Tiller Buds Research Articles

Transcriptome Analysis Reveals the Potential Molecular Mechanisms of Tiller Bud Development in Orchardgrass.

Tillering is a special type of branching and one of the important contributors to the yield of cereal crops. Strigolactone and sucrose play a vital role in controlling tiller formation, but their mechanism has not been elucidated completely in most crops. Orchardgrass (Dactylis glomerata L.) is an important perennial forage with prominent tillering ability among crops. To date, the mechanism of tillering in orchardgrass is still largely unknown. Therefore, we performed a transcriptome and miRNA analysis to reveal the potential RNA mechanism of tiller formation under strigolactone and sucrose treatment in orchardgrass. Our results found that D3, COL5, NCED1, HXK7, miRNA4393-z, and miRNA531-z could be key factors to control tiller bud development in orchardgrass. In addition, strigolactones might affect the ABA biosynthesis pathway to regulate the tiller bud development of orchardgrass, which may be related to the expression changes in miRNA4393-z, NCED1, and D10. miRNA531-z could be involved in the interaction of strigolactones and sucrose in regulating tillering. These results will be further used to clarify the potential mechanism of tillering for breeding new high-tillering and high-production orchardgrass varieties and beneficial to improving the production and reproduction of crops.

Unlocking the Multifaceted Mechanisms of Bud Outgrowth: Advances in Understanding Shoot Branching.

Shoot branching is a complex and tightly regulated developmental process that is essential for determining plant architecture and crop yields. The outgrowth of tiller buds is a crucial step in shoot branching, and it is influenced by a variety of internal and external cues. This review provides an extensive overview of the genetic, plant hormonal, and environmental factors that regulate shoot branching in several plant species, including rice, Arabidopsis, tomato, and wheat. We especially highlight the central role of TEOSINTE BRANCHED 1 (TB1), a key gene in orchestrating bud outgrowth. In addition, we discuss how the phytohormones cytokinins, strigolactones, and auxin interact to regulate tillering/branching. We also shed light on the involvement of sugar, an integral component of plant development, which can impact bud outgrowth in both trophic and signaling ways. Finally, we emphasize the substantial influence of environmental factors, such as light, temperature, water availability, biotic stresses, and nutrients, on shoot branching. In summary, this review offers a comprehensive evaluation of the multifaced regulatory mechanisms that underpin shoot branching and highlights the adaptable nature of plants to survive and persist in fluctuating environmental conditions.

Changes in bud bank and their correlation with plant community composition in degraded alpine meadows.

Bud banks are considered a crucial factor in regulating the species composition of grassland communities and maintaining the ecological function of alpine grasslands. However, few studies have paid attention to the dynamic changes of bud banks from undisturbed to severely degraded alpine meadows. Therefore, this study examined the correlations between plant diversity and bud bank traits at different stages of alpine meadows degradation. Grass biomasses and plant diversity were found to be highest in moderately degraded meadows, and sedge biomasses were highest in lightly degraded meadows. Lack of disturbance and moderate disturbance by herbivores increased the bud bank density of alpine meadows. Consistent with the changes in bud bank density, bud bank diversity was highest in undisturbed meadows. The structural equation model indicated that the densities of rhizome and the densities and diversities of tiller buds play crucial roles in facilitating the greater diversity of the plant community. Our findings suggest that the diversities and densities of rhizome and tiller buds in the degradation stages are synchronized with changes in plant diversity, and in the regenerative ability of bud banks, which largely determine the outcome of restoration in degraded meadows. These findings could provide a frame of reference for effectively restoring degraded alpine regions by regenerating bud banks. The potential driving force and renewal capacity of bud banks should be taken into account in restoring the Qinghai-Tibet Plateau's degraded meadow.

Don't panic any more: MORE PANICLES 3 increases rice yield at elevated CO2 levels.

Don't panic any more: MORE PANICLES 3 increases rice yield at elevated CO2 levels.

Effects of different phosphorus levels on tiller bud development in hydroponic Phyllostachys edulis seedlings.

