不同核桃品种的耐寒性及其渗透调节机制

Cold-tolerance and Osmoregulation Mechanism of Walnut Cultivars

以‘香玲’、‘鲁W06-1’、‘西洛3号’3个核桃品种（优系）为材料,对低温胁迫各材料的耐受情况及相应渗透调节物质含量和总蛋白质表达的变化情况进行分析,以揭示低温胁迫下不同核桃品种（优系）的渗透调节机制和蛋白质组分差异。结果显示：（1）3个核桃品种（优系）休眠枝条解剖结构分析表明,‘鲁W06-1’一年生休眠枝条的木质部比率最大,‘西洛3号’的韧皮部厚度显著大于其他两个品种（优系）。（2）随胁迫温度降低和胁迫时间的延长,枝条相对电导率（REC）逐渐升高,且‘西洛3号’的相对电导率均大于‘鲁W06-1’和‘香玲’。（3）核桃枝条可溶性糖、可溶性蛋白和游离脯氨酸含量均随温度降低先增加后减小,但各品种（优系）增至最大值的温度不同,其中‘鲁W06-1’枝条积累可溶性蛋白的速度和幅度较大,且各低温胁迫处理后的枝条可溶性糖和游离脯氨酸的含量也更高;3种渗透调节物质含量之间均呈极显著正相关关系,可溶性糖与游离脯氨酸含量的相关系数达0.844,表明二者对低温胁迫的应答反应密切相关。（4）在不同胁迫温度和胁迫时间处理后,核桃枝条的蛋白质表达谱带总体相似,但检测出6条表达量明显增加的差异条带,它们的分子量范围为38.9～87.9 kD。研究表明,3个核桃品种（优系）的耐寒性强弱为‘鲁W06-1’〉‘香玲’〉‘西洛3号’;低温胁迫下,核桃枝条迅速积累可溶性蛋白,然后积累可溶性糖和游离脯氨酸,并以耐寒性较强品种（优系）积累速度更快、积累量更大,且耐寒性较强的品种（优系）枝条蛋白谱带出现较多表达量增加的条带。

Three walnut cultivars （superior line）,‘Xiangling’,‘Lu W06-1’ and ‘Xiluo 3’,were used as experimental materials to study their cold-tolerance and the effect of different low temperatures and times on walnut’s osmolytes content and protein expression.Results showed that：（1）The ratio of xylem of ‘Lu W06-1’s 1-year-old twigs was the largest,and thickness of phloem of ‘Xiluo 3’ was significant larger than that of others.（2）With the temperature decreasing,relative electric conductivity （REC） increased gradually,and the REC of ‘Xiluo 3’ was almost larger than that of other two walnut cultivars （superior line） under every treatment.（3）The contents of soluble sugar （SS）,free proline （FP） and soluble protein （SP） increasing firstly and then decreasing.However,the temperatures that increased to maximum value were still different.The SP contents of ‘Lu W06-1’ increased faster and larger,and its SS and FP contents were always larger than that of others under treatments.There were significant positive correlations between any two osmolytes of the three osmolytes,especially the correlation coefficient between SS and FP,which was 0.844.These indicated that their respond to cold stress were linked by a close relationship.（4）Electrophoretic protein patterns showed similar among different treatments,but there were significant accumulation existed in 6 protein bands of walnut branches when exposed to low temperature,which was from 38.9 kD to 87.9 kD.The cold tolerance abilities were ranked in the following order：‘Lu W06-1’〉‘Xiangling’〉‘Xiluo 3’.When exposed to low temperature,SP content of walnut branches accumulated rapidly,then SS and FP increased.In addition,more accumulated protein bands were detected in walnut branch which was more cold-tolerant.