ZmRAP2.7, an AP2 Transcription Factor, Is Involved in Maize Brace Roots Development.

Jieping Li,Fanjun Chen,Guohua Mi,Yuanqing Wang,Lixing Yuan,Pengcheng Li,Yanqing Li

doi:10.3389/fpls.2019.00820

Jieping Li, Fanjun Chen + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2019.00820

Copy DOI

Abstract

In maize, shoot-borne roots dominate the whole root system and play essential roles in water and nutrient acquisition and lodging tolerance. Shoot-borne roots initiate at shoot nodes, including crown roots from the belowground nodes and brace roots from aboveground nodes. In contrast to crown roots, few genes for brace roots development have been identified. Here, we characterized a maize AP2/ERF transcription factor, ZmRAP2.7, to be involved in brace roots development. ZmRAP2.7 expressed in all types of roots, and the encoded protein localized in the nucleus with transcriptional activation activity. A maize transposon insert mutant RAP2.7-Mu defective in ZmRAP2.7 expression revealed a decreased number of brace roots but not crown roots. Maize Corngrass1 mutant, which showed an elevated expression of ZmRAP2.7, however, revealed an increased number of brace roots. The ZmRAP2.7-based association analysis in a maize panel further identified a SNP marker at the fifth exon of gene to be associated with number of brace roots. These results uncovered a function of ZmRAP2.7 in brace roots development and provided the valuable gene and allele for genetic improvement of maize root systems.

Highlights

Roots are essential organs for exploring and exploiting soil resources, such as water and mineral nutrients, and providing anchorage (Lynch, 1995, 2007; Hodge et al, 2009)
Increased number of shoot-borne roots in Corngrass1 was mainly explained by brace roots, while the number of crown roots was similar between two genotypes
To define the function of ZmRAP2.7 in maize brace roots development, the expression pattern of ZmRAP2.7 in different organs was surveyed from database (B73 genome V3, https:// www.maizegdb.org/)

Summary

Introduction

Roots are essential organs for exploring and exploiting soil resources, such as water and mineral nutrients, and providing anchorage (Lynch, 1995, 2007; Hodge et al, 2009). Root system architecture (RSA) is fundamental for crop growth and productivity, under abiotic stress condition (de Dorlodot et al, 2007). Maize (Zea mays L.) is one of the most important food and feed crop, and the productivity is sensitive to nutrient deficiency, drought stress, and root lodging in high-density populations (Mueller et al, 2012; Lobell et al, 2014; Xue et al, 2017). Identification of QTLs or genes for RSA is required to provide the valuable targets for marker-assisted selection or genetic modification to promote root-based approach on crop yield improvement

Methods

Results

Conclusion