The variety is characterized by high frost-winter resistance (90 % on average over three years of trials), can withstand a temperature decrease at the level of the tillering node to minus 20°C in winter. The variety has a high reparation ability in spring. The variety ‘Sultan’ forms well-filled grain with a grain unit of 780–801 g/l. Crude protein in grain is of 14.9–15.6 %, and 26.8–28.5 % of gluten. The variety has high values of rheological properties, namely the specific work of dough deformation according to the alveograph (flour strength) is 275 e.u., the valorimetric value is 60 %. On average, over the three years of the study, the volume yield from 100 g of flour was 576 ml3, the general baking assessment was 4.6 points. The variety can be recommended for cultivation in the south-east of the Republic of Tatarstan.

Overexpression of TaMYB4 Confers Freezing Tolerance in Arabidopsis thaliana.

Freezing stress is one of the main factors limiting the growth and yield of wheat. In this study, we found that TaMYB4 expression was significantly upregulated in the tillering nodes of the strong cold-resistant winter wheat variety Dongnongdongmai1 (Dn1) under freezing stress. Weighted gene co-expression network analysis, qRT-PCR and protein-DNA interaction experiments demonstrated that monodehydroascorbate reductase (TaMDHAR) is a direct target of TaMYB4. The results showed that overexpression of TaMYB4 enhanced the freezing tolerance of transgenic Arabidopsis. In TaMYB4 overexpression lines (OE-TaMYB4), AtMDHAR2 expression was upregulated and ascorbate-glutathione (AsA-GSH) cycle operation was enhanced. In addition, the expression of cold stress marker genes such as AtCBF1, AtCBF2, AtCBF3, AtCOR15A, AtCOR47, AtKIN1 and AtRD29A in OE-TaMYB4 lines was significantly upregulated. Therefore, TaMYB4 may increase freezing tolerance as a transcription factor (TF) in Arabidopsis through the AsA-GSH cycle and DREB/CBF signaling pathway. This study provides a potential gene for molecular breeding against freezing stress.

Formation of winter wheat productivity elements and their relation to sowing quality in the central part of the right-bank forest-steppe of Ukraine

This article presents the research results on "Zolotokolosa" winter wheat variety sowing quality and its impact on field emergence, tillering coefficient, and productive tiller formation. The studies showed that it is quite challenging to adjust the seeder for accurate sowing rate, and the deviation over the three-year research period reached up to 5.1 %. The accuracy of seed burial depth with disc drills was relatively low, fluctuating around an average of 4.24, 4.6, and 4.3 cm compared to the planned depth of 4.5 cm. However, significant variation was observed within designated plots during the vegetation period of 2018–2019 (3.4–5.2 cm), 2019–2020 (3.5–5.9 cm), and 2020–2021 (3.4–5.3 cm). Field emergence depended significantly on weather conditions and soil moisture, being favorable in 2018 and 2019 with rates of 95.3 % and 94.1 %, respectively. However, the summer-autumn drought negatively affected field emergence in 2020, resulting in a lower rate of 85.5 % compared to previous years. The depth of tillering node burial during the research period ranged from 1.85 to 1.9 cm. More significant fluctuations were observed within designated plots during the vegetation period, ranging from 1.5 to 2.2 cm. The correlation coefficient between seed burial depth and tillering node burial depth was positive (r = 0.554, r = 0.095, r = 0.237). The coefficient of productive tillering showed slight variation over the years of research. During the vegetation period of 2018–2019, it averaged 1.56, while in the subsequent years it was 1.60 and 1.54, respectively. The highest number of productive tillers, exceeding the sowing rate of 5.5 million seeds per hectare, was formed during the 2019–2020 vegetation period, with an average of 717.6 tillers/m2 . However, there was significant variation in this value within the designated plots, ranging from 605 to 869 tillers/m2 or 84.3 % to 121.1 % of the average density. In the 2018–2019 vegetation period, the average number of productive tillers was 709.4/m2 , with fluctuations within the designated plots ranging from 588 to 869 tillers/m2 or 82.1 % to 122.5 % of the average density. The lowest number of productive stalks of wheat was recorded in 2020–2021, which can be attributed to a relatively dry autumn vegetation period. On average, there were 646.8 tillers/m2 . The density fluctuated the most within the designated plots that year, ranging from 499 to 863 tillers/m2 or 77.1 % to 133.4 % of the average density. The research methods employed included field observation, laboratory analysis, comparative analysis, data synthesis, and mathematical-statistical analysis. Key words: winter wheat, sowing quality, field emergence, tillering coefficient, productive tillering.

