Study The Influence By Two Pathogenic Funguses Infection On Mango CHS Gene Expression

Chalcone synthase(CHS)catalyzes 1 Acyl-CoA and 3 Malonyl-CoA to condensate into a chalcone for building C6-C3-C6 basic carbon skeleton in plant.Diversity flavonoids derive from chalcone under enzymatic reactions.So CHS is one of the most important enzyme proteins in the flavonoids synthase pathway.Chalcone and its derivatives have been known to be antibacterial and antifungal.And there are some references indicating that CHS gene is involved in plant resistance to pathogen infection process.The inhibitory effects of chalcone to eleven different mango pathogens were in tested in this study.The DNA and cDNA sequences of mango CHSI and CHS2 gene were amplified through homologous cloning method.The structures of the proteins(MiCHS1 and MiCHS2)were analyzed by bioinformatics.The differential expressions of CHS genes in different mango tissues,as well as CHS gene expressions responding to the infection of pathogens,treatments of foliar fertilizer and fungicides were determined using real-time PCR.(1)We verified that chalcone has inhibitory activity to eleven different mango pathogens.Among them,Botryosphaeria dothidea(PZ5),causal agent of mango stem end rot,was most sensitive to the chalcone,while Fusarium proliferatum(MMD27),causal gent of mango malformation was least.(2)The length of MiCHS1 and MiCHS2 genes' cDNA sequence are 1173 bp and 1194 bp respectively.Both genes contain two extons and one intron.Bioinformatics analyze showed that protein MiCHSl and MiCHS2 have no signal polypeptides,but contain more one Malonyl-CoA binding-sites.The two proteins belong to superfamily of carboxylase enzyme.Comer?a-helix and(?-folding are the main secondary structures of the proteins.(3)Real-time PCR results showed that MiCHSl gene was the key MiCHS gene in mango tissues.CHS gene was most frequently expressed in leaves,then in fruits,while expressed least in shoots and buds.(4)When Mango leaves were infected by pathogens,the MiCHS gene expression was up-regulated firstly and then down-regulated.There was a synchronous increase or decrease relationship between chalcone level and expression level of MiCHS gene in leaves.(5)Foliar fertilizer,such as Namei,Guoxi,Kangcui,Bifengbao,copper sulfate or Fupeng,up-regulated MiCHSl and MiCHS2 genes' expression in leaves of mango.Fungicides,such as thiophanate methyl,carbendazim,thiabendazole or propiconazole could up-regulate MiCHSl and MiCHS2 genes' expression in leaves of Mango too.