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从NCBI搜索的2282条香蕉EST中,发掘出含有SSR的EST序列110条,共有122个SSR位点,检出率为5.3%。SSR位点可分为37种重复单元,平均长度为20bp,其中二、三核苷酸重复单元的SSR占主导地位,分别占总SSR的33.1%和47.6%。GA和GAA是二、三核苷酸中的优势重复类型,分别占二、三核苷酸重复类型的75.7%和36.0%;其他重复类型所占比例均不足10%,而四核苷酸重复类型最少,为4.0%。设计的63对EST-SSRs引物中,有41对EST-SSRs引物对巴西蕉基因组DNA能扩增出产物,占总引物数的65.1%。应用进一步筛选出的重复性好、多态性高的19对引物对49个香蕉品种(系)进行PCR扩增。每对引物扩增的多态性带数目为4~12个,平均7.58个;引物多态信息量变化范围为0.3572~0.8744,平均0.7324。在相似系数为0.63的水平可将49个品种聚为2个类群:一类为含B基因组香蕉品种;另一类为不含B基因组的香蕉品种,表明EST-SSR引物可以应用于香蕉品种资源分类的研究。
From 2282 banana ESTs searched by NCBI, 110 EST sequences containing SSRs were found, with 122 SSR loci with a detection rate of 5.3%. The SSR loci can be divided into 37 kinds of repeat units with an average length of 20 bp. The SSRs of the two or three nucleotide repeat units dominate, accounting for 33.1% and 47.6% of the total SSR, respectively. GA and GAA are the dominant repeat types in the two and three nucleotides, accounting for 75.7% and 36.0% of the two and three nucleotide repeat types respectively; all the other repeat types share less than 10%, whereas the tetranucleotide repeat The least type is 4.0%. Among the 63 EST-SSR primers designed, 41 pairs of EST-SSR primers could amplify the genomic DNA of Brazil banana, accounting for 65.1% of the total number of primers. Nineteen banana cultivars (lines) were further amplified by PCR using 19 pairs of primers with good repeatability and high polymorphism. The number of polymorphic bands amplified by each primer ranged from 4 to 12 with an average of 7.58. The informative range of primer polymorphism varied from 0.3572 to 0.8744 with an average of 0.7324. At the similarity coefficient of 0.63, 49 cultivars could be grouped into two groups: one is banana variety containing B genome and the other is banana variety without B genome, indicating that EST-SSR primers can be applied to banana variety resources Classification studies.