CARBOHYDRATE PARTITIONING IN 185 ACCESSIONS OF GRAMINEAE GROWN UNDER WARM AND COOL TEMPERATURES
CARBOHYDRATE PARTITIONING IN 185 ACCESSIONS OF GRAMINEAE GROWN UNDER WARM AND COOL TEMPERATURES
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DOI：
10.1016/s0176-1617(89)80051-3
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发表时间：
1989-03-01
影响因子：
4.3
通讯作者：
ASAY, KH
中科院分区：
文献类型：
--
作者：
CHATTERTON, NJ;HARRISON, PA;ASAY, KH
将碳水化合物储备分配为果聚糖和淀粉不应被认为是草中碳水化合物储存的替代形式。这两种聚合碳水化合物形式同时出现在冷季禾草的叶片中。温度对185份牧草中178份的TNC、蔗糖和淀粉的积累有深远的影响。7个例外中有6个是暖季植物，它们的光合作用在10摄氏度/5摄氏度时可能很慢。在25°c /15°c和10°c /5°c条件下，唯一能积累同样多TNC的冷季植物是土本草（Elymus tsukushiensis）。低温下果聚糖积累的增强支持了果聚糖在植物体内积累的假设，即当碳固定超过植物的转运和利用时。结果表明，在温暖的温度下，土国羊草（Elymus tsukushiensis）积累了123 mg gSDW-1果聚糖，这表明凉爽的温度并不总是所有草类完整叶片中果聚糖积累的先决条件。然而，来自冈瓦尼亚的冷季物种，那些属于丹冬属、针茅属、稻谷属和稻谷属的植物，即使在低温下也明显不产生果聚糖。暖季植物在温暖或寒冷的条件下可能都不会积累果聚糖。果聚糖在许多冷季物种的草叶中的积累可能并不总是与先前报道的高蔗糖浓度有关。在大量冷季品种中，果聚糖与蔗糖或果聚糖与淀粉浓度的相关性很低。我们得出的结论是，果聚糖不能替代任何其他形式的碳水化合物进行储存，因为平均而言，在有利于果聚糖积累的条件下生长的冷季植物叶片中的每种非结构碳水化合物成分与果聚糖含量低时一样高或更高。果聚糖的积累不以任何其他形式的非结构性碳水化合物为代价。在同一温度下，除了果聚糖在10℃/5℃生长外，两种草的非结构碳水化合物成分的平均含量相似，因此我们得出结论，果聚糖是碳水化合物的辅助储存形式。这种作用与液泡中果聚糖的积累使光合作用在其他储存池饱和的低温下继续进行的假设是一致的。有趣的是，在这个实验中，不合成果聚糖的冷季草比那些代谢果聚糖的草在春天开始生长得晚。
Partitioning of carbohydrate reserves into fructan and starch should not be considered as alternative forms of carbohydrate storage in grasses. Both polymeric carbohydrate forms occurred concurrently in leaves of cool-season grasses. Temperature had a profound effect upon the accumulation of TNC, sucrose, and starch in 178 out of 185 grass accessions included in this study. Six of the seven exceptions were warm-season plants that probably photosynthesize slowly at 10.degree.C/5.degree.C. The only cool-season accession to accumulate as much TNC at 25.degree.C/15.degree.C as at 10.degree.C/5.degree.C was Elymus tsukushiensis. Enhanced fructan accumulation during cool temperatures supports the hypothesis that fructans may accumulate in plants when carbon fixation exceeds plant translocation and utilization. The fact that Elymus tsukushiensis accumulated 123 mg gSDW-1 fructan during warm temperatures, indicates that cool temperatures are not always a prerequisite for fructan accumulation in intact leaves of all grass species. However, cool-season species of Gondwanic origin, those belonging to the genera Danthonia, Stipa, Oryzopsis, and Phragmities, apparently do not produce fructan even when plants are subjected to cool temperatures. Warm-season plants probably do not accumulate fructan under either warm or cold conditions. Fructan accumulation in grass leaves of many cool-season species may not always be associated with high sucrose concentrations as previously reported. The correlations between concentrations of leaf fructan and sucrose or fructan and starch, taken over a large number of cool-season species, are rather low. We conclude that fructan is not an alternative to any other form of carbohydrate for storage because, on the average, each nonstructural carbohydrate component was as high or higher, in leaves of cool-season plants growing in conditions conducive to fructan accumulation, than when fructan content was low. Fructan accumulation was not at the expense of any other form of nonstructural carbohydrate. Because the mean content of each nonstructural carbohydrate component was similar in the two grass types within a temperature, except for fructan in 10.degree.C/5.degree.C grown plants, we conclude that fructan is an ancillary form of carbohydrate storage. Such a role is compatible with the hypothesis that fructan accumulation in the vacuole allows photosynthesis to continue at cool temperatures when other storage pools are saturated. Interestingly, the cool-season grasses included in this experiment, which did not synthesize fructan, begin growth later in the spring than those that metabolize fructan.