Characterization of watermelon anther and its programmed cell death-associated events during dehiscence under cold stress
The ‘neglected’ thermophile fruit crop of watermelon was first used as a model crop to study the PCD associated with anther dehiscence in cold-exposed condition during anther development.
Anther dehiscence ensures normal pollen release and successful fertilization at fruit-setting stages in flowering plants. However, most researches pertinent to anther dehiscence are centered on model plant and/or major field crops under optimal growth condition. Due to anther indehiscence in cold condition, crop plants of thermophile tropical or subtropical fruit crops fail to accomplish timely pollination and fertilization, resulting in a great yield loss annually. Herein, we developed an ideal model crop for studying the programmed cell death (PCD) associated with anther dehiscence under low-temperature stress using the S-shaped spiral anther in watermelon as instead. Our results revealed that, including the tapetal cell layers, both cells of the interlocular septum and the stomium were blocked in PCD associated with anther dehiscence at 15 °C. Likewise, TUNEL assays visualized the evidence that low temperature at 15 °C interferes with not only the PCD of tapetal cells, but also the PCD of interlocular septum and stomium. Furthermore, the expressions of genes correlated with PCD of tapetum and stomium were significantly inhibited at 15 °C, suggesting that low temperature affects anther dehiscence by inhibiting PCD of sporophytic tissue-related gene expressions. The findings of the current research provide mechanistic insights into anther indehiscence leading to poor fruit-setting for thermophile fruit crop such as watermelon under adverse cold condition in flowering.
KeywordsAnther dehiscence Cold stress PCD Thermophile crop Watermelon
This work was supported by National Natural Science Foundation of China (Grant No. 31672175), the Key Science and Technology Program for Agricultural (Vegetable) New Variety Breeding of Zhejiang Province (2016C02051-4-1) and the Earmarked Fund for Modern Agro-Industry Technology Research System of China (CARS-26-17).
Author contribution statement
XL, ZH, and MZ conceived and designed the study. XL, SC and NL performed the experiments. XL, JY and JL analyzed the data, and XL and MZ wrote the paper. All authors reviewed the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no competing interests.
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