结缕草的抗寒性与体内碳水化合物、脯氨酸、可溶性蛋白季节动态变化的关系

为了阐述结缕草抗寒性与碳水化合物、脯氨酸含量及可溶性蛋白含量季节动态变化的关系,在2008年10月-2009年5月期间,以‘兰引3号’结缕草(Zoysia japonica ‘Lanyin No.3’)为材料,研究在自然温度变化过程中,‘兰引3号’结缕草地下根茎碳水化合物、脯氨酸含量、可溶性蛋白含量的季节性动态变化及其与LT₅₀变化的关系。结果表明,在越冬前后,‘兰引3号’结缕草地下根茎LT₅₀呈先降低后升高的季节变化趋势,可溶性总糖含量、蔗糖含量、果糖含量及可溶性总糖/淀粉、脯氨酸含量、可溶性蛋白含量伴随田间气温变化均呈先升高后又降低的趋势,淀粉含量则呈先降低后又升高的趋势;‘兰引3号’结缕草地下根茎LT₅₀季节变化与可溶性总糖含量、果糖含量、可溶性总糖/淀粉、可溶性蛋白含量季节变化之间显著负相关,而与蔗糖含量、淀粉含量、脯氨酸含量的季节变化间不存在显著的相关性。     

蓝舌病病毒新型NS4蛋白的亚细胞定位分析及功能预测

蓝舌病病毒(bluetongue virus,BTV)编码4种非结构蛋白(NS1~NS4),其中NS4是新发现的非结构蛋白。为深入探索该新型非结构蛋白的功能,本研究首先采用生物信息学分析其序列结构特征及可能的功能域,结果发现NS4蛋白的N端α-螺旋结构域中具有富含碱性氨基酸的核定位信号(NLS),而C端α-螺旋结构域中具有亮氨酸拉链结构的核输出信号(NES)。为进一步证实NS4的亚细胞定位,本试验构建了表达NS4全长及其缺失突变体的重组质粒,结果显示缺失NLS的NS4重组蛋白弥散在胞浆,而缺失NES后NS4重组蛋白只定位于细胞核,表明NS4蛋白亚细胞定位具有核-胞浆穿梭过程。最后结合3D同源建模发现NS4与CCAAT增强子结合蛋白(C/EBPβ)等具有较高的同源性,据此推测NS4可能为转录调控蛋白,与DNA或其他转录因子存在相互作用。总之,本研究为NS4蛋白的功能研究提供了更多新线索和新思路,填补了BTV基础研究的空白。     

Does the “high sugar” trait of perennial ryegrass cultivars express under temperate climate conditions?

The objective was to evaluate water‐soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m² each, three blocks): four PRG cultivars (diploid standard cultivar, “2nSt”; tetraploid standard cultivar, “4nSt”; diploid high sugar cultivar developed in New Zealand, “2nHSNZ”; and tetraploid high sugar cultivar developed in Europe, “4nHSEU”) and two agronomic managements (“favourable,” defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha^?1 year^?1; “unfavourable,” defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha^?1 year^?1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12‐month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the “high sugar” trait, where a genetic × environment interaction might be operating.     

Relationships between reproductive output, morpho-physiological traits and life span in Lesquerella (Brassicaceae)

The development of perennial industrial crops could contribute to increase agriculture sustainability and yield stability in arid environments. Since perennial plants allocate resources preferentially to perpetuation and to structural and functional characters that provide drought tolerance, they tend to have lower reproductive output (yield) than their congeneric annuals. Four species of Lesquerella native to arid regions were evaluated to understand the relationships between reproduction, drought tolerance, and their association with the plant's life span. We assessed the following set of characters (defined as plant strategies): phenology, gas exchange, specific leaf area, leaf area ratio, total biomass and biomass allocation. Annual (Lesquerella gracilis and Lesquerella angustifolia) and perennial (Lesquerella mendocina and Lesquerella pinetorum) species were compared under water limiting conditions. Within this set of species differences in structural and functional characters were observed. The annual, L. gracilis showed a plant strategy characterized by high reproductive output, harvest index (HI) and specific leaf area (SLA). L. mendocina (perennial), produced more total biomass, but had a low reproductive output, and also showed characters that provide drought tolerance (high allocation to roots-root mass ratio (RMR), and storage-total non structural carbohydrates (TNC) and low SLA). The annual L. angustifolia and the perennial L. pinetorum had intermediate plant strategies (i.e. intermediate values of traits typically related with annual or perennial life span). In the case of L. pinetorum we found some traits common to L. mendocina: long vegetative period, high biomass, CO₂ assimilation rate (A), and water use efficiency (WUE), and low SLA. The high reproductive output in L. pinetorum was a result of both, higher total biomass and longer growing season compared to the annuals, and of higher HI in relation to the other perennial. These differences in plant strategies among perennial Lesquerella show that there are different combinations of traits that could be used as criteria for the selection of a perennial crop in programs of domestication for Patagonia and others arid lands.     

