Mapping The Loci Governing Gynoecious And Research Of The Mechanism Of Bisexual Flower Development Induced By Silver Nitrate In Bitter Gourd

Bitter gourd（Momordica Charantia L.2n=2X=22）is an annual vine herb in Cucurbitaceae,with high nutritional value and health care function,which has important research significance.As a hybrid parent,the gynoecious lines of bitter gourd have the advantages of increasing yield and simplifying seed production procedures.Therefore,studying the localization of gynoecious genes can provide excellent gene resources and screening markers for bitter gourd breeding,which is beneficial to accelerate the process of gynoecious transfer.This project plans to use the newly constructed genetic segregation population to locate the gynoecious loci,in order to screen possible candidate genes,and lay the foundation for the application of the gynoecious gene of bitter gourd in breeding.and fertility were observed,and the molecular mechanism of AgNO₃treatment of male induction was analyzed from the transcriptome level.The main results are as follows:1.Study on genetic rule of whole female form in Momordica Charantia.In this study,an F₂genetic isolation population（KG5GyZ population and Y1GyZ population）was constructed using an inbred line KG5 with a female flowering rate of 7.41%and an inbred line with a female flowering rate of 38.46%as the male parent.By chi-square test,two recessive loci controlled females in KG5GyZ population,while one recessive loci controlled females in Y1GyZ population,indicating a single gene isolated population.This indicates that there may be multiple all-female loci in bitter gourd,and the number of gynoecious loci may be different under different genetic backgrounds of hybrid materials.2.Mapping the loci governing gynoecious in KG5GyZ population.BSA-seq analysis was carried out by constructing gynoecious and hermaphroditic DNA mixing pools in KG5GyZ population,and it was found that there were two regions controlling gynoecious loci in KG5GyZ population,namely MC01 on chromosome 1 and MC08 on chromosome 8.SNP/Indel loci were selected from the mixed pool to develop markers,Combined with the genotypes and phenotypes of individual plants on MC01 and MC08 in this population,the preliminary prediction of gynoecious loci on MC01 and MC08.3.Mapping the loci governing gynoecious in Y1GyZ population.Using the markers on MC01 and MC08 to scan the single-gene population Y1GyZ,linkage analysis found that the gynoecious loci in the Y1GyZ population was located on MC01（gy1）.Based on phenotype and encrypted marker scan results,Gy1was located between the markers 20519538 and 21014352,the physical distance between the two markers was about 494.8 Kb.And there were 27 annotated genes in the interval.Including copper transport adenosine triphosphate enzyme RAN1,chromatin remodeling factor CHR4,MADS-Box family transcription factor FBP24,thioredoxin O₂,Plant PPR family protein At4g20090,ethylene response transcription factor and other genes related to plant sex differentiation or flower organ development.4.The mechanism of silver nitrate-induced bisexual flowers formation.Gynoecious materials of gynoecious bitter gourd were preserved by attracting males with AgNO₃,and the gynoecious plants of bitter gourd were induced by AgNO₃to appear bisexual flowers,and the effect of bisexual flowers lasted for about10 d.Through different pollination combinations and pollen tube elongation tests,it was found that the pollen of the bisexual flowers was fertile,but the pistil was not.It was preliminarily speculated that the pistil of the bisexual flowers of bitter gourd could not swell and produce seeds normally after pollination.RNA-seq analysis was carried out on the shoot tips of AgNO₃sprayed for 24 h on gynoecious shoots,and 207 differentially expressed genes were identified by differential expression analysis,of which 192 genes were up-regulated and 15 genes were down-regulated.Differential gene annotation found genes related to plant sex differentiation,including CYP450 family genes,SWEET protein,ACC synthesis-related protein,pollen development-related protein NAC,and glutathione transferase.The roles of these differential genes in the development of bisexual flowers of bitter gourd need further experiments to prove.