Abstract
In photoperiod-sensitive genic male sterile rice (Oryza sativa L.) pollen abort in long day and high temperature, and revert to fertility in short day length and low temperature growth conditions. This type of control of rice plant fertility can facilitate production of hybrid rice using two lines (photoperiod-sensitive genic male sterile (PGMS) and restorer) system. Our objective in this study was to determine anatomical changes in PGMS rice pollen cells induced by long day length and high temperature growth conditions that are responsible for the cell abortion. All materials in this study were sown at Zhejiang University research field at Hangzhou, China 30°15’ N. Seeds of ZAU11S106, a PGMS rice line, were sown so as to obtain two bulks, 1) Extreme sterile pollen bulk and 2) fertile pollen bulk. Rice plants for extreme sterile pollen bulk were sown on March 18th and those for fertile pollen bulk on July 15th, so that they flowered under 13 h or more and under less than 13 h respectively of day light. Transmission electronic microscopes were used to study histological sections of anthers while light microscopes were used to examine whole pollen cells. The tapetal layers and the cytoplasm of the sectioned ZAU11S106 rice anthers from extreme sterile pollen bulk were deformed but those from fertile pollen bulk were normal when compared to the control rice lines ZAU11F121 and Xusui163. Pollen cells from anthers of extreme sterile pollen bulk had eroded exine and intine, missing or damaged nucleus, and disintegrating cytoplasm that lead to cell abortion. Our conclusion is that, cell abortion observed in extreme sterile pollen bulk of photoperiod genic male sterile rice, display “programmed cell death–like behavior”. Key words: Pollen cell abortion, photoperiod genic male sterile rice, programmed cell death-like, tapetum.
Highlights
IntroductionCells systematically die due to environmental conditions such as pathogen attack, aging, and for development and homeostasis (Bouillet and Strasser, 2002; Pozo and Lam, 1998; Vaux and Strasser, 1996)
Cell death in a programmed manner has been reported in both plants and animals
Our objective in this study was to determine anatomical changes in photoperiod-sensitive genic male sterile (PGMS) rice pollen cells induced by long day length and high temperature growth conditions that are responsible for the cell abortion
Summary
Cells systematically die due to environmental conditions such as pathogen attack, aging, and for development and homeostasis (Bouillet and Strasser, 2002; Pozo and Lam, 1998; Vaux and Strasser, 1996). The major type of programmed cell death (PCD), has been reported in both plants and animals (Greenberg, 1996; Mittler et al, 1997; Yamada et al, 2001; Bouillet and Strasser, 2002). Cysteine proteases called caspases regulate animal programmed cell death (Whyte, 1996) and in plants, protease(s) that participate in hypersensitive plant responses to pathogens have been reported (Pozo and Lam, 1998)
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