12个苜蓿品种根部非结构性碳水化合物含量的季节性变化

研究不同紫花苜蓿品种晚秋和早春时期根部非结构性碳水化合物含量的季节变化动态,以期为当地紫花苜蓿推广应用提供理论依据。以国内外12个紫花苜蓿品种为试验材料,通过测定其在晚秋和早春时期根部可溶性糖、还原糖、总糖和淀粉含量,对不同紫花苜蓿品种抗寒生理特性进行了比较研究。结果表明,秋季和春季不同苜蓿品种根部可溶性糖、还原糖和总糖含量以及可溶性糖/淀粉值差异显著(P0.05),淀粉含量在秋季差异显著(P0.05),春季差异不显著(P0.05)。从晚秋至翌年早春,不同苜蓿品种根部非结构性碳水化合物含量下降幅度差异较大,可溶性糖含量下降率为8.71%~41.43%,淀粉下降率为51.21%~79.37%,还原糖下降率为17.47%~56.16%,总糖下降率为26.10%~48.78%。聚类分析可将12个苜蓿品种分为三类:第一类为根部低淀粉含量类,包含M1和M8号二个品种,淀粉含量低于3.0%;第二类为根部高淀粉含量类,包含M3、M4、M6、M7和M11号五个品种,淀粉含量在3.91%~4.82%之间;第三类为根部高可溶性糖含量类,包括M2、M5、M9、M10、M12五个品种,可溶性糖含量在8.0%以上,淀粉含量在3.0%~4.0%之间。     

Photosynthetic Activity and Soluble Carbohydrate Content Induced by the Cold Acclimation Affect Frost Tolerance and Resistance to Microdochium nivale of Androgenic Festulolium Genotypes

The aim of the experiment was to verify whether changes in photosynthetic activity measured by means of chlorophyll fluorescence techniques and soluble carbohydrate level induced during pre-hardening and cold acclimation in androgenic forms of Festulolium are related to their winter hardiness and pathogen resistance. The study was performed on six androgenic genotypes of Festulolium, which differ in their degrees of winter hardiness. The chlorophyll fluorescence parameters and sugar content were measured in the control plants, pre-hardened at 12 °C and cold-acclimated at 2 °C. Cold acclimation at 2 °C, preceded by pre-hardening at 12 °C, induced a decline in maximum PSII quantum efficiency ( F _v/ F _m) and in non-photochemical quenching (NPQ). Exposure to 2 °C also resulted in reduced efficiency of energy conversion in photochemical processes ( q _p). The soluble carbohydrate amount increased in the susceptible genotypes and was associated with a decline in NPQ and current quantum yield of PSII (φ_PSII). In resistant plants, a decrease in the sugar content was observed, which could be explained by their consumption in metabolic processes initiated during cold acclimation. The changes in sugar content were associated with a decline in NPQ and q _p.     

Carbohydrate profiles in the graft union of young sweet cherry trees grown on dwarfing and vigorous rootstocks

In composite (scion–rootstock) dwarfing fruit trees, an overgrowth at the graft union is often observed, the severity of which is correlated with degree of dwarfing. The graft union of dwarfing sweet cherry (Prunus avium L.) rootstocks may limit soluble sugar transport or starch mobilization, leading to localized accumulation. Soluble sugars and starch were measured in the tissues surrounding the graft union of young ‘Rainier’ (2002) and ‘Lapins’ (2003) sweet cherry trees on ‘Gisela 5’ (‘Gi 5’; dwarfing) and ‘Colt’ (vigorous) rootstocks. Separate rootstock shank, rootstock, graft union, and scion tissues were analyzed for both starch and soluble sugar content throughout the growing season in both years. Starch concentrations did not vary among locations within the graft union for ‘Rainier’ on either the dwarfing or vigorous rootstock, or for ‘Lapins’ on the dwarfing stock. However, for ‘Lapins’ on ‘Colt’, starch was highest in the rootstock shank and declined vertically (rootstock shank ? rootstock > union > scion). Soluble sugar concentrations were generally similar to or higher in scions on ‘Gi 5’ than on ‘Colt’, and were similar to or lower in the rootstock and rootstock shank on ‘Gi 5’ than on ‘Colt’. Results suggest that rootstock has a significant effect of localized accumulations of carbohydrates above and within the graft union of ‘Gi 5’ and below the graft union of ‘Colt’.     