Optimizing plant spatial competition can change phytohormone content and promote tillering, thereby improving wheat yield.

As an important type of interplant competition, line-spacing shrinkage and row-spacing expansion (LSRE) can increase the number of tillers and improve resource utilization efficiency in wheat. Wheat tillering is closely related to various phytohormones. However, it is unclear whether LSRE regulates phytohormones and their relationship to tillering and wheat yield. This study evaluated tillering characteristics, phytohormone content in tiller nodes at the pre-winter stage, and grain yield factors for the winter wheat variety Malan1. We used a two-factor randomized block trial design with two sowing spacings of 15cm (15RS, conventional treatment) and 7.5cm (7.5RS, LSRE treatment) at the same density and three sowing-date groups (SD1, SD2, and SD3). LSRE significantly promoted wheat tillering and biomass at the pre-winter stage (average increases of 14.5% and 20.9% in the three sowing-date groups, respectively) and shortened the accumulated temperature required for a single tiller. Changes in the levels of phytohormones, including decreased gibberellin and indole acetic acid and increased zeatin riboside and strigolactones, were determined by high-performance liquid chromatography and were shown to be responsible for the tillering process under LSRE treatment in winter wheat. LSRE treatment can improve crop yield by increasing the number of spikes per unit area and grain weight. Our results clarified the changes in tillering and phytohormones content of winter wheat under LSRE treatment and their correlation with grain yield. This study also provides insights into the physiological mechanisms of alleviating inter-plant competition to improve crop yield.

Influence of global warming on hydrothermal indicators and overwintering of winter cereals in the conditions of Prysyvashsha

Topicality. Climate change due to global warming determines important and relevant areas of re-search activities at the current stage of agricultural development. Climate change affects the potential of natural resources therefore the limits of these changes are taken into account when determining the ways of agricultural production development. Purpose. To determine the impact of global warming as a result of changing climatic conditions on the overwintering of winter cereals in Prysyvashsha. Materials and Methods. The research materials were long-term observations of the basic climatic indicators at the Heni-chesk Experimental Station of the SE Institute of Grain Crops of NAAS. Results. Changes of the main climatic indicators against the background of global warming in Prysyvashsha for the 2004–2020 were analyzed. During 2015–2018, the soil freezing depth and the minimum temperature at the depth of the tillering node of winter cereals during the winter period were investigated. An increase in the average annual air temperature was recorded, which caused a decrease in the soil freezing depth and an increase in its temperature at the depth of the tillering node and shortening of the winter period. Conclusions. According to the results of the study, there is an essential need to find more optimal dates for sowing winter wheat and barley as one of the key segments of agrotechnical measures, which provides better adaptation of winter crops and increase their productivity when grown in new environmental conditions in the arid Steppe zone of Ukraine. Key words: global warming, climate change, air temperature, soil temperature, precipitation, winter wheat, winter barley, sowing dates, depth of soil freezing

Propagation strategies of Deyeuxia angustifolia in heterogeneous habitats

Plants utilize different strategies in different environments to maximize population expansion. Understanding plant reproductive strategies in heterogeneous habitats is therefore important for explaining plant ecological adaptability, and for effectively managing and conserving ecosystems. We wanted to explore the reproductive strategy transformation of D. angustifolia in heterogeneous habitats, as well as the environmental factors driving and affecting its reproductive characteristics. To do this we measured the reproductive characteristics of D. angustifolia, as well as the soil physical and chemical properties of these heterogeneous habitats. The density, biomass per unit area, and proportion of aboveground biomass in swampy meadows were significantly higher compared to other habitats. The proportion of rhizome node buds gradually increased from swampy to typical to miscellaneous grass meadows, while the proportion of tillering node buds decreased. The allocation of sexual reproduction within D. angustifolia populations was significantly and positively correlated with plant rhizome biomass and negatively correlated with the number of tillering node buds. The propagation strategies of D. angustifolia in heterogeneous habitats were consistent with CSR theory (Competitor, Stress-tolerator, and Ruderal). The proportions of inflorescence (2.07 ± 0.52%; 1.01 ± 0.15%) and root (23.8 ± 1.5%; 19.6 ± 1.4%) biomass in miscellaneous and typical meadows were high, which tended toward the “Ruderal” adaptation strategy. In swampy meadow, D. angustifolia invested mostly in vegetative growth to produce tiller node buds (14426.67 buds/m2; 46%) and ramets (1327.11 ± 102.10 plants/m2), which is characteristic of the “Competitor” strategy. Swamp D. angustifolia resisted flooding by maintaining a resource balance in its body, and was therefore biased toward the “Stress-tolerator” strategy. Environmental factors accounted for 74.63% of reproductive characteristic variation, in which the interpretative proportions of soil water content, dissolved organic carbon, ammonia nitrogen, and nitrate nitrogen were significant (p < 0.01). When soil water content, dissolved organic carbon, and nitrate nitrogen increased, D. angustifolia tended toward the C strategy; in contrast, when soil water content decreased, amine nitrogen and available phosphorus increased, and D. angustifolia tended toward the R strategy. In a stressful environment, the escape mechanism constitutes an increased rhizome and sexual reproduction investment. In contrast, for suitable habitats, tillering node buds increased in order to expand the population via new plant production, which was the propagation strategy of D. angustifolia in heterogeneous habitats.

