Identification Of Heat Tolerance In Chinese Kale And The Expression Analysis Of Heat Tolerance Transcription Factor MBF1c

Chinese Kale( Brassica oleracea var.alboglabra Bailey) alsoknown as white flower Chinese kale,is one of the specialvegetables in south China. It is loved by people because ofrispanddelicious, rich nutrition. Chinese kale is a thermophilic vegetable, which can,t well grow at high temperature. High temperaturewould prevent chinese kale from growing and result in poor quality of its seedlings, seriously influencyield and quality in later period in summer and autumn. Ten chisnses kale lines were usedto study their growth,heat injury index,malondiadehyde(MDA),proline,free protein,electric conductivity and the activites of SOD, POD, CATby using spectrophotometer,aiming to provide theoretical reference for screeing heat-resistant materials and breeding of chinese kale.The resultsareas following:Compared with reference temperature, in the temperature stress(37℃), the overground and underground part weightof plantdecreased, and that of varities with stronger tolerance to heat decreased less, the internodelongincreasedand that of varities with stronger tolerance to heat increased less.Heat damage index and relative growth under the temperature of 37 ℃showed significant correlation with heat tolerance.Both of them could be used to determine the heat-tolerant ability of chinese kale lines,which can be most quick and convenient.With the stress temperatureup,the content of Pro, soluble protein showed trendofincreased.Besides,hightemperature alsoincreasedtheactivityof SOD, POD, CAT,but the magnitude in No1 was more bigger than No59.Along with the increase temperature,MDA content and relative electric conductivityincreased in chinese kale and the that of varities with stronger tolerance to heat increased less that with susceptive to heat. The correlationship was significant between the change in free protein content, activity of SOD, POD, CAT and heat damage index, growth under the treatment of 40℃.It was significant between the change in content of proline, MDA andheat damage index, growth under the treatment of 37℃. The difference in heat tolerance among the varieties could be indicated by physiological and chemical index under 37℃ or 40℃.After thetreatment of 37℃for 1hour the expression variation of MBF1 cwas increased by quantitation PCR.The expression variation of MBF1 c in heat-resistantvarieties was higher than those in heat-susceptible. Accordingto the comprehensive analysis,No25 wasthe most heat-tolerant lines.