An appropriate amount of phosphate fertilizer can improve the germination rate of bamboo buds and increase the bamboo shoot output. However, the underlying biological mechanisms of phosphate fertilizer in bamboo shoot development have not been systematically reported. Herein, the effects of low (LP, 1μM), normal (NP, 50μM) and high (HP, 1000μM) phosphorus (P) on the growth and development of moso bamboo (Phyllostachys edulis) tiller buds were first investigated. Phenotypically, the seedling biomass, average number of tiller buds and bud height growth rate under the LP and HP treatments were significantly lower than those under the NP treatment. Next, the microstructure difference of tiller buds in the late development stage (S4) at three P levels was analyzed. The number of internode cells and vascular bundles were significantly lower in the LP treatments than in the NP treatments. The relative expression levels of eight P transport genes, eight hormone-related genes and four bud development genes at the tiller bud developmental stage (S2-S4) and the tiller bud re-tillering stage were analyzed with real-time polymerase chain reaction. The results showed that the expression trends for most P transport genes, hormone-related genes and bud development genes from S2 to S4 were diversified at different P levels, and the expression levels were also different at different P levels. In the tiller bud re-tillering stage, the expression levels of seven P transport genes and six hormone-related genes showed a downward trend with increasing P level. REV expression level decreased under LP and HP conditions. TB1 expression level increased under HP condition. Therefore, we conclude that P deficiency inhibits tiller bud development and re-tillering, and that P depends on the expression of REV and TB1 genes and auxin, cytokinin and strigolactones synthesis and transporter genes to mediate tiller bud development and re-tillering.

MORE PANICLES 3, a natural allele of OsTB1/FC1, impacts rice yield in paddy fields at elevated CO2 levels

Improving crop yield potential through an enhanced response to rising atmospheric CO2 levels is an effective strategy for sustainable crop production in the face of climate change. Large-sized panicles (containing many spikelets per panicle) have been a recent ideal plant architecture (IPA) for high-yield rice breeding. However, few breeding programs have proposed an IPA under the projected climate change. Here, we demonstrate through the cloning of the rice (Oryza sativa) quantitative trait locus for MORE PANICLES 3 (MP3) that the improvement in panicle number increases grain yield at elevated atmospheric CO2 levels. MP3 is a natural allele of OsTB1/FC1, previously reported as a negative regulator of tiller bud outgrowth. The temperate japonica allele advanced the developmental process in axillary buds, moderately promoted tillering, and increased the panicle number without negative effects on the panicle size or culm thickness in a high-yielding indica cultivar with large-sized panicles. The MP3 allele, containing three exonic polymorphisms, was observed in most accessions in the temperate japonica subgroups but was rarely observed in the indica subgroup. No selective sweep at MP3 in either the temperate japonica or indica subgroups suggested that MP3 has not been involved and utilized in artificial selection during domestication or breeding. A free-air CO2 enrichment experiment revealed a clear increase of grain yield associated with the temperate japonica allele at elevated atmospheric CO2 levels. Our findings show that the moderately increased panicle number combined with large-sized panicles using MP3 could be a novel IPA and contribute to an increase in rice production under climate change with rising atmospheric CO2 levels.

OsPIN2 is involved in OsSPL14/17-inhibited tiller bud outgrowth in response to phosphate deficiency in rice

Phosphorus (P) is an essential nutrient for food crops. P-deficiency inhibits tiller development of rice; thus, an understanding of the P-modulated tiller development mechanism is crucial for grain yield. Auxin and strigolactones (SLs) have been implicated as regulators of tiller formation in rice. However, the relationships between the two in P-modulated tiller development are unclear. Here we found that low-P (LP) inhibited rice tiller formation and tiller bud elongation, with higher levels of SLs. The strong interaction between D53 (SL signaling repressor) and SPL14 and 17 (SPL14/17) inhibited their transcriptional activities under normal P (NP) condition, and mutations of SPL14/17 eliminated their inhibitory effects on tiller formation under LP condition, showing SPL14/17 act downstream of SLs signaling to inhibit tiller formation under P-deficiency in rice. Meanwhile, the expression levels of PIN2 were down-regulated under conditions of either LP and NP treated with GR24 when compared with NP condition, demonstrating SLs negative regulation of PIN2 transcription under LP condition. Further study showed that SPL14/17 inhibited the transcription expression of PIN2, and the knockout of PIN2 reduced tiller development by LP condition. Therefore, we presented that, under NP condition, bindings of D53 to SPL14/17 repress their transcriptional inhibition, reversing SPL14/17-inhibited PIN2 transcription and promoting tiller development. Proteasomal degradation of D53 releases SPL14/17, thus repressing PIN2 transcription and preventing production of tillering under LP condition.