Transcriptome analysis of brassinolide under low temperature stress in winter wheat.

Low temperatures are the main abiotic factor affecting wheat growth. Brassinolide is a novel plant hormone that can improve the cold resistance of plants; however, the molecular mechanism of brassinolide in winter wheat at low temperatures remains unclear. In this study, winter wheat Dongnong dongmai 1 was sprayed with 0.01, 0.1, or 1.0 mg·L-1 brassinolide (BR) at the three-leaf stage, and tillering nodes were sampled at different temperatures (5, -10 and -25 °C), and then physiological indexes were determined and the transcriptome was sequenced. The results showed that the optimum concentration of brassinolide for cold resistance is 0.1 mg·L-1. A total of 15 302 (8198 upregulated and 7104 downregulated) differentially expressed genes (DEGs) were identified in the B1 vs D1 comparison (B1 represents 5 °C 0.1 mg·L-1 BR treatment, D1 represents 5 °C control); 3386 (1930 upregulated and 1456 downregulated) differentially expressed genes (DEGs) were identified in the B2 vs D2 comparison (B2 represents -10 °C 0.1 mg·L-1 BR treatment, D2 represents -10 °C control); and 2684 (2102 upregulated and 582 downregulated) differentially expressed genes (DEGs) were identified in the B3 vs D3 comparison (B3 represents -25 °C 0.1 mg·L-1 BR treatment, D3 represents -25 °C control). Further studies showed that these DEGs were mainly involved in carbon fixation in photosynthetic organs, photosynthesis and plant-pathogen interactions, all of which were related to stress and energy metabolism. This indicates that brassinolide can produce substances that improve cold resistance in wheat seedlings. This study provides a theoretical basis for further research on the improvement of cold resistance in winter wheat by brassinolide.

Comparative evaluation of the productivity of winter crops (wheat [Triticum aestivum L.], rye [Secale cereale L.], triticale [Triticosecale Witt.]) in the western forest-steppe of Ukraine

The aim of the study was to determine the parameters of adaptability of winter crop varieties for cultivation in the western forest-steppe zone of Ukraine (2019-2021). The subject of the study were wheat (Triticum aestivum L.) varieties: Vodogray bilotserkivsky, Oberig Myronivsky, Mudrist odeska; rye (Secale ?ereale L.): Knyazhe, Kobza, Kharkivyanka; triticale (Triticosecale Witt.): Markian, Molfar, Obrij myronivsky. The tests were carried out in the field. The area of the experimental plot was 55 m2, and the placement of varieties was consecutive with three repetitions. The results showed that under the basic cultivation technologies and weather conditions of the growing seasons, the grain productivity of soft wheat varieties varied from 4.88 (Mudrist odeska) to 5.39 t ha-1 (Oberig Myronivsky); rye - from 5.55 (Kharkivyanka) to 6.32 t ha-1 (Kobza); triticale - from 6.45 (Markian) to 6.74 t ha-1 (Obrij myronivsky). The results obtained allow to conclude that ecologically plastic varieties of winter crops in the conditions of the studied soil-climatic zone accumulate a sufficient amount of sugar in the tillering nodes - 25-30%, ensure overwintering of plants - 94-96%, are resistant to the main diseases, which contributes to the production of high-quality seeds to ensure the cultivated area in the region and the efficiency of seed production.

Genome-Wide Identification of Wheat KNOX Gene Family and Functional Characterization of TaKNOX14-D in Plants.

