过氧化氢调控菜心采后木质化的机理初探

Regulation of Hydrogen Peroxide on the Lignification of Chinese Flowering Cabbage after Harvest

摘要:

为研究过氧化氢（Hydrogen peroxide，H2O2）在菜心贮藏保鲜中的作用，该研究用5 mmol/L H2O2浸泡处理鲜切菜心，置于4 ℃下贮藏，对贮藏期内菜心薹茎的品质变化、酶活性、基因表达差异进行分析，初步明确H2O2信号对鲜切菜心茎木质素合成的调控作用。结果显示：H2O2处理导致菜心的呼吸速率、茎木质素含量及内源H2O2含量增加，贮藏12 d时，茎木质素含量增加了35.78%，H2O2含量提高2.71倍；木质素合成途径关键酶的苯丙氨酸解氨酶（phenylalanine ammonia-lyase，PAL）、肉桂醇脱氢酶（Cinnamyl alcoholdehydrogenas，CAD）在贮藏9 d比对照组酶活性分别提高85.70%、15.53%。基因水平分析发现，H2O2处理提高了木质素合酶基因（POD37、PAL4、PAL8）、活性氧生成酶基因（RbohB、RbohG）及其清除酶基因（SOD1、SOD2、SOD3、CAT3）在不同贮藏时期内的表达。综上所述，5 mmol/L H2O2处理导致了采后薹茎木质素的增加，加快品质劣变，不利于菜心贮藏保鲜效果，推测H2O2处理通过影响活性氧平衡系统，对内源H2O2含量进行调节，影响木质素合成。该研究结果说明H2O2在采后贮藏保鲜过程中具有重要调节作用。

Abstract:

The effect of hydrogen peroxide on the storage and preservation of Chinese flowering cabbage were investigated by soaking in 5 mmol/L hydrogen peroxide and stored at 4 ℃. The changes of lignin content, activity of enzymes and relative expression levels of genes that involved in lignin biosynthesis in stem were carried out to explore the influence of H2O2 signal on the regulation of lignin synthesis of Chinese flowering cabbage. The results showed that respiration rate, lignin content, and endogenous H2O2 content of Chinese flowering cabbage were promoted by the hydrogen peroxide treatment. When stored for 12 days, the stem lignin content increased by 35.78% and H2O2 content increased by 2.71 times. Meanwhile, the activity of enzymes involved in lignin biosynthesis were accelerated by H2O2 treatment i.e., the activity of phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol dehydrogenas (CAD) was increased by 85.70% and 15.53%, respectively, after storage for 9 days. The relative gene expression levels of lignin biosynthesis gene and involved in reactive oxygen generating, SOD1, SOD2, SOD3, and CAT3 involved in reactive oxygen scavenging were upregulated by H2O2 treatment during storage. These results indicated that the lignification of stalk in Chinese flowering cabbage was promoted by 5mM H2O2 treatment. It is concluded that H2O2 may alter the endogenous H2O2 content by affecting the homeostasis of ROS system, thereby, regulating the biosynthesis of lignin to affect the stalk lignification.