Effects On AsA Related Gene Expression Of Rosa Roxburghii Tratt By Four Abiotic Factors

Cili?Rosa roxburghii Tratt?,was a lately-domesticated fruit tree.Research shows AsA participate in plant signal transduction,and the biosynthesis of plant AsA may be regulated by endogenous plant hormone and external plant growth regulators?PGR?.So‘Guinong 5' was used to investigate the influence of different type PGRs to the AsA biosynthesis of Rosa roxburghii fruits in vitro and vivo conditions.On this basis,in order to screen and identify the effective PGRs and its possible mechanism to the AsA biosynthesis of Rose roxburghii fruits,we analyzed the expression of related genes participating in AsA biosynthesis after treating with different type PGRs.Obtain the main results of this study are as follows:?1?Fruits of Rosa roxburghii Tratt‘Guinong 5'was used to investigate the effects of divalent cations of Ca²⁺ and Cu²⁺ on expression of the genes involved in L-ascorbic acid?AsA?biosynthesis and accumulation using the methods of incubation in vitro.The results showed that exogenous Ca²⁺ had a positive role in promoting AsA accumulation,while Cu²⁺ accelerated AsA degradation during incubation.Quantitative real-time PCR analysis showed that expression of GalLDH and GPP in L-galactose biosynthetic pathway and DHAR and MDHAR in recycling pathway upregulated sigificantly when fruit flesh tissues was incubated with Ca²⁺,indicating that this divalent cation took part in regulation of gene transcription.Exogenous Cu²⁺showed a slightly exhibition of GalLDH and GGP expression but failed to down-regulate the expression of AAO or APX,which suggests that As A degradation incubating Cu²⁺ occuerd not primarily on the transcription level.?2?The effects of seven exogenous growth substances on the synthesis and accumulation of AsA in the fruit of Rosa roxburghii were studied by means of in vitro feeding.The effects of three exogenous growth substances on the synthesis and accumulation of AsA in Rosa roxburghii were studied by field spraying method.Promote or inhibit the action of exogenous growth substances may regulate the mechanism.The results showed that ABA,IBA,SA and BR significantly promoted the accumulation of AsA in vitro,and after 24 h,GA3?MeJA and DA-6 all decreasedthe content of AsA in the flesh significantly?p<0.05?AsA content?compared with the control?,which GA3 and MeJA treatment is most obvious.The results of field spraying test showed that BR promoted the accumulation of AsA and the inhibitory effect of GA3 and MeJA on AsA accumulation.Further analysis of qRT-PCR showed that both GA3 and MeJA showed a consistent and significant down-regulation of GGP and GalUR respectively in both in vitro and in-field application.GGP,GPP,GDH,GalLDH,MIOX,DHAR and MDHAR were up-regulated in BR,especially on GGP,especially in the process of As A synthesis and regeneration.?3?The effect of drought stress on the accumulation of AsA and the expression of related genes was studied by means of potted water control.The results showed that mild and moderate drought had no significant effect on the accumulation of AsA,but the content of AsA decreased significantly with the increase of stress.Further gene expression analysis showed that GME,GGP and GDH genes involved in AsA synthesis pathway showed a certain degree of upregulation,while MIOX gene showed a slight decrease trend during the drought process.The levels of AAO and APX,which participate in the oxidative decomposition of AsA,were significantly increased at the later stage of treatment?consistent with the sharp decrease in AsA?,which may be responsible for the decrease in AsA content.Among all the tested genes,only the expression of DHAR gene was highly consistent with that of stress-treated fruit,suggesting that the gene plays an important role in regulating the accumulation of AsA in the fruit of Rosa under drought stress.?4?The effect of UV radiation on the accumulation of AsA and the expression of synthetic genes in the fruit of Rosa roxburghii were studied by UV irradiation and masks.The results showed that enhanced UV radiation could accelerate the growth of AsA in the initial accumulation period,and the growth rate of AsA in the rapid accumulation period was the same as that in the control.Reduced UV radiation could reduce the accumulation of AsA in fruits at 50-70 days,However,the content of AsA increased rapidly in the last 10 days,and the content of AsA in the fruit was significantly higher than that in the control.Further analysis of gene expression showed that the trend of expression of GalLDH gene was the same as that of fruitAsA,and the change trend of GME and MIOX gene expression was consistent with that of fruit AsA when the UV radiation was weakened.