Genetic analysis of nutritional quality traits in sorghum

Lexingtons Muthama Nduulu, Purdue University

Abstract

Although sorghum is the major source of protein for millions of people in the developing countries, its low nutritional quality make it less competitive as a food and feed crop. To increase the efficiency of screening and selection of sorghum for increased levels of protein digestibility, quick and reliable assays that can be used to phenotype large populations are required. The recent development of the turbidity assay, which can be used to assay up to 200 samples a day, is a significant achievement for sorghum nutritional quality research. Several experiments (for protein digestibility) were performed to test the sensitivity and reliability of the assay and the results showed that the assay is repeatable and reliable for use in evaluating sorghum grain for protein digestibility. Continuous research for improved nutritional quality at Purdue University has enabled the development of a sorghum mutant line, P-851171, with a mutation that alters the protein bodies from the less digestible normal smooth and spherical shape to a folded and irregular shape that is comparable to maize in digestibility. P-851171 was developed from crosses between a high-lysine opaque mutant, P-721Q, and a high yielding agronomically elite line. This study was conducted to determine the inheritance of high protein digestibility and high lysine concentration in P-851171 and to establish the association between the two traits. The inheritance results suggested a one-gene partial dominance model for both high protein digestibility and high lysine concentration consistent with prior results for high lysine concentration. The map distance between hpd and opaque was estimated to be 42.7 cM suggesting that the two traits are unlinked. Results of QTL analysis indicated that both hpd and opaque loci were each associated with a SSR marker, Txp113, in linkage group A.

Degree

Ph.D.

Advisors

McIntyre, Purdue University.

Subject Area

Agronomy|Genetics

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