Auxin Concentration Research Articles

Integrated Methylome and Transcriptome Analysis between Wizened and Normal Flower Buds in Pyrus pyrifolia Cultivar 'Sucui 1'.

Here, cytosine methylation in the whole genome of pear flower buds was mapped at a single-base resolution. There was 19.4% methylation across all sequenced C sites in the Pyrus pyrifolia cultivar 'Sucui 1' flower bud genome. Meantime, the CG, CHG, and CHH sequence contexts (where H = A, T or C) exhibited 47.4%, 33.3%, and 11.9% methylation, respectively. Methylation in different gene regions was revealed through combining methylome and transcriptome analysis, which presented various transcription trends. Genes with methylated promoters exhibited lower expression levels than genes with non-methylated promoters, while body-methylated genes displayed an obvious negative correlation with their transcription levels. The methylation profiles of auxin- and cytokinin-related genes were estimated. And some of them proved to be hypomethylated, with increased transcription levels, in wizened buds. More specifically, the expression of the genes PRXP73, CYP749A22, and CYP82A3 was upregulated as a result of methylation changes in their promoters. Finally, auxin and cytokinin concentrations were higher in wizened flower buds than in normal buds. The exogenous application of paclobutrazol (PP333) in the field influenced the DNA methylation status of some genes and changed their expression level, reducing the proportion of wizened flower buds in a concentration-dependent manner. Overall, our results demonstrated the relationship between DNA methylation and gene expression in wizened flower buds of P. pyrifolia cultivar 'Sucui 1', which was associated with changes in auxin and cytokinin concentrations.

BTA2 regulates tiller angle and the shoot gravity response through controlling auxin content and distribution in rice.

Tiller angle is a key agricultural trait that establishes plant architecture, which in turn strongly affects grain yield by influencing planting density in rice. The shoot gravity response plays a crucial role in the regulation of tiller angle in rice, but the underlying molecular mechanism is largely unknown. Here, we report the identification of the BIG TILLER ANGLE2 (BTA2), which regulates tiller angle by controlling the shoot gravity response in rice. Loss-of-function mutation of BTA2 dramatically reduced auxin content and affected auxin distribution in rice shoot base, leading to impaired gravitropism and therefore a big tiller angle. BTA2 interacted with AUXIN RESPONSE FACTOR7 (ARF7) to modulate rice tiller angle through the gravity signaling pathway. The BTA2 protein was highly conserved during evolution. Sequence variation in the BTA2 promoter of indica cultivars harboring a less expressed BTA2 allele caused lower BTA2 expression in shoot base and thus wide tiller angle during rice domestication. Overexpression of BTA2 significantly increased grain yield in the elite rice cultivar Huanghuazhan under appropriate dense planting conditions. Our findings thus uncovered the BTA2-ARF7 module that regulates tiller angle by mediating the shoot gravity response. Our work offers a target for genetic manipulation of plant architecture and valuable information for crop improvement by producing the ideal plant type.

Screening of flower bud differentiation conditions and changes in metabolite content of Phalaenopsis pulcherrima

Using the Phalaenopsis pulcherrima (P. pulcherrima) as the test material, the optimal conditions for flower bud differentiation were selected by setting different photoperiods and temperatures. The process of flower bud differentiation was observed, and changes in the content of carbohydrates, hormones, and other metabolites during flower bud differentiation were studied. The results showed that the optimum time of illumination was 16 h. d−1 and the temperature was 30 ℃ / 25 ℃. According to the characteristics of the flower bud development of P. pulcherrima, the differentiation process can be divided into six periods: the initial differentiation phase, inflorescence primordium differentiation phase, flower primordium differentiation phase, sepal primordium differentiation phase, petal primordium differentiation phase, and column and pollinia differentiation phase. The soluble sugar content in the leaves showed a trend of first increasing and then decreasing. The soluble sugar content was highest 30 days after the treatment, when the differentiation of the inflorescence primordium was completed. The starch content first decreased, then increased, and finally decreased. The starch content was lowest at 30 days of treatment and highest at 35 days. The soluble protein content in the leaves reached a maximum after 30 days of treatment. With the continuous differentiation of flower buds, the soluble protein content showed an overall decreasing trend. The zeatin (ZT) content reached a maximum at day 35, showing an overall decreasing trend from days 35 to 50 and reaching a minimum at day 50. The gibberellin (GA3) and auxin (IAA) content first decreased and then increased during the process of flower bud differentiation. The changes in soluble sugar and soluble protein content during flower bud differentiation are consistent, while the changes in GA3 and IAA are consistent.

