Huber S C, Wilson R F, Burton J W
United States Department of Agriculture, Agricultural Research Service, North Carolina State University, Raleigh, North Carolina 27650.
Plant Physiol. 1983 Nov;73(3):713-7. doi: 10.1104/pp.73.3.713.
Soybean (Glycine max L. Merr.) germplasm, essentially isogenic except for loci controlling male sterility (ms(1)) and nodulation (rj(1)), were developed to study the effects of reproductive development and nitrogen source on certain aspects of photosynthesis. Plants were sampled from flowering (77 days after transplanting) until maturity (150 days after transplanting). With all four genotypes, net carbon exchange rates were highest at flowering and declined thereafter. Photosynthetic rates of the sterile genotypes (nodulated and non-nodulated) declined more rapidly than the fertile genotypes, and after 105 days, both sterile genotypes maintained low but relatively constant carbon exchange rates (<3 milligrams CO(2)/gram fresh weight per hour). Photosynthetic rates and starch accumulation (difference between afternoon and morning levels) declined with time. The sterile genotypes attained the highest morning starch levels, which reflected reduced starch mobilization. After 92 days, the proportion of photosynthetically fixed carbon that was partitioning into starch (relative leaf starch accumulation) in the sterile genotypes increased dramatically. In contrast, relative leaf starch accumulation in the fertile genotypes remained relatively constant with time. Throughout the test period, all four genotypes maintained leaf sucrose levels between 5 and 15 micromoles glucose equivalents per gram fresh weight.The activities of sucrose phosphate synthase (SPS) in leaf extracts of the four genotypes declined from 77 to 147 days. Nodulated genotypes tended to maintain higher activities (leaf fresh weight basis) than did the non-nodulated genotypes. In general, relative leaf starch accumulation was correlated negatively with the activity of SPS (normalized with leaf net carbon exchange rate) in leaf extracts for all four genotypes during early reproductive development, and for the fertile genotypes at all sampling dates. In contrast, leaf sucrose content was correlated positively with SPS activity during early reproductive development. These results suggested that a direct relation existed between the activity of SPS and starch/sucrose levels in soybean leaves. However, the interaction between these processes also may be influenced by other factors, particularly when leaf photosynthetic rates and plant demand for assimilates is low, as in the sterile genotypes.
大豆（Glycine max L. Merr.）种质除了控制雄性不育（ms(1)）和结瘤（rj(1)）的基因座外基本同基因，被用于研究生殖发育和氮源对光合作用某些方面的影响。从开花期（移栽后77天）到成熟期（移栽后150天）对植株进行采样。对于所有四种基因型，净碳交换率在开花期最高，此后下降。不育基因型（结瘤和不结瘤）的光合速率比可育基因型下降得更快，105天后，两种不育基因型都保持较低但相对恒定的碳交换率（<3毫克二氧化碳/克鲜重/小时）。光合速率和淀粉积累（下午和上午水平的差异）随时间下降。不育基因型的早晨淀粉水平最高，这反映了淀粉动员减少。92天后，不育基因型中分配到淀粉中的光合固定碳比例（相对叶片淀粉积累）急剧增加。相比之下，可育基因型中的相对叶片淀粉积累随时间保持相对恒定。在整个测试期内，所有四种基因型的叶片蔗糖水平保持在5至15微摩尔葡萄糖当量/克鲜重之间。四种基因型叶片提取物中蔗糖磷酸合酶（SPS）的活性从77天到147天下降。结瘤基因型往往比不结瘤基因型保持更高的活性（以叶片鲜重计）。总体而言，在生殖发育早期，对于所有四种基因型以及在所有采样日期的可育基因型，相对叶片淀粉积累与叶片提取物中SPS的活性（以叶片净碳交换率标准化）呈负相关。相反，在生殖发育早期，叶片蔗糖含量与SPS活性呈正相关。这些结果表明SPS的活性与大豆叶片中的淀粉/蔗糖水平之间存在直接关系。然而，这些过程之间的相互作用也可能受到其他因素的影响，特别是当叶片光合速率和植物对同化物的需求较低时，如在不育基因型中。