Changes in soluble carbohydrates, lipid peroxidation and antioxidant enzyme activities in the embryo during ageing in wheat grains

Soluble sugar contents and antioxidant enzyme activities were measured in the embryo of wheat (Triticum aestivum L., cv Charger) seeds throughout their storage under two conditions (45 °C and 100% relative humidity (RH), and 30 °C and 75% RH) to investigate whether grain deterioration during ageing was related to lipid peroxidation resulting in a decrease in the efficiency of the antioxidant defence system, and in changes in sugar metabolism. The half-viability period (P₅₀) was only 6 d at 45 °C and 100% RH against about 3.75 months at 30 °C and 75% RH. However, sensitivity of grains to accelerated ageing carried out at 45 °C and 100% RH increased during their pre-storage at 30 °C and 75% RH. Loss of grain viability at 45 °C and 100% RH was associated with an accumulation of H₂O₂ which was concomitant with a progressive decrease in catalase (CAT) and superoxide dismutase (SOD) activities, and with an increase in glutathione reductase (GR) activity. However, malondialdehyde content did not change, suggesting that there was no lipid peroxidation during such an ageing. In return, ageing of grains at 30 °C and 75% RH was not associated either with strong changes in CAT, SOD and GR activities or with an accumulation of H₂O₂. When there was no correlation between CAT, SOD and GR activities and seed viability, there was a linear correlation between CAT activity and seed vigour evaluated by the T₅₀ during ageing at 45 °C and 100% RH. Sugar metabolism in wheat embryo largely depended on ageing conditions. Loss of grain viability at 45 °C and 100% RH was associated with a marked decrease in sucrose (Su) and a slight increase in raffinose (Ra), and subsequently in the Ra/Su ratio. At 30 °C and 75% RH, seed ageing was associated with an increase in both sugars but with no strong increase in Su/Ra ratio. Our results suggest that ageing was associated with various mechanisms depending on the conditions of ageing, and that accelerated ageing at 45 °C and 100% RH was not the only model to consider in order to understand the mechanisms involved in seed deterioration.     

Source : sink ratio and leaf senescence in maize:: II. Nitrogen metabolism during grain filling

Leaf senescence in a recent maize (Zea mays L.) hybrid is delayed relative to that in an older maize hybrid and the trait is associated with an improvement of the ratio of assimilate supply (i.e., source) and demand (i.e., sink) during grain filling. This study examined whether effects of source : sink ratio of leaf longevity in an old and more recent hybrid are associated with changes in leaf nitrogen (N) concentration and N uptake during grain filling. A 3-year field study was conducted with maize hybrids Pride 5 (old) and Pioneer 3902 (recent) grown at two soil-N levels: 150 kg⁻¹ N ha⁻¹ was broadcast in the high N treatment while none was added to the low N treatment. Four imposed source : sink treatments ranged from partial defoliation to no grain. Leaf N of the control treatments did not differ between the two hybrids, but the decline in leaf N from the control to the no-sink treatment was larger for Pioneer 3902 than for Pride 5. Total N uptake in above-ground portions was 10 and 18% greater in the new than in the old hybrid under low and high soil-N conditions, respectively. The difference in the total N uptake between the two hybrids could be attributed to post-silking N uptake. The proportion of N in the grain derived from post-silking N uptake was 60% for Pioneer 3902 and 40% for Pride 5 and this proportion was positively associated with the source : sink ratio. Higher rates of N uptake in Pioneer 3902 vs. Pride 5 appear to be, in part, the result of higher rates of dry matter accumulation of the newer hybrid during grain filling.     

钢筋混凝土楼板非结构性裂缝控制

本文论述了钢筋混凝土楼板非结构性裂缝的类型及产生原因,并提出应抓好砼施工过程中的几个重要环节来控制裂缝。