银杏雌雄株核型及性别早期鉴定

以银杏茎尖及根尖为试材，采用压片法对雌雄株核型及性别早期鉴定进行了深入研究，结果表明，①银杏雌雄株核型一致，唯一差异就是雌株第１０对亚中部着丝粒染色体的长臂上各有一个随体，而雄株这对染色体仅一条染色体具有随体，属异型染色体，即性染色体，如果用ＸＹ表示雄株这一对染色体，则雌株可用ＸＸ表示。因此，雌株核型为２ｎ＝２ｘ＝２４＝２２ＡＣ［４ｍ（２ｓａｔ）＋６ｓｍ＋１２ｓｔ］＋ＸＸ；雄株核型为２ｎ＝２ｘ＝２４＝２２Ａ［Ｃ４ｍ（２ｓａｔ）＋６ｓｍ＋１２ｓ］＋ＸＹ，进一步证实了银杏的性别决定机制属ＸＹ型；②根据ＸＹ性别决定机制，借助胚培技术对７５株银杏实生幼苗进行了性别早期鉴定，雌株为３１珠，占４１．３％，雄株为４４株，占５８．７％

Studies on the Karyotype and Early Verification of the Female and Male Plants of Ginkgo biloba

Ginkgo biloba is a strictly dioecious plant and early verification of its sex is very important . The karyotype and early verification of the female and male plants of Ginkgo biloba were studied in this paper, The results showed that (1 )The karyotype of female and male plants of Ginkgo biloba are identical. The only difference is that the ovulate tree has four chromosomes bearing satellites ,while the staminate tree has only three chromo- somes bearing satellites . For the male tree ,one of the tenth sub-median chromosomes bears a satellite ,which are believed to be the sex chromosomes . An XY type of sex determination is assumed since the heteromorphic pair of chromosomes in the male . Therefore, the karyotype of female plant of Ginkgo, biloba is 2n = 2x = 24 = 22A[4m(2sat) +6sm +12st]+ XX, the karyotype of male plant of Ginkgo biboba is 2n=2x=24=22A[4m (2sat)+6sm+12st]+XY. (2)The sex of 75 young seedlings are verified,according to the XY type,to be 31 female seedlings (41. 3% ) and 44 male seedlings (58. 7% ).