SPOC domain-containing protein Leaf inclination3 interacts with LIP1 to regulate rice leaf inclination through auxin signaling.

Su-Hui Chen,Hong-Wei Xue,Li-Juan Zhou,Ping Xu,Hao Yu

doi:10.1371/journal.pgen.1007829

Abstract

Leaf angle is an important agronomic trait and influences crop architecture and yield. Studies have demonstrated the roles of phytohormones, particularly auxin and brassinosteroids, and various factors in controlling leaf inclination. However, the underlying mechanism especially the upstream regulatory networks still need being clarified. Here we report the functional characterization of rice leaf inclination3 (LC3), a SPOC domain-containing transcription suppressor, in regulating leaf inclination through interacting with LIP1 (LC3-interacting protein 1), a HIT zinc finger domain-containing protein. LC3 deficiency results in increased leaf inclination and enhanced expressions of OsIAA12 and OsGH3.2. Being consistent, transgenic plants with OsIAA12 overexpression or deficiency of OsARF17 which interacts with OsIAA12 do present enlarged leaf inclination. LIP1 directly binds to promoter regions of OsIAA12 and OsGH3.2, and interacts with LC3 to synergistically suppress auxin signaling. Our study demonstrate the distinct effects of IAA12-ARF17 interactions in leaf inclination regulation, and provide informative clues to elucidate the functional mechanism of SPOC domain-containing transcription suppressor and fine-controlled network of lamina joint development by LC3-regulated auxin homeostasis and auxin signaling through.

Highlights

Rice is one of the most important crops in the world and breeding rice varieties with ideal architecture is a vital strategy for improvement of grain yields [1, 2]
Our study demonstrate the distinct effects of IAA12-ARF17 interactions in leaf inclination regulation, and provide informative clues to elucidate the functional mechanism of SPOC domain-containing transcription suppressor and fine-controlled network of lamina joint development by leaf inclination3 (LC3)-regulated auxin homeostasis and auxin signaling through
Leaf angle is a major trait of ideal architecture of crops that associates with photosynthetic efficiency and yields

Summary

Introduction

Rice is one of the most important crops in the world and breeding rice varieties with ideal architecture is a vital strategy for improvement of grain yields [1, 2]. Studies by using mutants or transgenic approaches indicate that altered biosynthesis or signaling of brassinosteriods (BRs) lead to the change of leaf inclination, such as BR-deficient mutant dwarf4-1 [9], ebisudwarf (d2) [10], dwarf (brd1) [5], BR signaling mutant d61-1, 2 (weak mutant alleles of OsBRI1) [11], or rice plants with reduced expression of OsBZR1 [12]. It is noticed that BR stimulates while auxin suppresses the leaf inclination through regulating the cell division or elongation at adaxial side of lamina joint and auxin coordinates with BR to control the lamina joint development [6, 7, 16]. Ethylene may participate in BR-induced leaf inclination [17] and repressed expression of a gibberellin signaling negative regulator, SPINDLY, leads to increased leaf angles [18]

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