Effect Of Pumpkin Rootstock On Genetic Variation Of Self-fertile Progency Of Grafted Pumpkin

In order to explore the genetic variation sources of phenotypic traits of the sexual offspring of grafted pumpkin and understand the stability and genetic mechanism of the newly formed variation,the seeds of the grafted plants were grafted on the rootstocks of inbred pumpkin'Beiguan'and'360-3',and the agronomic traits of G₁ and the second G₂ of the grafted plants were investigated and analyzed.The variation and stability of different traits in two generations of grafted plants were analyzed.Meanwhile,in order to prove the genetic mechanism of grafting variation,the technical system suitable for this material was preliminarily optimized and established by methylation-sensitive amplification polymorphism analysis,which provided a new way to make full use of the potential of epigenetics in crop improvement.The main results are as follows:?1?Through the analysis of agronomic traits of G₁ generation population and rootstock traits of grafted pumpkin,it was found that the leaf length,leaf width,leaf area,internode length,stem diameter,petiole diameter and first female flower node position of G₁ generation maintained the scion traits.The petiole length,pulp color,seed width and seed thickness traits were affected by rootstocks.The convex and concave shape of the base of the petiole,umbilical convex and concave shape of the petiole of G₁generation were affected by rootstocks.The morphological traits of rootstock fruits appeared in all traits,and the variation analysis showed that the three main variation traits of petiole length,a value and seed width of G₁ generation of grafted pumpkin had different performances among different lines,while the seed thickness traits had no difference among lines.It was concluded that phenotypic variation existed in G₁generation of grafted pumpkin.?2?The analysis of agronomic traits of G₂ generation of grafted pumpkin population,rootstocks and scions showed that G₂ generation of grafted pumpkin herited the main variation traits of G₁ generation of grafted pumpkin.There were significant differences in leaf width,petiole length,stem diameter,petiole diameter,fresh color a,seed length,seed width,seed thickness and seed shape index between grafted pumpkin G₂ generation and scions.The petiole length,seed width and seed thickness had continuous variation,and the leaf width and 100-grain weight had atavistic heredity.G₂ generation of grafted pumpkin,there were still morphological traits of rootstock fruits in the shape of base convex and concave,umbilical convex and concave,and transverse section of handle.Therefore,the genetic variation of petiole length,seed width,seed thickness and fruit morphological traits occurred in G₂ generation of grafted pumpkin.?3?In order to explore the genetic mechanism of the variation characters of grafting,a pumpkin MSAP system,the first step of the best system Hap??Hpa?/MSP??0.5?l,time was 2h;0.4?l EcoR??5U/?L?,time was 6h;the best digest-ligation system,containing 21?l of ligation product,1?l adoptors,the connection time was 12h.The optimal pre-amplification reaction system included 2?l digest-ligation products,1.5?L Mg²⁺,2?l dNTP?2.5 mmol/L?,0.6?l Taq polymer?5 U/?L?,0.4?l primers?10?mol/L?.The optimal selective amplification reaction system,there were 4?l of pre-amplification products which was diluted 120 times.finally,36 pairs of specific primers with good amplification effect and clear bands were selected from 81 pairs of primers,and the MSAP amplification was carried out by the best reaction system.This experiment has laid a foundation for the study of pumpkin methylation.