Soluble carbohydrates in desiccation tolerance of yellow lupin seeds during maturation and germination

Maturing yellow lupin seeds were desiccation tolerant. Glucose, sucrose and cyclitols (mainly D-pinitol, D-chiro-inositol and myo-inositol) were predominant at the early stages of seed growth. Accumulation of the raffinose family oligosaccharides (RFOs) and the galactosyl cyclitols including galactinol, digalactosyl myo-inositol, galactopinitol A, galactopinitol B, trigalactopinitol A, ciceritol, fagopyritol B1 and fagopyritol B2 appeared during seed maturation; their increase correlated with seed germinability after desiccation. The loss of desiccation tolerance after seed germination was also studied. For the desiccation tolerance test, intact seedlings were dried rapidly or slowly followed by rehydration. Soluble carbohydrates were assayed before and after drying. Root tissues were more sensitive to desiccation than hypocotyl tissues and completely lost desiccation tolerance within 36 h of imbibition after both fast and slow-drying treatments. Survival of hypocotyls decreased gradually up to 96 h after imbibition. Loss of RFOs and galactosyl cyclitols in axis tissues preceded visible germination. Loss of desiccation tolerance was accompanied by loss of RFOs and galactosyl cyclitols and an increase in reducing sugars in cotyledon, hypocotyl and radicle tissues. Drying did not induce the accumulation of RFOs and galactosyl cyclitols in seedling tissues.