基于染色体核型的玉米地方品种聚类分析

以40个西南地区玉米地方品种为材料,通过细胞学鉴定分析其主要核型参数,并采用最长距离法对其进行聚类分析。结果表明,40个玉米地方品种的全组染色体长度、最长染色体长度、最短染色体长度、长度比、平均着丝点指数、平均臂比和核不对称系数平均值分别为89.56μm、5.84μm、2.64μm、2.46、35.62%、1.48和59.06%,其对应变幅分别为61.51~103.82μm、3.62~7.50μm、0.98~4.33μm、1.41~5.21、26.93%~40.33%、1.05~2.43和51.20%~70.90%,其中,17份玉米地方品种存在B染色体;40个玉米地方品种的平均遗传距离为10.05,变幅为3.09~46.57。基于7个核型参数可将40个玉米地方品种在遗传距离15.98处划分为6类,第Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ类分别包含3、9、4、14、8、2个品种。40个玉米地方品种供试材料间存在较大的核型差异,这在细胞水平上表明西南地区玉米地方品种具有丰富的遗传变异。

Cluster Analysis of Maize Landraces Based on Karyotype Parameters

Fourty maize landraces collected from Southwest China were used as materials,and their mainly karyotype parameters were identified using cytological technology,subsequently,cluster analysis of those maize landraces were conducted by the longest distance method.The results indicated that B chromosomes(Bs) existed in 17 maize landraces,and the total chromosome length,the longest chromosome length,the smallest chromosome length,the ratio of chromosome length,the mean centromere index,the mean arm ratio,as well as the index of karyotypic asymmetry of fourty maize landraces were on an average of 89.56 μm,5.84 μm,2.64 μm,2.46,35.62%,1.48 and 59.06%,respectively,and the corresponding amplitude variations were 61.51-103.82 μm,3.62-7.50 μm,0.98-4.33 μm,1.41-5.21,26.93%-40.33%,1.05-2.43 and 51.20%-70.90%,respectively.In addition,the mean genetic distance among those maize landraces was on average of 10.05,ranging from 3.09 to 46.57.Based on these seven karyotype parameters,40 maize landraces could distinctively be clustered into six groups under the genetic distance of 15.98,group Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ and Ⅵ were consisted of 3,9,4,14,8 and 2 maize landraces,respectively.Great karyotype difference was found in 40 maize landraces,suggesting that abundant genetic variance existed in maize landraces at cytological level in Southwest China.