Abstract
BackgroundThermo-sensitive male-sterility based on Aegilops kotschyi cytoplasm (K-TCMS) plays an important role in hybrid wheat breeding. This has important possible applications in two-line hybrid wheat breeding but the genetic basis and molecular regulation mechanism related to fertility restoration are poorly understood. In this study, comparative transcriptome profiling based on RNA sequencing was conducted for two near-isogenic lines comprising KTM3315R and its sterile counterpart KTM3315A, a total of six samples (3 repetitions per group), in order to identify fertility restoration genes and their metabolic pathways.ResultsIn total, 2642 significant differentially expressed genes (DEGs) were detected, among which 1238 were down-regulated and 1404 were up-regulated in fertile anthers. Functional annotation enrichment analysis identified important pathways related to fertility restoration, such as carbohydrate metabolism, phenylpropanoid metabolism and biosynthesis, as well as candidate genes encoding pectin methylesterase and flavanone 3-hydroxylase. Moreover, transcription factor analysis showed that a large number of DEGs were mainly involved with the WRKY, bHLH, and MYB transcription factor families. Determination of total soluble sugar and flavonoid contents demonstrated that important metabolic pathways and candidate genes are associated with fertility restoration. Twelve DEGs were selected and detected by quantitative reverse-transcribed PCR, and the results indicated that the transcriptome sequencing results were reliable.ConclusionsOur results indicate that identified DEGs were related to the fertility restoration and they proved to be crucial in Aegilops kotschyi cytoplasm. These findings also provide a basis for exploring the molecular regulation mechanism associated with wheat fertility restoration as well as screening and cloning related genes.
Highlights
Thermo-sensitive male-sterility based on Aegilops kotschyi cytoplasm (K-TCMS) plays an important role in hybrid wheat breeding
The heat map showed that excluding the upregulation of WRKY3 in KMF compared with KMA, the other 13 differentially expressed genes (DEGs) were downregulated. bHLH47, bHLH63, and MYB44 were downregulated in KMF, but the remaining transcription factors were upregulated, i.e., bHLH and MYB. These findings suggest that WRKY, bHLH, and MYB family transcription factors may affect fertility restoration in K-TCMS lines
Traes_2BS_88CF42F2E, Traes_2DL_10A4DDD75, and Traes_2DS_F6307AF21 were downregulated in fertile anthers, but the other key enzymes encoded by these DEGs were upregulated in fertile anthers. These results indicate that the upregulation of carbohydrate metabolism and phenylpropanoid biosynthesis as well as metabolism-related genes in fertile (KMF) anthers may ensure the normal development and fertility of pollen
Summary
Thermo-sensitive male-sterility based on Aegilops kotschyi cytoplasm (K-TCMS) plays an important role in hybrid wheat breeding. This has important possible applications in two-line hybrid wheat breeding but the genetic basis and molecular regulation mechanism related to fertility restoration are poorly understood. Heterosis is one of the most successful strategies for increasing crop yields and it has been exploited widely in plant breeding systems [1]. In this context, cytoplasmic male sterility (CMS) can create sterile male gametophytes without affecting the agronomic performance and this cost-effective system facilitates hybrid seed production [2, 3]. Due to its huge genome and long breeding cycle, the use of CMS in wheat production is still a challenge
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