Abstract
Genetic male sterility (GMS) facilitates hybrid seed production in crops including cotton (Gossypium hirsutum). However, the genetic and molecular mechanisms specifically involved in this developmental process are poorly understood. In this study, small RNA sequencing, degradome sequencing, and transcriptome sequencing were performed to analyze miRNAs and their target genes during anther development in a GMS mutant (‘Dong A’) and its fertile wildtype (WT). A total of 80 known and 220 novel miRNAs were identified, 71 of which showed differential expressions during anther development. A further degradome sequencing revealed a total of 117 candidate target genes cleaved by 16 known and 36 novel miRNAs. Based on RNA-seq, 24, 11, and 21 predicted target genes showed expression correlations with the corresponding miRNAs at the meiosis, tetrad and uninucleate stages, respectively. In addition, a large number of differentially expressed genes were identified, most of which were involved in sucrose and starch metabolism, carbohydrate metabolism, and plant hormone signal transduction based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The results of our study provide valuable information for further functional investigations of the important miRNAs and target genes involved in genetic male sterility and advance our understanding of miRNA regulatory functions during cotton anther development.
Highlights
Upland cotton (Gossypium hirsutum) is an important cultivated economic crop that provides the majority of natural textile fiber materials worldwide
To identify miRNAs involved in cotton anther male sterility, six small RNA libraries were constructed using the total RNA extracted from developing anthers at three developmental stages in the Genetic male sterility (GMS) mutant ‘development in a GMS mutant (Dong A)’ (S-1, S-2, and S-3) and its fertile WT (WT-1, WT-2, and WT-3) and sequenced on an Illumina HiSeq 2000 analyzer (Wei et al 2013a, b)
Analyzing the unique reads in the libraries between the WT and its GMS mutant libraries, we found that only 1335784 (10.17%), 1802655 (11.42%), and 1409362 (11.16%) of the unique miRNAs were shared between the WT and its GMS mutant at the three anther developmental stages, respectively (Fig. S1)
Summary
Upland cotton (Gossypium hirsutum) is an important cultivated economic crop that provides the majority of natural textile fiber materials worldwide. Breeding cotton cultivars with high-fiber quality and lint yield has been critical to meet increased economic demand. The utilization of hybrid vigor is a key strategy for improving cotton yield and quality with higher effectiveness (Huang, Yang et al 2016). It is necessary for scientists to perform intensive investigations of the genetic and molecular mechanisms of male sterility. Male sterility provides crucial breeding tools for harnessing hybrid vigor and Molecular Genetics and Genomics (2020) 295:645–660 provides important materials with which to study stamen and pollen development. Because most CMS systems have stringent restorers, cytoplasmic negative effects, and unstable sterility (Schnable and Wise 1998), the GMS system has attracted more attention from the cotton breeding community for cultivating hybrid cotton with high fiber quality and yield. Many studies have focused on cotton GMS, the molecular mechanism involved in this developmental process is still poorly understood
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