Transcriptome and metabolome reveal the role of flavonoids in poplar resistance to poplar anthracnose
Linxuan Zhang, Hangbin Bao, Fanli Meng, Yue Ren, Chengming Tian
Abstract
Poplar anthracnose, caused mainly by Colletotrichum gloeosporioides, is one of the most important diseases occurring in poplar plantations in China, and it causes serious economic and ecological losses every year. Different poplar crosses and species have different degrees of resistance to poplar anthracnose; Populus × canadensis is resistant, P. tomentosa is susceptible, and P. × beijingensis exhibits intermediate resistance. To investigate the reasons for differences in resistance to poplar anthracnose, we performed metabolomic and transcriptomic analyses of these three poplars. Metabolomic analyses showed that, after C. gloeosporioides infection, 117, 112, and 52 secondary metabolites accumulated in P. × canadensis, P. × beijingensis, and P. tomentosa, respectively; of which 31, 27, and seven, respectively, were flavonoids. The total flavonoids content was higher in P. × canadensis and P. × beijingensis than in P. tomentosa. Transcriptomics analyses showed that, after infection with C. gloeosporioides, the transcript levels of most flavonoid biosynthesis genes were highest in P. × canadensis, followed by P. × beijingensis, and lowest in P. tomentosa. These results were verified by qRT-PCR. Therefore, we speculate that the degree of anthracnose resistance in poplar is related to the types and contents of flavonoids and the transcript levels of genes in the flavonoid biosynthesis pathway. This information will be useful for devising new strategies to control poplar anthracnose and to breed new, resistant poplar materials.