Tiller Number1 encodes an ankyrin repeat protein that controls tillering in bread wheat

Wheat (Triticum aestivum L.) is a major staple food for more than one-third of the world’s population. Tiller number is an important agronomic trait in wheat, but only few related genes have been cloned. Here, we isolate a wheat mutant, tiller number1 (tn1), with much fewer tillers. We clone the TN1 gene via map-based cloning: TN1 encodes an ankyrin repeat protein with a transmembrane domain (ANK-TM). We show that a single amino acid substitution in the third conserved ankyrin repeat domain causes the decreased tiller number of tn1 mutant plants. Resequencing and haplotype analysis indicate that TN1 is conserved in wheat landraces and modern cultivars. Further, we reveal that the expression level of the abscisic acid (ABA) biosynthetic gene TaNCED3 and ABA content are significantly increased in the shoot base and tiller bud of the tn1 mutants; TN1 but not tn1 could inhibit the binding of TaPYL to TaPP2C via direct interaction with TaPYL. Taken together, we clone a key wheat tiller number regulatory gene TN1, which promotes tiller bud outgrowth probably through inhibiting ABA biosynthesis and signaling.

Cyclic growth and tillering of layered polycrystalline zinc hydroxide sulfate and the resulting dendritic fractals

Two-dimensional dendritic fractals of layered zinc hydroxide sulfate (LZHS) were allowed to grow on a porous ZnO substrate-coated glass slide in an aqueous ZnSO4 solution through the dissolution-redeposition process. The generated LZHS seeds with polycrystalline structure gradually evolved into two-dimensional dendritic fractals with a diameter of 50∼100 μm through a plant-like growth mode involving tillering and the formation of layered tiller buds at branch ends. Such tiller mechanism is proposed to explain the evolution of LZHS fractals based on results obtained by the scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and energy dispersive X-ray detection. The synthesized polycrystalline LZHS fractals can be topologically converted into hierarchical nanostructured zinc oxide by thermal pyrolysis combined with an alkaline wash process. After the modification by octyltrimethoxysilane, the topological zinc oxide surfaces, corresponding to the immersion time of 2, 4 and 6 h, showed superhydrophobic property with a water contact angle of 153.4°, 157.6°, and 164.7°, respectively. The enhanced hydrophobicity of zinc oxide films compared with the porous ZnO substrate surface is mainly attributed to the topological fractal morphologies and hierarchical nanostructures.

Soil Moisture Rather than Soil Nutrient Regulates the Belowground Bud Bank of Rhizomatous Species Psammochloa villosa in Arid Sand Dunes

In arid and semi-arid sand dune ecosystems, belowground bud bank plays an important role in population regeneration and vegetation restoration. However, the responses of belowground bud bank size and composition to sand burial and its induced changes in soil environmental factors have been rarely studied. In arid sand dunes of Northwestern China, we investigated belowground bud bank size and composition of the typical rhizomatous psammophyte Psammochloa villosa as well as three key soil environmental factors (soil moisture, total carbon and total nitrogen) under different depths of sand burial. Total buds and rhizome buds increased significantly with increasing burial depth, whereas tiller buds first increased and then decreased, with a peak value at the depth of 20–30 cm. Soil moisture increased significantly with sand burial depth, and was positively correlated with the number of all buds and rhizome buds. Soil total carbon concentration first increased and then decreased with sand burial depth, and total nitrogen concentration was significantly lower under deep sand burial than those at shallow depths, and only the number of tiller buds was positively correlated with soil total nitrogen concentration. These results indicate that soil moisture rather than soil nutrient might regulate the belowground bud bank of P. villosa, and that clonal psammophytes could regulate their belowground bud bank in response to sand burial and the most important environmental stress (i.e., soil moisture). These responses, as the key adaptive strategy, may ensure clonal plant population regeneration and vegetation restoration in arid sand dunes.

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.

