Horbowicz M, Brenac P, Obendorf R L
Department of Soil, Crop and Atmospheric Sciences, Cornell University Agricultural Experiment Station, Cornell University, Ithaca, N.Y. 14853-1901, USA.
Planta. 1998 May;205(1):1-11. doi: 10.1007/s004250050290.
O-alpha-D-Galactopyranosyl-(1-->2)-D-chiro-inositol, herein named fagopyritol B1, was identified as a major soluble carbohydrate (40% of total) in buckwheat (Fagopyrum esculentum Moench, Polygonaceae) embryos. Analysis of hydrolysis products of purified compounds and of the crude extract led to the conclusion that buckwheat embryos have five alpha-galactosyl D-chiro-inositols: fagopyritol A1 and fagopyritol B1 (mono-galactosyl D-chiro-inositol isomers), fagopyritol A2 and fagopyritol B2 (di-galactosyl D-chiro-inositol isomers), and fagopyritol B3 (tri-galactosyl D-chiro-inositol). Other soluble carbohydrates analyzed by high-resolution gas chromatography included sucrose (42% of total), D-chiro-inositol, myo-inositol, galactinol, raffinose and stachyose (1% of total), but no reducing sugars. All fagopyritols were readily hydrolyzed by alpha-galactosidase (EC 3.2.1.22) from green coffee bean, demonstrating alpha-galactosyl linkage. Retention time of fagopyritol B1 was identical to the retention time of O-alpha-D-galactopyranosyl-(1-->2)-D-chiro-inositol from soybean (Glycine max (L.) Merrill, Leguminosae), suggesting that the alpha-galactosyl linkage is to the 2-position of D-chiro-inositol. Accumulation of fagopyritol B1 was associated with acquisition of desiccation tolerance during seed development and maturation in planta, and loss of fagopyritol B1 correlated with loss of desiccation tolerance during germination. Embryos of seeds grown at 18 degrees C, a condition that favors enhanced seed vigor and storability, had a sucrose-to-fagopyritol B1 ratio of 0.8 compared to a ratio of 2.46 for seeds grown at 25 degrees C. We propose that fagopyritol B1 facilitates desiccation tolerance and storability of buckwheat seeds.
O-α-D-吡喃半乳糖基-(1→2)-D-手性肌醇，在此命名为荞麦糖醇B1，被鉴定为荞麦（甜荞，蓼科）胚中主要的可溶性碳水化合物（占总量的40%）。对纯化化合物和粗提物水解产物的分析得出结论，荞麦胚含有五种α-半乳糖基D-手性肌醇：荞麦糖醇A1和荞麦糖醇B1（单半乳糖基D-手性肌醇异构体）、荞麦糖醇A2和荞麦糖醇B2（二半乳糖基D-手性肌醇异构体）以及荞麦糖醇B3（三半乳糖基D-手性肌醇）。通过高分辨率气相色谱分析的其他可溶性碳水化合物包括蔗糖（占总量的42%）、D-手性肌醇、肌醇、棉子糖、棉子糖和水苏糖（占总量的1%），但没有还原糖。所有荞麦糖醇都能被生咖啡豆中的α-半乳糖苷酶（EC 3.2.1.22）轻易水解，表明存在α-半乳糖基键。荞麦糖醇B1的保留时间与大豆（大豆，豆科）中O-α-D-吡喃半乳糖基-(1→2)-D-手性肌醇的保留时间相同，这表明α-半乳糖基键连接在D-手性肌醇的2位。在植物种子发育和成熟过程中，荞麦糖醇B1的积累与获得脱水耐受性相关，而在萌发过程中荞麦糖醇B1的丧失与脱水耐受性的丧失相关。在18℃条件下生长的种子胚，这种条件有利于提高种子活力和耐贮性，其蔗糖与荞麦糖醇B1的比例为0.8，而在25℃条件下生长的种子该比例为2.46。我们认为荞麦糖醇B1有助于荞麦种子的脱水耐受性和耐贮性。
