低温促进毛竹叶片类黄酮合成及相关基因的表达模式分析

Low Temperature Promotes Flavonoid Synthesis and Expression Pattern Analysis of the Related Genes in Leaves of Phyllostachys edulis

摘要:

类黄酮在植物耐低温胁迫方面发挥着重要作用，为揭示低温对毛竹(Phyllostachys edulis)叶片中类黄酮合成的影响，采用分光光度法测定了不同生长时期和低温胁迫下毛竹幼苗叶片中的类黄酮含量，通过生物信息学方法对毛竹类黄酮早期生物合成关键酶基因进行了鉴定，并用qPCR方法分析了其表达模式。结果表明，随着叶片的生长，类黄酮含量呈现先升高后降低的趋势，而低温下，功能叶片中类黄酮含量则呈现上调趋势，且在8 h时达极显著水平。在毛竹基因组中鉴定了类黄酮早期生物合成3个酶基因家族共29个成员，包括20个查尔酮合酶基因(PeCHSs)、8个查尔酮异构酶基因(PeCHIs)和1个黄酮-3-烃化酶基因(PeF3H1)，这些基因的启动子中均含有响应低温及其他非生物胁迫的调控元件。PeCHSs倾向在根和叶中表达, 而PeCHIs为组成型表达。在不同生长时期的叶片中，仅PeCHS1表达与类黄酮的含量变化趋势一致；而低温胁迫下，3个PeCHSs、2个PeCHIs和PeF3H1在功能叶片中呈上调表达，与类黄酮含量变化趋势一致。因此，毛竹可能通过提高类黄酮早期生物合成酶基因的表达量促进类黄酮的合成来响应低温胁迫。

Abstract:

Flavonoids play an important role in plant resistance to low temperature stress. To reveal the effects of low temperature on flavonoid synthesis in leaves of Phyllostachys edulis, the content of flavonoid in leaves of bamboo seedlings at different growth stages and under low temperature stress was determined by spectrophoto- metric method, the key enzyme genes of early biosynthesis of flavonoid in bamboo were identified by bioinfor- matics methods and their expression patterns were analyzed using qPCR. The results showed that the flavonoid content increased at first and then decreased, while that in the functional leaves increased under low temperature and reached significant level at 8 hours. There were a total of 29 members, belonging to three gene families, involved in early biosynthesis of flavonoid in P. edulis, including 20 chalcone synthase genes (PeCHSs), eight chalcone isomerase genes (PeCHIs) and one flavanone-3-hydroxylase gene (PeF3H1), the promoters of these genes all contained regulatory elements in response to low temperature and other abiotic stress responses. The PeCHSs tended to be expressed in roots and leaves, while PeCHIs expressed constitutively. Only the expression trend of PeCHS1 was consistent with the content of flavonoid in P. edulis leaves at different growth stages, while six key enzyme genes (3 PeCHSs, 2 PeCHIs and PeF3H1) were upregulated continuously in functional leaves under low temperature, which was consistent with the change trend of flavonoid content. Therefore, Phyllostachys edulis might respond to low temperature stress by increasing the expression of genes involved in early biosynthesis of flavonoid.