OAR@ICRISATCharacterization of low Ca2+ stress-induced embryo apoptosis response genes and their regulation of embryo developmentHChenauthorCZhangauthorT CCaiauthorYDengauthorS BZhouauthorR KVarshneyauthorW JZhuangauthorCa2+ deficiency in soil induces early embryo abortion in peanut, producing empty pods, or ill-filled pods, especially under drought condition, 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, which were classified to be stress responses, catabolic process, carbohydrate and lipid metabolism, embryo morphogenesis, and regulation. The cell retardation with cell wall degradation was caused by up-regulated cell wall hydrolases and down-regulated cellular synthases genes. Two CYP707A4 genes, encoding abscisic acid (ABA) 8’-hydroxylases, key enzymes for ABA catabolism, were up-regulated by 21-fold under Ca2+-deficient conditions, 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 CYP707A4 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. A set of varieties with different sizes of pods were evaluated for their tolerance to calcium stress, and we found that big pod varieties showed less tolerance to low calcium and more easy to produce ill-filled pods or empty pods. Drought will make worse of the phenomenon. Soil supplied with rich calcium will improve the pods filling and greatly reduce number of empty pods. We conclude big-pod varieties easier to produce empty pods are also associated with calcium level in the soil.Genetics and Genomics2017-02Conference or Workshop Item

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