Wide hybridization in sorghum with tertiary gene pool for diversification of parental lines

Sorghum (S. bicolor) is a great millet that constitutes the staple food in many parts of the world and is cultivated in the semi-arid tropics. The grain is bestowed with traits that make it amenable for many value-added products, thus increasing the demand. Considerable progress is achieved in increasing the yield in the past through exploitation of primary gene pool species and secondary gene pool species to a very limited extent, but further increase is challenging and it necessitates bringing in the genetic diversity from other gene pools. Tertiary gene pool of sorghum has not been exploited so far due to limitations of cross-incompatibility. We accomplished inter-specific hybridization in sorghum with the wild species of tertiary gene pool. Derivatives from three inter-specific crosses (ISCs), Sorghum bicolor x S. versicolor (ISC304 and ISC320) and S. bicolor x S. usumbarense (ISC812), with the parental lines of popular Indian sorghum hybrids, 27B and 126B, are developed. Thirteen promising lines are identified, and they are subjected to field evaluation and molecular analysis to develop inter-specific derivatives that are equivalent to parent progenitors in agronomic traits yet diverse enough genetically. Analysis of phenotypic data in conjunction with genotype data revealed that derivatives of S. usumbarense are promising as compared to derivatives from S. versicolor, derivatives of S. usumbarense are closely clustered as compared to that of S. versicolor, and all the derivatives carry genomic regions from both the parents, with S. bicolor genome being predominant. GGE biplot analysis identified three genotypes (ISC320-5, ISC320-2, and ISC812-2) as highly promising. We successfully generated promising inter-specific derivatives from the tertiary gene pool in sorghum for ready use in crop improvement programs. Inter-specific hybridization followed by a single backcross is used to widen the genetic base of sorghum parental lines. Thirteen derivatives from three inter-specific crosses are evaluated in the field for six seasons. Morphological data for six seasons in conjunction with molecular data are used for characterization of these lines. Morphological and molecular clustering revealed that Sorghum versicolor derivatives are more dispersed than those of S. usumbarense. Genetically diverse lines with good agronomic performance for use in sorghum breeding programs are identified.