Embryonic Development and Changes of Endogenous Hormones in Interspecific Hybrids between Peanut (A. hypogaea L.) and Wild Arachis Species

The peanut cultivar Yuhua 15 was used as female parent to cross with wild species A. correntina and A. macedoi, re- spectively, with intervarietal cross Yuhua 15×Baisha 1016 as check. There were no significant differences observed in pegging percentage among all the crosses. It indicated normal fertilization in the interspecific crosses. Embryo development was observed through paraffin sections, and contents of endogenous hormones including IAA, GA 3 , ZR+DHZR, and ABA in the developing embryos of hybrids were determined with ELISA. In comparison with normal seed development of Yuhua 15×Baisha 1016 and Yuhua 15×A. correntina, Yuhua 15×A. macedoi was incompatible due to a deterred embryo development at approximately 12–17 days after pollination followed by the hyperplasia of integument into the embryo sac which suppressed further development of the embryo and finally resulted in abortion. Compared with two compatible crosses, the ABA content and ratios of ABA to total of other auxin in developing embryos of cross (Yuhua 15×A. macedoi) were relatively higher at the early development stage, while the contents of IAA, GA 3 , and ZR+DHZR remained at a relatively lower level, which speculates on that abnormal hormone ac- tivities may be an important reason leading to the abortion of hybrid embryos. Peg bases of Yuhua 15×A. macedoi were treated with IAA, KT, or mixture of the two, showing that the exogenous hormones can increase the length of ovule.