Effects of Photoperiod and Light Quality on Germination and Growth of Camellia sinensis 'HuangKui'.

Light, as a critical environmental factor, plays a pivotal role in photosynthesis, ultimately influencing the timing of bud flush in tea plants. However, the synergistic effects of different photoperiods and light qualities on the timing of bud flush in the albino tea cultivar 'HuangKui' (later germination variety) remain unknown. Thus, the objective of this study was to investigate the effects of different photoperiods (12L/12D, 14L/10D, 16L/8D, and 18L/6D, where L = the number of daylight hours and D = the number of hours of darkness) and ratios of red (R) to blue (B) light (R/B 1:1, R/B 1:2, R/B 1:3, and R/B 2:1) on the germination and growth of the albino tea variety 'HuangKui'. In our study, we examined how different photoperiods and red light and blue light affected tea germination and growth by investigating the timing of bud flush, photosynthesis, chlorophyll content, and growth indicators. First, our study showed that 'HuangKui' germinated 4 days, 2 days, and 1 day earlier under the 16L/8D photoperiod at the one bud and one leaf period compared with plants cultivated under the 12L/12D, 14L/10D, and 18L/6D photoperiods under light simulating the solar spectrum. Also, the growth of 'HuangKui' was maximumly promoted under the 16L/8D photoperiod treatment. Additionally, the earliest germination of 'HuangKui' was observed for the 16L/8D photoperiod under the R/B 2:1 (red/blue) treatment compared with the other treatments. Moreover, the greatest plant height, length of the new shoots, and new leaf areas were detected in the albino tea variety 'HuangKui' under R/B 2:1. Moreover, the contents of auxin (indole acetic acid, IAA) and trans-zeatin (tZ) under R/B 2:1 were significantly higher than those under the R/B 1:1 and control treatments with the 16L/8D photoperiod. Additionally, the auxin-related expression levels of CsIAA13, CsGH3.1, CsAUX1, and CsARF2 under the R/B 2:1 treatment were significantly higher than those in the control. The expression of CsARR-B, a positive regulator of cytokinin-related genes, was significantly higher under the R/B 2:1 treatment than under the control treatment, while the opposite result was found for the expression of the negative regulator CsARR-A. Therefore, the R/B 2:1 treatment with the 16L/8D photoperiod was an appropriate means of timing the bud flush for the albino tea variety 'HuangKui', which may be related to IAA or tZ signal transduction. In conclusion, our research offers a novel lighting strategy that promotes the germination and growth of albino tea cultivars.

ESTABLISHMENT OF AN EFFICIENT MICROPROPAGATION PROTOCOLS FOR THREE KENAF (HIBISCUS CANNABINUS L.) CULTIVARS

This study was aimed to establish an efficient micropropagation protocol for three popular kenaf (Hibiscus cannabinus L.) cultivars (V36, HF992 and KB6) using different types of plant growth regulators (PGR’s) on Murashige and Skoog medium (MS). The shoot tip, cotyledon and hypocotyl isolated from 2 weeks old seedlings were used as explants. MS medium fortified with different types and concentrations of cytokinins and auxin were evaluated for establishment callus formation, shoot multiplication and rooting. Among different PGR’s used, 5.0 mg/l 2iP + 0.1 mg/l NAA was the best concentration for direct shoot regeneration from cotyledon with shooting percentage of 55% in HF992 cultivar. In multiple shoot induction experiment, 1.0 mg/l TDZ + 0.1 mg/l NAA mg/l concentration has induced the highest (10.4) shoots/explant. Moreover, indirect shoot regeneration was established from callus which was induced from cotyledon, maximum callus induction percentage (88.75%) was recorded on 0.5 mg/l TDZ and 1.0 mg/l NAA in V36 variety. While, for shoot elongation and rooting, MS media half strength supplemented with 1.0 mg/l kinetin + 1.0 mg/l IBA was found to be an optimum concentration.

