Cytoplasmic male sterility is crucial for the utilization of hybrid heterosis and it possibly occurs in parallel with tapetal programmed cell death (PCD) and oxidative metabolism responses. However, little is known about the mechanisms that underlie pollen abortion in wheat. Therefore, we obtained two isonuclear alloplasmic male sterile lines (IAMSLs) with Aegilops kotschyi and Ae. juvenalis cytoplasm. Compared with the maintainer line, cytochemical analyses of the anthers demonstrated that the IAMSLs exhibited anomalous tapetal PCD and organelles, with premature PCD in K87B1-706A and delayed PCD in Ju87B1-706A. We also found that the dynamic trends in reactive oxygen species (ROS) were consistent in these two IAMSLs during anther development and they were potentially associated with the initiation of tapetal PCD. In addition, the activities of ROS-scavenging enzymes increased rapidly, whereas non-enzymatic antioxidants were downregulated together with excess ROS production in IAMSLs. Real-time PCR analysis showed that the expression levels of superoxide dismutase, catalase, and ascorbate peroxidase genes, which encode important antioxidant enzymes, were significantly upregulated during early pollen development. Thus, we inferred that excessive ROS and the abnormal transcript levels of antioxidant enzyme genes disrupted the balance of the antioxidant system and the presence of excess ROS may have been related to aberrant tapetal PCD progression, thereby affecting the development of microspores and ultimately causing male sterility. These relationships between the mechanism of PCD and ROS metabolism provide new insights into the mechanisms responsible for abortive pollen in wheat.
Cytoplasmic male sterile (CMS) lines are important tools for hybrid production but they cannot produce viable pollen. Breeding new CMS lines and studying their sterility mechanism in wheat (Triticum aestivum L.) greatly facilitates the process of hybrid wheat breeding. We conducted transcriptome sequencing for a recently identified Mu-CMS line with Aegilops uniaristata Vis. cytoplasm, named U706A, and its isonuclear maintainer line (706B) at the binucleate stage, which was a critical period when abortion occurred. We found that most of the genes involved in phosphatidylinositol metabolism and pectin degradation were downregulated, as well as genes encoding the MYB21 and MYC2 transcription factors, in U706A compared with 706B. In addition, pectin contents indicated that the production of pectin has been enhanced from the binucleate stage to the trinucleate stage, owing to the downregulation of pectin-degradation-related genes in U706A at the binucleate stage, which confirmed the reliability of the sequencing results. We also discovered that the accumulation period of pectin content in U706A is abnormal compared with 706B, which may be an important reason for abortion. Some differentially expressed genes that might be related to the sterile phenotype were verified by quantitative RT-PCR. Therefore, we suggest that the downregulation of these genes possibly leads to the anther not to crack; the tapetum and microspore membrane system is less metabolised, and the abnormal pectin accumulation results in microspore nutrient deficiencies and abnormal development. These findings provide novel insights into the mechanism responsible for pollen abortion in CMS, which may facilitate hybrid wheat breeding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.