Inheritance of Glycinebetaine Deficiency in Sorghum

Abstract

Glycinebetaine (N,N,N‐trimethylglycine; betaine) accumulates in many species of the Poaceae and Chenopodiaceae. This accumulation is thought to be a metabolic response to osmotic stress which protects enzymes during heat and dehydration. Glycinebetaine deficient mutations have been identified and their genetic control elucidated in cereal crops including barley (Hordeum vulgare L.) and maize (Zea mays L.) The objective of this study was to determine the mode of inheritance of newly identified glycinebetaine deficient lines of sorghum [Sorghum bicolor (L.) Moench], Crosses were made between three high glycinebetaine (>20 μmol gfw−1) and three glycinebetaine deficient (<1 μmol gfw−1) varieties from which F1, F2, and backcross progenies were generated. A colorimetric assay was used to screen leaf samples collected from field grown parental, F1, and segregating progenies for glycinebetaine levels. Reciprocal F1 plants in each cross were not significantly different from each other. Approximately one‐fourth of the F2 plants in each cross exhibited the glycinebetaine deficiency, supporting the theory of single gene inheritance. Backcrosses to deficient parents segregated 1:1 for deficiency, further supporting this hypothesis. Gene action was primarily additive based on generation mean analysis of high and low parents, F1 progenies, and backcrosses to the respective parents. A small degree of dominance for glycinebetaine production was exhibited in the F1 generation.