Effect of Dwarfing Induced by Uniconazole-P on Snow Tolerance of the Faba Bean (Vicia faba L.)

Abstract

To clarify the effect of artificial dwarfing induced by uniconazole-P, a gibberellin biosynthesis inhibitor, on the snow tolerance of faba bean, we examined the snow damage, non-structural carbohydrate (NSC) concentration, and resistance to snow molds of the seedlings treated with uniconazole-P. Artificial dwarfing markedly decreased snow damage caused by continuous snow cover for 62 days. NSC concentration, which affects physiological snow tolerance and snow mold resistance, was lower in dwarfed plants than in non-dwarfed plants. However, there was no difference in the rate of decrease of NSC concentration between dwarfed and non-dwarfed plants under cold and dark conditions simulating snow cover. In inoculation tests, the lesions of Pythium iwayamai and Sclerotinia trifoliorum on the leaves detached from dwarfed plants were shorter than those on the leaves from non-dwarfed plants. In artificially dwarfed plants, the leaves were thicker and darker in color, and mesophyll cells were larger and denser than those in the non-dwarfed plants. Our findings suggest that the artificial dwarfing caused by uniconazole-P increased the resistance of the leaves to snow molds, thereby increasing snow tolerance, without increasing NSC concentration. The microstructural changes that occur with dwarfing may be a factor in snow tolerance.     

Changes in Freezing Tolerance and its Relationship with the Contents of Carbohydrates and Proline in Overwintering Centipedegrass (Eremochloa ophiuroides (Munro) Hack.)

Abstract

The objective of this study was to clarify the changes in the contents of endogenous carbohydrates and proline in the stolons and leaves of centipedegrass (Eremochloa ophiuroides (Munro) Hack.), during the natural cold acclimation (hardening) and de-acclimation (dehardening) in relation to freezing tolerance in the field at the transition zone between temperate and subtropical areas in China. The contents of carbohydrates and proline, and freezing tolerance estimated by LT₅₀, which is the temperature at which 50% of the electrolytes in the organ was measured in the leachate, were determined at 10-day intervals from October 1, 2001 to April 18, 2002. It was indicated that the freezing tolerance of stolons increased (LT₅₀ of stolons decreased) quickly, as temperature dropped before winter, but that of leaves which senesced along with the drop in temperature did not. The freezing tolerance of stolons decreased gradually along with the rise in temperature above 5 °C in spring, when the overwintered plants started to grow. The contents of proline and soluble carbohydrates, including sucrose, fructose and glucose, increased as LT₅₀ decreased when temperature dropped below 5 °C before winter, and decreased as LT₅₀ increased in early spring. Correlation analysis revealed that the freezing tolerance of stolons of centipedegrass significantly and positively correlated with the contents of proline and soluble carbohydrates, and the ratio of the soluble carbohydrates to starch. Thus, the freezing tolerance of stolons, which are critical organs that determine the winter surviving ability, largely depended on the content of soluble carbohydrates and the ratio of soluble carbohydrates to starch in centipedegrass. The possible relationship between freezing tolerance and carbohydrate metabolism was also discussed.     

冷驯化和ABA对茶树抗寒力及其体内脯氨酸含量的影响

本文研究了冷驯化和ABA对茶树抗寒力及其体内脯氨酸含量的影响,结果表明：通过冷驯化或者ABA处理,茶树经历了驯化再到脱驯化的过程,相应地茶树的抗寒力也发生了很大的变化,由驯化前的几乎为0逐渐增大,而随着脱驯化的进行又迅速恢复到驯化前的水平。低温驯化的临界温度为7℃左右,脱驯化的临界温度为9℃左右。人工低温驯化和ABA处理,茶树抗寒力的提高幅度没有自然冷驯化下的大。对三种处理下茶树体内脯氨酸含量的变化的研究发现,冷驯化中茶树体内脯氨酸含量变化是对外界条件变化的一种综合反应,很难说明单一的脯氨酸含量与抗寒力之间的因果关系。     

马铃薯幼苗在冷驯化期间的生理生化变化

以霜冻敏感的中薯3号和耐冻的野生马铃薯03079-435(Solanum acaule)的幼苗为试材,对其总叶绿素含量、丙二醛(MDA)含量、脯氨酸含量、可溶性糖含量、可溶性蛋白含量的变化进行测定。结果表明:冷驯化期间(4℃/2℃,昼/夜),两者的总叶绿素含量都呈先降后升的变化趋势;03079-435叶片的脯氨酸含量先升高后降低,总体呈升高趋势,而中薯3号叶片的脯氨酸含量逐渐降低;两个基因型的可溶性糖和可溶性蛋白含量均有所升高,中薯3号叶片的可溶性蛋白含量增加幅度明显低于03079-435。推断幼苗叶片脯氨酸和可溶性蛋白含量的增加与冷驯化能力的增强密切相关。     

