低温胁迫下不同耐冷性番茄品种幼叶细胞Ca^2＋分布变化的差异

采用焦锑酸钙沉淀的电镜细胞化学方法,研究了低温胁迫与冷锻炼下不同耐冷性番茄品种幼叶细胞Ｃａ＾２＋定位分布的变化。结果表明：正常生长条件下,番茄幼叶细胞Ｃａ＾２＋主要存在于液泡和细胞间隙内,细胞质中含量很低,且耐冷性不同品种之间无明显差异。经５℃低温处理２４ｈ后,耐冷品种细胞内Ｃａ＾２＋分布变化明显,胞内钙库（即液泡）释放Ｃａ＾２＋进入细胞基质,细胞间隙中仍有大量Ｃａ＾２＋存在;而冷敏感品种无明显变化。当处理４８ｈ后,耐冷品种细胞Ｃａ＾２＋分布趋向于恢复到处理前的状态,而冷敏感品种则在细胞内形成较大的钙沉淀颗粒,多分布于绿体被膜与质膜内侧,细胞间隙内Ｃａ＾２＋颗粒也集中聚集成团。昼１５℃／夜８℃条件下的冷锻炼对不同耐冷性番茄幼叶细胞内Ｃａ＾２＋分布的影响也表现不同。     

大白菜干烧心病发生过程中Ca^2＋—ATPase活性的变化

人为诱导大白菜干烧心病发生,通过超速离心制备心叶组织细胞膜微囊,测定各细胞器膜的Ｃａ２＋－ＡＴＰａｓｅ活性变化。结果表明,随缺钙天数增加,细胞膜总Ｃａ２＋－ＡＴＰａｓｅ、ＰＭ－Ｃａ２＋－ＡＴＰａｓｅ和ＴＮ－Ｃａ２＋－ＡＴＰａｓｅ活性迅速上升,在处理后第３天达到高峰,随后逐渐下降,而潜在性Ｃａ２＋－ＡＴＰａｓｅ活性却呈逐渐上升趋势。同时,细胞膜透性和丙二醛含量逐渐增大,超氧化物歧化酶（ＳＯＤ）和过氧化物酶（ＰＯＤ）活性则逐渐下降。推测该病的发生与细胞膜钙泵活性变化诱导的钙的第二信使功能有关。     

黄瓜幼叶细胞中钙调素的免疫胶体金定位

 采用免疫胶体金电镜技术对黄瓜幼叶叶肉细胞中的钙调素(CaM)进行定位。结果表明：适温下生长的黄瓜幼苗叶肉细胞中的CaM主要分布于细胞核和叶绿体内，细胞核中CaM主要存在于染色质和核仁上，叶绿体中CaM主要存在于类囊体膜上；线粒体中也有一定量的CaM分布；细胞质、液泡、液泡膜及质膜上只有少量CaM存在；而细胞壁和细胞间隙却很难发现显示CaM存在的金颗粒。     

番茄钙肥示踪研究初报

４５Ｃａ标记番茄表明；富钙的石灰性土壤中，番茄缺钙是和钙在植株体内的运输及分配有关，钙在番茄体内的运输缓慢；主茎中的钙很少输向侧枝果实；果实中的钙输向主茎生长点的比例亦不多．只要适时适量向果实喷钙，可提高番茄产量，改善品质，大大降低缺钙生理病害，从而延长贮存期，提高经济效益。     

低温胁迫下不同耐冷性番茄品种幼叶细胞Ca~(2 )分布变化的差异

采用焦锑酸钙沉淀的电镜细胞化学方法 ,研究了低温胁迫与冷锻炼下不同耐冷性番茄品种幼叶细胞Ca2 定位分布的变化。结果表明 :正常生长条件下 ,番茄幼叶细胞Ca2 主要存在于液泡和细胞间隙内 ,细胞质中含量很低 ,且耐冷性不同品种之间无明显差异。经5℃低温处理 2 4h后 ,耐冷品种细胞内Ca2 分布变化明显 ,胞内钙库 (即液泡 )释放Ca2 进入细胞基质 ,细胞间隙中仍有大量Ca2 存在 ;而冷敏感品种无明显变化。当处理 4 8h后 ,耐冷品种细胞Ca2 分布趋向于恢复到处理前的状态 ,而冷敏感品种则在细胞内形成较大的钙沉淀颗粒 ,多分布于叶绿体被膜与质膜内侧 ,细胞间隙内Ca2 颗粒也集中聚集成团。昼 15℃ /夜 8℃条件下的冷锻炼对不同耐冷性番茄幼叶细胞内Ca2 分布的影响也表现不同     

