不同含水量的豌豆种子萌发时物质动员及代谢研究

不同含水量的豌豆种子在饱和水蒸气中保持7d过程中,含水量低于萌动临界含水量时,子叶中贮藏蛋白质和淀粉的动员不能启动;含水量达到或超过萌动临界含水量,贮藏物质的动员被启动,豌启种子萌动后,子叶中蛋白质和淀动员程度与种子含水量呈正相关,前3d物质动员的程度比后4d强烈得多,因此,含水量是豌豆种子萌发时物质动员的启动因子和调节因子,同时,豌豆种子的含水量直接影响胚轴的生长状况。     

大豆子叶衰老的细胞学观察

以萌发后不同时期的大豆子叶为材料,通过普通光镜和荧光显微镜观察,分析了不同时期子叶细胞的结构变化及子叶细胞内蛋白质和淀粉含量的组织化学变化.结果表明,随着种子萌发时期的延长,子叶细胞内的蛋白质和淀粉含量逐渐减少,在子叶衰老过程中,细胞内蛋白质首先消耗殆尽,淀粉的消耗速度较蛋白质慢;大豆子叶细胞在萌发后第18天时出现典型的植物编程性死亡的形态学特征,子叶细胞内营养物质的消耗诱发子叶细胞发生细胞凋亡.     

高等植物胚胎的发育生物学研究——Ⅴ.水稻种胚发育过程中胚和胚乳内几种碳水化合物含量及淀粉酶活力的动态 高锦华;唐锡华

在开花后6～15天稻胚分化过程中,胚内淀粉、总糖和非还原糖含量逐渐地增加,但在胚器官原基分化完成后淀粉含量明显下降。胚分化期淀粉酶活力增加显著,尤其是β-淀粉酶活力较高,变化幅度大;胚器官原基分化完成后酶活性亦下降。以单位胚干重或每胚细胞计算的结果基本上亦表现了相似的趋势。稻胚分化发育过程中淀粉是处于不断被贮存同时不断被利用的状态,它积极参与了胚胎发育的代谢过程。至于β-淀粉酶可能在降解淀粉、提供能源,为合成蛋白质及纤维素等物质提供碳架方面起着重要作用。当胚分化完成后胚乳中淀粉含量仍有少量增加。在胚乳中α-淀粉酶活力低,变化幅度小,而β-淀粉酶活力在发育初期很高,以后下降,但活力仍比α-淀粉酶高,可能它在发育前期亦有类似在胚内的作用。     

黄皮种子脱水敏感性与萌发事件的研究

黄皮种子对脱水非常敏感,含水量从51%下降至22．4%,种子的发芽率和发芽指数为零,是典型的顽拗性种子。自然脱水时,种子中可溶性糖的含量增加,淀粉的含量下降;磷酸化酶,异柠檬酸裂解酶以及胚轴中α-和β-淀粉酶的活性先增加然后下降;子叶中α-和β-淀粉酶的活性呈下降趋势．这些变化类似于吸水萌发的黄皮和豌豆种子。可以认为黄皮种子脱水敏感性的原因是在脱落时萌发。随着萌发过程的进行,水分成为限制因子,使种子生活力丧失。     

黄皮种子脱水敏感性与萌发事件的研究

黄皮种子对脱水非常敏感,含水量从51％下降至22.4％,种子的发芽率和发芽指数为零,是典型的顽拗性种子。自然脱水时,种子中可溶性糖的含量增加,淀粉的含量下降;磷酸化酶,异柠檬酸裂解酶以及旺轴中α—和β—淀粉酶的活性先增加然后下降;子叶中α—和β—淀粉酶的活性呈下降趋势。这些变化类似于吸水萌发的黄皮和豌豆种子。可以认为黄皮种子脱水敏感性的原因是在脱落时萌发。随着萌发过程的进行,水分成为限制因子,使种子生活力丧失。     

百合鳞茎发育过程中碳水化合物含量及淀粉酶活性变化

以兰州百合和亚洲系"精粹"百合为试材,探讨了鳞茎发育过程中不同部位淀粉、可溶性糖含量和淀粉酶活性的变化。结果表明,母鳞茎作为百合萌发阶段的代谢源,其外部鳞片是代谢更为活跃的部位。淀粉和可溶性糖含量同时增加是百合新鳞茎开始膨大的标志。蔗糖是百合鳞茎中可溶性糖的主要形态,还原糖的变化体现了碳水化合物的供应及转化。淀粉酶在百合鳞茎发育过程中对调节和平衡碳水化合物的形态起重要作用。     

