Studied On Meiosis Process Of Pollen Mother Cells(PMC) Of Natural Triploid Loquat

Four natural triploid loquat lines:(D425(Jinfeng),D327(Jinfeng),A313(Dawuxing),E39 (Zaohong No.3)),screened out from three domestic loquat varieties' seedling plants,were materials for this sdudy.The method of flame-drying protocol after enzyme digestion of cell wall was used to prepare meiosis chromosome in this experiment.Process of meiosis of pollen mother cells(PMC)was observed,and mainly analyzed the correlation between the meiosis developmental period of loquat pollen mother cells and transverse diameters of flowers,chromosome structure during diakinesis,chromosome separation and abnormal phenomenon and speculated the homology of genomes contained in these four natural triploid loquat lines.The main results were as follows:1,Loquat pollen mother cells' meiosis was in the same way with most of dicotyledon,as simultaneous type,that is to say,processes of meiosis were fundamentally simultaneous.There was a certain relevance between male gamete development periods and diameter of flowers,anther's color,when the diameter of flowers was 4.2～5.6 mm,pollen mother cells were in the period of meiosis,anther color changed gradually from white to milky,light yellow,yellow,snuff color. Among different lines,there was difference between the diameter of flowers and pollen mother cells developmental period.2,Trivalent,bivalents and univalents were main chromosome valent formation during diakinesis of D425 pollen mother cells,a small number of tetravalents,quinquevalents and hexavalents were existed.The main configurations of chromosomes during diakinesis were 17Ⅲ. 13Ⅲ+2Ⅱ+4Ⅰ+1Ⅳ.12Ⅲ+2Ⅱ+6Ⅰ+1Ⅴ.14Ⅲ+3Ⅱ+3Ⅰ.10Ⅲ+7Ⅱ+7Ⅰ. 10Ⅲ+3Ⅱ+5Ⅰ+1Ⅳ+1Ⅵ.13Ⅲ+2Ⅱ+4Ⅰ+1Ⅳ,and so on..The average configuration was 10.85Ⅲ+4.37Ⅱ+4.81Ⅰ+0.59Ⅳ+0.37Ⅴ+0.13Ⅵ.Trivalent accounted for 51.39 percent around. There were at least 10 trivalent chromosomes,and at most 17 ones in a single cell.Secondly,the bivalents and the univalents accounted for 20.68%and 22.77%respectively.There were high homology among genomes contained in D425 line,therefore,this line may be inferred to a natural homologous tripioid.3,Trivalent,bivalents and univalents were main chromosome valent formation during diakinesis of D327 pollen mother cells,a small number of tetravalents,quinquevalents and hexavalents were existed.The main configurations were:14Ⅲ+3Ⅱ+3Ⅰ.17Ⅱ+17Ⅰ.9Ⅲ+8Ⅱ+8Ⅰ.17Ⅲ. 12Ⅲ+5Ⅱ+5Ⅰ.12Ⅲ+5Ⅱ+1Ⅰ+1Ⅳ.14Ⅲ+1Ⅱ+1Ⅰ+1Ⅵ.14Ⅲ+2Ⅱ+1Ⅰ+1Ⅴ. 13Ⅲ+2Ⅱ+4Ⅰ+1Ⅴ,and so on.The average configuration was 9.06Ⅲ+6.63Ⅱ+6.16Ⅰ+0.44Ⅳ+0.14Ⅴ+0.11Ⅵ.Trivalent chromosomes were about 52.98 percent, the amount variation of trivalent chromosomes contained in a single cell from 7 to 17;Other formation of valents were mainly bivalents and univalents,which accounted for 22.41%and 21.33%. D327 line was similar with D425 line,which was inferred may be a natural homologous triploid.4,Trivalent,bivalents and univalents were main chromosome valent formation during diakinesis of A313 pollen mother cells,a small number of tetravalents,quinquevalents and hexavalents were existed.The main configurations of chromosomes during diakinesis were:17Ⅲ. 13Ⅲ+3Ⅱ+2Ⅰ+1Ⅳ.14Ⅲ+1Ⅱ+3Ⅰ+1Ⅳ.14Ⅲ+3Ⅱ+3Ⅰ.10Ⅲ+7Ⅱ+7Ⅰ.11Ⅲ+1Ⅱ+1Ⅰ+1Ⅳ+1Ⅴ+1Ⅵ.11Ⅲ+2Ⅱ+2Ⅰ+3Ⅳ,and so on.The average configuration was 10.30Ⅲ+5.43Ⅱ+2.76Ⅰ+0.91Ⅳ+0.41Ⅴ+0.09Ⅵ.A single cell contained at least three and a maximum of 17 trivalent chromosomes.Bivalents and univalents accounted for 28.17 percent and 27.65 percent respectively, which together accounted for 55.82 percent,and trivalent chromosome configurations only accounted for 40.75%,which showed that the homology among three genomes in this strain was lower,the line may be a natural source and homologous triploid.5,Among the configurations of meiosis chromosomes of E39 line,the trivalent accounted for about 81.68 percent,only a few of bivalents,univalents,tetravalents and hexavalents were observed. The main configurations of chromosome at diakinesis were:17Ⅲ.16Ⅲ+1Ⅱ+1Ⅰ.15Ⅲ+2Ⅱ+2Ⅰ. 14Ⅲ+3Ⅱ+3Ⅰ.2Ⅳ+14Ⅲ+1Ⅰ,3Ⅳ+13Ⅲ,2Ⅳ+13Ⅲ+2Ⅱ.1Ⅳ+13Ⅲ+2Ⅱ+2Ⅰand 1Ⅵ+2Ⅳ+12Ⅲ+1Ⅰ,and so on.The average configuration was 13.97Ⅲ+6.63Ⅱ+6.63Ⅰ+0.12Ⅳ+0.06Ⅵ.A single cell contained at least 12 trivalent chromosomes and at most 17 ones.More trivalent chromosome configurations showed that the homology among three genomes contained in this line was high,which inferred the line was a typical natural homologous triploid.6,There existed anomalies in the processes of meiosis of the four natural triploid loquat lines, which included laggard chromosome in metaphaseⅠand anaphaseⅠ,single-bridged of chromosome in anaphaseⅠ,chromosome unequal separation,micronucleus,telophaseⅠlaggard chromosome, metaphaseⅡparallel spindle,anaphaseⅡlaggard chromosome,chromosome separated inequaUy into triad,and so on.These meiosis abnormal phenomena often caused fertility of triploid loquat decline.This paper observed and analyzed the meiosis processes of four natural triploid loquat lines, speculated the homology of genomes contained in the lines,which would provided theoretical support for the breeding of triploid seedless loquat.