Multi--Parent Advanced Generation Inter-Crosses (MAGIC) for Genetic Diversification and Enhanced Yield Stability in Post Rainy Sorghum [Sorghum bicolor(L.) Moench]

Abstract

Post-rainy (Rabi) sorghum grows under residual soil moisture conditions and is important for food and fodder security especially during dry seasons in semi-arid regions of India. Unlike rainy sorghum being dominated with hybrids ,post rainy sorghum growing areas are cultivated with varieties especially landrace selections. Genetic improvement of rabi sorghum is hindered by lack of phenotypic variability among breeding lines. Most of the present day improved varieties are the result of pur-line selection practiced among the local /popular varieties. The available varieties have a moderate resistance to biotic and abiotic stresses with moderate average yield (900Kg/ha) but there is a lot of scope to increase up to 1200Kg/ha in near future by reorienting and strengthening rabi breeding programs. Identifying natural allelic variation that underlines quantitative trait variation remains a fundamental problem in genetics. Most studies have employed either simple synthetic populations with restricted allelic variation or performed association mapping on a sample of naturally occurring haplotypes. Both of these approaches have some limitations, therefore alternative resources for the genetic dissection of complex traits continue to be sought. Nevertheless, Breeders and Molecular geneticists have routinely used populations derived from bi-parental crosses for variety development and mapping quantitative trait loci (QTLs). Most of the varieties in self- pollinated crops like sorghum are based on single crosses between two parents and bi-parental populations have only one opportunity for crossing over . In this context, a novel multi-genotype breeding strategy to achieve genetic diversity within a variety where multi-genotype varieties of Rabi sorghum have to be developed through convergent crossing of multiple parental lines. Development of MAGIC populations helps to promote inter-crossing and shuffling of the genome. Such populations are now attractive for researchers due to the development of high – throughput SNP genotyping platforms and advances in statistical methods to analyze data from such populations.