Genetic analysis of the raffinose oligosaccharide pathway in lentil seeds

Two lentil (Lens culinaris) cultivars, Syrian Local Large (SLL) and PANT-L-406 (PL), have been used to study the genetics of the raffinose family of oligosaccharides (RFO) and a related compound, ciceritol, which is a galactosyl cyclitol, The RFO and ciceritol are the major soluble alpha-galactosides in lentil seeds. Crosses were made between the two lentil lines and the patterns of inheritance for the total alpha-galactoside content and for individual RFO compounds (raffinose, stachyose, verbascose) and ciceritol were determined in the embryos and seed coats from single seeds of the reciprocal F(1)s, the F(2)s and ten F-3 families. The inheritance patterns for each of the alpha-galactosides were complex and much of this complexity was attributed to an interaction between the embryo and its surrounding testa. A clear-cut segregation pattern was observed for verbascose, This was the result of PL embryos having very low, or no, verbascose. The F-2 embryos had a segregation ratio of 3 high to 1 low level for this compound, suggesting that within this cross a low verbascose content was determined by a single recessive gene. There was good evidence from the F-2 and F-3 generations of a negative correlation between low levels of verbascose and high levels of ciceritol, which suggests a metabolic link between the RFO pathway and the pathway leading to ciceritol. The data are discussed in terms of defining strategies for genetically manipulating the alpha-galactoside composition in lentil seeds, such that their negative effects on nutrition may be overcome without reducing significantly their positive role in abiotic stress resistance.