Ploidy Identification And Phenotypic Diversity Analysis Of New Germplasm Of Apple Anther Culture

Haploid breeding is important for modern breeding.The haploid plants were mutagenized and chromosomes doubled form a double haploid pure line,which can shorten breeding cycle and enrich germplasm resources^[1].Anther culture is an effective way to induce haploid artificially.At present,anther culture has been widely used in many plants such as wheat,peppers and sweet orange,And successfully combined with cross breeding and transgenic technology to form a relatively complete breeding technology system^[2-4].Apple is a woody plant with a highly heterozygous genome,long childhood,and self-incompatibility.Therefore,it is difficult to obtain homozygousplantsusingtraditionalmulti-generationself-crossing methods^[5].Apple anther culture obtained homozygous genotype plants,which has stable target trait,convenient genetic analysis and improved selection efficiency^[6].It is an important material for hybrid breeding and genetic analysis^[7].The homozygous genotype lines originated from different apple pollen grains,so their botanical characteristics,biological characteristics,and induced culture,root conditions were different.Therefore,it is significant to observe and analyze the ploidy,growth characteristics,rooting conditions and field observations.The main purpose of this study is ploidy analysis,select rooting conditions and transplanting conditions,obtain good comprehensive characters of apple homozygous genotypes.Through the rooting status,plant traits and transplanting observation and analysis.The result is as follows:1.Homozygous genotype strains obtained:After anther culture of apple,a total of 40 anther culture regeneration lines were obtained,including 20'Gala'apples,5'Fuji'apples,7'Red Star'apples and 8'Danxia'apples.All apple lines were homozygous genotypes detected by SSR markers.2.Ploidy analysis of homozygous genotypes:The ploidy test on 32homozygous genotypes of'Red Star','Fuji'and'Gala'apples,and the results showed that homozygous genotypes include 27 diploids,1 haploid?derived from"Gala"?,1 triploid?derived from"Red Star"?and 3 tetraploid?derived from"Red Star","Fuji""Gala"?,accounted for 84.38%of the diploid.Therefore,the main ploidy of the apple homozygous genotype was diploid,and the ploidy differentiation rate of the'Red Star'apple homozygous genotype was the highest,which was 28.57%.3.Leaf morphological analysis of different ploidy homozygous genotypes:Compared with diploid,the haploid lines showed narrower leaf base,narrow leaf shape,thin petiole,lighter leaf color,Sawtooth shallow.Compared to diploids,the polyploidy lines showed that the leaf bases became wider,the leaf shape was broadly elliptical,the leaf color became darker,and the leaf margins became darker.In addition,there are variations in other traits,such as haploid leaf shape becoming narrower and longer,the performance of the leaf index increased.4.Selection of rooting medium for apple homozygous genotypes:Rooting-inducing hormones have an impact on the rooting of the'Red Star','Fuji'and'Gala'apple homozygous genotypes..From the rooting status,the lack of IBA concentration significantly reduced the rooting rate,root number,and root length of apple homozygous genotype lines.The results of this study showed that adding 2-3 mg L^-11 rooting hormone?IBA?is appropriate.5.Characters analysis of apple homozygous genotypes:The number of leaves,roots,root length,plant height,petiole length,and leaf shape index of apple homozygous genotype lines were analyzed and compared.The results showed that'Red star'apple homozygous genotype DH0-1,DH0-3,DH0-4,DH0-7 lines;'Fuji'apple homozygous genotypes DH1-3 lines;'Gala'apple homozygous genotypes DH2-2,DH2-4,DH2-12,DH2-20 lines;'Danxia'apple homozygous genotypes DH3-3,DH3-4,DH3-8 lines comprehensive characters were better.6.Transplanting technology of apple homozygous genotype:In this study,two methods were used for simulating seedlings of'Danxia'homozygous genotype lines.One way is to transplant directly after opening the lid,the other way is to put the lid in the greenhouse for 5-7 days,open the lid and add distilled water and place it for 2-3 days for transplanting.The results showed that three strains survived directly after transplanting and the survival rate reached 37.50%.In the greenhouse,the lid was placed for 5-7days,and the lid was placed in distilled water and transplanted for 2-3 days without plant survival.