Genetic analysis of the raffinose family oligosaccharides in common bean

Common bean(Phaseolus vulgaris L.) is a nutritionally complete food, but contains anti nutritional compounds that reduce digestibility. One group of compounds includes the raffinose family oligosaccharides (RFOs) (raffinose, stachyose, and verbascose), which are partly responsible for flatulence after beans are eaten. RFOs stabilize cell membranes during seed desiccation and when the seed rehydrates during germination. While low levels of RFOs are desirable nutritionally, high levels may enhance germination and emergence, particularly in cold, wet soils. Eight landraces selected for high and low sucrose, raffinose, and stachyose content, were crossed in a diallel mating design to investigate genetic control of the RFOs. Derivatized soluble sugars were measured using gas-liquid chromatography. Fructose, sucrose, raffinose, and stachyose were detected. In the F,, fructose varied from 0.1 to 2.5 mg.g(-1) dry weight (DW), sucrose from 17.2 to 56.5 mg.g(-1) DW, raffinose from 0.1 to 4.1 mg.g(-1) DW, and stachyose ranged from 7.6 to 43.7 mg.g(-1) DW. Griffing's analysis estimates of general combining ability were on average, 16.5 times larger than specific combining ability for all the RFOs, indicating that additive genetic variance was most important. Significant reciprocal differences were detected in the F-1 and F-2. but not in the F-3. RFO accumulation was partially dominant as indicated by Hayman's analysis. Narrow sense heritability averaged over F-2 and F-3 generations for sucrose, raffinose, stachyose, total sugar, and total oligosaccharides were 0.22, 0.54, 0.44,0.17, and 0.27, respectively. Moderate heritabilities indicate that manipulation of RFO accumulation in this set of bean lines would probably need to be done on a progeny row basis with replication.