Improvement of Cold Tolerance in Horticultural Crops by Genetic Engineering

Abstract

Chilling and freezing temperatures often adversely affect the productivity and quality of horticultural plants. Attempts to enhance cold tolerance through traditional breeding have achieved limited success, mainly due to the complexity of the genetics associated with a plant's response to low temperatures. Recently, the improvement of cold tolerance by genetic engineering has been achieved in many species. Nevertheless, transgenic plants with greater tolerance have been reported in only a few horticultural examples. Their production has led to a new era in improving performance. In this review, we first present recent advances in understanding cold acclimation. We then describe a few cases in which improved cold tolerance has been achieved with transgenic plants.     

Freeze tolerance and physiological changes during cold acclimation of giant reed [Arundo donax (L.)]

Arundo donax L. (Poaceae), giant reed, is a rhizomatous shrubby grass that is cultivated in subtropical and warm temperate regions for a multitude of uses. Recently, it has been identified as a leading sustainable, non‐food crop for lignocellulosic biofuels due to its low ecological and agronomic demands. Lack of cold hardiness may limit its diffusion into colder areas of the transition zone. The objectives of this study were to (i) quantify freeze tolerance (LT₅₀) of cold‐acclimated and non‐acclimated Arundo donax L. plants using reproducible, controlled environment conditions, (ii) determine the effect of prolonged exposure to freeze stress on tolerance by keeping plants at a constant, sublethal temperature and (iii) study the relationship of non‐structural carbohydrates (total soluble sugars, glucose, fructose and sucrose) and proline accumulation with cold hardiness. In vitro‐propagated plants of the Honduran and Hungarian ecotypes of Arundo donax L. were chosen for this study. Cold acclimation treatment was imposed for 1 week using a controlled environment chamber set at 10°C and with a 12‐h photoperiod of 200 μmol m^?2 s^?1 photosynthetically active radiation. Freeze tolerance ranged from ?12·8°C (Honduran) to ?16·4°C (Hungarian ecotype). In all the organs analysed, total soluble sugars significantly increased during cold acclimation, with concentrations between 1·8‐ and 4·7‐fold higher than in non‐acclimated plants. The higher concentrations of sugars and proline in cold‐acclimated plants were positively associated with enhanced giant reed freeze tolerance (2·9°C lower). Our results confirm that during cold acclimation, metabolic changes related to increased freezing tolerance occur in giant reed.     

低温锻炼对香蕉幼苗能量代谢和抗冷性效应的研究

以不同品种及同一品种不同苗龄的香蕉幼苗为材料,以６－磷酸葡萄糖脱氢酶（Ｇ６ＰＤＨａｓｅ）和腺苷三磷酸酶（ＡＴＰａｓｅ）活性的动态变化为依据,研究３℃低温锻炼对香蕉幼苗代谢途径改变和能量变化与抗冷性的效应。结果表明,低温锻炼提高了各种香蕉幼苗的Ｇ６ＰＤＨａｓｅ和ＡＴＰａｓｅ活性,但不同品种及相同品种不同苗龄苗提高程度不同,抗冷性较强的品种（巴西）提高幅度较小,苗龄较小的瓶苗提高程度大于苗龄较大的袋苗。进一步分析发现,上述２种酶活性变化与幼苗抗冷性提高密切相关。      

低温锻炼对香蕉幼苗钙调蛋白含量及其可能调节酶类活性的影响

首次对不同抗冷性的香蕉幼苗在低温锻炼中钙调蛋白(CaM)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、腺苷三磷酸酶(ATPase)、膜伤害率及幼苗存活率的动态变化过程进行测定。结果表明,低温锻炼提高了幼苗叶片中CaM含量和SOD、POD及ATPase活性,降低了膜伤害率,从而提高了幼苗的存活率,但不同抗冷性品种上述各项指标变化略有差异。进一步分析发现,在低温锻炼期间,不同抗冷性香蕉幼苗的CaM含量和SOD、POD及ATPase活性都呈现先上升后下降的动态变化趋势,而且它们的变化与幼苗抗冷性的提高存在着明显的相关性,据此推测CaM可能参与SOD、POD及ATPase活性的调节。     

