| As the population continues to increase,the demand for food expands,and the implementation of the national potato staple food strategy,the potato planting area continues to rise,and the contradiction between the land use of crops has become increasingly prominent.The method that can improve the utilization rate of cultivated land has important theoretical and practical significance.Planting potato grafted tomato seedlings can simultaneously harvest tomatoes above the ground and potato tubers below the ground,which improves the utilization rate of cultivated land.In this study,the potato variety"Zhongshu No.3"and the tomato variety"Golden Pearl"were used as the test materials,and different grafting treatments were carried out using the oblique bonding method,which were treated as tomato/potato（T/P）and potato/potato（P/P）and tomato/tomato（T/T）are controls（CK）.The differences in agronomic traits,yield and other agronomic traits were compared,and the tuber extract RNA was taken at 40d,60d,and 80d after grafting to perform transcriptome sequencing analysis.The differentially expressed genes in three periods were analyzed to discuss potato grafting tomato pairs.The influence of tuber growth and the expression of related genes will provide a reference for further research on the high-yield molecular mechanism of grafted potato and diversified planting and production of potato.The main results are as follows:（1）Growth performance of grafted plantsThrough grafting,the average growth rate of T/P after grafting was 0.812 cm d-1,which was significantly increased by 42.5%compared with P/P,which promoted the growth of aerial parts and showed a slow-fast-slow growth trend.The number and length of stolons after grafting at 40d,60d,and 80d were 3,5,4,and 6.1cm,4.1cm,and 3.3cm respectively,and the number of tubers was 1,4,and 3,respectively.Compared with P/P,the number of potato stolons decreased and the length became longer.The results showed that tomato scion promotes the elongation of potato stolons and inhibits the swelling of the stolon tips to form tubers;potato skin color,potato color and potato The shape did not change in the three periods,the fruit shape of tomato became smaller,but its number increased,and the yield of eggplant fruit did not change significantly.（2）Performance of fruit and tuber yield and quality of grafted plantsAccording to the measurement of the yield and quality of potato pieces and eggplants,the yield of potato pieces and T/P was 5380.9kg/hm2and 19476.2kg/hm2,which was significantly lower than that of P/P.There was no significant difference in the tomato yield of T/T;the vitamin C,protein and reducing sugar contents of T/P and P/P tubers increased gradually during the three periods,of which the contents of vitamin C and protein reached the maximum at 80d.Values 22.4mg/100g,23.9mg/100g,3.6mg/g,3.7mg/g,no significant difference;T/P reducing sugar content reached a maximum of 2.4%at 60d,P/P reached a maximum at 80d 1.6%;the reducing sugar content of T/P tubers at the mature stage was significantly increased by 73.3%compared to P/P,while the dry matter and starch content were decreased by15.14%and 23.87%,respectively,reaching significant levels;the titrable acid content in eggplant Decreased by 63.5%,the sugar-acid ratio increased by 67.9%than T/T,and the content of lycopene,soluble sugar and vitamin C did not change significantly.This indicated that grafting did not affect the vitamin C and protein formation of potato nuggets,inhibited the synthesis of dry matter and starch,and promoted the formation of reducing sugars.The content of tomato lycopene,soluble sugar and vitamin C had no effect,inhibited the formation of fruit acid and improved the quality of tomato.（3）Screening analysis of differential expression of grafted tuber genesUsing RNA-seq sequencing technology and bioinformatics to analyze the gene expression in the tubers after grafting,T/P had 217 genes up-regulated and 77 genes down-regulated at 40 days after grafting;105 genes were up-regulated at 60 days after grafting,95 genes were down-regulated;80d after grafting,the differential gene expression was significantly increased compared with the previous two periods,of which 2,564 genes were up-regulated and 2,493 were down-regulated;242 genes were expressed at 40d compared to 60d after P/P grafting Up-regulated,426down-regulated expressions,195 genes expressions were up-regulated,281down-regulated expressions compared with 80d after grafting,and 133 genes expressions were up-regulated,and 98 down-regulated expressions compared with80d;Compared with 60d,19 genes were up-regulated,22 were down-regulated,40d was compared with 80d,14 genes were up-regulated,30 were down-regulated,and60d and 80d were 116 genes up-regulated,611 down-regulated expression.（4）Functional annotation and enrichment analysis of differentially expressed genesAccording to the classification and enrichment analysis of GO,the differential genes in tubers are mainly enriched in the processes of microtubule movement,kinesin complex,and microtubule binding at 40 days after T/P grafting;the differential genes in tubers are mainly at 60 days after grafting Enriched in cells,cell responses to stimulation,and FMN binding;80 days after grafting,differential genes in tubers were mainly enriched in histone H3-K9 methylation,chloroplast matrix,microtubule binding and other processes.The results of KEGG enrichment showed that the differential genes were mainly enriched in plant hormone signal transduction,sulfur metabolism,nitrogen metabolism and alanine,aspartic acid and glutamine in three periods of 40d,60d and 80d after grafting.Metabolic pathways such as acid metabolism;P/P is mainly enriched in plant hormone signal transduction,starch and sucrose metabolism,arachidonic acid metabolism,sulfur metabolism,and some essential amino acid metabolism pathways at 40d,60d,and 80d after grafting;T/P is mainly enriched in glycolysis/gluconeogenesis,photosynthesis,nitrogen metabolism,pyrimidine and 40d,60d,80d after grafting.Pathways such as purine metabolism and mismatch repair.It can be seen from the above that after the potato is grafted to the tomato,its signal transduction,nutrient synthesis and metabolism regulate the growth and development of the grafted plant and the formation and accumulation of nutrients of the tuber.（5）Verification of transcriptome sequencing resultsAccording to the annotation of the differentially expressed genes in the RNA-seq sequencing analysis results,10 candidate genes with obvious expression differences were screened and verified by real-time fluorescence quantitative PCR.The results were consistent with the results of transcriptome sequencing analysis. |