The KNOX genes play important roles in maintaining SAM and regulating the development of plant leaves. However, the TaKNOX genes in wheat are still not well understood, especially their role in abiotic stress. In this study, a total of 36 KNOX genes were identified, and we demonstrated the function of the TaKNOX14-D gene under mechanical injury and cold stress. Thirty-six TaKNOX genes were divided into two groups, and thirty-four TaKNOX genes were predicted to be located in the nucleus by Cell-PLoc. These genes contained five tandem duplications. Fifteen collinear gene pairs were exhibited in wheat and rice, one collinear gene pair was exhibited in wheat and Arabidopsis. The phylogenetic tree and motif analysis suggested that the TaKNOX gene appeared before C3 and C4 diverged. Gene structure showed that the numbers of exons and introns in TaKNOX gene are different. Wheat TaKNOX genes showed different expression patterns during the wheat growth phase, with seven TaKNOX genes being highly expressed in the whole growth period. These seven genes were also highly expressed in most tissues, and also responded to most abiotic stress. Eleven TaKNOX genes were up-regulated in the tillering node during the leaf regeneration period after mechanical damage. When treating the wheat with different hormones, the expression patterns of TaKNOX were changed, and results showed that ABA promoted TaKNOX expression and seven TaKNOX genes were up-regulated under cytokinin and auxin treatment. Overexpression of the TaKNOX14-D gene in Arabidopsis could increase the leaf size, plant height and seed size. This gene overexpression in Arabidopsis also increased the compensatory growth capacity after mechanical damage. Overexpression lines also showed high resistance to cold stress. This study provides a better understanding of the TaKNOX genes.

Low red/far-red ratio can induce cytokinin degradation resulting in the inhibition of tillering in wheat (Triticum aestivum L.).

Shoot branching is inhibited by a low red/far-red ratio (R/FR). Prior studies have shown that the R/FR suppressed Arabidopsis thaliana branching by promotes bud abscisic acid (ABA) accumulation directly. Given that wheat tiller buds are wrapped in leaf sheaths and may not respond rapidly to a R/FR, systemic cytokinin (CTK) may be more critical. Here, systemic hormonal signals including indole-3-acetic acid (IAA), gibberellins (GA) and CTK and bud ABA signals in wheat were tested under a low R/FR. The results showed that a low R/FR reduced the percentage of tiller occurrence of tiller IV and the tiller number per plant. The low R/FR did not rapidly induced ABA accumulation in the tiller IV because of the protection of the leaf sheath and had little effect on IAA content and signaling in the tiller nodes. The significant change in the CTK levels was observed earlier than those of other hormone (ABA, IAA and GA) and exogenous cytokinin restored the CTK levels and tiller number per plant under low R/FR conditions. Further analysis revealed that the decrease in cytokinin levels was mainly associated with upregulation of cytokinin degradation genes (TaCKX5, TaCKX11) in tiller nodes. In addition, exposure to a decreased R/FR upregulated the expression of GA biosynthesis genes (TaGA20ox1, TaGA3ox2), resulting in elevated GA levels, which might further promote CTK degradation in tiller nodes and inhibit tillering. Therefore, our results provide evidence that the enhancement of cytokinin degradation is a novel mechanism underlying the wheat tillering response to a low R/FR.

Cold stress triggers freezing tolerance in wheat (Triticum aestivum L.) via hormone regulation and transcription of related genes.

Low temperatures limit the geographic distribution and yield of plants. Hormones play an important role in coordinating the growth and development of plants and their tolerance to low temperatures. However, the mechanisms by which hormones affect plant resistance to extreme cold stress in the natural environment are still unclear. In this study, two winter wheat varieties with different cold resistances, Dn1 and J22, were used to conduct targeted plant hormone metabolome analysis on the tillering nodes of winter wheat at 5 °C, -10 °C and -25 °C using an LC-ESI-MS/MS system. We screened 39 hormones from 88 plant hormone metabolites and constructed a partial regulatory network of auxin, jasmonic acid and cytokinin. GO analysis and enrichment of KEGG pathways in different metabolites showed that the 'plant hormone signal transduction' pathway was the most common. Our study showed that extreme low temperature increased the most levels of auxin, cytokinin and salicylic acid, and decreased levels of jasmonic acid and abscisic acid, and that levels of auxin, jasmonic acid and cytokinin in Dn1 were higher than those in J22. These changes in hormone levels were associated with changes in gene expression in synthesis, catabolism, transport and signal transduction pathways. These results differ from the previous hormone regulation mechanisms, which were mostly obtained at 4 °C. Our results provide a basis for further understanding the molecular mechanisms by which plant endogenous hormones regulate plant freezing stress tolerance.

