冬油菜和春油菜在冷驯过程中膜脂分子的变化

研究了冬油菜和春油菜两种油菜品种在4℃冷驯3天后11类151种膜脂分子的变化,计算了其中膜脂的相对含量、双键指数和碳链长度值。结果发现油菜膜脂的膜脂分子组成模式及其冷驯诱导的膜脂分子组成变化与前期实验中的拟南芥情况非常相似,冷驯3天诱导的膜脂分子组成变化较小,但是膜脂的双键指数略有升高,春油菜双键指数和冷驯积累的脯氨酸含量都比冬油菜多。上述结果说明,油菜的冷驯需要更多的时间,春油菜对冷驯比较敏感。     

大豆种子吸胀冷害抗性与其质体膜脂不饱和度正相关

吸胀冷害是干种子在吸胀阶段遭受低温造成不萌发的现象,结果可能造成农作物损失严重。虽然吸胀过程中细胞膜的修复是关键事件,而且细胞膜在响应水分和温度胁迫中扮演重要角色,但是种子吸胀过程中膜变化的过程,特别是膜流动性变化过程研究较少。本文比较了吸胀冷害耐受型（LX）和敏感型（R5）两个大豆品种在吸胀冷害过程中膜脂不饱和度（double bond index, DBI）的变化,结果发现,LX和R5在常温（25℃）吸胀时变化趋势一致,质体膜脂DBI升高,质体外膜脂中磷脂酰甘油(phosphatidylglycerol, PG)分子DBI下降。LX和R5在低温（4℃）吸胀时DBI变化有很大差异,低温吸胀仅仅延缓了耐受型LX中质体膜脂DBI的升高,但是敏感性R5质体膜脂DBI不仅没有升高反而下降。用浓度33%的聚乙二醇 (polyethylene glycol, PEG)引发没有直接引起DBI变化,但是所引起的细微而显著的变化可能为萌发做好准备。PEG引发处理后的R5在吸胀冷害后第二和第三阶段质体膜脂DBI迅速增加,这个增加模式与LX的DBI增加相似。结果表明,吸胀冷害延缓或者阻滞了质体膜脂不饱和度的升高,大豆种子的吸胀冷害抗性与质体膜脂不饱和度正相关,提高质体膜质DBI可以提高吸胀冷害抗性。     

磷脂酶Dδ缺失加剧UV-B诱导的膜伤害

检测了拟南芥野生型（WS）及磷脂酶Dδ缺失突变体在UV-B辐射下的膜脂分子变化,并比较了二者在紫外辐射下的膜脂含量、双键指数及碳链长度的差异。结果发现,紫外辐射导致植株膜脂发生了降解,其中叶绿体膜脂MGDG和DGDG是膜伤害的主要作用靶点,而且突变体中的膜脂降解比野生型剧烈。上述结果说明磷脂酶Dδ的缺失会加剧紫外辐射诱导的膜伤害,导致植株对紫外辐射更加敏感。     

WCS120 protein family and proteins soluble upon boiling in cold-acclimated winter wheat

The amount of proteins soluble upon boiling (especially WCS120 proteins) and the ability to develop frost tolerance (FT) after cold acclimation was studied in two frost-tolerant winter wheat cultivars, Mironovskaya 808 and Bezostaya 1. Protein gel blot analysis, mass spectrometry (MS) and image analysis of two-dimensional gel electrophoresis (2-DE) gels were used to identify and/or quantify the differences in protein patterns before (non-acclimated, NA) and after 3 weeks of cold acclimation (CA) of the wheats, when FT increased from -4 degrees C (lethal temperature (LT(50)), for both cultivars) to -18.6 degrees C in Bezostaya 1 and -20.8 degrees C in Mironovskaya 808. Only WCS120 protein was visible in NA leaves while all five WCS120 proteins were induced in the CA leaves. Mironovskaya 808 had higher accumulation of three members of WCS120 proteins (WCS120, WCS66 and WCS40) than Bezostaya 1. MS analysis of total sample of proteins soluble upon boiling showed seven COR proteins in the CA samples and only three COR proteins in the NA samples of cultivar Mironovskaya 808 (MIR). In conclusion, the level of the accumulation of WCS120, WCS66 and WCS40 distinguished our two frost-tolerant winter wheat cultivars. Moreover, the differences of CA and NA samples of the MIR were shown by liquid chromatography (LC)-tandem mass spectrometry (MS/MS).     