Evaluation of propiconazole, a triazole-containing fungicide as an inhibitor of strigolactone production

The inhibitory effect of propiconazole on strigolactone (SL) production and Striga hermonthica emergence were evaluated using rice plants. A significant reduction in SL levels was detected in root and root exudates after rice was treated with different doses of propiconazole. Propiconazole induced second tiller bud outgrowth in rice seedlings. In accordance with the results of 4-deoxyorobanchol levels in root and root exudates, propiconazole-treated rice attenuated the degree of infestation of the root parasitic weed, S. hermonthica. Overall, these results suggest that propiconazole has potential as a plant growth regulator for agriculture and a new scaffold for developing potent inhibitors of SL production.

Identification of LsPIN1 gene and its potential functions in rhizome turning of Leymus secalinus

BackgroundContinuous tilling and the lateral growth of rhizomes confer rhizomatous grasses with the unique ability to laterally expand, migrate and resist disturbances. They play key roles especially in degraded grasslands, deserts, sand dunes, and other fragile ecological system. The rhizomatous plant Leymus secalinus has both rhizome buds and tiller buds that grow horizontally and upward at the ends of rhizome differentiation and elongation, respectively. The mechanisms of rhizome formation and differentiation in L. secalinus have not yet been clarified.ResultsIn this study, we found that the content of gibberellin A3 (GA3) and indole-3-acetic acid (IAA) were significantly higher in upward rhizome tips than in horizontal rhizome tips; by contrast, the content of methyl jasmonate and brassinolide were significantly higher in horizontal rhizome tips than in upward rhizome tips. GA3 and IAA could stimulate the formation and turning of rhizomes. An auxin efflux carrier gene, LsPIN1, was identified from L. secalinus based on previous transcriptome data. The conserved domains of LsPIN1 and the relationship of LsPIN1 with PIN1 genes from other plants were analyzed. Subcellular localization analysis revealed that LsPIN1 was localized to the plasma membrane. The length of the primary roots (PRs) and the number of lateral roots (LRs) were higher in Arabidopsis thaliana plants overexpressing LsPIN1 than in wild-type (Col-0) plants. Auxin transport was altered and the gravitropic response and phototropic response were stronger in 35S:LsPIN1 transgenic plants compared with Col-0 plants. It also promoted auxin accumulation in root tips.ConclusionOur findings indicated that LsPIN1 plays key roles in auxin transport and root development. Generally, our results provide new insights into the regulatory mechanisms underlying rhizome development in L. secalinus.

Response of under-ground bud bank to degradation in an alpine meadows on the Qinghai-Tibet Plateau, China.

Exploring the diversity and formation mechanism of under-ground bud banks is essential for understanding the renewal of plant populations and community succession. However, there are few studies on the response of bud bank size and composition to different degradation gradients in alpine meadows. In view of this, we investigated the size and composition of bud bank under four degradation gradients (non-degraded:ND, lightly degraded:LD, moderately degraded:MD, and heavily degraded:HD) caused by overgrazing in a typical alpine meadow in Tibet, China, using a unit area excavation sampling method, and analyzed the correlation between above-ground plant community composition and bud bank density. Our results showed that: (i) in the ND alpine meadow, rhizome buds were dominant, in the LD, tiller buds were dominant, and in the MD, root-sprouting buds were dominant; (ii) total bud bank and cyperaceae bud density decreased with increasing degradation gradient, the density of leguminosae was insignificant in each degradation gradient, and the density of gramineae and forb were dominant in LD and MD meadows, respectively; (iii) total bud bank density was significantly and positively correlated with total above-ground biomass in the LD gradient, tiller bud density was significantly positively correlated with the species diversity index of above-ground vegetation under the ND gradient, rhizome bud density was significantly and positively correlated with total above-ground biomass in the LD gradient, and root-sprouting density was significantly negatively correlated with total above-ground biomass in ND meadows, but was significantly positively correlated with the species diversity index of the LD gradient. Therefore, our research shows that rhizome buds are more important in ND meadow habitats, tiller buds are more important in LD meadow habitats, and root-sprouting buds are more important in MD meadows. The response of bud banks to degradation gradient varies with different types of bud banks and different functional groups of plants, and the survival strategy of bud banks is of great value for community restoration and regeneration, which should be paid more attention to in subsequent alpine meadow research.

