小麦2B染色体新SSR标记开发

Development of Novel SSR Markers on Wheat Chromosome 2B

为开发用于小麦育种的新SSR分子标记,利用普通小麦中国春2B染色体25Mb的DNA序列进行了SSR筛选,在检测到的2852个SSR中80.40%是二核苷酸重复。二、三、四、五核苷酸重复序列分别有6,30,17,1种类型。二核苷酸中GA/CT、AG/TC、AT/TA数量最多,分别占SSR总数的20.44%,19.00%,17.15%;三核苷酸中CTT/GAA的数量最多,占SSR总数的2.56%;四、五核苷酸重复出现的频率都较低。进一步分析SSR的重复次数,发现二核苷酸重复次数总体较高,重复次数≥10的SSR数量有327个,占所有二核苷酸序列的14.26%,其中,AG/TC、AT/TA的重复次数≥10的SSR数量分别有98,97个。三核苷酸的重复次数总体偏低,重复次数≥8的SSR数量仅有62个,占所有三核苷酸序列的11.55%,其中TTC/AAG的重复次数≥8的SSR数量最多,有12个。四核苷酸中只有ACAT/TGTA、TAGA/ATCT的重复次数分别达到了16,14次,其他重复基元的重复次数主要为5~7次。根据筛选到的SSR位点共设计合成了135对SSR引物,发现有101对(74.81%)引物在小麦品系Cf5019-21和Cf5240-41扩增出清晰的DNA条带,17对引物在二者间表现出差异扩增。

In order to develop novel SSR markers for wheat breeding ,simple sequence repeat(SSR)was identified from a 25 Mb region according to the Chinese Spring 2B chromosome reference sequence. In 2 852 SSR loci identified,80.40% belonged to dinucleotides repeat.Six,thirty,seventeen,one kinds of SSR repeats were found in dinucleotide,trinucleotide,tetranucleotide,pentanucleotide repeats,respectively. For dinucleotides,GA/CT, AG/TC, AT/TA had the highest frequencies,occupying 20.44%,19.00%,17.15% of all SSR loci identified,respectively;for trinucleotides,CTT/GAA had the highest frequency,occupying 2.56% of all SSR loci identified;whereas the frequencies of tetranucleotide and pentanucleotide repeats were relatively low. Furthermore,the replication numbers were higher in dinucleotide than others,and 327 SSR loci which occupied14.26% of all dinucleotides loci identified were with ≥10 replications. The numbers of SSR loci with ≥10 replications for AG/TC and AT/TA reached 98 and 97, respectively. The replication numbers in trinucleotide were relatively low,and 62 SSR loci which occupied11.55% of all trinucleotides loci identified were with ≥8 replications. The number of TTC/AAG with ≥8 replications was the biggest,reached 12. For tetranucleotide,the numbers in ACAT/TGTA and TAGA/ATCT reached16 and14,respectively,and the replication numbers in other repeats of tetranucleotide varied between 5 and 7. Based on the found SSR loci,135 SSR primer pairs were designed and synthesized. Of these,101(74.81%)SSR primer pairs amplified clear products in wheat lines Cf5019-21 and Cf5240-41,and17 SSR primer pairs showed polymorphism between them.