Antagonistic Action of Strigolactone and Cytokinin in Bud Outgrowth Control
Antagonistic Action of Strigolactone and Cytokinin in Bud Outgrowth Control
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DOI：
10.1104/pp.111.186783
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发表时间：
2012-01-01
期刊：
影响因子：
7.4
通讯作者：
Beveridge, Christine A.
中科院分区：
文献类型：
--
作者：
Dun, Elizabeth A.;de Saint Germain, Alexandre;Beveridge, Christine A.
长期以来，细胞分裂素(CK)一直被认为是植物芽生长的促进剂，但具体是如何与其他植物激素协同实现这一点尚不清楚。最近发现的作为长期寻找的枝条抑制激素的链内酯(SLS)使我们能够测试CK和SL是如何协调调节豌豆(Pisum Sativum)的芽生长的。我们发现，缺乏SL的植株比野生型植株对低浓度的局部施CK刺激芽的生长更敏感。此外，与SL突变植株相比，野生型植株的芽几乎完全抵抗供应给维管系统的CK的刺激。无论外源激素是局部供应还是供应到木质部，SL和CK对芽的生长都有拮抗作用。这些数据表明，SLS不影响CK向腋芽的输送，反之亦然。相反，这些数据结合剂量反应实验表明，SLS和CK可以直接在芽中发挥作用，控制它们的生长。这些激素可能会聚在芽生长调控途径的一个共同点上。豌豆BRANCHED1是一种在芽中强烈表达的TCP转录因子，被认为在芽分枝过程中作用于SLS下游，受CK和SL调节，不需要蛋白质合成，并且与观察到的芽生长反应相关。
Cytokinin (CK) has long been implicated as a promoter of bud outgrowth in plants, but exactly how this is achieved in coordination with other plant hormones is unclear. The recent discovery of strigolactones (SLs) as the long-sought branch-inhibiting hormone allowed us to test how CK and SL coordinately regulate bud outgrowth in pea (Pisum sativum). We found that SL-deficient plants are more sensitive to stimulation of bud growth by low concentrations of locally applied CK than wildtype plants. Furthermore, in contrast with SL mutant plants, buds of wild-type plants are almost completely resistant to stimulation by CK supplied to the vasculature. Regardless of whether the exogenous hormones were supplied locally or to the xylem stream, SL and CK acted antagonistically on bud outgrowth. These data suggest that SLs do not affect the delivery of CK to axillary buds and vice versa. Rather, these data combined with dose-response experiments suggest that SLs and CK can act directly in buds to control their outgrowth. These hormones may converge at a common point in the bud outgrowth regulatory pathway. The expression of pea BRANCHED1, a TCP transcription factor expressed strongly in buds and thought to act downstream of SLs in shoot branching, is regulated by CK and SL without a requirement for protein synthesis and in a manner that correlates with observed bud growth responses.