Elumalai Karpagam, Srinivasan Alarmelu
Division of Crop Improvement, ICAR-Sugarcane Breeding Institute, Coimbatore, Tamil Nadu 641007 India.
3 Biotech. 2023 Dec;13(12):399. doi: 10.1007/s13205-023-03823-5. Epub 2023 Nov 14.
One hundred and seventy two introgressed hybrids from four different introgression groups and in three nobilized stages (F, BC,and BC) involving two genera viz., Sugarcane ( s) and ,and Coimbatore (Commercials) clones were studied for yield and quality traits, and as well with 30 SSR markers (simple sequence repeats) for diversity and population structure. The yield and quality components of the introgressed hybrids from improved , improved , (Pathri) and (IK-76-76) showed significant variation. The traits viz., cane height, single cane weight and cane yield showed the highest level of phenotypic and genotypic variation. 456 polymorphic alleles in all with values ranging from 6 (SMC 863-GC) to 24 (NKS 43) with an average of 15 alleles per primer were studied. Polymorphism information content (PIC) generated by 30 SSR primers varied from 0.57 (NKS 1) to 0.94 (NKS 34) and the highest average PIC (0.93) was observed in hybrids of (SSH). The highest number of observed and effective alleles, and Shannon's index were also registered by introgressed hybrids of SSH and the lowest variability was observed with hybrids of Co canes x . SSR-based population genetic measures identified three mating groups involving improved , improved and Coimbatore canes with maximum variability. Structure analysis identified 51 introgressed hybrids with abundant genetic variation and low gene flow as a new germplasm source for future sugarcane breeding programmes. Fifty-nine rare alleles were detected, and structure analysis revealed a low degree of admixture between the generated hybrids. Low gene flow estimates from group I (: 1.052, where mostly F and BC hybrids were grouped together) explained that the maximum variability from parental clones was inherited until the BC generation, and high values of in group III also indicated that most of the wild alleles were fixed in the BC population. Structure and cluster analysis (PCoA, UPGMA) explained that the grouping of introgressed hybrids is highly correlated to different stages of nobilization. UPGMA and PCoA methods grouped the individuals into three major clusters, with a clear differentiation of F and backcross hybrids grouped under different internal sub-clusters. The occurrence of wide genetic variability in the population and elite hybrids with a unique genetic base can be exploited in breeding programmes to develop trait specific donors for genetic enhancement and to mitigate climate change
对来自四个不同渐渗群体、处于三个纯合阶段（F、BC₁和BC₂）、涉及甘蔗（Saccharum）和斑茅（Erianthus）两个属的172个渐渗杂交种以及哥印拜陀（商业品种）无性系进行了产量和品质性状研究，并使用30个SSR标记（简单序列重复）分析了其多样性和群体结构。改良CP、改良Co、Pathri和IK - 76 - 76的渐渗杂交种的产量和品质成分表现出显著差异。茎高、单茎重和茎产量等性状表现出最高水平的表型和基因型变异。共研究了456个多态性等位基因，其值范围为6（SMC 863 - GC）至24（NKS 43），每个引物平均有15个等位基因。30个SSR引物产生的多态性信息含量（PIC）从0.57（NKS 1）到0.94（NKS 34）不等，在SSH杂交种中观察到最高平均PIC（0.93）。SSH渐渗杂交种的观察等位基因数、有效等位基因数和香农指数也最高，而Co甘蔗×斑茅杂交种的变异性最低。基于SSR的群体遗传分析确定了三个交配组，涉及改良CP、改良Co和哥印拜陀甘蔗，具有最大变异性。结构分析确定了51个具有丰富遗传变异和低基因流的渐渗杂交种，作为未来甘蔗育种计划的新种质资源。检测到59个稀有等位基因，结构分析表明所产生的杂交种之间的混合程度较低。第一组的低基因流估计值（: 1.052，其中大部分F和BC₁杂交种聚集在一起）表明，亲本无性系的最大变异性一直遗传到BC₁代，第三组的高值也表明大多数野生等位基因在BC₂群体中固定。结构和聚类分析（PCoA、UPGMA）表明，渐渗杂交种的分组与纯合的不同阶段高度相关。UPGMA和PCoA方法将个体分为三个主要聚类，F和回交杂交种在不同的内部子聚类中有明显区分。群体中广泛的遗传变异性以及具有独特遗传基础的优良杂交种可用于育种计划，以开发性状特异性供体用于遗传改良和缓解气候变化
