Study On An Ethylene-Related Mutant Ecs1 In Arabidopsis

Ethylene, one of the six plant hormones, is widely present in the plant and regulates a variety of processes of growth and development. These effects include "triple response", stimulating root initiation, inhibiting seedling elongation, promoting fruit ripening and so on.A homozygous mutant ecsl (epidermal cell swelling) which was isolated from an EMS (0.2%) mutagenesized Arabidopsis population was used in this study, ecsl shows rounded leaves, shorter petioles, swollen cells in epidermal of leaves and hypocotyls. It shows shorter, thicker hypocotyl in the dark, a similar phenotype of ethylene "triple response". It has shorter root, increased root hairs number in the light. Thus, we speculate that it may be related to ethylene metabolism, ecsl shows reduced sensitivity to ACC when exogenous application of the ethylene precursor ACC. In the condition of exogenous application of AVG and Ag+, the ethylene synthesis inhibitor and ethylene action inhibitor respectively, the root and hypocotyl length of ecsl shows no significant disparity, but the root hair number reduced significantly in ecsl. Gas chromatograph analysis showed that the ethylene content in ecsl was two times than that in the wild type. Hence we speculate that ECS1 may be involved in the ethylene biosynthesis pathway or signal transduction.However, the results by yeast two-hybrid system displayed that there was no direct interaction between ECS1 and some key ethylene signal pathway components including EIN3, CTR1, EBF, MAPK6, EDF1, ERF1, or some key ethylene biosynthesis pathway components including ACS5, ACS6, ACS7. We also constructed double mutant between ecsl and ethylene signal pathway mutant like etrl-3, ein3-l,ctrl-1. The genetic analysis indicated that ECS1 may not participate in ethylene signaling.All of these results suggested that ECS1 may be not involved in the ethylene signaling pathway, but may be related to the ethylene biosynthesis pathway. Simultaneously, we speculated that ECS1 may interact with some unknown signaling pathway to affects the epidermal cell morphogenesis.