苹果采后Ca2+、K+外渗及胞外Ca2+的变化

与‘富士’苹果相比,‘辽伏’、‘新红星’苹果乙烯释放率较高,达到高峰较早,果肉软化较快,Ｃａ＾２＋、Ｋ＾＋外渗率呈逐渐升高趋势;外源ＭｇＳＯ４诱导的果肉圆片Ｃａ＾２＋渗漏量明显增多,其变化动态是先下降,后回升。富士苹果的Ｃａ＾２＋、Ｋ＾＋外渗率无明显增加。外源钙处理对新红星苹果Ｃａ＾２＋、Ｋ＾＋外渗率的影响较小。     

苹果叶片受斑点落叶病菌侵染过程中细胞Ca2+定位及MdCPK的表达

以苹果感病品种‘红星’和抗病品种‘红玉’为材料,研究了苹果与斑点落叶病菌（Alternaria alternata apple pathotype）互作过程中超微结构,细胞Ca2+分布,以及在钙信号转导途径中具有重要作用的钙依赖蛋白激酶基因（CDPK）的表达,探讨钙信号在苹果防御斑点落叶病菌侵染中的作用。结果表明,在未接种状态下,叶肉细胞结构完好,叶绿体呈卵圆形沿细胞边缘排列,Ca2+主要分布在细胞间隙和液泡中,‘红玉’细胞间隙Ca2+密度比‘红星’大。接种斑点落叶病菌8 h,‘红星’叶肉细胞中的Ca2+沉淀主要分布在胞质中,而液泡等细胞器中减少;‘红玉’的Ca2+沉淀主要集中在胞质和筛管分子中,液泡和细胞间隙中减少,且趋向于在细胞壁外围和液泡膜上沉积。接种18 h,‘红星’叶肉细胞间隙Ca2+沉淀密度增加,而‘红玉’中的Ca2+沉淀主要集中在叶肉细胞的胞质和液泡,以及筛管分子中。接种24 h,‘红星’叶肉细胞结构已发生形变,质膜发生裂解,筛管壁木质化加厚,Ca2+沉淀主要分布在液泡中;‘红玉’叶片细胞结构完好,Ca2+沉淀主要分布在液泡和胞质中。接种36 h,‘红星’叶肉细胞受到菌丝入侵,结构和形态遭到破坏,在未受损叶肉细胞中Ca2+沉淀主要集中在液泡中,在受损的细胞中Ca2+沉淀无序地散布在受损细胞周围及细胞间隙;此时‘红玉’叶肉细胞中Ca2+沉淀主要集中在胞质和液泡中,并且能够保持Ca2+动态平衡。在接种后不同阶段,‘红星’和‘红玉’叶片中MdCPKs基因呈现不同的表达特点：大多MdCPKs在‘红玉’中的表达量在24 h达到最高值;‘红星’中在36 h达到表达峰值,且表达量也比‘红玉’中低得多。上述结果表明,钙信号响应斑点落叶病菌侵染,在抗病苹果品种‘红玉’中,Ca2+内流是细胞质Ca2+上升的主要来源;在感病品种‘红星’中,细胞器Ca2+释放是细胞质Ca2+的主要来源。‘红玉’苹果MdCPKs基因响应病菌侵染比‘红星’苹果早而且强烈。     

缺钙引起的苹果果实病害及防治

缺钙引起的苹果果实病害及防治王高鹏钙在植物体内以果胶钙的形式参与细胞壁的组成．可防止细胞和液泡中物质外渗，起着平衡细胞生理活动的作用。同时，钙也是一些酶和辅酶的活化剂，关系到蛋白质合成和碳水化合物的输送。若果实中有充足的钙，可保持膜不分解，延缓果实变...     

