Current Advances in Molecular Basis and Mechanisms Regulating Leaf Morphology in Rice.

Peizhou Xu,Baolin Han,Asif Ali,Xianjun Wu

doi:10.3389/fpls.2018.01528

Abstract

Yield is majorly affected by photosynthetic efficiency. Leaves are essential structure for photosynthesis and their morphology especially size and shape in a plant canopy can affect the rate of transpiration, carbon fixation and photosynthesis. Leaf rolling and size are considered key agronomic traits in plant architecture that can subsidize yield parameters. In last era, a number of genes controlling leaf morphology have been molecularly characterized. Despite of several findings, our understanding toward molecular mechanism of leaf rolling and size are under-developed. Here, we proposed a model to apprehend the physiological basis of different genes organized in a complex fashion and govern the final phenotype of leaf morphology. According to this leaf rolling is mainly controlled by regulation of bulliform cells by SRL1, ROC5, OsRRK1, SLL2, CLD1, OsZHD1/2, and NRL1, structure and processes of sclerenchyma cells by SLL1 and SRL2, leaf polarity by ADL1, RFS and cuticle formation by CFL1, and CLD1. Many of above mentioned and several other genes interact in a complex manner in order to sustain cellular integrity and homeostasis for optimum leaf rolling. While, leaf size is synchronized by multifarious interaction of PLA1, PLA2, OsGASR1, and OsEXPA8 in cell division, NAL1, NAL9, NRL1, NRL2 in regulation of number of veins, OsCOW1, OsPIN1, OsARF19, OsOFP2, D1 and GID in regulation of phytohormones and HDT702 in epigenetic aspects. In this review, we curtailed recent advances engrossing regulation and functions of those genes that directly or indirectly can distress leaf rolling or size by encoding different types of proteins and genic expression. Moreover, this effort could be used further to develop comprehensive learning and directing our molecular breeding of rice.

Highlights

Rice is a model plant of monocots and an important crop that feeds more than half of the population around the globe
Studies have reported that reduced or increased expression level of ROC5 can affect leaf rolling, it serves as a negative regulator leaf rolling by mediating number and size of bulliform cells
NRL2 protein interacted with RL14 and distresses contents of cellulose, lignin and differentiation of sclerenchymatous cells (Zhao et al, 2016). These findings suggested that sclerenchymatous cells play their part in regulation of leaf rolling

Summary

INTRODUCTION

Rice is a model plant of monocots and an important crop that feeds more than half of the population around the globe. Transgenic plants with reduced expression level of RL14 or NRL1, or overexpression of OsMYBL103L displayed adaxial rolling of leaves due to reduced size of bulliform cells. Studies have reported that reduced or increased expression level of ROC5 can affect leaf rolling, it serves as a negative regulator leaf rolling by mediating number and size of bulliform cells. Rice SLL1 encodes a transcription factor of KANADI family and its loss-of-function mutant showed extreme rolling of leaves phenotype caused by defective development of sclerenchymatous cells on the abaxial side. Keeping in view function of these genes in cell division (i.e., size and number), their use in breeding can provide an effective tool to engineer plants with more leaf area for better agronomic yield Plant hormones such as auxin and gibberellins are necessary for plant development and play a substantial role in regulation of leaf size. TDD1 (TRYPTOPHAN DEFICIENT DWARF MUTANT 1) and TABLE 1 | List of rice genes controlling leaf rolling and size

DNL1 FIB GH3-5 GID2 HDT702 LC2 MKB3 miRNA159 NAL1

CONCLUSION