Strigolactones and Cytokinin Interaction in Buds in the Control of Rice Tillering.

Shoot branching is among the most crucial morphological traits in rice (Oryza sativa L.) and is physiologically modulated by auxins, cytokinins (CKs), and strigolactones (SLs) cumulatively in rice. A number of studies focused on the interplay of these three hormones in regulating rice tiller extension. The present study primarily aimed at determining the impact of different treatments, which were used to regulate rice tiller and axillary bud development on node 2 at the tillering stage and full heading stage, respectively. Transcription levels of several genes were quantified through qRT-PCR analysis, and an endogenous auxin and four types of CKs were determined through LC-MS/MS. Both nutrient deficiency and exogenous SL supply were found to inhibit rice tiller outgrowth by reducing the CK content in the tiller buds. Furthermore, supplying the inhibitor of both exogenous SLs and endogenous SL synthesis could also affect the expression level of OsCKX genes but not the OsIPT genes. Comparison of OsCKX gene expression pattern under exogenous SL and CK supply suggested that the induction of OsCKX expression was most likely via a CK-induced independent pathway. These results combined with the expression of CK type-A RR genes in bud support a role for SLs in regulating bud outgrowth through the regulation of local CK levels. SL functioned antagonistically with CK in regulating the outgrowth of buds on node 2, by promoting the OsCKX gene expression in buds.

Effects of enhancing leaf nitrogen output on tiller growth and carbon metabolism in rice

<p id="C3">Nitrogen fertilizer application is one of the main cultivation measures to raise the yield, and high nitrogen level has limited contribution to grain yield due to limited nitrogen translocation in rice. To clarify the effects of nitrogen allocation on rice growth, we constructed<italic> pOsSUT1::AtAMT1.2 </italic>transgenic rice, the ammonium transporter gene <italic>AtAMT1.2</italic> specific expression in phloem to promote leaf nitrogen output. The growth and yield of transgenic plants were measured under HN (high nitrogen) and LN (low nitrogen) conditions. Compared to WT plants, more tillers and higher grain yield were detected in transgenic plants in response to HN condition. The sugar output in leaves was increased, and the relative expression levels of the strigolactone pathway related genes<italic> OsTB1</italic> and <italic>OsD14</italic> in tiller buds were down-regulated. Our results indicated that the increase of leaf nitrogen export by overexpressing <italic>AtAMT1.2</italic> gene could promote sugar translocation from leaves to tillering buds, which improved the growth of tiller, increased the effective tiller number and nitrogen use efficiency.

Nitrogen limits zinc‐mediated stimulation of tillering in rice by modifying phytohormone balance under low‐temperature stress

AbstractZinc (Zn) can improve resistance of rice plants to abiotic stress and promote the recovery of rice tillers by influencing auxin (IAA) synthesis, Zn absorption is closely related to nitrogen (N) concentrations; however, the mechanisms by which Zn regulates rice tiller recovery at low temperatures under different N levels are rarely studied. In this study, a solution culture experiment was conducted at two temperatures, three different Zn concentrations, and two N concentrations. Low temperature during the vegetative stage damaged the rice antioxidant system, suppressed nutrient uptake, and decreased the number of tillers. Increasing Zn application improved the resistance of rice plants to low‐temperature stress under normal N levels, enhanced nutrient absorption, improved tiller bud cytokinin (CTK) concentrations, and the CTK/IAA ratio, which accelerated tiller recovery relative to plants receiving standard Zn treatment. Shoot Zn concentrations were positively correlated with tiller numbers at normal N levels. High N attenuated the positive effect of Zn on rice tillering at low temperatures due to higher shoot Zn and IAA accumulation, and lower tiller buds CTK/IAA ratios. However, appropriate Zn application under high N levels was conducive to breaking tiller dormancy and promoting tillering growth spurts when recovering to normal temperature, which was related to the synergistic regulation of hormone balance and nutrient absorption by N and Zn. In conclusion, Zn could enhance rice low‐temperature stress resilience and facilitate tiller recovery via balancing the hormones in tiller buds. However, higher environmental N limited the stimulation of Zn on rice tillering under low temperature.

INTERMEDIUM-C mediates the shade-induced bud growth arrest in barley.

