Functional Diversification of euANT/PLT Genes in Oryza sativa Panicle Architecture Determination.

Ai My Luong,Hélène Adam,James Tregear,Fabrice Ntakirutimana,Ngan Giang Khong,Quang Hoa Le,Marie Fournel,Carole Gauron,Stefan Jouannic,Pablo Affortit,Thi Nhu Le,Michel Lebrun

doi:10.3389/fpls.2021.692955

Abstract

Grain yield, which is one of the most important traits in rice breeding, is controlled in part by panicle branching patterns. Numerous genes involved in the control of panicle architecture have been identified through mutant and QTL characterization. Previous studies suggested the importance of several AP2/ERF transcription factor-encoding genes in the control of panicle development, including the AINTEGUMENTA/PLETHORA-like (euANT/PLT) genes. The ANT gene was specifically considered to be a key regulator of shoot and floral development in Arabidopsis thaliana. However, the likely importance of paralogous euANT/PLT genes in the regulation of meristem identities and activities during panicle architecture development has not to date been fully addressed in rice. In this study, we observed that the rice euANT/PLT genes displayed divergent temporal expression patterns during the branching stages of early panicle development, with spatial localization of expression in meristems for two of these genes. Moreover, a functional analysis of rice ANT-related genes using genome editing revealed their importance in the control of panicle architecture, through the regulation of axillary meristem (AM) establishment and meristem fate transition. Our study suggests that the paralogous euANT/PLT genes have become partially diversified in their functions, with certain opposing effects, since they arose from ancestral gene duplication events, and that they act in regulating the branching of the rice panicle.

Highlights

Rice is a staple food for over half of the population in the world, and around one billion people depend economically on rice cultivation
Expression Diversity of euANT/PLT Genes During Panicle Development In O. sativa ssp. japonica, the AP2 subfamily consists of 27 genes divided into three groups, namely, the euAP2, basalANT, and euANT/PLT groups, in comparison with A. thaliana with 18 genes in total
Clade A contains OsPLT1∼6 proteins, which are more related to the A. thaliana PLT4/BABYBOOM (PLT4/BBM), PLT1, PLT2, and PLT5/AIL5 proteins plus AP2/EREBP86, which shows a close relationship with A. thaliana PLT3/AIL6 and PLT7/AIL7

Summary

Introduction

Rice is a staple food for over half of the population in the world, and around one billion people depend economically on rice cultivation. Rice PLETHORA Genes Function in Panicle spikelets produced on the higher-order branches (Ikeda et al, 2004; Xing and Zhang, 2010; Tanaka et al, 2013). The architecture of the mature inflorescence is initially determined during the reproductive phase, through meristematic activities that define the branching pattern along with flower positioning (Xing and Zhang, 2010; Kyozuka et al, 2014). During the elongation of primary branches (ePBM), the PBMs generate AMs, which may develop into secondary and higher-order branches or be transformed into lateral spikelet meristems (SpMs). Both PBMs and secondary branch meristems (SBMs) eventually form a terminal SpM. The RM, PBM, and ePBM/AM stages are indeterminate (i.e., meristematic cells are maintained), whereas the SpM is determinate in that the stem cells lose their activity (Ikeda et al, 2004; Tanaka et al, 2013; Kyozuka et al, 2014)

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