A study on a mechanism of tipburn incidence and selection of resistant cultivars in lettuce

点击翻译按钮获取中文摘要

Lettuce(Lactuca sativa L.) tipburn is a physiological disorder caused by calcium deficiency that decreases the crop value. In this study, an efficient method was established to evaluate lettuce resistance to tipburn in vitro. A sensitive cultivar identified by this method was validated its utility as indicator plants to monitor environmental conditions. On the other hand, to identify the responsible gene for tipburn incidence, four cDNAs corresponding to cation/H^+(CAX) exchanger were isolated from lettuce(LsCAX2, 3a, 3b, and 5). Sequence alignment revealed that both A and B domains which involved in calcium selection were conserved in two LSCAXs. The different expression of LsCAX genes by CaCl_2 between sensitive and resistant cultivars suggested the relevance of these genes to tipburn incidence. AtDREB1A was supposed to be another responsible gene. Overexpression of AtDREB1A in lettuce resulted in increasing tip-burned leaves. This result indicated that tipburn incidence is involved in stress response of lettuce.