孕穗期低温对小麦生理抗寒性的影响

为了解孕穗期小麦的生理抗寒性,以参加黄淮海麦区区试的24个小麦品种(系)为材料,采用盆栽试验,在人工气候室内模拟孕穗期低温胁迫,测定和分析了低温处理后小麦叶片相对电导率、丙二醛(MDA)含量、可溶性糖含量、可溶性蛋白含量、游离脯氨酸含量及超氧化物歧化酶(SOD)和过氧化物酶(POD)活性的变化。结果表明,孕穗期低温胁迫后,小麦叶片相对电导率、MDA含量、可溶性糖含量、SOD活性显著高于对照,POD活性显著低于对照,可溶性蛋白和游离脯氨酸含量的变化在品种(系)间存在差异。从7个性状的相对值来看,相对电导率最高,POD活性最低。通过隶属函数法和极点排序法计算得到的参试小麦平均隶属度值和综合排序值分别为0.17~0.64和1.93~4.02,二者与叶片可溶性糖含量、可溶性蛋白含量、SOD活性呈显著正相关,与相对电导率和MDA含量呈负相关。根据平均隶属度值和综合排序值,将参试小麦品种(系)抗寒性聚为5类,其中冀麦585和石B05-7388的孕穗期抗寒性最强,山农055843和C-44抗寒性最弱。     

甘蓝型油菜抗寒性的研究——Ⅰ.渗透调节与抗寒性的关系

在越冬期间,两个抗寒性不同的甘蓝型油莱品种叶片抗寒性的测定结果表明:抗寒锻炼期间,甘蓝型油菜抗寒能力逐渐提高,渗透势随抗寒力的增强而降低,可溶性糖等溶质含量增加,总含水量、自由水含量下降,束缚水含量上升,束缚水/自由水比值增大。元月初,上述物质的变化达到峰值,两个品种间的差异亦达最大值。渗透势、游离脯氨酸含量、总含水量及束缚水/自由水比值可以作为甘蓝型油菜品种抗寒性鉴定的生理生化指标。     

乙烯利提高香蕉幼苗抗寒性的生理效应

用200 mg/L乙烯利喷洒香蕉幼苗叶片1 d,再于8℃低温胁迫1 d后,研究乙烯利对香蕉幼苗抗寒性的影响.结果表明:乙烯利预处理提高了香蕉叶片的SOD、POD、CAT活性和香蕉叶片的游离脯氨酸和可溶性蛋白含量;降低了丙二醛含量.表明乙烯利可通过提高抗氧化酶活性和减少膜损伤来增强香蕉幼苗抗寒性.     

Seasonal distribution of herbage mass and nutritive value of Prairiegrass (Bromus catharticus Vahl)

A reliable supply of herbage is a crucial feature of forage‐based livestock systems. Forage resources with winter‐active growth habits can help extend the growing season in early spring and late autumn in regions with mild‐winter conditions while drought‐ and heat‐tolerant plants help meet herbage needs during summer in humid temperate regions. The prairiegrass (Bromus catharticus, Vahl) cultivars, Grassland Dixon and Grasslands Lakota, provide resistance to foliar disease and cold in addition to sustained productivity when soil moisture is low, and could be useful over a wide range of growing conditions. The cultivars were sown in spring or summer to determine seasonal distribution of productivity and nutritive value of herbage grown in a cool‐temperate region. Stands established rapidly regardless of sowing time or cultivar and were virtually pure prairiegrass once plants were well‐established. Stand composition of broadcast sowings tended to be stable in subsequent growing seasons, whereas the amount of prairiegrass varied in no‐till stands. In the growing seasons after establishment, cumulative dry matter (DM) yield of Lakota was similar regardless of when it was sown, whereas DM yield of Dixon differed with sowing time and was less in spring‐ than summer‐planted stands. Rapid stand establishment, significant late‐season yield, consistent concentrations of crude protein, non‐structural carbohydrate and total digestible nutrients in herbage, and dominance of sward composition, suggest that prairiegrass cultivars, Dixon and Lakota, are excellent resources for forage‐based livestock production systems in humid temperate conditions.     

