Sesame phytohormone and phenotype response to waterlogging

Abstract

To explore the phytohormone and phenotype responses to waterlogging stress in sesame,tolerant ZZM2541 and susceptible Ezhi 2 were treated with waterlogging for 3h,9h and 15 h at flowering stage. By liquid chromatography- tandem mass spectrometry( LC- MS / MS),the top 3rd leaves and stem tips of these 2 genotypes were investigated for indole acetic acid( IAA) and abscisic acid( ABA) contents at each time point and 20 h after drainage. Phenotype changes were analyzed including shedding leaves and plant heights,and the contents of chlorophyll in the top 3rd leaves before and 72 h after the initial of waterlogging. Results showed endogenous IAA contents in the top 3rd leaves were both increased during the first 9h of waterlogging,and started to decrease after 9h.But the contents were continued to increase in stem tips after 9h of waterlogging. Especially,IAA content in ZZM2541 was always higher than that of Ezhi 2 throughout the stress. The contents of ABA in both genotypes decreased continuously until 15 h of waterlogging and then increased,although they increased more rapidly in the tolerant genotype ZZM2541 and reached about twice of the susceptible one after drainage. Relatively,the plant height and chlorophyll content in the top 3rd leaves( with more leaf abscission) of tolerant ZZM2541 were less affected by waterlogging stress,which could be a protective mechanism. In summary,IAA content at the initial stage of waterlogging( within 9h) and ABA at 20 h after drainage could be used to differentiate the above 2 genotypes.