Abstract:

In order to study the response of mycelia of different Lentinula edodes strains to heat stress， comprehensively evaluate their heat resistance and screen out key indicators， 9 Lentinula edodes strains were used as experimental materials， and 25 ℃ normal temperature culture (CK) and 37 ℃ heat stress treatment were carried out during the mycelia growth period. The growth rate， dry weight， thiobarbituric acid reactive substances (TBARS)， protein carbonyl (PCO)， superoxide dismutase (SOD)， catalase (CAT)， peroxidase (POD)， laccase， carboxymethyl cellulase， hemicellulase and amylase activities of mycelia under different treatments were determined. The comprehensive evaluation of heat resistance and screening of key indicators were carried out by correlation analysis， principal component analysis， membership function and cluster analysis. The results showed that the growth rate and dry weight of mycelia after heat stress were significantly lower than those of CK， while the contents of TBARS， PCO and the activities of SOD， CAT， laccase， carboxymethyl cellulase， hemicellulose and amylase were extremely significantly higher than those of CK， and the activity of POD was significantly higher than that of CK. Among 9 strains， Xinqiu 7 had the biggest variation range on the growth rate， the activities of laccase， hemicellulose， amylase， and the TBARS content， which were 66.55%， 82.42%， 46.03%， 75.27% and 23.64%， respectively. The dry weight of 109 decreased the most， which was 77.81%. The PCO content of 808 increased the most， which was 43.77%. The activities of SOD and POD of 212 were 1.64 and 4.48 times of CK， respectively. The CAT of Jiuxiangqiu 7 increased by 49.90%. The carboxymethyl cellulase activity of 1513 decreased by 60.87 %. Correlation analysis showed that there was a significant positive correlation between SOD and POD activity， and POD activity was significantly negatively correlated with TBARS content. Based on the comprehensive evaluation D value of heat resistance， 9 strains were classified into 3 types. TypeⅠ included 212， Jiuxiangqiu 7， 238 and 0912； type Ⅱ included 9608， 808， 1513 and 109； type Ⅲ only included Xinqiu 7； and the heat resistance of 3 types showed Ⅰ>Ⅱ>Ⅲ. The best regression model was established by stepwise regression analysis. The growth rate of mycelia， TBARS content， SOD and POD activity were selected as the key identification indexes， which could quickly identify the heat resistance of mycelia. Above results provided a theoretical basis for the breeding of heat-resistant core germplasm of Lentinula edodes in southern Xinjiang.

Key words: Lentinula edodes, heat stress, restore growth rate, thiobarbituric acid reactive substances （TBARS）, antioxidant enzyme

摘要：

为研究不同香菇菌株菌丝对热胁迫的响应，综合评价其耐热性，筛选出关键指标，以9个香菇菌株为试验材料，在菌丝生长期分别进行25 ℃常温培养（CK）和37 ℃热胁迫处理，测定不同处理下菌丝的生长速度、干重、硫代巴比妥酸反应物（thiobarbituric acid reactive substances，TBARS）、蛋白质羰基（protein carbonyl，PCO）、超氧化物歧化酶（superoxide dismutase，SOD）、过氧化氢酶（catalase，CAT）、过氧化物酶（peroxidase，POD）、漆酶、羧甲基纤维素酶、半纤维素酶及淀粉酶的生理活性，并通过相关性分析、主成分分析、隶属函数及聚类分析进行耐热性综合评价。结果表明，热胁迫后菌丝的生长速度、干重较CK极显著下降，而TBARS 、PCO含量和SOD、CAT、漆酶、羧甲基纤维素酶、半纤维素及淀粉酶活性较CK极显著上升，POD活性较CK显著上升。其中，新秋 7的生长速度和漆酶、半纤维素、淀粉酶活性的降幅及TBARS含量的增幅最大，分别为66.55%、82.42%、46.03%、75.27%、23.64%；109的干重降幅最大，为77.81%；808的PCO含量增幅最大，为43.77%；212的SOD、POD活性增幅最大，分别为CK的1.64、4.48倍；久香秋 7的CAT增幅最大，为49.90%；1513的羧甲基纤维素酶活性降幅最大，为60.87%。相关性分析表明，SOD与POD活性呈极显著正相关；POD活性与TBARS含量呈极显著负相关。以耐热性综合评价D值进行排序分类，将9个菌株划分为3个类群，Ⅰ类包含212、久香秋7、238和0912；Ⅱ类包含9608、808、1513和109；Ⅲ类仅包含新秋7；3个类群的耐热性表现为Ⅰ>Ⅱ>Ⅲ。经逐步回归分析建立了最佳回归模型，筛选出菌丝生长速度、TBARS含量及SOD和 POD活性为耐热性关键鉴定指标，可快速鉴定菌丝的耐热能力。以上研究结果为南疆地区选育耐热香菇核心种质提供理论依据。

关键词: 香菇, 热胁迫, 生长速度, 硫代巴比妥酸反应物, 抗氧化酶