Is calcium deficiency the real cause of bitter pit? A review.

Bitter pit is a disorder affecting the appearance of apples. Susceptibility is genetically controlled by both the cultivar and rootstock, with both environmental and horticultural factors affecting its severity and proportional incidence. Symptoms appear more frequently at the calyx end of the fruit and consist of circular necrotic spots, which take on a "corky" appearance visible through the peel. Bitter pit may develop before harvest, or after harvest, reducing the proportions of marketable fruit. In this review, current knowledge of the factors associated with the occurrence of bitter pit in apples is summarized and discussed along with their interactions with Ca uptake and distribution to fruit. This disorder has been previously linked with localized Ca deficiencies in fruit during its development. However, these relationships are not always clear. Even with over a century of research, the precise mechanisms involved in its development are still not fully understood. Additional factors also contribute to bitter pit development, like imbalances of mineral nutrients, low concentration of auxins, high concentration of gibberellins, changes in xylem functionality, or physiological responses to abiotic stress. Bitter pit remains a complex disorder with multiple factors contributing to its development including changes at whole plant and cellular scales. Apple growers must carefully navigate these complex interactions between genetics, environment, and management decisions to minimize bitter pit in susceptible cultivars. Accordingly, management of plant nutrition, fruit crop load, and tree vigor still stands as the most important contribution to reducing bitter pit development. Even so, there will be situations where the occurrence of bitter pit will be inevitable due to cultivar and/or abiotic stress conditions.

Plant metabolic responses to soil herbicide residues differ under herbivory in two woodland strawberry genotypes

The use of glyphosate-based herbicides (GBHs) to control weeds has increased exponentially in recent decades, and their residues and degradation products have been found in soils across the globe. GBH residues in soil have been shown to affect plant physiology and specialised metabolite biosynthesis, which, in turn, may impact plant resistance to biotic stressors.In a greenhouse study, we investigated the interactive effects between soil GBH residues and herbivory on the performance, phytohormone concentrations, phenolic compound concentrations and volatile organic compound (VOC) emissions of two woodland strawberry (Fragaria vesca) genotypes, which were classified as herbivore resistant and herbivore susceptible. Plants were subjected to herbivory by strawberry leaf beetle (Galerucella tenella) larvae, and to GBH residues by growing in soil collected from a field site with GBH treatments twice a year over the past eight years.Soil GBH residues reduced the belowground biomass of the susceptible genotype and the aboveground biomass of both woodland strawberry genotypes. Herbivory increased the belowground biomass of the resistant genotype and the root–shoot ratio of both genotypes. At the metabolite level, herbivory induced the emission of several VOCs. Jasmonic acid, abscisic acid and auxin concentrations were induced by herbivory, in contrast to salicylic acid, which was only induced by herbivory in combination with soil GBH residues in the resistant genotype. The concentrations of phenolic compounds were higher in the resistant genotype compared to the susceptible genotype and were induced by soil GBH residues in the resistant genotype.Our results indicate that soil GBH residues can differentially affect plant performance, phytohormone concentrations and phenolic compound concentrations under herbivore attack, in a genotype-dependent manner. Soil GBH altered plant responses to herbivory, which may impact plant resistance traits and species interactions. With ongoing agrochemical pollution, we need to consider plant cultivars with better resistance to polluted soils while maintaining plant resilience under challenging environmental conditions.

A Single-step Generation of AlissAID-based Conditional Knockdown Strains Using Nanobody that Targets GFP or mCherry in Budding Yeast.

