Research For The Biological Characteristics,Karyotype And ISSR Molecular Marker For A New Strain-’Chuanzao’ Loquat

The ’Chuanzao Loquat’ was a new bud mutant line, which was from ’Zaozhong 6’ in Fujian province, and found in Hanyuan country. Its fruit quality was obviously superior than ’Zaozhong 6’, and showed the characteristic of early maturing. In the progress of variety selection, it was the key step that found the variation, analyzed it and distinguished it from modification caused by the environment. Phenophase investigation and karyotype analysis combined with Inter Simple Sequence Repeat (ISSR) were adopted to judge the possibility of identify the mud variation by ISSR, and find out whether the characteristic of early maturing was genetic variation or moditication. The main results were as follows:1.’Chuanzao Loquat’ showed a upright shape and green treetop, the fruit weight 45g-80g, which had orange-yellow skin and orange-red pulp.’Chuanzao Loquat’ branched out and unfolded leaves in the middle of January, ended up with four times of sprout till the middle of December; The first florescence occurred in the midmonth of July, the second and third florescence occurred in the end of august and October respectively. The florescence were three times a year and each progress sustained one and half a month; The period of fruit coloration was the midmonth of November, end of January and midmonth of April, reached the standard of harvesting in one and a half month.2. The chromosome quantity of ’Chuanzao Loquat’ and ’Zaozhong 6’ were the same, which was 2n=34, the karyotype formula was 2n=34=18m+16sm, contained 18 middle contromere chromosomes,16 submedian centromeres. The longest arm/ shortest arm ratio and average arm ratio of ’Chuanzao Loquat’ were 1.74 and 1.87 respectively, which showed significant differences to ’Dawuxing Loquat’.3. To creat a system which was suitable for ’Chuanzao Loquat’, L2s(55) Orthogonal design was used to optimize the ISSR-PCR system. With analiysis and mark, the ISSR system for’Chuanzao Loquat’ were 25μl, with dNTPs 0.25mmol/l, Mg2+ 1.5mmol/l, primer 0.5μmol/l, Taq polymerase 2.5U/μl and template DNA 40ng/25μl, 10×PCR-buffer 2.5μl.4. A total of 14 primers were screened out to evaluate genetic relationship of 13 samples. With ISSR-PCR,165 bands were found, including 108 polymorphism bands and the polymorphism ratio was 65.45%. By amplified 13 samples with UBC895, the polymorphism ratio reached 100%.84 bands were found in the amplified progress between ’Chuanzao Loquat’ and ’Zaozhong 6’,122 bands between ’Chuanzao Loquat’ and ’Maomu’, the polymorphism ratio were 0.1071 and 0.1967 respectively.5. With ISSR analysis, the genetic similarity of 13 samples were 0.6184-0.8244. For’Chuanzao Loquat’, the maximum was 0.7920 between’Maomu’,0.7717 and 0.7444 for ’Zaozhong 6’and ’Wanzhogn’ respectively. The minimum genetic similarity was 0.6525, came in the research for ’Chuanzao Loquat’ and ’Dawuxing’ The genetic relationship clustering figure was constructed by NTS YSpc. According to the figure,’Chuanzao Loquat’ and ’Zaozhong 6’could be separated during the genetic similarity index was 0.7580. It classified 13 samples into 4 groups with the genetic similarity index of 0.7160.