渗透胁迫下Ca^2＋对龙眼叶片光合色素及膜脂过氧化的影响

对ＰＥＧ渗透胁迫下的离体龙眼叶片进行Ｃａ（ＮＯ３）２处理,结果表明,Ｃａ２＋可以减缓渗透胁迫引起的叶绿素含量下降和膜脂过氧化作用。Ｃａ２＋的作用可被Ｃａ２＋专一螯合剂ＥＧＴＡ所削弱。     

涂膜苹果在贮藏期间钙信使组分的变化

海藻酸钠涂膜金冠苹果后,可减少腐烂,保持果实品质。涂膜抑制了果实成熟衰老过程中可溶性Ｃａ２＋的增加和Ｃａ２＋－ＡＴＰａｓｅ活性下降,推迟ＣａＭ峰值的出现,表明钙信使系统与苹果果实的衰老有关。     

大白菜干烧心病的形态结构及生理生化变化

以人为诱发大白菜(Brassica Campestris L.ssp.pekinensis(Lour)Olsson.)干烧心病的方法,研究了该病发生发展过程中叶片形态结构及生理生化的变化。结果表明:随着叶片中钙含量的下降,干烧心病症逐渐出现。在此过程中,光合强度降低,膜受损伤,糖含量及电解质外渗率渐增,粘液外溢于叶表;解剖结构观察可见质膜内陷,有囊状小泡形成,细胞器逐步解体;随之,可溶性果胶剧增,胞壁损伤,最后细胞解体死亡,残存固形物充塞了胞壁内外。对叶片排水器黑变与干烧心病发生的独立性检验,表明二者无相关性。     

The relationship between leaf growth,calcium accumulation and distribution,and tipburn development in field-grown butterhead lettuce

The change in calcium (Ca) concentration with time, the distribution of Ca within various leaves, and leaf and tipburn development were studied in field-grown lettuce (Lactuca sativa L.) cultivar ‘Cobham Green’.Ca distribution between and within leaves followed two distinct patterns. The average concentrations in the outer leaves were always higher than in the inner leaves. The concentrations at the periphery of the outer leaves was always greater than in the midrib, whereas for the inner leaves the converse was true.Tipburn only occurred in the inner leaves; it developed on only those leaves and those parts of the leaf which expanded most rapidly.Thus, tipburn development appears to depend on the supply of Ca relative to the rate of leaf growth.     

Tipburn of Chinese cabbage in relation to calcium nutrition and distribution

Heading Chinese cabbage (Brassica campestris ssp. pekinensis Rupr.) grown with low Ca or B developed dark tan lesions near the leaf margins. A synergistic effect of low Ca and low B accompanied the development of this symptom. Plants grown under humid conditions were free of tipburn. Plants grown under less humidity developed tipburn. Total chemical analysis revealed a steady decrease in total Ca from the outer to the inner leaves. Fractional chemical analysis showed 7 times more water-soluble Ca in the outer than in the inner leaves, and 2 times more 1 N NaCl-soluble Ca in the outer than in inner leaves. Threshold concentration of water-soluble forms of Ca for tipburn was around 3.0 mg/g dry weight. Data suggest that root pressure flow is required to move adequate amounts of water-soluble Ca to the wrapper leaves to prevent tipburn of Chinese cabbage.     

The effect of boron on tipburn and auxin activity in lettuce

Lettuce plants (Lactuca sativa L.) grown in a boron deficient nutrient medium developed tipburn. Their leaves showed no overall increased auxin activity compared with those of control plants until they were 66 days old, when boron deficient plants showed a relative increase in the activity of one auxin. It is postulated that tipburn in lettuce may be caused by interacting factors including calcium and boron deficiences, and the ontogenetic age of the plant. Environmental and cultivar effects on the incidence of tipburn indicate that agronomic or genetic control measures may become feasible, if the mechanism controlling its expression can be further elucidated.     

Review ArticleInternal tipburn of cabbage (Brassica oleracea var. capitata)

Summary

Internal tipburn of cabbage (Brassica oleracea var. capitata) is a serious quality defect. The discolouring and desiccation of inner head leaves may render whole yields useless. The disorder is regarded as a localized calcium ficiency. The ficiency is not caused by reduced calcium availability to the plant, but rather by calcium transport characteristics within the plant. Because of the absence of transpiration from the inner head leaves of the cabbage plant, calcium is transported to the meristematic tissues in the head mainly by root pressure flow or because of meristematic sink activity during the night. High growth rates are known to increase the incidence of internal tipburn. Probably because of the increased demand for calcium per unit of time, the result of disruption in the calcium transport to the head is more serious. Conditions of even transpiration between day and night, whether high or low, reduce root pressure flow to the head and thereby may induce development of internal tipburn. A combination of high growth rates and low root pressure flow during periods of prolonged dry, sunny weather with high transpiration rates during the day as well as during the night, may be especially important in inducing internal tipburn, because of insufficient calcium influx in the cabbage head under such conditions. As initiation of calcium deficiency in growing tissue is a subcellular process, visible symptoms of internal tipburn may be expressed only later. Growers are primarily advised to cultivate internal tipburn resistant cultivars. Recommendations to limit the occurrence of internal tipburn are formulated.     

