Abstract
BackgroundThe discovery of male sterile materials is of great significance for the development of plant fertility research. Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) is a variety of non-heading Chinese cabbage. There are few studies on the male sterility of wucai, and the mechanism of male sterility is not clear. In this study, the male sterile mutant MS7–2 and the wild-type fertile plant MF7–2 were studied.ResultsPhenotypic characteristics and cytological analysis showed that MS7–2 abortion occurred at the tetrad period. The content of related sugars in the flower buds of MS7–2 was significantly lower than that of MF7–2, and a large amount of reactive oxygen species (ROS) was accumulated. Through transcriptome sequencing of MS7–2 and MF7–2 flower buds at three different developmental stages (a–c), 2865, 3847, and 4981 differentially expressed genes were identified in MS7–2 at the flower bud development stage, stage c, and stage e, respectively, compared with MF7–2. Many of these genes were enriched in carbohydrate metabolism, phenylpropanoid metabolism, and oxidative phosphorylation, and most of them were down-regulated in MS7–2. The down-regulation of genes involved in carbohydrate and secondary metabolite synthesis as well as the accumulation of ROS in MS7–2 led to pollen abortion in MS7–2.ConclusionsThis study helps elucidate the mechanism of anther abortion in wucai, providing a basis for further research on the molecular regulatory mechanisms of male sterility and the screening and cloning of key genes in wucai.
Highlights
The discovery of male sterile materials is of great significance for the development of plant fertility research
Phenotypic and cytological characterization of MS7–2 The phenotypic characterization comparison of the MS7–2 and MF7–2 lines showed that MS7–2 exhibited no significant differences in morphological indicators such as plant type and leaf color from MF7–2 (Fig. 1 A, D)
In this study, we first determined the abortion stage of the male sterile mutant MS7–2 by phenotypic and cytological observation, following which we analyzed the transcriptome of the mutant MS7–2 and fertile plant MF7–2 at different stages of flower bud development
Summary
The discovery of male sterile materials is of great significance for the development of plant fertility research. Male sterility in Brassica crops is considered as an ideal pollination control system for hybrid seed production. Two types of male sterility occur in wucai, including CMS and GMS. The sterility of CMS is controlled by the cytoplasmic genome, which is maternally inherited, and its fertility can be restored by restoring genes located in the nuclear genome [5]. Compared with CMS, GMS has an obvious disadvantage, that only 50% of maternal plants are male sterile plants, which requires the removal of the remaining 50% of male fertile plants [7, 8]. GMS is becoming more and more popular in commercial seed production because of its advantages of relatively complete fertility, no effect of cytoplasmic type, wide restorer lines, and highly pure hybrid F1 seeds [9]
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