磷脂酶Dδ缺失加剧UV-B诱导的膜伤害

检测了拟南芥野生型（WS）及磷脂酶D8缺失突变体在uV-B辐射下的膜脂分子变化,并比较了二者在紫外辐射下的膜脂含量、双键指数及碳链长度的差异。结果发现,紫外辐射导致植株膜脂发生了降解,其中叶绿体膜脂MGDG和DGDG是膜伤害的主要作用靶点,而且突变体中的膜脂降解比野生型剧烈。上述结果说明磷脂酶D8的缺失会加剧紫外辐射诱导的膜伤害,导致植株对紫外辐射更加敏感。     

拟南芥叶片衰老过程中细胞溶血磷脂和膜脂不饱和度的变化

细胞膜的流动性和渗透性的改变是植物衰老过程中一个内在的、具有破坏性的变化。膜脂组成中,溶血磷脂的出现是膜伤害的一个重要标志;膜脂双键数目的变化是影响膜流动性的主要因素。应用脂类组学的方法,检测了拟南芥野生型及其磷脂酶Dδ (PLDδ)缺失型突变体在离体诱导的、脱落酸（abscisic acid, ABA）和乙烯（ethylene）促进的衰老过程中,溶血磷脂（lysophospholipids, lysoPLs）的分子变化,并通过计算膜脂双键指数（double bond index, DBI）表征了膜流动性的变化。结果表明,在离体诱导的衰老过程和乙烯促进的衰老过程中,溶血磷脂的总含量和各溶血磷脂分子的变化不显著,而在ABA促进的衰老过程中溶血磷脂总含量和部分溶血磷脂分子均显著升高;在上述三种衰老处理下,总膜脂的DBI均下降,但是离体诱导和激素促进的的衰老过程中各类膜脂的DBI的变化却不同。同时我们还发现,抑制PLDδ基因表达降低了ABA促进的衰老过程中溶血磷脂的产生、减缓了ABA和乙烯促进的衰老过程中总的膜脂的DBI的降低。     

Low temperature differentially affects tillering in spring and winter wheat in association with changes in plant carbon status

The higher tillering potential of winter wheat cultivars as compared to spring ones has been attributed to an earlier tillering onset in the former. Tillering in grasses is known to depend on temperature and light environment, and may be mediated by plant C status. The aim of this work was to elucidate whether differences in carbohydrate accumulation between wheat types at low temperature may contribute to differences in tillering potential. A set of experiments with contrasting temperatures was conducted in both field enclosures (high irradiance, three experiments) and growth chambers (low irradiance, two experiments). The relative tiller production rate (RTR) was the highest in winter cultivars grown in cool field enclosures, and the lowest in spring cultivars in growth chambers, either cool or warm. Plant C status was inversely related to temperature the response being more pronounced in winter cultivars. Components of RTR, site filling and phyllochron, responded differently to environment and plant C status. Phyllochron increased with temperature, and was inversely correlated to sugar concentration irrespective of cultivar type. Site filling increased with irradiance in both cultivar types while sugar concentration contributed additively to its promotion solely in winter cultivars. Nevertheless, variation in site filling was larger in percentage than variation in phyllochron (200% and 41%, respectively, between most contrasting treatments). Thus, differences in tillering potential between winter and spring wheats may be attributed not only to the earlier tillering onset in the former but also to their differential response to environment and C status.     

拟南芥角果衰老过程中膜脂的变化

角果发育对某些物种的生殖发育具有重要的作用。拟南芥种子附着在角果里,角果在早期发育时进行光合作用,角果成熟后开裂散落种子之前,其细胞会经历一个衰老的过程。一般植物细胞在衰老过程中要经历膜脂降解的过程,但是角果细胞衰老过程仍未知。通过比较角果衰老过程中拟南芥野生型(WS)及与膜脂代谢密切相关的磷脂酶Dδ缺失突变体(PLDδ KO)中膜脂分子的组成情况、膜脂含量、相对含量及双键指数值,结果发现,在拟南芥角果衰老过程中：(i)质体膜脂和质体外膜脂显著下降;(ii)不同膜脂降解速率不一样,质体膜脂的降解比质体外膜脂的降解快;(iii)总的双键指数DBI下降;(iv)磷脂酶Dδ缺失突变体(PLDδ KO)的角果膜脂组成的基本水平和变化样式与野生型(WS)非常相似。结果说明,角果在衰老过程中发生了膜脂的激烈降解。据此推测：(i) 膜脂水解产物可能转移到种子中用于储藏脂三酰甘油的合成;(ii) 质体膜脂相对含量下降和质体外膜脂相对含量上升导致了总的DBI下降;(iii) PLDδ参与了角果衰老中的膜脂代谢。     

Formation of phenol compounds in various cultivars of wheat (Triticum aestivum L.)