The role of calcium,boron and some divalent ions in leaf tipburn of strawberry

Strawberry leaf tipburn occurs commonly in some cultivars in Britain during the summer outdoors, although usually only mildly. Outbreaks are occasionally severe in glasshouses. The damage arises at the time of leaf emergence, but is most evident after leaf expansion.Although the disorder can be induced by deficiencies of boron or calcium in the rooting medium, it also occurs where these elements are freely supplied in nutrient solutions. Where neither calcium nor boron were deficient, drops of aqueous solutions of calcium salts (but not of boric acid) applied to buds and emerging leaves greatly reduced or prevented tipburn. Drops containing manganese, magnesium or strontium salts also reduced tipburn, while drops containing oxalate or citrate induced it. The addition of small amounts of EDTA to the drops decreased the effectiveness of the manganese, magnesium and, to a lesser extent, strontium salts, but not that of calcium nitrate.The evidence suggests that tipburn is caused by a localised shortage of calcium occurring just before and during leaf emergence, resulting either from a deficiency of calcium at the roots or, more frequently, from an inadequate rate of uptake or transport of calcium.     

Relationship between tipburn and leaf mineral composition in strawberry

Malformation of emerging leaves with distortion of leaf tips, a condition known as tipburn, is frequently observed in strawberry. Calcium (Ca) deficiency has been considered the main cause of tipburn. The aim of the present study was to analyse the relationship between leaf mineral composition and the incidence of tipburn in three short-day strawberry (Fragaria x ananassa Duch.) cultivars (‘Ventana’, ‘Camarosa’ and ‘Candonga’) submitted to different concentrations of Ca. The studies were conducted in a hydroponic system in a greenhouse. Calcium was added as Ca(NO₃)₂ at 2 mM, 3 mM, 4 mM and 5 mM. A completely randomized block design (4 Ca concentrations × 3 cultivars) with three replications was used. Each replicate consisted of 12 plants grown in a polyethylene bag (100 cm × 18 cm × 3 cm) filled with coconut peat. Crown diameter and tipburn incidence were evaluated throughout the experimental period, and at the end of the experiment leaf mineral composition was assessed. In general, plants with larger crown diameters had a greater incidence of tipburn. The ‘Candonga’ cultivar had the smallest incidence of tipburn, while the ‘Camarosa’ and ‘Ventana’ cultivars were more susceptible. There was no correlation between level of Ca applied and incidence of tipburn. The incidence of tipburn was associated with foliar K:Ca and K:Mg ratios. Ratios above 3.40 for K:Mg and 1.77 for K:Ca represented a risk of more than 50% of tipburn incidence, when overall means for all cultivars and levels of Ca were used.     

The influence of relative humidity and nutrition on leaf tipburn of strawberry

Leaf tipburn of strawberry, a localised calcium deficiency causing malformation of emerging leaves, was induced by high relative humidity and alleviated by diluting the nutrient solution or by reducing the level of potassium, magnesium or nitrate in otherwise standard solutions. Increasing the phosphate content of the solution had no effect, while supplementing the calcium nitrate to above sufficiency levels of calcium increased tipburn. Leaf calcium (% dry weight) decreased temporarily during leaf emergence and was lower in affected emerging leaves than in comparable healthy ones     

热胁迫下辣椒叶肉细胞中Ca2+分布的变化

在适宜生长温度下,Ca^2 主要分布于辣椒叶肉细胞间隙及细胞壁中,热胁迫后细胞间隙及其壁中Ca^2 大量进入细胞质,叶绿体结构受到破坏后其中的Ca^2 也释放出来,使细胞质中Ca^2 浓度增高。热胁迫可能是通过诱导Ca^2 在细胞中分布的变化而导致其受到伤害。