A single nucleotide polymorphism in an R2R3 MYB transcription factor gene triggers the male sterility in soybean ms6 (Ames1)

Junping Yu,Chunbao Zhang,Wei Li,Limei Zhao,Min Xu,Ying Zhang,Peng Wang,Guolong Zhao,Aigen Fu

doi:10.1007/s00122-021-03920-0

Junping Yu, Chunbao Zhang + Show 7 more

Open Access

https://doi.org/10.1007/s00122-021-03920-0

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Abstract

Key messageIdentification and functional analysis of the male sterile gene MS6 in Glycine max.Soybean (Glycine max (L.) Merr.) is an important crop providing vegetable oil and protein. The male sterility-based hybrid breeding is a promising method for improving soybean yield to meet the globally growing demand. In this research, we identified a soybean genic male sterile locus, MS6, by combining the bulked segregant analysis sequencing method and the map-based cloning technology. MS6, highly expressed in anther, encodes an R2R3 MYB transcription factor (GmTDF1-1) that is homologous to Tapetal Development and Function 1, a key factor for anther development in Arabidopsis and rice. In male sterile ms6 (Ames1), the mutant allele contains a missense mutation, leading to the 76th leucine substituted by histidine in the DNA binding domain of GmTDF1-1. The expression of soybean MS6 under the control of the AtTDF1 promoter could rescue the male sterility of attdf1 but ms6 could not. Additionally, ms6 overexpression in wild-type Arabidopsis did not affect anther development. These results evidence that GmTDF1-1 is a functional TDF1 homolog and L76H disrupts its function. Notably, GmTDF1-1 shows 92% sequence identity with another soybean protein termed as GmTDF1-2, whose active expression also restored the fertility of attdf1. However, GmTDF1-2 is constitutively expressed at a very low level in soybean, and therefore, not able to compensate for the MS6 deficiency. Analysis of the TDF1-involved anther development regulatory pathway showed that expressions of the genes downstream of TDF1 are significantly suppressed in ms6, unveiling that GmTDF1-1 is a core transcription factor regulating soybean anther development.

Highlights

Soybean (Glycine max (L.) Merr.) is a major crop providing plant protein and oil in the food supply, but it has a relatively low yield (Palmer et al 2001)
Results from genetic mapping, comparative high-throughput sequencing, conservation study, phylogenetic analysis, complementary experiment, gene expression patterns and differential expressions of genes in the Tapetal Development and Function 1 (TDF1)-involved regulatory pathway all lead to the conclusion that the male sterility of ms6 from T295H is caused by the missense mutation at the Glyma.13G066600 locus (MS6), which encodes a soybean homolog of TDF1, GmTDF1-1 (Figs. 2-5, 7)
TDF1 is a well-known R2R3 MYB transcription factor required for appropriate tapetum development (Zhu et al 2008; Cai et al 2015)

Summary

Introduction

Soybean (Glycine max (L.) Merr.) is a major crop providing plant protein and oil in the food supply, but it has a relatively low yield (Palmer et al 2001). Hybrid breeding technology, Communicated by Istvan Rajcan. There are two types of male sterility (MS), i.e., genic male sterility (GMS) controlled by nuclear MS genes and cytoplasmic male sterility (CMS) co-conditioned by mitochondrial CMS genes and nuclear fertility restorer genes (Guo and Liu 2012). Based on the stability of the MS phenotype, GMS could be further subdivided into two groups, the stable GMS and the environmental-sensitive GMS (EGMS). The hybrid breeding systems applied today include the CMS-based three-line system and the EGMS-based twoline system (Kim and Zhang 2018). For the CMSbased three-line system, the genetic resources of fertility restorer lines are limited.

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