The Auxin-inducible degron (AID) system is a genetic tool that induces rapid target protein depletion in an auxin-dependent manner. Recently, two advanced AID systems-the super-sensitive AID and AID 2-were developed using an improved pair of synthetic auxins and mutated TIR1 proteins. In these AID systems, a nanomolar concentration of synthetic auxins is sufficient as a degradation inducer for target proteins. However, despite these advancements, AID systems still require the fusion of an AID tag to the target protein for degradation, potentially affecting its function and stability. To address this limitation, we developed an affinity linker-based super-sensitive AID (AlissAID) system using a single peptide antibody known as a nanobody. In this system, the degradation of GFP- or mCherry-tagged target proteins is induced in a synthetic auxin (5-Ad-IAA)-dependent manner. Here, we introduce a simple method for generating AlissAID strains targeting GFP or mCherry fusion proteins in budding yeasts. Key features • AlissAID system enables efficient degradation of the GFP or mCherry fusion proteins in a 5-Ad-IAA-depending manner. • Transforming the pAlissAID plasmids into strains with GFP- or mCherry- tagged proteins.

Mapping the membrane orientation of auxin homeostasis regulators PIN5 and PIN8 in Arabidopsis thaliana root cells reveals their divergent topology

PIN proteins establish the auxin concentration gradient, which coordinates plant growth. PIN1-4 and 7 localized at the plasma membrane (PM) and facilitate polar auxin transport while the endoplasmic reticulum (ER) localized PIN5 and PIN8 maintain the intracellular auxin homeostasis. Although an antagonistic activity of PIN5 and PIN8 proteins in regulating the intracellular auxin homeostasis and other developmental events have been reported, the membrane topology of these proteins, which might be a basis for their antagonistic function, is poorly understood. In this study we optimized digitonin based PM-permeabilizing protocols coupled with immunocytochemistry labeling to map the membrane topology of PIN5 and PIN8 in Arabidopsis thaliana root cells. Our results indicate that, except for the similarities in the orientation of the N-terminus, PIN5 and PIN8 have an opposite orientation of the central hydrophilic loop and the C-terminus, as well as an unequal number of transmembrane domains (TMDs). PIN8 has ten TMDs with groups of five alpha-helices separated by the central hydrophilic loop (HL) residing in the ER lumen, and its N- and C-terminals are positioned in the cytoplasm. However, the topology of PIN5 comprises nine TMDs. Its N-terminal end and the central HL face the cytoplasm while its C-terminus resides in the ER lumen. Overall, this study shows that PIN5 and PIN8 proteins have a divergent membrane topology while introducing a toolkit of methods for studying membrane topology of integral proteins including those localized at the ER membrane.

Proteomic investigation reveals molecular mechanisms of plant height regulation in foxtail millet

Plant height is an essential characteristic of agronomic traits, and an ideal plant height is essential for high crop yield. Foxtail millet (Setaria italica) has been regarded as a novel diploid C4 model crop. The proteomic profiles of the internode, node, and leaf in two foxtail millet varieties with different heights, Ci846 and Yugu 18, were investigated at the jointing stage in our study. There were different degrees of the enrichment processes such as plant hormone signal transduction, the MAPK signaling pathway, and so on. In particular, the proper content of auxin could activate downstream SiARFs-SiSAURs expression, which enhances the length of internodes. Haplotype analysis of SiSAUR-like revealed two differential haplotypes of associated plant height, Hap1 and Hap2. The molecular marker SiSAUR-like-FCM1-2 can effectively separate Hap1 and Hap2 in different materials. Two additional genes, designated SiGH3 and SiTCH4, were found to be associated with plant height regulation. In conclusion, this study not only uncovers the crucial role of auxin regulators in modulating plant height during the jointing stage, but also provides molecular markers that are invaluable for molecular breeding efforts. The findings of this research help to elucidate the molecular mechanisms of plant height determination and preparation for crop variety innovation and breeding.

