Post-pollination endogenous phytohormone levels in reproductive organs in two interspecific Arachis crosses differing in compatibility

Wild Arachis species are of great value to the genetic improvement of the cultivated peanut; however, incompatibility hinders the utilization of the species outside section Arachis. Imbalance of endogenous phytohormones was hypothesized, but not yet well confirmed and elucidated. Using UPLC-ESI–MS/MS, we were able to determine the phytohormone levels in flower bases 3 days after pollination and pegs/pods 5 and 10 days after soil penetration. The results showed that, in terms of significantly changed phytohormones, the proportion of down-regulated auxins and cytokinins gradually increased as reproductive development progressed. Significant reduction in the levels of gibberellins in pegs/pods was also recorded. This study suggested that to overcome incompatible obstacles in wide crosses in the genus Arachis, early post-pollination application of hormone mixtures incorporating auxins, cytokinins and gibberellins should be beneficial.