EFFECT OF 24-EPIBRASSINOLIDE ON THE PHYSIOLOGICAL AND GENETIC CHANGES ON TWO VARIETIES OF PEPPER UNDER SALT STRESS CONDITIONS

Abstract

This study investigates the effects of using 24-epibrassinolide on two varieties of pepper (Capsicum annuum L.) to decrease the adverse effects of salinity stress. The growth parameters; carotenoid; proline; total anthocyanins; minerals concentrations; isozymes electrophoresis; RAPD-PCR and some leaf anatomical characters in the tested pepper plants (Capsicum annuum L.) varieties were evaluated. The data showed that EBR reduces the reduction in both fresh and dry weights of the 2 varieties of pepper induced by NaCl-stress on 2 varieties of pepper. Proline increased in 2 varieties in the studied in response to NaCl and EBR treatments. Carotenoid decreased with salinity stress, whereas application of 24- epibrassinolide significantly increased carotenoids in the 2 varieties at salinity and EBR 0.1-ppm. Anthocyanins significantly increased with salt and EBR in both varieties. In addition, foliar application of EBR upon NaCl stressed plants, improved the content and uptake of the nutrients (N, P and K) and decreased Na+ percentage in the 2 studied varieties. The thickness of mesophyll width, dimensions of main vascular bundle and number of stomata were decreased at salt stress in comparison with the control .On the other hand these anatomical characters increased as increasing in concentrations 24- epibrassinolide (EBR). Moreover, the diameter of vascular bundle in the leaf blade decreased in two plants. Our observations indicated that pretreatment with 24-epibrassinolide caused improved the above-mentioned attributes. Therefore, it is clear that 24-epibrassinolide provide protection against a salt stress by increasing the activity of some antioxidative enzymes resulted in mitigation of oxidative stress caused by salinity in pepper.