Chromosome Karyotype And Peroxidase Isoenzyme Analysis Of Nut-used Cultivars Of Ginkgo Biloba

Ginkgo biloba is an ancient relic plant in in the gymnosperms.Ginkgo biloba is a chinese rare tree species which can be used to make food,timber,medicine and ornamental tree.For many purposes,in China Ginkgo biloba has been cultivated for thottsands of years and its genetic improvements have been developed in recent years.Ginkgo biloba has many cultivars though it is a single genera and single species tree.So it is necessary to breed new cultivars of Ginkgo biloba that many existing cultivars will be distinguished and classified.In order to supplement or amend the identification and classification,some cultivars' karyotype and peroxidase isoenzyme are studied which are select from 5 groups of nut-used cultivars in our experiment.The results showed as following:1.Chromosome numbers are 2n=2x=24 in six cultivars.Chromosome ploidy doesn't change and its indicate that hereditary stability of Ginkgo biloba is high.2.The relative length(the proportion of one chromosome's length in chromosome complelnent) of chromosomes is no significant difference in six cultivars.It indicate that the characters of respective chromosome in chromosomes complement are stable, cspecially in length.3.The absolute length of chromosomes is significant different in six cultivars except 'xiaojinzhui'-'dajinzhui','xiaoyuanling'-'damaling' and 'xiaoyuanling-qixingguo'.The absolute length of chromosomes can be used to identify different cultivars.4.The Arm ratios and centromeric types of chromosomes are different between six cultivars.The two parameters are also useful reference for cultivars identification.5.Satellites are supposed to be not important for cultivars identification,considering that the number of satellites are small and different between male and female.6.Although centromeric bands and telomere bands appear on some of chromosomes in respective cultivar,there are no band on more chromosomes and the types of band are few.7.The analysis of peroxidase isoenzymes shows that six cultivars share the same four basic strips and five cultivars have special strips('damaling' and 'meihe' share the same special strips).