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 F 1 , F 2 , and backcross progenies were generated. A colorimetric assay was used to screen leaf samples collected from field grown parental, F 1 , and segregating progenies for glycinebetaine levels. Reciprocal F 1 plants in each cross were not significantly different from each other. Approximately one‐fourth of the F 2 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, F 1 progenies, and backcrosses to the respective parents. A small degree of dominance for glycinebetaine production was exhibited in the F 1 generation.