The Carotenoid Cleavage Dioxygenase Gene CCD7-B, at Large, Is Associated with Tillering in Common Wheat

Wenlong Yang,Linhe Sun,Ameer Mirbahar,Kehui Zhan,Aimin Zhang,Jiazhu Sun,Xueyuan Lou,Muhammad Shoaib

doi:10.3390/agriculture12020306

Abstract

Wheat, an important cereal crop, is responsible for the livelihoods of many people, and a component of national food security. Tillering, which determines plant architecture and spike number, is a critical agronomic trait of wheat. The carotenoid cleavage dioxygenase 7 (CCD7) has an important effect on the growth of tillers or lateral branches and lateral roots of plants. In order to study the relationship between CCD7 and tillering in wheat, CCD7-B was isolated from 10 Chinese wheat varieties with different tiller numbers. Subsequently, bioinformatics, allelic variation analysis, and field experiments were performed. Wheat CCD7-B belongs to the retinal pigment epithelial membrane receptor (RPE65) superfamily; it displays the greatest homology with monocot CCD7 proteins. Phylogenetic analysis of wheat CCD7-B proteins indicated division into dicotyledonous and monocotyledonous clades. Allelic variation analysis of CCD7-B via SrgAI enzyme digestion (a marker of cleaved amplified polymorphic sequences) suggested that 262 Chinese wheat micro-core collections and 121 Chinese wheat major cultivars from the Yellow and Huai River Valley winter wheat region can be divided into two groups: CCD7-B1 (C/T/T) and CCD7-B2 (G/C/A). CCD7-B1 showed better allelic variation than did CCD7-B2 for increasing the number of effective tillers of wheat varieties in China. This study provides reference data for the application of CCD7-B alleles to wheat breeding and supports further research regarding the mechanism of tillering in common wheat.

Highlights

Bread wheat (Triticum aestivum L., 2n = 6× = 42) is one of the most important cereal crops worldwide [1], along with maize (Zea mays L.) and rice (Oryza sativa L.) [2]; it is cultivated on 222 million hectares globally [3]
Bioinformatics, allelic variation analysis, and field experiments were performed to identify the effects of the carotenoid cleavage dioxygenase gene carotenoid cleavage dioxygenase 7 (CCD7)-B on wheat tiller numbers
Wheat CCD7-B belongs to the retinal pigment epithelial membrane receptor (RPE65) superfamily; it displays the greatest homology with monocot CCD7 proteins

Summary

Introduction

Wheat is a major staple food crop used by more than 30% of the world’s population [4]. Many physiological and agronomic traits affect the final yield of wheat; these traits include the number of spikes per unit area, number of grains per spike, thousand grain weight, chlorophyll content, photosynthetic rate, and water-soluble carbohydrates. Among these traits, tillering or shoot branching, which defines plant architecture and spike number, is considered a major determinant of wheat grain yield [1]

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