| Tomato(Solanum lycopersicum)is an important vegetable crop and a classic model plant for the research of fleshy fruits.At present,the growth and development,yield and quality of cultivated tomatoes have high environmental requirements and large labor and resource input costs,which has brought restrictions to modern agricultural production.Jasmonic acid(JA)is a plant growth regulator and signaling molecule that plays an important role in regulating plant growth and morphology.MYC2 is the core transcription factor in the JA signaling pathway,which can initiate and cascade amplify JA signaling and participate in multiple signaling pathway networks,which integrate optical signaling,hormone signaling,plant growth and development,etc.,but the regulatory mechanism of JA signaling on tomato growth and development is still unclear.The previous study of our laboratory found that TOR signaling has a regulatory effect on the growth and development of tomato seedlings,and it was found that Sl MYC2 might mediate the interaction between JA signaling and TOR signaling,thereby regulating the morphology of tomato seedlings.Therefore,this study took tomato as the research materials to explore the regulatory role of JA signaling in tomato growth and development,morphological formation and fruit formation,and the role of JA and TOR signaling interaction mediated by the key transcription factor Sl MYC2 in tomato seedling growth and development,laying a foundation for obtaining strong seedlings and improving yield and quality in production.The main results were as follows.(1)MeJA treatment inhibited the growth and development of tomato seedlings,inhibited the hypocotyl and root elongation of seedlings,and was concentration-dependent.MeJA treatment reduced the chlorophyll concentrations and net photosynthetic rate of tomato seedling leaves.Sl MYC2 participated in the regulation of JA signaling on tomato growth and development at seedling stage,which reduced the plant height,stem thickness and dry weight of tomato seedlings,but the overexpression of Sl MYC2 gene increased the root-to-apex ratio.JA signaling can regulate tomato seedlings to exhibit a more convergent phenotype,that is,plant height and stem thickness decrease,leaves become shorter,and leaf area decreases.Sl MYC2 can mediate JA signaling to regulate leaf morphology,size and growth state.The JA signaling pathway can regulate the growth and development process and plant morphology of tomato seedlings.(2)The JA signaling pathway can regulate the appearance,texture and nutritional flavor of ripe tomato fruit.JA signals can affect the shape of tomato fruits;Change fruit color by increasing the concentrations of pigments such as lycopene,carotenoids and anthocyanins in tomato fruit;By changing the concentrations and composition of pectin,a key component of the cell wall in the fruit,the softening of the ripe fruit of tomatoes was affected;Promote the accumulation of a variety of nutrients and flavor substances.(3)After AZD8055 treatment inhibited TOR activity,the hypocotyl and root elongation of tomato seedlings were inhibited,and it was concentration-dependent.The tomato seedlings showed a more convergent phenotype,that is,the plant height and stem thickness decreased,the overall leaf size became smaller,the leaf area decreased,and the leaf angle became smaller.The application of AZD8055 inhibited the activity of Sl TOR inhibited the photosynthetic ability of tomato seedlings,reduced the concentrations of chlorophyll a,net photosynthetic rate,etc.,and reduced the accumulation of dry matter in tomato seedlings.(4)Sl MYC2 can interact with the Sl TOR promoter and activate its gene expression,promoting the growth of tomato seedlings.Yeast single hybridization and Ch IP experiments showed that Sl MYC2 could bind directly to Sl TOR promoter.GUS staining and GUS enzyme activity determination showed that Sl MYC2 was co-transmuted with Sl TOR promoter,and compared with the control group,GUS staining was significantly deepened,and GUS enzyme activity was also significantly enhanced.At the same time,q RT-PCR analyzed the transcription expression level of Sl TOR,and the transcription level of Sl TOR was significantly upregulated in the Sl MYC2-OE strain,while the opposite trend was shown in the Sl MYC2-RNAi strain.The above results show that Sl MYC2 binds directly to the Sl TOR promoter and regulates its transcriptional expression.And validation experiments showed that overexpression of Sl MYC2 restored high JA levels and inhibition of growth by AZD8055 treatmentIn summary,Sl MYC2 binds to the Sl TOR promoter and activates the transcription of Sl TOR,mediating the interaction of JA signaling with TOR signaling,playing an important role in tomato growth,development,and quality regulation.This study laid a theoretical foundation for better understanding the function of plant JA signaling and providing a theoretical basis for molecular breeding. |
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