Gene characterization and molecular pathway analysis of reverse thermosensitive genic male sterility in eggplant (Solanum melongena L.)

Bing Li,Jianjun Zhao,Aixia Gu,Yanrong Wu,Jingjing Zhang,Shuangxia Luo,Xueping Chen,Xiurui Gao,Xiuqing Pan,Shuxing Shen

doi:10.1038/s41438-019-0201-z

Abstract

The naturally occurring mutant eggplant line 05ms was identified with reverse thermosensitive genic male sterility (rTGMS), but its temperature-responsive fertility mechanisms remain largely unknown. Here, we studied the flower morphology, anther cellular structure, and genome-wide gene expression of this rTGMS line. Candidate genes for thermosensitive male sterility during the microspore development of 05ms and the temperature-insensitive line S63 under low-temperature (LT) and high-temperature (HT) conditions were identified. Under LT, tapetum cells were vacuolated and had delayed disintegration in 05ms. RNA-seq analysis indicated that DEGs were enriched in the KEGG pathways ‘plant hormone signal transduction’, ‘starch and sucrose metabolism’, and ‘phenylpropanoid biosynthesis’. We identified two genes, 4CLL1 (Sme2.5_00368.1_g00010.1) and CKI1 (Sme2.5_10056.1_g00002.1), which could potentially regulate eggplant anther development and may be candidate genes for rTGMS. Finally, we propose a working model of anther abortion for rTGMS in eggplant. CKI1 responds to LT stress and causes expression changes in genes related to anther development, such as 4CLL1, and the cellular structure of the tapetum becomes abnormal, causing male sterility. The findings of this study explain the underlying molecular mechanisms of male sterility in eggplant rTGMS lines.

Highlights

Eggplant (Solanum melongena L.) is an important vegetable that is cultivated throughout the world
The reverse thermosensitive genic male sterility (rTGMS) line 05ms was a spontaneous mutation in long eggplant, favorable for the production of two-line hybrids
To globally identify genes and pathways participating in eggplant anther development under LT, we performed RNA-seq analysis and obtained complete transcriptome information that allowed us to understand the relationship between anther development and LT

Summary

Introduction

Eggplant (Solanum melongena L.) is an important vegetable that is cultivated throughout the world. Male sterile lines provide key breeding tools for hybrid seed production and offer essential materials for studying crop reproductive development[1]. Creating male sterile resources and studying the mechanism of male sterility in eggplant are essential for improving and selecting sterile lines, as well. CMS in vegetable crops, such as cabbage[3], radish[4], and pepper[5], has been extensively utilized. Several CMS lines in eggplant have been reported and are usually produced by distant crossing[6]. Studies concerning the application of male sterile lines are very limited because of several difficulties, including the narrow background of germplasm resources, the need for specific restoration genes, and the lack of restorer lines or advantages for the hybrid combinations

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Conclusion