Development of forage grasses with high quality and functionality based on genomic information of fructan

呋喃丹是果糖的聚合物，是水溶性碳水化合物的主要成分，在许多植物中积累，尤其是温带禾本科植物。果聚糖作为细胞质的一种调节物质，在抵御低温和干旱引起的渗透胁迫中发挥重要作用。果聚糖也是动物可消化的主要可溶性碳水化合物。果聚糖水平的增加似乎改善了植物的非生物胁迫以及动物的营养价值。鸭茅品种、品系、生态型及近缘亚种间的WSC和果聚糖含量存在显著差异。杂交试验表明，WSC含量受遗传控制。选育出了一株WSC含量高于标准栽培种的菌株.从多年生黑麦草（Lolium perenne L）中分离了与果聚糖生物合成有关的果糖基转移酶基因（1-FFT、6 G-FFT和1-SST），并利用在毕赤酵母（Pichia pastoris）中表达的重组蛋白进行了鉴定。6 G-FFT基因的分离在禾本科中尚属首次。6 G-FFT定位在连锁群3上，1-FFT和1-SST定位在连锁群7上。Real-time RT-PCR检测结果表明，在低温锻炼过程中，1-FFT基因在叶片和冠部组织中的表达量均有所增加.果聚糖含量的QTL与果聚糖生物合成基因位点不连锁。田间部分抗寒性QTL与果聚糖含量QTL相吻合.我们生产了过表达小麦呋喃丹生物合成基因（1-SST和6-SFT）的转基因多年生黑麦草植物。转基因植株果聚糖含量显著增加，耐冻害性显著提高。果聚糖生物合成基因的过表达似乎有助于提高植物对冷冻的耐受性。

Furctan, a polymers of fructose and a major component of water soluble carbohydrate (WSC), is accumulated in many plants, especially temperate grasses. Fructan plays important role as a regulatory substance of cytoplasm against osmotic stress caused by cold and drought. Fructan is also the main soluble carbohydrate digestible far animals. The increased level of fructan appears to improve abiotic stresses of plants as well as the nutritional value by animals.1. There were significant differences among cultivars, strains, ecotypes and related subspecies of cocksfoot (Dactylis glomerata L) for WSC and fiuctan contents. Crossing test demonstrated that Content of WSC was genetically controlled. A strain with higher content of WSC compared to standard cultavars was developed.2. Genes encoding fructosyltranferase involved with fructan biosynthesis (1-FFT,6G-FFT and 1-SST) were isolated from perennial ryegrass (Lolium perenne L) plants and identified using recombinant proteins expressed in the yeast Pichia pastoris. For 6G-FFT gene, present isolation was the first report in Gramineae. 6G-FFT gone was mapped on linkage group (LG) 3 and 1-FFT and 1-SST were mapped on LG 7. The increase in mRNA level of 1-FFT was obeserved in both leaves and crown tissues during cold acclimationn using Real-time RT-PCR method.3. QTLs for fructan content were not linked to the loci of fructan biosynthesis genes. Some of QTIs for winter hardiness in the filed were coincided with QTLs for c fructan content.4. We produced transgenic perennial ryegrass plants that overexpress wheat fuructan biosynthesis genes (1-SST and 6-SFT). Significant increases in fructan contents and tolerance to freezing damage were observed in transgenic plants. Overexpression of fructan biosynthesis genes appears to serve increased tolerance to freezing in plants.