ADP1 Affects Plant Architecture by Regulating Local Auxin Biosynthesis

Ruixi Li,Li-Jia Qu,Jieru Li,Karin Ljung,Angus Murphy,Shibai Li,Ondřej Novák,Genji Qin,Hongya Gu,Aleš Pěnčík,Tomohiko Tsuge,Takashi Aoyama,Jingjing Liu,Gregory P Copenhaver

doi:10.1371/journal.pgen.1003954

Abstract

Plant architecture is one of the key factors that affect plant survival and productivity. Plant body structure is established through the iterative initiation and outgrowth of lateral organs, which are derived from the shoot apical meristem and root apical meristem, after embryogenesis. Here we report that ADP1, a putative MATE (multidrug and toxic compound extrusion) transporter, plays an essential role in regulating lateral organ outgrowth, and thus in maintaining normal architecture of Arabidopsis. Elevated expression levels of ADP1 resulted in accelerated plant growth rate, and increased the numbers of axillary branches and flowers. Our molecular and genetic evidence demonstrated that the phenotypes of plants over-expressing ADP1 were caused by reduction of local auxin levels in the meristematic regions. We further discovered that this reduction was probably due to decreased levels of auxin biosynthesis in the local meristematic regions based on the measured reduction in IAA levels and the gene expression data. Simultaneous inactivation of ADP1 and its three closest homologs led to growth retardation, relative reduction of lateral organ number and slightly elevated auxin level. Our results indicated that ADP1-mediated regulation of the local auxin level in meristematic regions is an essential determinant for plant architecture maintenance by restraining the outgrowth of lateral organs.

Highlights

IntroductionPhyllotaxis of lateral organs, branching pattern, as well as size, shape and position of lateral organs all contribute to the overall architecture of a plant
Higher plants have a diverse range of body structures
Detailed studies have been focused on genetic factors that are crucial for maintenance of shoot apical meristem (SAM), initiation and outgrowth of axillary meristem (AM), proper growth rate for lateral organ development, and correct timing for reproduction and senescence [2]

Summary

Introduction

Phyllotaxis of lateral organs, branching pattern, as well as size, shape and position of lateral organs all contribute to the overall architecture of a plant. Plant architecture is largely determined by genetic programs and, to some extent, by environmental cues, such as light, humidity, temperature, nutrition, and plant density. Research on plant architecture has important agronomic implications because it has a direct impact on the suitability and productivity of a plant. One of the most successful modifications of plant architecture is the Green Revolution, which is based on the selection of wheat cultivars with shorter and sturdier stems, resulting in plants with enhanced yield via improved resistance to wind and rain [3]. Understanding the genetic and molecular mechanisms of the regulation of plant architecture would help us to modify agronomically useful traits and facilitate the breeding of high-yield crops

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