In vitro ear culture experiments were conducted to determine how the concentrations and combinations of sucrose and glutamine in medium were suitable for the accumulation of grain starch and protein in winter wheat (cv. Ningmai 9). The results showed that with the same level of glutamine supply, the grain weight and starch yield were increased but the protein formation was inhibited with increasing sucrose supply significantly. While with the same sucrose supply, both starch and protein accumulation in grains were increased with glutamine supply increase. Higher sucrose supply led to higher sucrose and starch content in grains, but lower activities of Sucrose Synthase (SS), Soluble Starch Synthase (SSS) and Granule Bound Starch Synthase (GBSS), whereas higher glutamine supply led to the higher starch yield and enzyme activities. In conclusion, starch accumulation in wheat grains was controlled not only by sucrose supply, but also by nitrogen supply. Protein accumulation in grains was positively associated with the ratio of glutamine/sucrose in the culture media. It suggested that controlling substrate composition during grain filling was one of the effective approaches for regulation of protein and starch formation in grains.%采用花后离体穗培养技术,研究蔗糖和谷氨酰胺不同浓度配比供应对冬小麦(宁麦9号)籽粒淀粉和蛋白质积累的影响.结果表明:在同样谷氨酰胺水平下,提高蔗糖供应水平能显著增加粒重,促进籽粒中淀粉积累,但降低蛋白质合成;在同样的蔗糖水平下,提高谷氨酰胺供应水平,既有利于籽粒中蛋白质积累,也促进淀粉合成.培养基中蔗糖浓度变化与籽粒蔗糖含量和淀粉产量消长趋势一致,而与籽粒中蔗糖合成酶(SS)、可溶性淀粉合成酶(SSS)和颗粒束缚淀粉合成酶(GBSS)活性消长趋势相反;培养基中谷氨酰胺浓度与籽粒淀粉产量和淀粉合成关键酶活性的变化趋势也一致.说明籽粒中淀粉合成既受蔗糖供应水平调节,也受氮供应水平调节.提高基质中谷氨酰胺/蔗糖比例对籽粒蛋白质含量和产量有正向调节效应.因此,改变小麦籽粒灌浆过程中的营养物组成是调控籽粒淀粉和蛋白质合成的有效途径之一.
展开▼