Pengaruh Jenis Dan Konsentrasi Auksin Terhadap Pertumbuhan Dan Perkembangan Tanaman Anggrek Dendrobium mirbelianum Secara In Vitro

This study aims to determine the effect of auxin type and concentration on the growth and development of orchid plants. The research was conducted at the Tissue Culture Biotechnology Laboratory, Faculty of Agriculture, Sam Ratulangi University Manado, and was carried out over 2 months from July to August 2023. This study used a factorial experiment in a Completely Randomized Design (CRD) with 5 replications consisting of two factors. The first factor is the type of auxin: IAA (A1), NAA (A2), and IBA (A3), and the second factor is the concentration of each auxin: 1 ml/l (K1), 2 ml/l (K2), and 3 ml/l (K3). The data were analyzed using analysis of variance, and if the results were significant, a 5% Least Significant Difference (LSD) test was conducted. The results showed that there was an interaction between the type and concentration of auxin on variables such as the number of roots, root length, root emergence time, number of leaves, number of shoots, and shoot height. Similarly, there was an effect of auxin concentration on each type of auxin, but there was a significant effect of individual auxin types (IAA, NAA, and IBA) on the root formation of Dendrobium mirbelianum orchids, affecting variables such as the number of roots, root length, root emergence time, number of leaves, number of shoots, and shoot height.

Indirect plant regeneration in Dioscorea rotundata and Dioscorea alata yam genotypes using different explants

Yam (Dioscorea sp.) is an important staple crop for millions of smallholder farmers in West Africa. In this study, we aimed to develop an efficient indirect plant regeneration system for three important yam genotypes “Kukrupa,” “Mankrong Pona” and “Matches.” The potential of leaf primordia, petioles and axillary bud explants for callus induction on Murashige and Skoog (MS) medium supplemented with different concentrations (0, 3, 5, 7 and 9 mg/l) of 2,4-dicholorophenoxy acetic acid (2,4-D) or picloram were tested. Callus induction was influenced by auxin concentration as well as explant. The highest callus induction was achieved using leaf primordia (“Kukrupa” and “Mankrong Pona”) explants on 3 mg/l picloram or axillary buds (“Matches”) on 5 mg/l picloram. Transfer of callus to 6-benzylaminoapurine (BAP) amended medium resulted in the formation of at least two shoots per callus clump. Plantlets were obtained on basic yam medium supplemented with 0.2 mg/l 1-naphthalene acetic acid (NAA), 3 mg/l kinetin and 0.5 mg/l BAP after four weeks. Post acclimatization plantlet survival was high (75 − 82.5%). The indirect plant regeneration protocol reported through this study helps in the improvement of important yam genotypes through tissue culture-oriented genome editing, in vitro mutagenesis and also for its mass propagation.

Deciphering of the morpho-physiological traits of two native grasses from Argentina with contrasting drought resistance strategies

Context Semiarid environments, such as the Patagonian shrublands, are characterised by having shrubby patches surrounded by grasses with different ecophysiological strategies to tolerate long dry periods. Aims We hypothesised that coexisting grasses of the Patagonian rangeland, already classified as drought-escaping or drought-tolerant, have different traits according to the season and the annual rainfall events. Methods Two dominant native grasses were selected: Pappostipa speciosa (evergreen) and Poa ligularis (deciduous). Samples were collected in the four seasons for the term of 1 year. Rainfall events and soil water content of each season were determined. Spring was the wettest season and autumn the driest. Physiological (relative water content, pigments, hormones), biochemical (polyphenols, antioxidant activity) and morphological traits were measured in the four seasons. Key results P. speciosa was characterised by keeping evergreen leaves with high production of polyphenols as secondary metabolites with high antioxidant capacity during the dry autumn and winter seasons. P. ligularis was characterised by high contents of gibberellin (GA1), auxin (IAA), total phenols, total flavonoids and tartaric acid esters, and high antioxidant capacity in roots during the autumn dry season. In addition, P. ligularis leaves had higher content of carotenoids and polyphenols than P. speciosa during the summer dry season. Conclusions The major adaptive strategy to tolerate dry periods is the high activity of the secondary metabolism, mainly in leaves in P. speciosa (a drought-tolerant grass) and in roots in P. ligularis (a drought-escaping grass). Implications Rainfall variations during a year can affect the phenological growth stages and the metabolism of two native grasses from Argentina characterised by different drought resistance mechanisms.

WUSCHEL RELATED HOMEOBOX5 and 7 maintain callus development by promoting cell division in Arabidopsis

In tissue culture, a high concentration of auxin in the callus induction medium (CIM) stimulates cell division and subsequent callus formation, which acquires root primordium-like characteristics necessary for cell pluripotency. In Arabidopsis, WUSCHEL-RELATED HOMEOBOX5 (WOX5) and its closest homolog WOX7, which are abundant in the middle cell layer of mature callus, play a crucial role in maintaining pluripotency by promoting auxin accumulation and enhancing cytokinin sensitivity. However, the mechanism by which WOX5/7 regulate callus formation remains unclear. In this study, we found that mutations in WOX5/7 resulted in a significant down-regulation of genes involved in the G2M and S phases during callus induction. Loss-of-function mutants of WOX5/7 exhibited reduced callus formation, which was correlated with decreased expression of CYCB1;1 compared to the wild-type. Furthermore, we provided evidence that WOX5 physically interacts with PHYTOCHROME A SIGNAL TRANSDUCTION1 (PAT1), which spatio-temporally co-expresses with WOX5 in early-induced callus, and up-regulates a subset of cycle-regulating genes targeted by PAT1. Collectively, our findings suggest a critical role for the WOX5-PAT1 protein complex in regulating cell cycle progression, thereby promoting the continuous growth capacity of pluripotent callus.

The Slow Growth of Adventitious Roots in Tetraploid Hybrid Poplar (Populus simonii × P. nigra var. italica) May Be Caused by Endogenous Hormone-Mediated Meristem Shortening.

Polyploidization produces abundant phenotypic variation. Little is currently known about adventitious root (AR) development variation due to polyploidization. In this study, we analyzed the morphological, cytological, and physiological variations in AR development between tetraploid and diploid Populus plants during in vitro rooting culture. Compared to the diploids, the AR formation times and rooting rates of the tetraploids' stem explants had non-significant changes. However, the tetraploid ARs exhibited significantly slower elongation growth than the diploid ARs. Cytological observation showed that the tetraploid ARs were characterized by shorter root meristems and reduced meristem cell numbers, suggesting the reasons for the slow AR elongation. Analysis of hormones and related metabolites during AR development demonstrated that the total auxin, cytokinin, and jasmonic acid contents were significantly lower in the tetraploid ARs than in those of the diploids, and that the ratio of total auxins to total CKs at 0 h of AR development was also lower in the tetraploids than in the diploids, whereas the total salicylic acid content of the tetraploids was consistently higher than that of the diploids. qPCR analysis showed that the expression levels of several hormone signaling and cell division-related genes in the tetraploid ARs significantly differed from those in the diploids. In conclusion, the slow elongation of the tetraploid ARs may be caused by the endogenous hormone-mediated meristem shortening. Our findings enhance the understanding of polyploidization-induced variation in AR development of forest trees.

Wind disturbance-based tomato seedlings growth control

Wind-disturbance is a potential eco-friendly technique for tackling leggy seedlings. This study uses orthogonal experimental design and seedlings vigour assessment by strong seedling index (SSI) to investigate wind-disturbance on regulating tomato seedlings growth. Changes in endogenous hormone levels and biomechanical properties of tomato seedlings were investigated using enzyme-linked immunosorbent assay and uniaxial tension tests. Results showed that factors influencing significantly SSI, in descending order, are wind disturbance time (T), seedling age at the onset of wind disturbance (SA), wind velocity (V), and interval time (I). The wind-disturbance effect was found to be optimal with SSI = 0.126 for a condition where V, T, I and SA values are 3 m s−1, 1 min, 30 min, and 15 days, respectively. V and T were positively correlated with the ethylene and abscisic acid content in seedling leaves, abscisic acid and auxin content in stems, cytokinin and ethylene content in roots, and the elastic moduli of stems and roots but negatively associated with the cytokinin content in stems and leaves, auxin and abscisic acid content in roots, and leaves’ elastic modulus. Wind disturbance mechanism for controlling seedlings growth involved eliciting the accumulation of abscisic acid in stems and leaves and reduction of the auxin content in roots to about the optimal threshold for roots growth thereby reducing seedling stems and leaves development and promoting a better roots growth and a high SSI. This work offers theoretical insights and technical guidance for utilising wind-disturbance as a sustainable seedling cultivation and personalised seedling management approach.