The formation of soluble phenol compounds, including flavonols, was studied in winter (Erythrospermum, Lutescens 230, and R 47-28) and spring cultivars (Lada) of wheat (Triticum aestivum L.). The contents of soluble phenol compounds and flavonols were 1.8-2.6 and 0.5-1.3 mg/kg fresh weight, respectively. These results illustrate the similarity of phenol metabolism in leaves of winter and spring wheat cultivars. The exception was the cultivar R 47-28 that accumulated the maximum amount of phenol compounds (e.g., flavonols). In this cultivar the ratio of flavonols reached 50% of total soluble phenol content. In other cultivars, this parameter did not exceed 25-35%. The data indicate that the cultivar R 47-28 differs from other wheat cultivars in the metabolism of phenol compounds. The observed differences are probably related to genetic modifications of the cultivar R 47-28 during selection.     

Seasonal changes in oleosomic lipids and fatty acids of perennial root nodules of beach pea

Seasonal changes in the fatty acid composition of phospholipids (PL), monoglycerides (MG), diglycerides (DG), free fatty acids (FA) and triglycerides (TG) separated from oleosomes (lipid bodies) of perennial root nodules of beach pea (Lathyrus maritimus) were analysed. Thin layer chromatography (TLC) revealed that PL and MG are the major lipids in nodule oleosomes. The fatty acid profile and overall double bond index (DBI) varied among lipid classes depending upon the season. High DBI in PL and MG found during late winter and early spring indicated that they may play a major role in winter survival and regeneration of perennial nodules. The DBI of DG was high at the end of the fall season and the DBI of FA and TG was high in summer months. The dominant fatty acids are C16:0 followed by C18:0 and C18:1. The levels of many unsaturated fatty acids such as C18:1, C18:2 and C18:3 increased while saturated fatty acid C18:0 decreased during winter. These unsaturated fatty acids possibly play an important role in the protection of nodule cells from cold stress. Nodules seem to retain some fatty acids and selectively utilize specific fatty acids to survive the winter and regenerate in spring.     

Plastid differentiation during androgenesis in albino and non-albino producing cultivars of barley (Hordeum vulgare L.)

In order to better understand androgenic albinism in barley, we compared plastid differentiation during anther culture in two cultivars, an albino (spring cultivar Cork) and a non-albino (winter cultivar Igri) producing cultivar. The ultrastructure of plastids and the relative amount of DNA containing plastids were followed in both cultivars during the androgenic process and correlated with the proportion of regenerated chlorophyllous plantlets. For androgenesis, anthers were collected at the uninucleate stage, during mid- or late-microspore vacuolation. At this stage DNA was detected in 15.3 ± 2. 7% of microspore plastid sections in the winter cultivar Igri, compared to 1.7 ± 0.5% in the spring cultivar Cork. In the winter cultivar Igri, starch was broken down after anther pretreatment but plastids divided rapidly during anther culture and thylakoids developed in the stroma. Prior to regeneration, plastids contained 2.0 ± 0.2 thylakoids per plastid and starch represented 26.1 ± 3.3% of the plastid volume. In the spring cultivar Cork, plastids followed a different developmental pathway. After anther pretreatment, microspore plastids differentiated exclusively into amyloplasts, accumulating starch and losing their thylakoids as well as their capacity to divide. This developmental pattern became progressively more marked, so that by the end of anther culture plastids contained 0.5 ± 0.4 thylakoids per plastid and starch represented up to 90.3 ± 4.3% of plastid volume. Following androgenesis, the response was similar in both cultivars except that the winter cultivar Igri provided 87.8% of chlorophyllous plantlets compared to 99.7% albino plantlets in the cultivar Cork. The results presented here suggest that the exclusive regeneration of albino plantlets in the spring cultivar Cork may be due to degradation of microspore plastid DNA during early pollen development, preventing the plastids from differentiating into chloroplasts under culture conditions. Received: 13 March 2000 / Revision accepted: 6 June 2000     

Development of pea bacterial blight caused by Pseudomonas syringae pv. pisi in winter and spring cultivars of combining peas (Pisum sativum) with different sowing dates

