Cytological Mechanism And Material Creation Of Citrus And Tomato Fruit Ripening

Autophagy plays an important role in plant growth and development.Previous laboratory studies have found that the expression of autophagy related gene SlATG8H is up-regulated during the color transformation process of tomato（Solanum lycopersicum）fruit,indicating that autophagy may participate in the color transformation process of tomato fruit,but the specific mechanism of action has not been reported.This study aims to explore the specific role of autophagy in the process of fruit color transformation from the perspective of autophagy.In addition,plants will also initiate autophagy under stress stress,by removing damaged organelles and reusing degraded substances to meet the normal survival of plants.This study intends to explore the specific functions of autophagy in citrus in response to nutrient stress（phosphorus deficiency）from the subcellular level,and the main results are as follows:1.The function of homologous ATG8 genes in plants was verified through yeast knockout recall: CsATG8 H in citrus,SlATG8H in tomato and AtATG8E in Arabidopsis thaliana,respectively.After obtaining the yeast ATG8 knockout,1.6mM CoCl₂ was used to process the yeast.It was found that the growth of the yeast was inhibited after the knockout,and the growth of the plant ATG8 homologous gene was restored to the normal state after the replacement of the yeast.These results indicated that CsATG8H in citrus,SlATG8H in tomato and AtATG8E in Arabidopsis thaliana could complement the ATG8 function in yeast,and ATG8 homologous genes in plants could exercise the ATG8 function.2.Construction of tomato autophagy mutant materials: In this study,tomato slatg8 h mutant was obtained by gene editing technology,and it was found that the fruit color transformation process was not significantly different from that of the wild type,indicating that the ATG8 homologous gene had functional redundancy.Therefore,we knocked out ATG5,a key autophagy gene,to obtain tomato autophagy mutant material slatg5,and observed that the mutant would show premature aging during the fruit color transfer process,which could not satisfy the completion of the normal plant color transfer process,so the fruit tomato color transfer process could not be observed.The later construction of citrus autophagy mutant the ATG7-RNAi material could not be observed because of the excessive growth cycle.3.Fruit color transfer phenotype identification of tomato tubulin MAP70 family mutant: The laboratory has previously constructed tomato tubulin MAP70 family mutant material,which combines tubulin and autophagy gene ATG8 with colocalization,and the color transfer phenotype identification was found the color transfer phenotype identification showed that map70crisp1/2/5 fruit color transfer process would advance;MAP70 overexpressed materials will be delayed in the process of fruit color transfer,and the final fruit color transfer cannot be completely completed.4.Lack of Pi induced autophagy in citrus calluses: The number of autophagosomes increased after treatment at 25%Pi during 1 day.The expression levels of PSR related genes and autophagy related genes in citrus callus samples were identified,and the results showed that the expression levels were up-regulated under 25%Pi culture.These results indicate that autophagy is implicated in citrus callosites in response to the Pi famine.In the process of hydroponic treatment of Huannong red pomelo,it was found that the main root system would be shorter and the lateral root would be longer when Pi was deficient.In conclusion,the ATG8 counterpart genes in plants can perform the ATG8 function and compensate for ATG8 deficiency in the single yeast genome.The autophagy mutant material constructed in this study failed to explain the function of autophagy in the process of fruit color transfer,so it is necessary to use the ATG7 interference material for research.In tomato,after MAP70 gene was knocked out,the color transformation of tomato fruit was advanced,while the color transformation was delayed after overexpression,indicating that MAP70 could affect the color transformation of tomato fruit.When the Pi element is deficient,autophagy in citrus cells will react,and the number of autophagosomes will rise to cope with the stress of the Pi element stress.