Zha Manrong, Zhao Yanhui, Wang Yan, Chen Bingxian, Tan Zecheng
College of Biology Resources and Environmental Sciences, Jishou University, Jishou, China.
Key Laboratory of Plant Resources Conservation and Utilization, College of Hunan Province, Jishou, China.
Front Plant Sci. 2022 Jul 1;13:837136. doi: 10.3389/fpls.2022.837136. eCollection 2022.
Shoot branching is among the most crucial morphological traits in rice ( 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 genes but not the genes. Comparison of gene expression pattern under exogenous SL and CK supply suggested that the induction of expression was most likely via a CK-induced independent pathway. These results combined with the expression of CK type-A 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 gene expression in buds.
分蘖是水稻最重要的形态特征之一，在生理上受生长素、细胞分裂素（CKs）和独脚金内酯（SLs）共同调控。许多研究聚焦于这三种激素在调节水稻分蘖伸长中的相互作用。本研究主要旨在确定不同处理的影响，这些处理分别用于在分蘖期和齐穗期调控水稻第2节上的分蘖和腋芽发育。通过qRT-PCR分析对几个基因的转录水平进行了定量，并通过LC-MS/MS测定了内源生长素和四种类型的细胞分裂素。发现营养缺乏和外源独脚金内酯供应均通过降低分蘖芽中的细胞分裂素含量来抑制水稻分蘖生长。此外，供应外源独脚金内酯和内源独脚金内酯合成的抑制剂也会影响基因的表达水平，但不影响基因。对外源独脚金内酯和细胞分裂素供应下基因表达模式的比较表明，基因表达的诱导最有可能通过细胞分裂素诱导的独立途径。这些结果与芽中细胞分裂素A型基因的表达相结合，支持了独脚金内酯通过调节局部细胞分裂素水平来调控芽生长的作用。在调节第2节上芽的生长方面，独脚金内酯与细胞分裂素起拮抗作用，通过促进芽中基因的表达来实现。
