高粱不同器官生长对NaCl胁迫的响应及其耐盐阈值

用砂基培养研究高粱不同器官生长对NaCl胁迫的响应及其耐盐阈值。NaCl胁迫下,独角虎和糖高粱均表现为生长叶叶鞘鲜重下降最大,其次是生长叶叶片、成熟叶叶鞘和叶片变化最小。长期胁迫单株叶片数及叶面积也明显下降。相同胁迫情况下,糖高梁的生长抑制明显大于独角虎。独角虎和糖高粱耐盐阈值分别为135和82mmol／LNaCI。以上结果表明独角虎耐盐能力明显大于糖高粱。讨论了不同器官生长抑制的机制。     

Differential Effects of Hunting on Pre-Dispersal Seed Predation and Primary and Secondary Seed Removal of Two Neotropical Tree Species

Many of the mammals undergoing drastic declines in tropical forests worldwide are important seed dispersers and seed predators, and thus changes in mammal communities due to hunting will affect plant recruitment. It has been hypothesized that larger-seeded species will suffer greater reductions in seed removal and thus greater increases in predispersal seed predation than smaller-seeded species. We compared primary and secondary seed removal and predispersal seed predation of two tree species between hunted and nonhunted sites in Central Panama. Seeds of Oenocarpus mapora (Arecaceae) are 16-times greater in size than those of Cordia bicolor (Boraginaceae). We quantified primary seed removal and predispersal seed predation using seed traps, and we assessed secondary seed removal using seed removal plots. Primary removal of C. bicolor was 43 percent lower in the hunted sites, while primary removal of O. mapora was not significantly different. Secondary removal of unprotected O. mapora seeds on the ground was 59 percent lower in hunted sites, while secondary removal of C. bicolor was not significantly different. Predispersal seed predation of O. mapora by mammals was significantly lower in hunted sites, while predispersal seed predation by insects was not significantly different in either species. In combination with other studies, our results suggest that seed size is not a reliable predictor of the impacts of hunting. Mammal defaunation differentially affects stages and modes of seed dispersal and seed predation of different plant species, suggesting that these influences are complex and related to multiple plant traits.     

Proline accumulation and nitrate reductase activity in contrasting sorghum lines during mid-season drought stress

Six lines of sorghum ( Sorghum bicolor L. Moench) with differing drought resistance (IS 22380, ICSV 213, IS 13441 and SPH 263, resistant and IS 12739 and IS 12744, susceptible) were grown under field conditions in the semi-arid tropics and analysed for proline and nitrate reductase activity (NRA; EC 1.6.6.1) during a mid-season drought. The resistant lines accumulated high levels of proline, while the susceptible lines showed no significant proline accumulation. Most of the proline was accumulated after growth of the plants had ceased. In a separate greenhouse experiment, most of the proline was found in the green rather than the fired portions of leaves. The levels returned to that of irrigated controls within 5 days of rewatering. Proline levels increased as leaf water potential and relative water content fell, and there was no apparent difference among the different sorghum lines with change in plant water status. Susceptible lines accumulated less proline than resistant lines as leaf death occurred at higher water potentials. Proline accumulation may, however, contribute to the immediate recovery of plants from drought. Leaf NRA reached high levels at about 35 days after sowing in both the stressed and irrigated plants, after which it declined. The decline in NRA was more pronounced in the stressed than in the irrigated plants and closely followed changes in the growth rate. Upon rewatering, NRA increased several-fold in all the lines and, in contrast to proline accumulation, genotypic differences in NRA were small, both during stress and upon rewatering. The high sensitivity of NRA to mild drought stress was reflected in the rapid decline of activity with small changes in leaf water potential and relative water content. The results are discussed in the light of a possible role for proline during recovery from drought, and the maintenance of NRA during stress and its recovery upon rewatering.     

