Investigation Of Seed-less Mechanism Of Watermelon(Citrullus Lanatus)Line 148

Watermelon with less seeds can be produced by using chromosome translocation parental lines.Compared with polyploid seedless?no seed?watermelon,it has the advantages of low seed production cost,high germination rate,high quality,early maturity and easy management,which is an effective way to improve watermelon quality and reduce production cost.However,there are very few studies on mechanism of watermelon translocation material.It is important study the mechanism of less seed,to elucidate the mechanism and cause of seed sterility,and to create a new type of high-quality less seed watermelon germplasm.In this study,watermelon material"148"and"JM"was used as crossing parents,and the F₁ generation"2018-Z-4"was under investigation.The F₁ generation meiosis behavior was analyzed at detail,and the"148"hybrid oligosaccharide phenotype was determined at the cytological level due to the translocation of chromosome fragments.The translocations were further located by molecular markers generated by genome resequencing.The main research results are summarized as follows:1.Statistics show that there is no significant seed number difference of"148"self-seeded melons and the number of"JM"self-seeded melons.While the seed number of F₁ generation is significantly lower than that of parental lines.2.Alexander staining method was used to observe fertility of mature pollen grains of"148","JM"and"2018-Z-4".The pollens of"148"and"JM"were 99.0%fertile,while pollen viability"2018-Z-4"were reduced to 45.0%.The proportion of fewer seeds in the hybrid generation was correlated with the proportion of aborted pollen.3.The correlation between pollen mother cell meiosis and bud diameter of wild type material"ZTC"was analyzed,and the reproductive development calendar of watermelon was established to provide convenience for subsequent experiments.4.The results showed that"148"germ cells carry out normal meiosis,while"2018-Z-4"had formed four-body ring structures at the bifilar stage.From the perspective of cytology,it was preliminarily inferred that"148"is a chromosome-translocated line,and the translocation was homozygous.5.The results showed that there was no significant difference in the expression levels of the seven key genes in the three materials,indicating that the possible position effect of the translocation in"148"did not affect the expression of the key genes,further confirming that the seed less phenotype in"148"hybrid offspring was not regulated by genes.6.Individual plant from F₂ generation were pooled to construct a screening population F₂ for the genetic law analysis of"2018-Z-4"less-seeded traits and the location of"148"translocation chromosome segments.The separation ratio indicated that the semi-sterile phenotype of watermelon pollen is controlled by translocation of one chromosome.7.Whole genome second generation sequencing identified the SNP and In Dels loci of the genome,and the translocation section was located at 15.94 Mb-18.03 Mb of chromosome 6,with a physical distance of 2.09 Mb.The whole genome second generation sequencing identified the SNP and In Dels loci of the genome,...