| In the process of clutivation, the vegetables often encounter unsuitable environmental factors. In the protected cultivation of vegetables,sub high temperature and high humidity occur frequently,due to its relatively closed characteristics.While in the open field, acid rain not only impacts vegetables’growth and development,but also has profound influence of vegetable diseases.It has great importance to research the effects of hard environment such as acid rain, sub-high temperature and high humidity to vegetable resistance and growth of pathogens. In this study, we use tomato plants (Solarium lycopersium L.) and pathogen which can cause disease as materials, to study the variety of different tomato germplasm diseases and resistance after injected Pseudomonas syringae pv.tomato strain DC3000, Botrytis cinerea and virus under different environmental factors such as acid rain,sub-high temperature and high humidity.The results are as follows:1. The change of tomato photosynthesis and resistance of Pseudomonas syringae pv.tomato strain DC3000 and Botrytis cinerea under simulate acid rain.Tomato leaves were suffered oxidative stress,MDA contents increased, the relative gene expression of fructose-1,6-bisphosphatase(FBPase), sedoheptulose-1,7-bisphosphatase (SBPase) and Rubisco small subunit gene(rbcS) were decreased significantly,all these changes lead to decrease of tomato net-photosynthesis rate.The diseases rate of Pst DC3000 and Botrytis cinerea increased by 50% and 300% respectively when injected by pathogens.While pretreatment tomato by brassinosteroid (BR),the decrease of net-photosynthesis rate and relative gene expression of Calvin cycle enzymes were alleviated and CFU of Pst DC3000, Actin gene expression of Botrytis cinerea are reduced.To analysis the mechanism we found that pretreatment tomato by BR increased the expression of resistance genes of PR1, NPR1, PIl1, PI2 etc,and simulated acid rain inhibited instead of increased the growth of phtogen Pst DC3000,Botrytis cinerea in vitro culture.So we can infer that exogenous BR improve resistance of tomato crop to alleviated Pst DC3000 and Botrytis cinerea.2. The variety and mechanism of tomato resistance to bacterial leaf spot disease under sub-high temperature and high humidity.The CFU of Pst DC3000 increased and disease rate increased by 60% under sub-high temperature and high humidity.Then we determined heat shock transcription factor (HsfA1α) and heat shock protein (HSPs) gene expression,we found that gene HsfAlα, Hsp20、Hsp40、Hsp90、Hsp100 all up-regulated when treated by sub-high temperature,while in HsfAla gene silenced plants, HsfAlα and HSPs genes all down-regulated and PR1gene up-regulated in comparison with TRV:0 plant materials.In addition, the growth of Pst DC3000 in vitro was significantly slower than that under normal temperature. All these results show that reduced resistance towards Pst DC3000 of tomato plants associated with HsfAlα transcription factor and its regulate HSPs expression.3. The variety and mechanism of tomato resistance to tobacco mosaic virus under sub-high temperature and high humidity. The sub-high temperature and high humidity environment not only increased the occurrence of tobacco mosaic virus, the resistant germplasm of TMV Tm-22 was also got diseases and showed phenomenon of resistance decline,which TMV-cp gene expression was significantly increased compared with the normal temperature control plants.Gene expression showed that gene EDS1 and SGT2 in the downstream of the R gene were not significantly up-regulated,while HsfAla and HSPs were significantly up-regulated in Tm-2 and its wild type Ailsa. The expression of HsfAla was significantly lower than that of TRV:0 and the incidence of TMV was significantly alleviated at room temperature and under high temperature in HsfA1α gene silenced tomato plants. It was inferred that the resistance decline/decrease to TMV of the resistant germplasm Tm-22 was associated with transcription factor HsfA1α.Its mechanism worth further research. |
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