Preliminary Identification Of PhDHFR Gene Function In Petunia

In animals,plants and other organisms,various metabolisms occur at all times.Folate is the core of plant metabolism.Folate plays an important role in all living organisms.It participates in the synthesis of important biological molecules,such as amino acids,nucleic acids,proteins,and so on.Plants can synthesize folate,but humans can't.Humans need dietary folate,and plant foods are the most important source.Folate biosynthesis control is important for plant growth.Dihydrofolate reductase(DHFR)is a key enzyme in folate biosynthesis.It reduces dihydrofolic acid to tetrahydrofolate.Tetrahydrofolate can participate in one-carbon transfer reactions and a series of biosynthetic reactions.Thymidylate synthase(TS)is a key enzyme in DNA biosynthesis.It catalyzes the methylation of uracil deoxynucleoside(dUMP)to thymidine(dTMP).Thymidine(dTMP)provides precursors for DNA synthesis.Therefore,TS plays an important role in DNA synthesis.In higher plants,DHFR/TS is a bifunctional enzyme.In this study,we preliminary identified the function of PhDHFR in petunia with the technology of VIGS.The main results were as follows:(1)The PhDHFR gene showed different expression levels in different developmental stages of petunia leaves with the highest expression level in young leaves.(2)Compared with control plants,the plants of PhDHFR silencing became dwarf,the plant type was compact,and the flowering was late.The leaves and calyx in the plants of PhDHFR silencing showed different degrees of deformity.The stems of PhDHFR silencing became shorter,and the epidermal cells became shorter and wider,and the arrangement was irregular.The content of folate in the leaves of PhDHFR-silenced plants was decreased.The chlorophyll content in the young leaf stage and the mature leaf stage was lower than control,especially at the base of young leaves.However,the chlorophyll content in the old leaves was higher than the control.The level of DNA methylation in leaves decreased atdifferent developmental stages.