Pea bacterial blight occurred by natural infection in a field trial on peas in 1995. Disease development in the winter cultivars Rafale, Frilene and Froidure was compared with that in the spring cultivars Baccara, Conquest and Bohatyr, each sown on six dates in October, November, December, mid-March, late March and April. Disease incidence had reached 100% plants affected in all treatments by mid-July. Disease severity was greater in winter-sown (October, November or December) than in spring-sown peas of each cultivar at each assessment. Significant (P < 0.05) differences in disease severity occurred between cultivars in the winter-sown plots in May and June and the spring cultivars were affected more severely than the winter cultivars. Comparison of areas under the disease progress curves for both disease incidence and severity also showed that the winter-sown peas were more affected by disease than spring-sown peas and that spring cultivars were more severely affected than winter cultivars. Yield was strongly correlated with disease severity. A linear regression model suggested that, for peas sown in October, November or December, a yield loss of 0.5 tha^-1 occurred for each 10% increase in canopy area affected by pea bacterial blight.     

Effects of cadmium on antioxidant enzyme and photosynthetic activities in leaves of two maize cultivars

Effects of cadmium (Cd(2+)) on photosynthetic and antioxidant activities of maize (Zea mays L.) cultivars (3223 and 32D99) were investigated. Fourteen-day-old cultivar seedlings were exposed to different Cd concentrations [0, 0.3, 0.6 and 0.9mM Cd(NO(3))(2).4H(2)O] for 8 days. The results of chlorophyll fluorescence indicated that different levels of Cd affected photochemical efficiency in 3223 much more than that in 32D99. In parallel, the level of Cd at 0.9mM caused oxidative damage but did not indicate cessation of PSII activity of the cultivars; plant death was not observed at highly toxic Cd levels. Additionally, the increase in Cd concentration caused loss of chlorophylls and carotenoid and membrane damage in both cultivars, but greater membrane damage was observed in 3223 than in 32D99. Depending on Cd accumulation, a significant reduction in dry biomass was observed in both cultivars at all Cd concentrations. The accumulation of Cd was higher in roots than in leaves for both cultivars. Nevertheless, cultivar 3223 transferred more Cd from roots to leaves than did 32D99. On the other hand, our results suggest that there were similar responses in SOD, APX and GR activities with increasing Cd concentrations for both cultivars. However, POD activity significantly increased at highly toxic Cd levels in 32D99. This result may be regarded as an indication of better tolerance of the Z. mays L. cultivar 32D99 to Cd contamination.     

A Comparison of Freezing Injury in Oat and Rye: Two Cereals at the Extremes of Freezing Tolerance

A detailed analysis of cold acclimation of a winter rye (Secale cereale L. cv Puma), a winter oat (Avena sativa L. cv Kanota), and a spring oat cultivar (Ogle) revealed that freezing injury of leaves of nonacclimated seedlings occurred at -2[deg]C in both the winter and spring cultivars of oat but did not occur in winter rye leaves until after freezing at -4[deg]C. The maximum freezing tolerance was attained in all cultivars after 4 weeks of cold acclimation, and the temperature at which 50% electrolyte leakage occurred decreased to -8[deg]C for spring oat, -10[deg]C for winter oat, and -21[deg]C for winter rye. In protoplasts isolated from leaves of nonacclimated spring oat, expansion-induced lysis was the predominant form of injury over the range of -2 to -4[deg]C. At temperatures lower than -4[deg]C, loss of osmotic responsiveness, which was associated with the formation of the hexagonal II phase in the plasma membrane and subtending lamellae, was the predominant form of injury. In protoplasts isolated from leaves of cold-acclimated oat, loss of osmotic responsiveness was the predominant form of injury at all injurious temperatures; however, the hexagonal II phase was not observed. Rather, injury was associated with the occurrence of localized deviations of the plasma membrane fracture plane to closely appressed lamellae, which we refer to as the "fracture-jump lesion." Although the freeze-induced lesions in the plasma membrane of protoplasts of spring oat were identical with those reported previously for protoplasts of winter rye, they occurred at significantly higher temperatures that correspond to the lethal freezing temperature.     

