Pests are the major enemy of agriculture and forestry production. It is reported that they cause staggering economic losses, reaching 250 billion dollars per year on a worldwide basis. They are also one of the primary reasons for significant yield losses in China.
In order to control pests, farmers have to apply pesticides extensively, which not only elevate costs tremendously, but pose a crippling threat to mankind and the environment. Therefore, cultivating strains with strong resistant to pests becomes the most eco-friendly, economical and effective approach.
The cultivation of Bacillus thuringiensis (Bt) cotton and Bt corn—genetically modified pest resistant varieties—plays a crucial role in killinglepidopteran pests. However, these Bt crops are not resistant to other pests. Moreover, people are also concerned about the safety of GM food. Thus, this technology has not yet applied to grain crops in China. This calls for an urgent need to cultivate new pest-resistant varieties.
Prof. SHU Qingyao, Prof. LOU Yonggen and Prof. YE Gongyin with the State Key Laboratory of Rice Biology, Zhejiang University, conducted a relevant research in collaboration with researchers from Jiaxing Academy of Agricultural Sciences, Wuxi Hupper Bioseed Ltd. and Newcastle University.
They report that biosynthesis of serotonin, a neurotransmitter in mammals, is induced by insect infestation in rice, and its suppression confers resistance to planthoppers and stem borers, the two most destructive pests of rice. Serotonin and salicylic acid derive from chorismate. In rice, the cytochrome P450 gene CYP71A1 encodes tryptamine 5-hydroxylase, which catalyzes conversion of tryptamine to serotonin. In susceptible wild-type rice, planthopper feeding induces biosynthesis of serotonin and salicylic acid, whereas in mutants with an inactivated CYP71A1 gene, no serotonin is produced, salicylic acid levels are higher and plants are more insect resistant. The addition of serotonin to the resistant rice mutant and other brown planthopper-resistant genotypes results in the loss of insect resistance. Similarly, serotonin supplementation in an artificial diet enhances the performance of both insects.
These insights demonstrate that regulation of serotonin biosynthesis plays an important role in defense, and may prove valuable for breeding insect-resistant cultivars of rice and other cereal crops.
Relevant findings are published in the May 7 issue of the journal of Nature Plants.