Tiller formation is a key agronomic determinant for grain yield in cereal crops. The modulation of this trait is controlled by transcriptional regulators and plant hormones, tightly regulated by external environmental conditions. While endogenous (genetic) and exogenous (environmental factors) triggers for tiller formation have mostly been investigated separately, it has remained elusive how they are integrated into the developmental program of this trait. The transcription factor gene INTERMEDIUM-C (INT-C), which is the barley ortholog of the maize domestication gene TEOSINTE BRANCHED1 (TB1), has a prominent role in regulating tiller bud outgrowth. Here we show that INT-C is expressed in tiller buds, required for bud growth arrest in response to shade. In contrast to wild-type plants, int-c mutant plants are impaired in their shade response and do not stop tiller production after shading. Gene expression levels of INT-C are up-regulated under light-limiting growth conditions, and down-regulated after decapitation. Transcriptome analysis of wild-type and int-c buds under control and shading conditions identified target genes of INT-C that belong to auxin and gibberellin biosynthesis and signaling pathways. Our study identifies INT-C as an integrator of the shade response into tiller formation, which is prerequisite for implementing shading responses in the breeding of cereal crops.

Regulation of dhurrin pathway gene expression during Sorghum\xa0bicolor development

Main conclusionDevelopmental and organ-specific expression of genes in dhurrin biosynthesis, bio-activation, and recycling offers dynamic metabolic responses optimizing growth and defence responses in Sorghum.Plant defence models evaluate the costs and benefits of resource investments at different stages in the life cycle. Poor understanding of the molecular regulation of defence deployment and remobilization hampers accuracy of the predictions. Cyanogenic glucosides, such as dhurrin are phytoanticipins that release hydrogen cyanide upon bio-activation. In this study, RNA-seq was used to investigate the expression of genes involved in the biosynthesis, bio-activation and recycling of dhurrin in Sorghum bicolor. Genes involved in dhurrin biosynthesis were highly expressed in all young developing vegetative tissues (leaves, leaf sheath, roots, stems), tiller buds and imbibing seeds and showed gene specific peaks of expression in leaves during diel cycles. Genes involved in dhurrin bio-activation were expressed early in organ development with organ-specific expression patterns. Genes involved in recycling were expressed at similar levels in the different organ during development, although post-floral initiation when nutrients are remobilized for grain filling, expression of GSTL1 decreased > tenfold in leaves and NITB2 increased > tenfold in stems. Results are consistent with the establishment of a pre-emptive defence in young tissues and regulated recycling related to organ senescence and increased demand for nitrogen during grain filling. This detailed characterization of the transcriptional regulation of dhurrin biosynthesis, bioactivation and remobilization genes during organ and plant development will aid elucidation of gene regulatory networks and signalling pathways that modulate gene expression and dhurrin levels. In-depth knowledge of dhurrin metabolism could improve the yield, nitrogen use efficiency and stress resilience of Sorghum.

Zinc application after low temperature stress promoted rice tillers recovery: Aspects of nutrient absorption and plant hormone regulation

Low temperature during the vegetative stage depresses rice tillering. Zinc (Zn) can promote rice tiller growth and improve plant resistance to abiotic stress. Consequently, Zn application after low temperature might be an effective approach to promote rice tiller recovery. A water culture experiment with treatments of two temperatures (12 °C and 20 °C) and three Zn concentrations (0.08 μM, 0.15 μM and 0.31 μM ZnSO4·7H2O) was conducted to determine by analyzing rice tiller growth, nutrient absorption and hormones metabolism. The results showed that low temperature reduced rice tiller numbers and leaf age, decreased as well. Increasing Zn application after low temperature could enhance not only rice tiller growth rate but also N metabolism and tillering recovery, and correlation analysis showed a significantly positive correlation between tiller increment and Zn and N accumulation after low temperature. In addition, higher cytokinin (CTK)/auxin (IAA) ratio was maintained by promoted synthesis of CTK and IAA as well as enhanced IAA transportation from tiller buds to other parts with increased Zn application after cold stress, which resulted in accelerated germination and growth of tiller buds. These results highlighted that Zn application after low temperature promoted rice tiller recovery by increasing N and Zn accumulation and maintaining hormones balance.