二色补血草地上部分的化学成分

二色补血草﹝Limonium bicolor ( Bunge) Kuntze﹞为补血草属( Limonium Mill.)越年生草本植物,耐盐碱和抗逆性强,全草均可入药,具有补血止血、调经益气、抗菌消炎和温中健脾的作用[1],含有黄酮、多糖、挥发油和甾体等成分[2-7],其中,黄酮类成分具有较强的抗氧化能力,多糖对Hela细胞有明显抑制作用[8-11]。前人对二色补血草化学成分和药理活性已有一定研究,但对其地上部分的化学成分尚缺乏系统分析。为此,作者对二色补血草地上部分乙醇提取物进行了分离和鉴定,为该种的进一步开发利用和药理药效研究提供基础实验数据。     

光质对紫背天葵生长、次生代谢和抗氧化胁迫的影响

以紫背天葵为供试材料,采用LED灯精量调控光质和光强,研究相同光照强度(350±5 μmol·m^-2·s^-1)下,白光(W)、红光(R)、蓝光(B)、黄光(Y)、红蓝混合光(RB)、红蓝黄混合光(RBY)对紫背天葵生长、次生代谢和氧化胁迫抗性的影响.结果表明:与白光(W)相比,红光(R)能够显著促进紫背天葵植株的生长以及干物质和可溶性糖含量的积累;而蓝光(B)则抑制紫背天葵的生长;叶绿素含量在有色光处理下均显著降低;虽然红蓝黄混合光(RBY)未能显著提升紫背天葵的干物质含量,但总酚、类黄酮和花青素含量显著提升,这些还原态物质的积累有利于提高紫背天葵的抗氧化能力,在增强自身抗逆性的同时提升营养价值.本研究为光质调控紫背天葵的多样化生产提供了理论依据.     

Biased dispersal of Metrioptera bicolor,a wing dimorphic bush‐cricket

In the highly fragmented landscape of central Europe, dispersal is of particular importance as it determines the long‐term survival of animal populations. Dispersal not only secures the recolonization of patches where populations went extinct, it may also rescue small populations and thus prevent local extinction events. As dispersal involves different individual fitness costs, the decision to disperse should not be random but context‐dependent and often will be biased toward a certain group of individuals (e.g., sex‐ and wing morph‐biased dispersal). Although biased dispersal has far‐reaching consequences for animal populations, immediate studies of sex‐ and wing morph‐biased dispersal in orthopterans are very rare. Here, we used a combined approach of morphological and genetic analyses to investigate biased dispersal of Metrioptera bicolor, a wing dimorphic bush‐cricket. Our results clearly show wing morph‐biased dispersal for both sexes of M. bicolor. In addition, we found sex‐biased dispersal for macropterous individuals, but not for micropters. Both, morphological and genetic data, favor macropterous males as dispersal unit of this bush‐cricket species. To get an idea of the flight ability of M. bicolor, we compared our morphological data with that of Locusta migratoria and Schistocerca gregaria, which are very good flyers. Based on our morphological data, we suggest a good flight ability for macropters of M. bicolor, although flying individuals of this species are seldom observed.     

Improved preparation and assay and some characteristics of Cl−-ATPase activity from Limonium vulgare

We present a revised method for the preparation, storage and assay of the Cl^?-ATPase activity responsible for salt secretion in Limonium vulgare. Altering the centrifugation step improved the yield and a linked-enzyme assay for ADP provided a sensitive method for continuous monitoring of Cl^?-ATPase activity. The activity of untreated membranes was low but fairly stable. Treatment with detergent gave strong stimulation of Cl^?-ATPase activity but caused a rapid decline in activity with time. $\text{V}{}_{\mathrm{<mtext>app</mtext>}}$ was approx. 6.5 μmoles/h per mg protein and $\text{K}{}_{\mathrm{<mtext>m,\; app</mtext>}}$ for ATP between 0.1 and 0.2 mM. Cl^? stimulated the activity up to a maximum at 0.13 M Cl^?, and the pH optimum was around 6.3 to 6.4.     

Screening of sorghum genotypes and biochemical changes for resistance to damage caused by Macrophomina phaseolina

Charcoal rot, caused by Macrophomina phaseolina, is the most common yield reducing constraint in sorghum. In the present study, eight cultivars of Sorghum bicolor were screened against M. phaseolina to determine its effects on several growth parameters as well as the content of phenols, salicylic acid (SA), total protein and peroxidase activity and were examined for their relationship, with disease resistance. Out of the eight cultivars tested, PJ-1430 was the most resistant and SU-1080, the most susceptible. The roots of plants were more affected by the pathogen than the shoots. The cultivar PJ-1430 produced a higher plant root and shoot dry mass and was associated with higher polyphenols, SA, peroxidases and thus sustained less oxidative damage whereas SU-1080 experienced maximum oxidative damage, so was considered susceptible to charcoal rot. A positive relationship was observed among various biochemical parameters and disease resistance of cultivars PJ-1430 and SU-1080.