Differences on the microsporogenesis and tapetal development of male fertile and cytoplasmic male sterile pepper (Capsicum annuum L.)

Abstract

To clarify the time and cause of pollen abortion, differences on the microsporogenesis and tapetum development in the anthers of male fertile maintainer line and cytoplasmic male sterile (CMS) line pepper were studied using transmission electron microscopy. The results showed that CMS line anthers appeared to have much greater variability in developmental pattern than male fertile maintainer line ones. The earliest deviation from normal anther development occurred in CMS line anthers at prophase I was cytomixis in some microspore mother cells (MMCs), and vacuolisation in tapetal cells. Then, MMCs in CMS line anthers developed asynchronously and a small part of ones at the different stage degenerated in advance appearing to have typical morphological features of programmed cell death (PCD). Most MMCs could complete the meiosis, but formed non-tetrahedral tetrad microspores with irregular shape and different size and uncertain number of nuclei, and some degenerated ahead of time as well. Tapetal cells in CMS line anther degenerated during meiosis, and were crushed at the tetrad stage, which paralleled the collapse of pollens. Pollen abortion in CMS line anthers happened by PCD themselves, and the premature PCD of tapetal cells were closely associated with male sterility.

Keywords:

• programmed cell death
• pollen abortion
• cytoplasmic male sterility
• Capsicum annuum

Acknowledgements

The authors thank Song Chen, School of Life Science, Hunan Normal University, Changsha, China, and Li Gu, Third Institute of Oceanography, State Oceanic Administration, Xiamen, China, for providing the technical support of transmission electron microscopy observation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Nature Science Foundation of China under grant numbers [31301773] and [31500200]; the Hunan Provincial Construct Programme of the Key Discipline in Ecology under grant number [0713], and the Cooperative Innovation Centre of Engineering and New Products for Developmental Biology of Hunan Province under grant number [20134486].