OsARF11 Promotes Growth, Meristem, Seed, and Vein Formation during Rice Plant Development.

Katherine Sims,Monika Gyongyi Macias Honti,Jim Mattsson,Nicole Szulc,Fatemeh Abedi-Samakush

doi:10.3390/ijms22084089

Abstract

The plant hormone auxin acts as a mediator providing positional instructions in a range of developmental processes. Studies in Arabidopsis thaliana L. show that auxin acts in large part via activation of Auxin Response Factors (ARFs) that in turn regulate the expression of downstream genes. The rice (Oryza sativa L.) gene OsARF11 is of interest because of its expression in developing rice organs and its high sequence similarity with MONOPTEROS/ARF5, a gene with prominent roles in A. thaliana development. We have assessed the phenotype of homozygous insertion mutants in the OsARF11 gene and found that in relation to wildtype, osarf11 seedlings produced fewer and shorter roots as well as shorter and less wide leaves. Leaves developed fewer veins and larger areoles. Mature osarf11 plants had a reduced root system, fewer branches per panicle, fewer grains per panicle and fewer filled seeds. Mutants had a reduced sensitivity to auxin-mediated callus formation and inhibition of root elongation, and phenylboronic acid (PBA)-mediated inhibition of vein formation. Taken together, our results implicate OsARF11 in auxin-mediated growth of multiple organs and leaf veins. OsARF11 also appears to play a central role in the formation of lateral root, panicle branch, and grain meristems.

Highlights

The rice plant (Oryza sativa L.) is one of the most important crops in the world and serves as a staple food source for over half of the global population
PCR, using primers matching the OsARF11 gene and inserted DNA, and subsequent sequencing of amplicons (Figures S1–S3) confirmed that a T-DNA is inserted in exon 11 of the OsARF11 open reading frame, while the TOS-17 line has a TOS-17 transposon inserted in the fifth exon (TRIM and TOS-17 databases)
The OsARF11 gene has appeared in gene expression studies and its protein as an interactor with other proteins with key roles in rice development, but a thorough analysis of its function based on mutant analysis has to-date been lacking

Summary

Introduction

The rice plant (Oryza sativa L.) is one of the most important crops in the world and serves as a staple food source for over half of the global population. There is an ongoing effort to characterize genes with functions in developmental processes that impact economically important quantitative traits such as shoot and root size, leaf width, number of panicles, seeds per panicle, and seed size. There are efforts to engineer rice with C4 traits such as high vein density and high rate of photosynthesis in leaf vein bundle sheath cells to reduce photorespiration [1,2]. The plant hormone auxin plays a role in many of these developmental programs since it regulates cell division and expansion, meristem development, and vascular patterning [3,4,5]. The auxin signaling pathway is simple, involved core proteins are represented by large gene families, allowing for a wide range of context-dependent cellular responses [10,11,12,13]. The main components of auxin signaling have been studied intensely in Arabidopsis thaliana L. and involve three protein families: the F-box TRANSPORT

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