328 [13]. Since gene flow can resist the effect of genetic drift within populations and prevent the differentiation of populations with full report Nm > l, the genetic drift would lead to genetic differentiation among populations as the value of Nm < l [48]. The Nm value in this study was 4.762, indicating that there was no significant genetic differentiation between the two groups or nine series. The low genetic differentiation (Gst) among populations was primarily caused by the high level of gene flow. However, compared to wild sugarcane (Gst = 0.209) [13] and weedy rice (Gst = 0.387) [38], the Gst (0.095) of 115 sugarcane parents was still at a low level.It is interesting that, in this study, both cluster and PCA analyses of individuals (including all the nine series) exhibited similar results: OTHER, YC, and GT series fell into three different groups and HoCP only belonged to Group I.

Furthermore, a limited space covered 90% CP series, 85% YT and ��ROC�� series, and only 50% YC series, respectively. It was obvious that the distribution of accessions in CP, YT, and ��ROC�� series was relatively narrow while it was broader in YC, FN, and OTHER series. The results revealed that the genetic basis of YC, FN, and OTHER was more extensive than CP, YT, and ��ROC�� series, which also suggested that more attention should be made on the application of new parents in sugarcane hybrid breeding in the future. It was not difficult to find in the dendrogram (Figure 2) and PCA (Figure 3) that the clusters or components were closely related to their breeding institutions.

It was also apparent that there were two pairs of four accessions (YT96-86 and YN73-204 at the level of GD = 0.50 and MT90-55 and HoCP93-750 at the level of 0.59) which the analysis failed to differentiate. Furthermore, the PCA analysis indicated that the plots of YT96-86 and YN73-204 or MT90-55 and HoCP93-750 overlapped entirely. This shows that the analysis could not differentiate between these accessions at the molecular level based on the five testing SSR loci and indicated that more SSR loci would be necessary for differentiation from MT90-55 to HoCP93-750 and from YT96-86 to YN73-204. For example, based on the pedigree, HoCP93-750 evolved from CP84-0722 and LCP81-030, while MT90-55 derived from CP57-614 and YC84-153 (Figures (Figures44 and and5).5).

From the pedigree of HoCP93-750 and MT90-55, it is obvious that we could not find the same parents Carfilzomib between the two sugarcane clones within five generations. Therefore, it is inaccurate to analyze the genetic structures, genetic diversity, or genetic relationships only by pedigree records. If we want to further identify the four sugarcane clones, more SSR loci should be applied.Figure 4The pedigree of HoCP93-750.Figure 5The pedigree of MT90-55.