The use of phenological data to calculate chilling units in Olea europaea L. in relation to the onset of reproduction

The aim of this study was to develop a practical method to evaluate the effective relationship between the amount of winter chilling and the response expressed as the spring reproductive re-starting dates in the olive (Olea europaea L.). Two olive cultivars growing in a special olive orchard in Umbria (central Italy) were studied over a 3-year period (1998-2000): the cultivar Ascolana, typical of central Italy, and the cultivar Giarraffa, typical of southern Italy. The spring reproductive restarts were assessed using data from detailed phenological observations made on 60 trees of each cultivar in an effort to establish the exact date of reproductive bud swelling. The chilling phenomenon was evaluated by using 341 functions derived from a formula developed by researchers at Utah State University to calculate chilling units. The mathematical functions are defined, and show the very close relationship between the amount of winter chilling and the spring reproductive response in the two cultivars in the orchard studied. The results can be used to define the relationship between local climate and plant development, and the mathematical approach can be used to draw maps that can show the suitability of different cultivars on the basis of local climatic conditions.     

Cold Hardening of Spring and Winter Wheat and Rape Results in Differential Effects on Growth,Carbon Metabolism,and Carbohydrate Content

The effect of long-term (months) exposure to low temperature (5[deg]C) on growth, photosynthesis, and carbon metabolism was studied in spring and winter cultivars of wheat (Triticum aestivum) and rape (Brassica napus). Cold-grown winter rape and winter wheat maintained higher net assimilation rates and higher in situ CO2 exchange rates than the respective cold-grown spring cultivars. In particular, the relative growth rate of spring rape declined over time at low temperature, and this was associated with a 92% loss in in situ CO2 exchange rates. Associated with the high photosynthetic rates of cold-grown winter cultivars was a 2-fold increase per unit of protein in both stromal and cytosolic fructose-1,6-bisphosphatase activity and a 1.5- to 2-fold increase in sucrose-phosphate synthase activity. Neither spring cultivar increased enzyme activity on a per unit of protein basis. We suggest that the recovery of photosynthetic capacity at low temperature and the regulation of enzymatic activity represent acclimation in winter cultivars. This allow these overwintering herbaceous annuals to maximize the production of sugars with possible cryoprotective function and to accumulate sufficient carbohydrate storage reserve to support basal metabolism and regrowth in the spring.     

宁夏国外小麦种质资源考察、引进和利用

国外小麦种质资源引进在宁夏小麦引种中发挥着重要的作用。碧玉麦、阿勃、墨卡(卡杰姆F-71)、WC-20(宁春37)、9186(宁冬6号)等国外小麦品种在宁夏生产上直接利用。宁夏春小麦的品质杂交选育始于1953年,利用国外小麦种质资源先后培育出斗地1号、宁春4号等50余个春麦品种。1990年宁夏国外冬麦种质资源的引进带动了宁夏引黄灌区冬麦北移和耕作改制的研究,也引发了宁夏冬麦品种杂交选育的研究。宁夏引黄灌区冬小麦品种的杂交选育的工作始于1991年,经过15年的努力,杂交选育出第一批冬麦品种宁冬10号、宁冬11号,2010年在冬麦生产上取代了明丰5088,不仅实现了宁夏引黄灌区冬小麦品种第3次更新、实现了小麦品种的5次更新,而且使宁夏小麦生产水平跃上新台阶,有力地促进宁夏引黄灌区耕作制度改善和种植业结构的调整。     

Changes of Membrane Stability in Potassium Stressed Plants

The maintenance of membrane function is critical to the ability of plants to resist environmental stresses; specifically, the stability and appropriate fluidity of membranes are crucial to their normal function. We previously demonstrated that plants adapt to long term potassium (K+) deficiency by accumulation of membrane lipids in leaves and maintenance of the lipid composition in roots. In this study, which involved Arabidopsis thaliana and its K+ deficiency tolerant relative Crucihimalaya himalaica, we first calculated the double bond index (DBI) as an indicator of membrane fluidity. After exposure to long term K+ deficiency stress, the DBI of the total lipids in leaves of Athaliana and Chimalaica showed no significant changes, whereas the DBI of the total lipids in the roots of these species showed slight increases. Changes in lysophospholipids (lysoPLs) levels, and digalactosyldiacylglycerol/monogalactosyldiacylglycerol (DGDG/MGDG) and phosphatidylcholine/phosphatidylethanolamine (PC/PE) ratios, all of which strongly reflect membrane stability, were also studied in K+ stressed Athaliana and Chimalaica. After long term K+ deficiency, total lysoPLs levels increased in Athaliana and Chimalaica leaves, but showed no significant changes in roots. DGDG/MGDG and PC/PE ratios were higher in Chimalaica leaves and roots than in those of Athaliana. These results indicate that Chimalaica exhibits superior membrane stability compared with Athaliana. This may explain its superior growth and tolerance under K+ deficient conditions.