Functional Analysis of Aux/IAAs and SAURs on Shoot Growth of Lagerstroemia indica through Virus-Induced Gene Silencing (VIGS)

Lu Feng,Jia Wang,Huitang Pan,Ming Cai,Qixiang Zhang,Jieru Liu,Xiaohan Liang,Yang Zhou,Tangren Cheng,Ye Zhang

doi:10.3390/f11121288

Abstract

The plant hormone auxin plays an important role in cell division and the elongation of shoots to affect the plant architecture, which has a great impact on the plant yield, fruit quality and ornamental value; however, the regulatory mechanism of auxin controlling shoot growth is unclear in crape myrtle. In this study, two auxin/indole-3-acetic acid (Aux/IAA) genes and four small auxin upregulated RNA (SAUR) genes of auxin response gene families were isolated from dwarf and non-dwarf progenies of Lagerstroemia indica and then functionally characterized. Sequence alignment revealed that the six genes contain typical conserved domains. Different expression patterns of the six genes at three different tissue stages of two types of progenies showed that the regulation mechanism of these genes may be different. Functional verification of the six genes upon shoot growth of crape myrtle was performed via virus-induced gene silencing. When the LfiAUX22 gene was silenced, a short shoot phenotype was observed in non-dwarf progenies, accompanied by decreased auxin content. Therefore, we preliminarily speculated that LfiAUX22 plays an important role in the shoot growth of crape myrtle, which regulates the accumulation of indole-3-acetic acid (IAA) and the elongation of cells to eventually control shoot length.

Highlights

As a key component of plant architecture, plant height is one of the most important characteristics in crops, horticultural crops and ornamental plants, because it plays an important role in increasing the yield, improving the fruit quality, reducing management costs, and improving landscape effects [1,2,3].At present, the studies on genes related to dwarfing traits have long been investigated in annual plants or model plants, such as rice [4,5], corn [6,7,8], wheat [6,7,8], while the mechanisms in woody plants remain poorly understood
According to our previous research, we screened out six genes differentially expressed in the auxin signal transduction pathway, of which two genes belong to the auxin/indole-3-acetic acid (Aux/indole-3-acetic acid (IAA)) family (LfiAUX22 and LfiIAA26), and four genes belong to the small auxin upregulated RNA (SAUR) family (LfiSAUR26, LfiSAUR31, LfiSAUR39, and LfiSAUR50) [40]
There was no difference in the coding region sequences of these genes in the two types of progenies

Summary

Introduction

As a key component of plant architecture, plant height is one of the most important characteristics in crops, horticultural crops and ornamental plants, because it plays an important role in increasing the yield, improving the fruit quality, reducing management costs, and improving landscape effects [1,2,3].At present, the studies on genes related to dwarfing traits have long been investigated in annual plants or model plants, such as rice [4,5], corn [6,7,8], wheat [6,7,8], while the mechanisms in woody plants remain poorly understood. As a key component of plant architecture, plant height is one of the most important characteristics in crops, horticultural crops and ornamental plants, because it plays an important role in increasing the yield, improving the fruit quality, reducing management costs, and improving landscape effects [1,2,3]. A short internode length is a key factor in the formation of dwarf woody plants, including dwarf peach [9,10], dwarf pear [11] and spur type apple [12]. Further investigations have shown that the cell number is determined by cell division within the shoot apical meristem (SAM) and intervening meristem, and the subsequent enlargement of these cells causes the elongation of the shoots, which in turn regulates the plant height [15].

Methods

Results

Conclusion