油茶种子萌发期间几种物质含量的变化

软枝油茶种子子叶内贮藏的脂肪和淀粉含量随萌发进程而递减;可溶性糖类含量无多大变化。输送至幼苗内的可溶性糖转化为淀粉。子叶内除非蛋白质氮量较稳定外,总氮、蛋白质氮和组成蛋白质的氨基酸种类与含量大都随萌发进程而减少,幼苗内的则相应递增·     

3种薯蓣属植物珠芽糖类含量变化与茎叶生长的关系

以山药、日本薯蓣和黄独3种薯蓣属植物为材料,研究珠芽育苗中其茎叶生长与珠芽内的干物质、淀粉、可溶性糖、还原糖含量和淀粉酶活性变化的关系.结果表明: 3种薯蓣在茎蔓生长过程中珠芽内的干物质和淀粉含量均逐渐降低.山药和黄独的珠芽可溶性糖含量在茎蔓生长初期不断增加,随着茎蔓节数继续增加又逐渐降低,而还原糖含量在叶片展开前不断增加,叶片展开后又急剧降低;日本薯蓣珠芽的可溶性糖和还原性糖含量随着茎蔓节数增加逐渐上升,但保持相对较低水平.3种薯蓣珠芽内α-淀粉酶活性均强于β-淀粉酶,其在茎蔓和叶片生长中发挥重要作用.研究发现,薯蓣珠芽内淀粉主要在α-淀粉酶作用下转化分解为还原糖和可溶性糖,从而为茎蔓和叶片生长提供能量,且还原糖含量与叶片生长的关系更为密切.     

沙地樟子松幼苗干旱致死过程中非结构性碳水化合物的变化

以2年生沙地樟子松幼苗为对象,通过持续自然干旱处理,研究当土壤含水量下降到田间持水量的60%、40%、30%、20%和15%时幼苗叶片水势及不同器官(一年生叶、当年生叶、茎、粗根和细根)的可溶性糖、淀粉和非结构性碳水化合物(NSC)的含量,分析沙地樟子松幼苗在干旱致死过程中各器官NSC的分配规律及其适应机制.结果表明: 土壤含水量从田间持水量的40%下降到15%,幼苗叶片凌晨及正午水势无显著变化.当土壤含水量从田间持水量的60%下降到30%,各器官可溶性糖、淀粉、NSC含量和可溶性糖/淀粉先下降后上升.从30%下降到20%,当年生叶、一年生叶、茎和细根可溶性糖、淀粉和NSC含量降低,而粗根可溶性糖含量增加,淀粉和NSC含量减少.从20%下降到15%,当年生叶、一年生叶和茎可溶性糖、淀粉和NSC含量降低,粗根可溶性糖和NSC含量下降,淀粉含量上升,细根可溶性糖含量减少,淀粉和NSC含量增加.沙地樟子松幼苗通过不断调整各器官NSC及其组分含量变化以适应不同干旱环境,土壤含水量下降到田间持水量的30%后,幼苗可溶性糖和NSC含量总体呈下降趋势,淀粉在粗根和细根中积累,幼苗可能因碳耗竭而死亡.     

毛竹受密竹链蚧危害导致其生理生化指标影响的研究

通过比较毛竹林受密竹链蚧不同程度危害后叶片中叶绿素、总糖、还原糖、蛋白质含量及含水量的差异,结果表明,毛竹受密竹链蚧危害后毛竹叶片生理生化指标与正常叶片存在显差异。     

The role of enzyme amylase in two germinating seed morphs of <Emphasis Type="Italic">Halopyrum mucronatum</Emphasis> (L.) Stapf. in saline and non-saline environment

The role of enzyme amylase in two germinating seed morphs, i.e. black and brown, of Halopyrum mucronatum in saline and non-saline environment was examined. Both seed morphs of this halophytic grass have variations in their moisture content, total lipid, protein, sugar, phenol and tannin contents. Black seed exhibited higher activity compared to brown in saline medium. Sugar mobilization in both seed morphs was also affected due to the difference in amylase activity. However, exogenous application of GA₃ in saline medium enhanced the amylase activity and sugar mobilization. Phenolic contents were similar except for vanillic acid which was found only in brown seeds while catechol was present only in black seeds. Phenols extracted from both seed morphs were applied to determine their effects on amylase activity. Phenolic extracts obtained from brown seeds showed higher degree of inhibition of amylase activity. Results are discussed in relation to seed coat phenols, leaching, amylase activity and sugar mobilization.     

Allelochemical stress produced by aqueous leachate of <Emphasis Type="Italic">Nicotiana plumbaginifolia</Emphasis> Viv.