Analysis of controlling genes for tiller growth of Psathyrostachys juncea based on transcriptome sequencing technology

BackgroundTillering is a complicated process in plant and is a significant trait that affects biomass and seed yield of bunch grass Psathyrostachys juncea, a typical perennial forage species. To clarify the regulatory mechanisms of tillering in P. juncea and to explore related candidate genes could be helpful to improve the seed and forage yield of perennial gramineous forages. We selected the tiller node tissues of P. juncea for transcriptome sequencing to determine the differentially expressed genes (DEG) between dense and sparse tillering genotypes. The metabolic pathway was studied, candidate genes were screened, and reference genes stability were evaluated.ResultsThe results showed that approximately 5466 DEGs were identified between the two genotypes with dense and sparse tillers of P. juncea, which significantly differed in tiller number. Tillering regulation pathways analysis suggested that DEGs closely related to the biosynthesis of three plant hormones, namely auxin (IAA), cytokinin (CTK), and strigolactones (SLs), while “biosynthesis of lignin” and “nitrogen metabolism” have remarkable differences between the dense and sparse tillering genotypes. Meanwhile, the reference gene Actin1, having the best stability, was screened from twelve genes with highest expression level and was used in verification of ten tillering related candidate genes.ConclusionsThe tillering mechanism of perennial grass P. juncea was expounded by transcriptome analysis of tiller node tissues. We demonstrated that dense-tillering genotypes may be distinguished by their low expression patterns of genes involved in SL, IAA, and high expression patterns of genes involved in CTK biosynthesis at the tillering stage, and nitrogen metabolism and lignin biosynthesis can also affect the number of tillers. Furthermore, the expression level of ten tillering related candidate genes were verified using Actin1 as reference gene. These candidate genes provide valuable breeding resources for marker assisted selection and yield traits improvement of P. juncea.

Maize straw mulching with uniconazole application increases the tillering capacity and grain yield of dryland winter wheat (Triticum aestivum L.)

Improvements in wheat tillering in dry-land farming systems can be achieved by reducing soil water loss by straw mulching and enhancing the capability of wheat roots to capture soil water and N. However, the effects of the application of maize straw mulching in combination with uniconazole application on wheat tillering is not yet investigated. Field experiments were conducted during 2017–2018 (dry, 167 mm) and 2018–2019 (favorable, 222 mm) to investigate the combined effects of uniconazole (0 and 10 mg kg-1) and maize straw mulching (0 and 7500 kg ha-1) on soil water and root distribution, phytohormone signal transduction, total N uptake, plant N nutrition, tillering capability, and the expression of critical genes and metabolites in response to wheat tillering. Compared with no mulch control, straw mulching combined with uniconazole application increased soil moisture content and root length in the 0–20 cm soil layer and thereby increased total N uptake. Owing to allometric increases in aboveground N content and plant dry mass, uniconazole application combined with straw mulching increased the dry mass per kg N uptake and N nutrition index in the tillering and stem extension stages. Improved N nutrition index led to higher tiller emergence rate and tiller occurrence rate of first primary tillers and thus increased the number of fertile spikes and grain yield. Multi-omics integration analysis revealed that the increased tillering capability was associated with abscisic acid and gibberellic acid-mediated phenylpropanoid biosynthesis and glycerophospholipid metabolism because of their critical roles in lignin biosynthesis and the maintenance of cell membrane integrity in tiller node cells. The collective results indicate that maize straw mulching combined with uniconazole application improved the capability of wheat roots to capture soil moisture and N in addition to increasing lignin biosynthesis, ultimately enhancing tillering capability and grain yield of dryland winter wheat.

Survey of overwintering trait in Chinese rice cultivars (Oryza sativa L)

Overwintering rice can survive through the natural cold-winter field environment, sprout from rice tillering node in the following spring, tiller, flower, seed, and being harvested in the following autumn, which is a type of an extreme case of cold tolerance of rice. The successful utilization of cold tolerance rice is the most economical strategy for the cold tolerance rice cultivar breeding project. This work aims to identify the OW rice for the future development of cold tolerance cultivars. Altogether 1034 Chinese existing rice cultivars including 735 (71.08%) conventional Japonica rice cultivars and 299 (28.92%) conventional Indica rice cultivars were collected and evaluated for their responses to low temperatures under the natural field cold-winter environment. Among them, altogether 262 (25.34%) conventional Japonica rice cultivars could withstand cold tolerance to 4 °C of the daily minimum temperatures in December 2019 throughout the cold-winter season and distributed in 13 provinces of China, survive through the natural cold-winter field environment, and sprout from rice tillering node in March 2020. Only 24 (2.32%) conventional japonica rice cultivars could withstand cold tolerance to 0 °C of the daily minimum temperatures in January 2021 throughout the cold-winter season, which could also sprout from rice tillering node in March 2021 and distributed in seven provinces of China. The present cold tolerance rice cultivars will provide beneficial breeding germplasm for the future cold tolerance rice breeding project and new strategies involved in elucidating the molecular mechanism of the cold tolerance of rice.