Strigolactone and Cytokinin Act Antagonistically in Regulating Rice Mesocotyl Elongation in Darkness
Strigolactone and Cytokinin Act Antagonistically in Regulating Rice Mesocotyl Elongation in Darkness
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DOI：
10.1093/pcp/pct150
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发表时间：
2014-01-01
影响因子：
4.9
通讯作者：
Nakazono, Mikio
中科院分区：
文献类型：
--
作者：
Hu, Zhongyuan;Yamauchi, Takaki;Nakazono, Mikio
Strigolactones(SLS)是一组控制植物生长发育的植物激素，包括枝条。先前对水稻矮秆(D)突变体SL相关表型的研究表明，SLS通过控制细胞分裂来抑制中胚轴的伸长。在此，我们发现在D10-1和D14-1突变体中，细胞分裂素(CK)反应型A反应调节因子(RR)基因的表达高于野生型。然而，d个突变体的中胚轴CK水平与野生型相差不大。另一方面，人工合成的CK(激动素)的应用促进了d突变体和野生型中胚轴的伸长。D10-1和d14-1的中胚轴对CK的敏感性高于野生型，表明d个突变体对CK敏感的A型RR基因上调和中胚轴的伸长增加主要是由于d个突变体对CK的敏感性增加所致。激动素和合成的SL(GR24)共处理证实了SL和CK对中胚轴伸长的拮抗作用。OsTCP5编码细胞分裂调节蛋白家族的转录因子，也受SL和CK的调控，其表达与中胚轴长度呈负相关。这些发现表明，OsTCP5参与了SL和CK控制的中胚轴在黑暗中的伸长。
Strigolactones (SLs) are a group of phytohormones that control plant growth and development including shoot branching. Previous studies of the phenotypes of SL-related rice (Oryza sativa) dwarf (d) mutants demonstrated that SLs inhibit mesocotyl elongation by controlling cell division. Here, we found that the expression of cytokinin (CK)-responsive type-A RESPONSE REGULATOR (RR) genes was higher in d10-1 and d14-1 mutants than in the wild type. However, CK levels in mesocotyls of the d mutants were not very different from those in the wild type. On the other hand, application of a synthetic CK (kinetin) enhanced mesocotyl elongation in the d mutants and the wild type. d10-1 and d14-1 mesocotyls were more sensitive to CK than wild-type mesocotyls, suggesting that the up-regulation of the CK-responsive type-A RR genes and the higher elongation of mesocotyls in the d mutants are mainly due to the increased sensitivity of the d mutants to CK. Co-treatment with kinetin and a synthetic SL (GR24) confirmed the antagonistic functions of SL and CK on mesocotyl elongation. OsTCP5, which encodes a transcription factor belonging to the cell division-regulating TCP family, was also regulated by SL and CK and its expression was negatively correlated with mesocotyl length. These findings suggest that OsTCP5 contributes to the SL- and CK-controlled mesocotyl elongation in darkness.