Differences between two wheat genotypes in the development of floret primordia and contents of pigments and hormones

Promoting more floret primordia within a spike to acquire fertile potential during the differentiation and pre-dimorphism phases is critical for increasing the number of fertile florets per spike (NFFs). However, it is yet unknown the physiological mechanism regulating the complex and dynamic process. This study aimed to clarify how intra-spike hormones, pigments, and assimilates coordinate with each other to regulate spike morphology and then floret primordia development. A two-year field experiment was conducted with two winter wheat genotypes: N50 (big-spike with greater NFFs) and SM22 (medium-spike with fewer NFFs). We monitored high temporal and spatial-resolution changes in the number and morphology of floret primordia within a spike, as well as in intra-spike hormones, pigments, and assimilates. Our results revealed that the big-spike genotype had more NFFs than the medium-spike genotype, not only because they had more spikelets, but also because they had greater NFFs mainly at central spikelets. More floret primordia at central spikelets had sufficient time to develop and acquire fertile potential during the differentiation phase (167–176 d after sowing, DAS) and the pre-dimorphism phase (179 DAS) for the big-spike genotype than the medium-spike genotype. Floret primordia with fertile morphology during the pre-dimorphism phase always developed into fertile florets during the dimorphism phase. Those early-developed floret primordia most proximal and intermediate to the rachis in the big-spike genotype developed faster than the medium-spike genotype. Correspondingly, the spike dry matter and pigments (chlorophyll a, chlorophyll b, carotene, and carotenoids) content during 170–182 DAS, auxin (IAA) and cytokinin (CTK) content on 167 DAS were significantly higher in the big-spike genotype than in the medium-spike genotype, while jasmonic acid (JA) content was significantly lower in the big-spike genotype compared to the medium-spike genotype during 167–182 DAS. Since the significant differences in intra-spike hormone content of the two genotypes appear earlier than those in dry matter and pigments, we propose a possible model that helped the N50 genotype (big-spike) to form more fertile florets, taking the intra-spike hormone content as a signaling molecule induced assimilates and pigments synthesis, which accelerated the development of more floret primordia during the differentiation phase and then acquired fertile potential during the pre-dimorphism phase, finally improved the NFFs. Our high temporal and spatial-resolution analysis provides an accurate time window for precision cultivation and effective physiological breeding to improve the number of fertile florets in wheat.

Optimizing Cucumis sativus seedling vigor: the role of pistachio wood vinegar and date palm compost in nutrient mobilization.

The goal of this research is to enhance the quality of cucumber seedlings grown in greenhouses by experimenting with various soilless culture mediums (CMs) and the application of pistachio wood vinegar (WV). The experimental setup was designed as a factorial experiment within a randomized complete block design (RCBD), in greenhouse conditions featuring three replications to assess the effects of different culture media (CMs) and concentrations of pistachio wood vinegar (WV) on cucumber seedling growth. Cucumber seeds were planted in three CMs: coco peat-peat moss, coco peat-vermicompost, and date palm compost-vermicompost mixed in a 75:25 volume-to-volume ratio. These were then treated with pistachio WV at concentrations of 0, 0.5, and 1%, applied four times during irrigation following the emergence of the third leaf. The study revealed that treating seedlings with 0.5% WV in the date palm compost-vermicompost CM significantly enhanced various growth parameters. Specifically, it resulted in a 90% increase in shoot fresh mass, a 59% increase in shoot dry mass, an 11% increase in root fresh mass, a 36% increase in root dry mass, a 65% increase in shoot length, a 62% increase in leaf area, a 25% increase in stem diameter, a 41% increase in relative water content (RWC), and a 6% improvement in membrane stability index (MSI), all in comparison to untreated seedlings grown in coco peat-peat moss CM. Furthermore, chlorophyll a, b, total chlorophyll, and carotenoid levels were 2.3, 2.7, 2.6, and 2.7 times higher, respectively, in seedlings treated with 0.5% WV and grown in the date palm compost-vermicompost CM, compared to those treated with the same concentration of WV but grown in coco peat-peat moss CM. Additionally, the Fv/Fm ratio saw a 52% increase. When plant nutrition was enhanced with the date palm compost-vermicompost CM and 1% WV, auxin content rose by 130% compared to seedlings grown in coco peat-peat moss CM and treated with 0.5% WV. The study demonstrates that using 0.5% WV in conjunction with date palm compost-vermicompost CM significantly betters the quality of cucumber seedlings, outperforming other treatment combinations.

