Diverse Roles of MAX1 Homologues in Rice.

Philip B Brewer,Apriadi Situmorang,Marek Marzec,Agnieszka Brąszewska

doi:10.3390/genes11111348

Abstract

Cytochrome P450 enzymes encoded by MORE AXILLARY GROWTH1 (MAX1)-like genes produce most of the structural diversity of strigolactones during the final steps of strigolactone biosynthesis. The diverse copies of MAX1 in Oryza sativa provide a resource to investigate why plants produce such a wide range of strigolactones. Here we performed in silico analyses of transcription factors and microRNAs that may regulate each rice MAX1, and compared the results with available data about MAX1 expression profiles and genes co-expressed with MAX1 genes. Data suggest that distinct mechanisms regulate the expression of each MAX1. Moreover, there may be novel functions for MAX1 homologues, such as the regulation of flower development or responses to heavy metals. In addition, individual MAX1s could be involved in specific functions, such as the regulation of seed development or wax synthesis in rice. Our analysis reveals potential new avenues of strigolactone research that may otherwise not be obvious.

Highlights

Strigolactones (SLs) were first discovered as stimulators of seed germination in species of the genera Orobanche, Phelipanche and Striga [1]
Protein sequences of rice MORE AXILLARY GROWTH1 (MAX1) homologues exhibited a range of identity from 48 to 80.8%, and in all sequences, the conserved domain for cytochrome P450 was present (Figure S1)
MAX1 homologues could be involved in different developmental processes and stress responses in rice

Summary

Introduction

Strigolactones (SLs) were first discovered as stimulators of seed germination in species of the genera Orobanche, Phelipanche and Striga [1]. Exudation of SLs from roots was found to promote hyphal branching of arbuscular mycorrhizal (AM) fungi [2]. SLs were described as a novel group of endogenous plant hormones, based on the analysis of mutants with semi-dwarf and high-branched phenotype [3,4]. Additional roles of SLs in plant growth and development, such as the regulation of the root system development [5], elongation of the mesocotyl and stem [6,7], vasculature formation and secondary growth [8,9] and leaf senescence [10], were discovered. Most SL biosynthesis appears to occur in vasculature, with resultant transport upwards in shoots or exudation out of roots [14]

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Discussion

Conclusion