The effects of aqueous leachate of Nicotiana plumbaginifolia Viv. on germination, seedling growth, amylase activity, sugar and starch contents of germinated seeds of maize (Zea mays L. cv. Uttam) were examined. Effects of leachate on photosynthetic pigments, protein content, activities of nitrate reductase and some antioxidants were also studied. Higher concentration of aqueous leachate of N. plumbaginifolia reduced the germination rate (GR). However, final germination percentage remained almost unaffected. Lower concentration of leachate stimulated the amylase activity and resulted in higher sugar content and GR. The increasing concentrations of leachate inhibited the conversion of starch into sugars. Allelochemicals decreased the amount of chlorophyll a, chlorophyll b, carotenoids, protein and nitrate reductase activity (NRA). The leachate of lower concentrations stimulated the activity of peroxidase but slight decrease was recorded in higher concentration. Superoxide dismutase and catalase exhibited concentration dependent increase except in seedlings treated with 100% concentration of leachate. Impairment of various metabolic activities due to leachate resulted in decreased root and shoot length.     

Promotion of radish cotyledon enlargement and reducing sugar content by zeatin and red light

Effects of zeatin on amino acid and sugar contents of detached radish (Raphanus sativus L.) cotyledons were investigated to determine if accumulation of these solutes contributes to cytokinin-enhanced growth. Protein and amino acid levels were not significantly affected, but in cotyledons incubated in light the hormone caused greater accumulations of reducing sugars than occurred in light controls. Continuous fluorescent light or a few minutes of red light increased both the growth rate and the reducing sugar levels compared to dark controls. A far red treatment following red light overcame the promoting effect of the latter. Amounts of reducing sugars were closely associated with growth under the above conditions. Activity of an unidentified amylase was elevated by continuous light or a red light treatment (nullifiable by far red), suggesting that reducing sugars were derived from starch. Zeatin-treated cotyledons exhibited less amylase activity than did light controls, perhaps implicating cytokinin-stimulated conversion of fats to sugars in light. In darkness zeatin promoted cotyledon growth but did not increase sugar levels nor amylase activity, suggesting that enhanced ion accumulation also contributes to the more rapid water uptake leading to growth.     

胚轴对萌发豌豆子叶中淀粉酶活性表达的影响

萌发豌豆的上、下肢轴均能诱导子叶中淀粉酶活性,外源GA和6—BA具有类似胚轴的作用。离体子叶的淀粉酶凝胶电泳只有一条活性极低的酶带,连生子叶中有两条酶带,其中由胚轴诱导新出现了一条活性很高的同工酶带,它的活性受亚胺环己酮的强烈抑制,而受放线菌素D影响不大。推测豌豆子叶中存在淀粉酶的长寿命mRN—A,胚轴和外源激素的作用在于促进mRNA的翻译。     

Amylase Activities in Attached and Excised Cotyledons and in Embryonic Axes of Pisum sativum L.

Amylase activity increased in attached cotyledons of peas, Pisumsativum L. var. Bördi, only during imbibition and remainedalmost constant up to 96 h after germination, but in excisedcotyledons the activity increased slightly at first then markedly.In contrast, the content of the reducing sugars was higher inattached cotyledons than in excised ones. A similar inverserelationship has been found between the concentration of reducingsugars in axes (both attached and excised) and amylase activity. The leakage from intact seeds contained more reducing sugarsthan the leakage from excised cotyledons, whereas the amountof proteins released from the cotyledons was four times greaterduring imbibition. This increase in amylase activity in excisedcotyledons is not thought to be the result of axis excision,but to be the result of the leakage of sugars from the cotyledonsduring incubation. These results suggest that the concentration of reducing sugarsmay be a factor that regulates amylase activity in vivo in boththe cotyledons and axis during the germination of pea seeds. (Received August 4, 1982; Accepted December 14, 1982)     

Mass transport of proform of a KDEL-tailed cysteine proteinase (SH-EP) to protein storage vacuoles by endoplasmic reticulum-derived vesicle is involved in protein mobilization in germinating seeds

A vacuolar cysteine proteinase, designated SH-EP, is expressed in the cotyledon of germinated Vigna mungo seeds and is responsible for the degradation of storage proteins. SH-EP is a characteristic vacuolar proteinase possessing a COOH-terminal endoplasmic reticulum (ER) retention sequence, KDEL. In this work, immunocytochemical analysis of the cotyledon cells of germinated V. mungo seeds was performed using seven kinds of antibodies to identify the intracellular transport pathway of SH-EP from ER to protein storage vacuoles. A proform of SH-EP synthesized in ER accumulated at the edge or middle region of ER where the transport vesicle was formed. The vesicle containing a large amount of proSH-EP, termed KV, budded off from ER, bypassed the Golgi complex, and was sorted to protein storage vacuoles. This massive transport of SH-EP via KV was thought to mediate dynamic protein mobilization in the cotyledon cells of germinated seeds. We discuss the possibilities that the KDEL sequence of KDEL-tailed vacuolar cysteine proteinases function as an accumulation signal at ER, and that the mass transport of the proteinases by ER-derived KV-like vesicle is involved in the protein mobilization of plants.     

