Identification of low Ca2+ stress‐induced embryo apoptosis response genes in Arachis hypogaea by SSH‐associated library lift (SSHaLL) |
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Authors: | Tie cheng Cai Ye Deng Shuangbiao Zhou Yixiong Zheng Shiwei Ma Ronghua Tang Rajeev K Varshney Weijian Zhuang |
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Institution: | 1. Fujian Provincial Key Laboratory of Crop Molecular and Cell Biology, Fujian Agriculture and Forestry University, Fuzhou, China;2. Cash Crops Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, China;3. International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT), Patancheru, India |
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Abstract: | Calcium is a universal signal in the regulation of wide aspects in biology, but few are known about the function of calcium in the control of early embryo development. Ca2+ deficiency in soil induces early embryo abortion in peanut, producing empty pods, which is a general problem; however, the underlying mechanism remains unclear. In this study, embryo abortion was characterized to be caused by apoptosis marked with cell wall degradation. Using a method of SSH cDNA libraries associated with library lift (SSHaLL), 62 differentially expressed genes were isolated from young peanut embryos. These genes were classified to be stress responses, catabolic process, carbohydrate and lipid metabolism, embryo morphogenesis, regulation, etc. The cell retardation with cell wall degradation was caused by up‐regulated cell wall hydrolases and down‐regulated cellular synthases genes. HsfA4a, which was characterized to be important to embryo development, was significantly down‐regulated under Ca2+‐deficient conditions from 15 days after pegging (DAP) to 30 DAP. Two AhCYP707A4 genes, encoding abscisic acid (ABA) 8′‐hydroxylases, key enzymes for ABA catabolism, were up‐regulated by 21‐fold under Ca2+‐deficient conditions upstream of HsfA4a, reducing the ABA level in early embryos. Over‐expression of AhCYP707A4 in Nicotiana benthamiana showed a phenotype of low ABA content with high numbers of aborted embryos, small pods and less seeds, which confirms that AhCYP707A4 is a key player in regulation of Ca2+ deficiency‐induced embryo abortion via ABA‐mediated apoptosis. The results elucidated the mechanism of low Ca2+‐induced embryo abortion and described the method for other fields of study. |
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Keywords: |
Arachis hypogaea
SSHaLL embryo abortion Ca2+ stress
Cyp707A4
abscisic acid |
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