花生种子耐脱水力的形成与可溶性糖累积的关系

Soluble Sugar and the Acquisition of Desiccation Tolerance in Peanut(Arachis hypogaea)Seeds

花生胚轴的耐脱水力在40－65DAP的发育后期逐渐增加，同时胚轴还原性糖／非还原性糖比值下降。缓慢干燥可同时诱导35DAP胚轴累积蔗糖与寡糖（水苏糖与棉籽糖）；外源ABA及高渗处理可诱导35DAP离体胚轴累积蔗糖，但不能累积寡糖（水苏糖）。耐脱水胚轴可溶性糖成分的模拟混合物可在水活度0．32及零上温度进入玻璃态；而不耐脱水胚轴的可溶性糖模拟混合物仅在零下温度进入玻璃态。模拟实验证明在干燥状态下可溶性糖与花生2S蛋白结合，并消除了2S蛋白的干燥结晶。

Accumulation of soluble sugars associated with the acquisition of desiccation tolerance in peanut (Arachis hypogaea L. ) seeds were studied. Desiccation tolerance of peanut axes was acquired progressively during 40 ~ 65 DAPembryogenesis (Fig. 1 ). The contents ofsucrose , raffinose and stachyose, the major oligosaccharides in peanut axes, increased and that of maltose declined withthe acquisition of desiccation toleranceduring embryogenesis (Fig. 2 ). Thecontent of sucrose and oligosaccharidesincreased synchronously with slow drying imposed on 35 DAP axes. In vitro incubation of 35 DAP embryos with ABA10-5 mol/L and an osmoticum inducedthe accumulation of sucrose, but not thatof oligosaccharides (Fig. 3). At a wateractivity of 0. 32, the soluble sugars from65 DAP axes (tolerant) can undergo vitrification at ambient temperature(11 .02℃ ), whereas those from 25DAPaxes (sensitive) underwent vitrificationonly at subzero temperature (-- 5. 24℃ )(Fig.4A, B). DSC thermograms showedevidence of interaction between solublesugars and 2S protein purified from peanut. axes, and which prevented thecrystallization of 2S protein at the dehydration level(Fig. 4C, D). We concludedthat soluble nonreduced sugars were involved in the acquisition of desiccationtolerance by peanut seeds.