Genome-wide analysis of the poplar homeobox gene family and the identification of PtHB180 as an important regulator of plant developmental processes and drought stress response

Homeobox (HB) transcription factors have been reported to regulate various developmental processes and hormone signaling and mediate plant adaption to abiotic stresses, including drought. As a major subfamily of HB family, KNOX genes have been widely studied in herbaceous plants. However, the behaviors of KNOX genes in regulating plant developmental processes and stress resistance in woody plants remain poorly understood. Here, we found a KNOX family gene in the model tree species Populus trichocarpa (hereafter “poplar”), PtHB180, which enhances drought tolerance by regulating developmental processes through auxin and gibberellin pathways and mediating the ABA signaling pathway leading to rapid stomatal closure. Overexpression lines of PtHB180 (PtHB180-OE) displayed pleiotropic phenotypes, including increased plant height and decreased leaf area by affecting auxin and/or gibberellin contents and signaling. PtHB180-OE plants also displayed improved drought tolerance under short- and long-term drought stress. Results of transcriptome sequencing suggested the involvement of genes related to ABA signaling in regulating drought tolerance in PtHB180-OE. Specifically, PtHB180-OE plants showed significantly enhanced stomatal sensitivity to exogenous ABA. Taken together, our results indicate that PtHB180 enhances drought tolerance in poplar via regulating plant architecture and mediating ABA signaling to close stomata. Therefore, PtHB180 can be used as a potential candidate gene to improve drought tolerance by genetic transformation in poplar and related plant species.

Effect of Different Concentrations of Auxin as Well as Cytokinin on Shoot Initiation, Formation and Multiplication of Pepino (Solanum muricatum Ait.) cv. Valentia with MS Semi-solid Medium

The pepino (Solanum muricatum Aiton) is conventionally propagated through vegetative means. But, this approach of propagation is not feasible for commercial production of plants and has at more time the chances of reduction yield. Therefore, the availability of quality planting material is of urgent need. Recently, there has been a promising approach for pepino multiplication at large scales through tissue culture because it generates a large number of contamination free plantlets in a minimum space and time. The combination of different growth regulators may be tried to maximize the initiation, growth and development of shoot in commercial propagation of pepino plants. The Minimum days taken for shoot initiation (5.21 days) was noted under BAP 3.00 mgl-1 + IBA 0.50 ppm, and minimum days taken for shoot development (40.82 days) was noted under of BAP 3.00 ppm + IBA 1.00 ppm. The highest length of shoot (9.52 cm) was produced in media supplemented with BAP 3.00 ppm + IBA 1.00 ppm. Maximum percent of developed shoots obtained from the established culture (67.79) was noted under the treatment of BAP 3.00 ppm + IBA 1.00 ppm; While maximum shoots per explants/ innoculums from the established culture (4.06) was noted under the treatment of BAP 3.00 ppm + IBA 1.00 ppm. Maximum number of leaves / plantlet from the established culture (10.85) was noted under the treatment of BAP 3.00 ppm + IBA 1.00 ppm and maximum fresh weight (mg) of shoot / plantlet obtained from the established culture (26.05 mg) was noted under the treatment of BAP 3.00 ppm + IBA 1.00 ppm.