Cassava is an important food crop and economic crop in the world. Tetranychus urticae is one of the important alien invasive pests and one of the four major cassava pests in China. Breeding and utilization of mite resistant varieties is an important means to realize green integrated pest control. The exploitation and utilization of secondary metabolites with mite resistance function and their regulation genes can effectively breed mite resistant varieties in crops. Flavonoid play an important role in plant defense against phytophagous pests, however, there is little knowledge about the function of flavonoid pathway genes in cassava resistance to mite. Based on this, this study used mite-resistant and mite-susceptible cassava cultivars were used to analyze the flavonoid pathway genes related to plant insect resistance and to analyze the difference of gene expression after mites fed for 1 d and 4 d, respectively. The results showed that, compared with before those mites fed, the relative expression of CHS, PGT1, F3H, FLS, LAR, C3'H and CYP93B_16 genes in the cassava cultivars of BREAD, SC9 and BAR900 showed a trend of first decreasing (1 d) and then increasing (4 d) to the levels before the mites feed (0 d), while the relative expression of the above genes in the mites-resistant cassava cultivars C1115, SC9 and Myanmar showed a trend of first significantly increasing (1 d) and then decreasing (4 d). However, they were all significantly higher than those of the levels before the mites feed (0 d). Further comparison of the differences in the expression of the flavonoids synthesis pathway gene in the mites-resistant and sensitive tapioca cultivars before and after mites was infested, it was found that after the pest of the two-spotted spider mites was harmed for 1 d, the expression of CHS, PGT1, FLS and C3'H in the mites-resistant cassava cultivars was significantly higher than that in the sensitive mites cassava varieties. Correlation analysis showed that the expression of the four genes was significantly and positively correlated with cassava mite resistance. Before mites (0 d) and 4 days after mites infestation, the expression of the above genes in mites-resistant cassava varieties was generally higher than that of the tapioca cultivars. The results speculated that mite-resistant cassava cultivar could activate flavonoid pathways to defend T. urticae infestation. This study would lay a theoretical foundation for further elucidating the molecular mechanism of cassava resistance to mite, and for breeding and creating mite-resistant cassava cultivars.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |