ROS accumulation-induced tapetal PCD timing changes leads to microspore abortion in cotton CMS lines

Area of Science:

• Plant genetics and molecular biology
• Reproductive biology in plants

Background:

• Cytoplasmic male sterility (CMS) is crucial for hybrid breeding but its molecular mechanisms, particularly the role of programmed cell death (PCD) and reactive oxygen species (ROS), are not fully understood in cotton.
• Two distinct CMS lines, Jin A and Yamian A, with different cytoplasmic origins were investigated to elucidate the underlying molecular basis of male sterility.

Purpose of the Study:

• To investigate the role of reactive oxygen species (ROS) and ROS-scavenging enzyme activities in the tapetal programmed cell death (PCD) of two cotton cytoplasmic male sterility (CMS) lines.
• To understand the molecular mechanisms leading to male sterility in cotton, focusing on the differential regulation of tapetal PCD and ROS metabolism.

Main Methods:

• Comparative analysis of anther development, tapetal PCD progression, and ROS accumulation in CMS lines (Jin A, Yamian A) and their respective maintainer lines (Jin B).
• Measurement of ROS levels and the activities of ROS-scavenging enzymes (POD, CAT, SOD).
• Investigation of potential sources of ROS, including mitochondrial activity and electron transport chain complex III, and assessment of ATP content.

Main Results:

• Jin A exhibited advanced tapetal PCD with increased ROS accumulation and decreased activities of POD and CAT, suggesting impaired ROS scavenging.
• Yamian A displayed delayed tapetal PCD with lower ROS content and higher SOD and POD activities compared to its maintainer.
• Mitochondrial ROS overproduction and overflow from complex III were identified as potential sources of excess ROS in Jin A, correlating with reduced ATP content.

Conclusions:

• Differential regulation of ROS generation and scavenging enzyme activities significantly impacts tapetal PCD progression and microspore development, leading to male sterility in cotton.
• In Jin A, accelerated tapetal PCD may be driven by mitochondrial ROS overproduction, resulting in energy deficiency and male sterility.
• These findings provide novel insights into the molecular mechanisms of cotton CMS and offer guidance for future research directions.