Effect Of Exogenous Jasmonic Acid(JA) On Metabolism Of Pyrethrin Pathway And Aphid Resistance Of Pyrethrum

Pyrethrum(Chrysanthemum cinerariifolium,syn.Tanacetum cinerariifolium)is asteraceae perennial ornamental herbaceous flower,which is also an insecticidal plants famous for natural pyrethrin extracting from its flower head.But the average pyrethrin content of widely cultivated pyrethrum varieties is low(about 1.5%-1.8%),making the demand of natural pyrethrin market exceeds the supply.Jasmonic acid(JA),a plant hormone widely existing in nature,is an important way to improve the plant secondary metabolites content.This thesis taking pyrethrum 'NO.34' genotypes as the main experimental materials,two different treatments,spraying and soaking are used.qRT-PCR,HPLC,GC-MS technologies are usedrespectivelyto research the effect of JA treatment on pyrethrin synthesis genes,pyrethrin content and inclusions.The objective of the present study was,therefore,to investigate effects of exogenous JA on metabolism of pyrethrin and resistance to aphids in pyrethrum plants.The results are as followings:1.The expression of pyrethrin synthesis genes,TcCDS,TcCYP,TcLOX,TcGLIP shows consistent trends after 300?M JA spraying treatment.4 genes raised to the highest expression levelwithin 2 hours.Pyrethrin content is lagging behind the synthetic genetic changes,significantly increased after 6 hours of treatment,while the leaf inclusions class raised to top in 2 hours to agree with gene expression quantity change trend.Major changeinclusionsare esters and terpenes.2.After 300?M JA soaking treatment,only TcCYP expression quantity increase significantly after treatment for 2 hours,while other 3 pyrethrin synthesis genes not raised.Pyrethrin content of treated plants and untreated plants at the same level in most of the time,but significantly higher than that of wild type plants after 24 hours.3.By comparing two JA treatment results,gene response is more rapid,consistent and larger after JA spraying treatment.The expression level of TcCYP is more than 24000 times than untreated plants,and the change of pyrethrin content is also more significant.The results show that the single hormone induced can start corresponding genes of pyrethrin synthesis metabolism,and long-term treatment effect is not obvious.4.Continuous long-term JA treatment can promote the formation of pyrethrum trichomes,and improve the resistance to aphid.Therefore,short time of JA treatment can stimulate the pyrethrin synthesis genes synergy to rise,facilitate the pyrethrin and other secondary metabolites accumulation.However long-term of JA treatment can promote formation of trichomes and aphid resistance of pyrethrum seedlings.Trichomes density promote 5/mm2,whileaphid resistance promote 20 per plant.This study laid foundation for revealing the relationship of hormone signal of pyrethrins metabolic gene function and regulation mechanism.It has a certain application value and practical significance for improving pyrethrin content and aphid resistance of pyrethrum.This thesis has paved the way for the pyrethrin synthesis pathway gene mining,of great significance in improving the pyrethrin content and pyrethrum aphid resistance.Then improve varieties and enhance pyrethrin production to ease market demand.