外源GABA对双孢蘑菇细胞壁代谢及木质化进程的影响

为了探究γ-氨基丁酸(γ-aminobutyric acid,GABA)处理对双孢蘑菇细胞壁代谢及木质化进程的影响,本文研究了5 mmol/L GABA处理对双孢蘑菇几丁质、纤维素、木质素含量以及细胞壁代谢和木质素合成的相关酶活力的影响(4℃贮藏12 d)。结果表明:GABA处理能显著(P<0.05)抑制双孢蘑菇几丁质酶和纤维素酶的活力,减缓几丁质和纤维素的降解,这说明GABA处理能较好维持细胞膜的结构和抗压力。在贮藏6 d后,双孢蘑菇中的木质素含量不断升高,木质化进程不断加深。相关性分析表明,木质素含量与苯丙氨酸解氨酶活力(PAL)活力呈极显著负相关(P<0.01),而与肉桂醇脱氢酶(CAD)活力呈极显著正相关(P<0.01)。GABA处理组木质素含量低于对照组,PAL活力高于对照组,而CAD活力却低于对照组,这说明GABA能够通过提高PAL活力和抑制CAD活力来降低双孢蘑菇木质素的积累,进而延缓其木质化进程。

Effects of Exogenous GABA on Cell Wall Metabolism and Lignification of Agaricus bisporus

In order to investigate the effect of γ-aminobutyric acid(GABA)treatment on cell wall metabolism and lignification of Agaricus bisporus,the effects of 5 mmol/L GABA treatment on chitin,cellulose,lignin contents,cell wall metabolism and lignin synthesis of A. bisporus were studied(storaged at 4℃ for 12 d). The results showed that GABA treatment could significantly(P<0.05)inhibit the activities of chitinase and cellulose,and slow down the degradation of chitin and cellulose in A. bisporus,indicating that GABA treatment could maintain the structure of cell membrane and resist pressure. After 6 d storage,the lignin contents increased dramatically,and the degree of lignification was improved. The correlation analysis showed that the lignin contents was negatively correlated with phenylalanine ammonia lyase(PAL)activity(P<0.01)and positively correlated with cinnamyl alcohol dehydrogenase(CAD)activity(P<0.01). The lignin contents of GABA treatment group was lower than that of control group,and the activities of PAL and CAD were higher and lower than that of control group,respectively,which indicated that GABA could reduce the lignin accumulation of A. bisporus by increasing PAL activity and inhibiting CAD activity,and then delayed its lignification process.