The antagonistic regulation of seed germination by the phytohormones abscisic acid (ABA) and gibberellic acid (GA) has been well-established. However, how these phytohormones antagonistically regulate root growth and branching (tillering in rice, Oryza sativa) remains obscure. Rice TILLER ENHANCER (TE) encodes an activator of the APC/C^TE E3 ubiquitin ligase complex that represses tillering but promotes seed germination. In this study, we identified a dual role of GA and APC/C^TE in regulating root growth. High GA levels can activate APC/C^TE to promote the degradation of rice SHORT-ROOT1 (OsSHR1, a key factor promoting root growth) in the root meristem (RM) or MONOCULM1 (MOC1, a key factor promoting tillering) in the axillary meristem (AM), leading to restricted root growth and tillering, while low GA levels can activate the role of APC/C^TE in stimulating RM cell division to promote root growth. In addition, moderate enhancement of ABA signaling helps maintain the RM and AM size, sustaining root growth and tillering by antagonizing the GA-promoted degradation of OsSHR1 and MOC1 through the SnRK2-APC/C^TE regulatory module. We conclude that APC/C^TE plays a key role in regulating plant architecture by mediating the crosstalk between ABA and GA signaling pathways.

植物激素脱落酸（ABA）和赤霉酸（GA）对种子萌发的拮抗调节作用已被证实。然而，这些植物激素如何拮抗地调节根系生长和分枝（水稻的分蘖）仍然不清楚。水稻分蘖增强剂( TE ) 编码 APC/C ^TE E3 泛素连接酶复合物的激活剂，可抑制分蘖但促进种子萌发。在这项研究中，我们确定了 GA 和 APC/C ^TE在调节根生长中的双重作用。高GA水平可以激活APC/C ^TE ，促进水稻根分生组织（RM）中的SHORT-ROOT1（OsSHR1，促进根生长的关键因子）或腋生分生组织中的MONOCULM1（MOC1，促进分蘖的关键因子）的降解(AM)，导致根系生长和分蘖受限，而低 GA 水平可以激活 APC/C ^TE刺激 RM 细胞分裂的作用，从而促进根系生长。此外，适度增强 ABA 信号传导有助于维持 RM 和 AM 大小，通过 SnRK2-APC/C ^TE调节模块拮抗 GA 促进的 OsSHR1 和 MOC1 降解，从而维持根系生长和分蘖。我们得出结论，APC/C ^TE通过介导 ABA 和 GA 信号通路之间的串扰在调节植物结构中发挥关键作用。