| Sugarcane is the important sugar crops and the renewable biomass energy crop with development potential. Sugarcane parents is the foundation of sugarcane breeding. Study on the genetic diversity of sugarcane parents can help guide the selection of parent and cross combinations in sugarcane cross breeding, then improving the efficiency of sugarcane breeding. Sugarcane smut is an important bottleneck that affect the sustainable development of our country's sugarcane industry. Resistance breeding is the most economical and effective way to control the sugarcane smut, and smut resistance evaluation of parents is the foundation of breeding for disease resistance. This study was to know the genetic diversity analysis of 75 sugarcane parents including sugarcane parents, E.arundinaceus and three Saccharum officinarum based on SCo T and ISSR markers. Meantime, do smut resistance identification and evaluation of 34 of them. The main results of this study are as follows:(1) 24 SCo T primers and 15 ISSR primers that yielding clear, reproducible bands patterns were selected to evaluate genetic diversity of 75 sugarcane parents. A total of 227 distinct bands were obtained in SCo T analysis, with 200 bands being polymorphic. The average number of amplified bands per primer was 9.5. The percentage of polymorphic bands was 88.11%. Average polymorphism information index(PIC) was 0.8159. The number of alleles(Na) was 1.8811, the number of effective alleles(Ne) was 1.4725, Nei`s gene diversity index(H) was 0.2853, and the Shannon`s information index(I) was 0.4342. As for ISSR analysis, a total of 146 bands were observed, of which 123 were polymorphic, and the average number of polymorphic bands per primer was 9.7. Percentage of polymorphic bands was 84.25%. Average polymorphism information index(PIC) was 0.8361. The number of alleles(Na) was 1.8425, the number of effective alleles(Ne) was 1.4644, Nei`s gene diversity index(H) was 0.2770, and the Shannon`s information index(I) IV was 0.4198, respectively. The above data indicated that these two kinds of molecular markers were all suitable for the analysis of genetic diversity of sugarcane parents.(2) The genetic similarity coefficient detected by SCo T marker ranged from 0.524 to 0.850, with the mean of 0.687, while the genetic similarity coefficient detected by ISSR markers varied from 0.452 to 0.863 with the mean of 0.658, and the total 373 bands based on SCo T+ISSR data were integrated into one matrix to assess the genetic relationship between 75 sugarcane parents. The data ranged from 0.542(ROC22/Ho CP95-988) to 0.831(ROC25/ ROC20), with the mean of 0.687.(3) The results of cluster analysis and principal component analysis based on SCo T, ISSR and SCo T+ISSR markers data showed that 75 sugarcane parents could be divided into two groups(A and B). According to SCo T+ISSR markers data based on genetic similarity coefficient(GS) 0.67. Group A was primarily comprised of 42 species containing all Q-series, all CP-series, Ho CP-series, all Yuetang-series, etc. 32 species consisted of group B, which contained all Taitang-series, all Guitang-series, three Saccharum officinarum, Qianzhe, and Ganzhe, etc.(4) The results in this study showed that the genetic diversity of the tested sugarcane was abundant, and the genetic similarity was high among the Q-series from Australia, CP-series and Ho CP-series from America, and Yuetang from China. Meantime, Taitang-series from Taiwan of China, Guitang-series, Qiantang-series, Ganzhe-series together with three Saccharum officinarum species grouped in Cluster B, probably due to the their high genetic similarity.(5) The results of smut resistance identification showed that the level of resistance to highly resistant(HR) of the parents have Q171, ROC1, Neijiang 57-614, with accounting for 8.8%. Funong 95-1702, N:Co376, CP93-1382, CP65-357, Ganzhe 95-108, ROC5 were resistant to smut(R), accounting for 17.6%. The members of Brazil 618, Yuetang89-113 and Taiyou were moderately resistant to smut(MR), accounting for 8.8%. Yuetang86-368, ROC16, Q179, Q191, Ho CP95-988, Taitang89-1626, Ying8, F177 are performed moderately susceptible to smut(MS), accounting for 23.5% of the tested parents. Q205, ROC23, N:Co310, Liucheng 03-48, Q189, F134, Yuetang 83-271, Guitang 94-119, TH10, Ganzhe 14 were susceptible to smut(S), accounting for 29.4%. Besides, Zhanjiangzhong, Yuetang06-666, Ho TH409, 08-144 were highly susceptible to smut(HS), accounting for 11.8%. In addition, this test explored the grading method of sugarcane smut resistance. |
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