Development of protein bodies and accumulation of carbohydrates in a soybean (Leguminosae) shriveled seed mutant

The soybean seed mutant T311, when grown under specific environmental conditions, produces shriveled seed. This research investigated changes in development of protein bodies and accumulation of carbohydrates during seed development by comparing the mutant with P2180 seeds. The shriveled seeds contained larger protein bodies but fewer protein bodies per cell than round seeds. Protein bodies in T311 seeds included more dispersed crystals and less globoid regions than P2180 seeds. The elemental compositions of the crystals and of whole seeds in T311 were different from that in P2180 seeds. Starch breakdown was reduced with concomitant lower soluble sugar content in T311 seeds after the D11 stage (10.0-11.9 mm long seeds). The reduced starch breakdown and lowered soluble sugar content were consistent with lower a-amylase activity and earlier and greater water loss in T311 seeds. Changes in development of protein bodies and accumulation of carbohydrates were associated with the development of the shriveled seeds.     

Influence of the Embryonic Axis on Protein Hydrolysis in Cotyledons of Cucurbita maxima

Four-day time course studies of the hydrolysis of cotyledonal storage protein were conducted on intact seeds, seed cotyledons detached from their embryonic axes and on detached cotyledon pairs germinated in the presence of three excised embryonic axes of Cucurbita maxima Duch., cv. Chicago Worted Hubbard. Detached cotyledons germinated alone showed little hydrolysis of the storage protein. However, the amount of protein hydrolysis of the detached cotyledon pairs germinated in the presence of three excised embryonic axes was comparable to the amount hydrolyzed in the cotyledons of intact germinating seeds. Visual growth differences among these treatments were also evident. The size and yellow color intensity of the fourth day treatments were shown to increase in the following order: detached cotyledon pairs alone, intact seedlings, detached cotyledon pairs in the presence of three excised axes. The growth of the hypocotyl and radical was also modified by removal of the cotyledons. These findings suggest that storage protein degradation and cotyledonal growth are controled by the axis. They also indicate that the cotyledons have some influence on the growth of the axes. Time-course studies were made on the hydrolysis of storage protein in the cotyledons of squash and on the distribution of the hydrolytic products during the germination of light- and dark-grown plants. The storage protein was not hydrolyzed during the first 24 hours. It was hydrolyzed at a uniform rate from 1 to 5 days and at a slightly decreased rate from 5 to 7 days. Most of the hydrolytic products were transported to the axial tissue. Proteinase activity in the cotyledons rapidly increased during germination to a maximum level at 2 to 3 days. This was followed by a decline to about the initial value after 7 days.     

两种品质类型花生品质形成与子叶细胞超微结构的关系

在大田条件下研究了两种品质类型花生(Arachis hypogaea)品质形成的动态差异及其子叶细胞超微结构的差异。结果表明, 高蛋白品种‘XB023’的蛋白质含量在籽仁发育前期较高油品种‘鲁花9号’低, 后期显著高于‘鲁花9号’, 且成熟期籽仁8种必需氨基酸组分含量均高于‘鲁花9号’, 其中谷氨酸、赖氨酸和亮氨酸含量差异极显著; ‘XB023’脂肪含量在籽仁发育期一直低于‘鲁花9号’。‘XB023’各时期的籽仁可溶性糖含量和油酸/亚油酸(O/L)值均显著低于‘鲁花9号’。两品种在果针入土10天时子叶细胞即形成淀粉粒、脂体和蛋白体, 随后脂体、蛋白体的数量不断增加, 淀粉粒先增大后逐渐缩小解体。‘XB023’的脂体达到最大的时间早于‘鲁花9号’, 而‘鲁花9号’的脂体快速积累的时间比‘XB023’长。两品种蛋白体大小都在果针入土40天时达到最大值, ‘XB023’的蛋白体在籽仁发育后期数量增加较快。高蛋白品种较高的蛋白质含量由其子叶细胞中较大蛋白体的大小和较多的蛋白体数量决定, 而高油品种较高的脂肪含量是由其较多的脂体数量决定。