Carbohydrate Metabolism During Wintering Period in Four Zoysiagrass Genotypes

Abstract

A key barrier to widespread use of warm-season grasses in the transition zone between the temperate and subtropical climates is represented by the winter dormancy, a temporary suspension of visible growth of any plant structure including the meristem. In this environment, species with different photosynthetic carbon cycle coexist, leading to asynchrony in growth among warm- and cool-season grasses. The objectives of the present study were (i) to assess the carbohydrate content in four representative zoysiagrasses Zoysia japonica ‘El Toro’, ‘Meyer’, Z. pacifica, and Z. matrella ‘Zeon’ during three successive phases of vegetation phenology, senescence, dormancy, and green-up, and (ii) to characterize the metabolic responses to phenological variations under natural acclimation. Japanese lawn grass genotypes ‘El Toro’ and ‘Meyer’ showed longer dormancy periods than fine-leaved Z. pacifica and ‘Zeon’. In Japanese lawn grass genotypes, the progressive decline of photosynthetic pigments was similar to that observed in the color retention. Over the experimental period, a significantly greater amount of starch reserves was observed in sprigs (horizontal stems) in the Japanese lawn grasses than in the fine-leaved zoysiagrasses. In general, total soluble sugars (TSS) in leaves and sprigs did not show evidence of sugar starvation during the senescence phase. TSS increased significantly during cold acclimation, resulting in a higher metabolic activity at the onset of green-up to support spring regreening in all zoysiagrasses except ‘Meyer’ leaves.     

冬小麦雪腐病苗期抗病性鉴定方法及抗病种质资源筛选

为了筛选冬小麦雪腐病人工接种抗病性鉴定方法及抗病种质资源,采用正交试验设计,比较了喷雾法、涂抹法和灌根法对冬小麦雪腐病苗期抗病性的鉴定效果以及不同材料的抗病性.结果表明,三种方法比较,采用喷雾法,于冬小麦1叶期,以浓度为105个孢子·mL-1进行接种,为冬小麦雪腐病苗期抗病性鉴定最适宜的方法.利用该鉴定方法以及9株雪腐病菌对8份冬小麦材料进行了抗病性鉴定,发现供试材料间以及同一材料对不同菌株间的抗病性均存在差异.8份冬小麦材料中,冬麦1号抗病性最强,对菌株Gn-rh2免疫,对其他8个菌株均表现为抗病;抗病性最弱的为东农冬麦377;其他品系的抗病性介于两者之间.9个菌株的致病力也存在差异,菌株Gn-rh4毒力最强,Gn-rh2毒力最弱.     

播种至苗期不同阶段冻害与持续时间对玉米幼苗建成及抗性生理的影响

以先玉335为供试品种，基于寒地典型玉米种植生态区的田间温度动态，采用两因素完全随机设计，分别设置冻害发生阶段和冻害持续时间处理，比较分析各处理组合条件下玉米幼苗形态建成及抗性生理指标的变化差异。研究表明，玉米播种至出苗各阶段发生冻害胁迫后，可不同程度延长玉米出苗时间、降低成苗率，甚至导致幼苗全部死亡。播后早期冻害通过降低种子贮藏物质转运效率，加剧膜脂过氧化，削弱叶片光能捕获能力等一系列不可逆影响，抑制幼苗形态建成，这些不利影响程度随冻害持续时间的延长而不断加强。播后冻害可诱导存活植株体内可溶性蛋白、脯氨酸、可溶性糖等渗透调节物质含量维持较高水平，以改善植株对低温环境的适应能力。玉米播种至出苗各阶段受冻害胁迫影响均较显著，且以播种10 d后植株对冻害最为敏感。     

不同抗寒性冬小麦叶鞘质膜的稳定性表现

为了解叶鞘质膜稳定性与小麦抗寒性的关系,以返青率不同的4个冬小麦品种(系)为材料,研究寒地冬小麦越冬期叶鞘质膜稳定性变化及其影响因素。结果表明,低温下,冬小麦叶鞘相对电导率与自由水和总水分含量呈显著正相关,丙二醛含量与SOD和POD活性、AsA含量呈显著正相关;封冻后,抗寒性强的冬麦品种(系)的SOD活性和GSH含量显著高于抗寒性弱的品种(系)。在深度封冻期保持叶鞘质膜稳定性有助于增强冬小麦抗寒性。     

不同播期对麦绿素用大麦产量和品质的影响

为了给麦绿素用大麦新品种(系)科学种植、提高产量和改善品质提供试验依据，研究了不同播期对麦绿素用大麦品种生长期、产量和品质的影响。结果表明,随着播期的推迟，麦绿素用大麦品种从播种到出苗、第一次收获所需天数依次延长。大麦苗收获三期的鲜叶总产量和干物质积累量均以10月10日和10月30日播种的最高，品质也较优；9月20日和10月20日播种的品质最优,产量也较高；而11月9日和11月19日播种的产量低、品质差。因此，麦绿素用大麦的适宜播期应为9月20日至10月30日。     

红麻雄性不育系、保持系及杂交F2代越冬期间抗寒性的比较研究

以红麻细胞质雄性不育系、保持系及杂交F2代为材料,鉴定其越冬期间,在自然低温胁迫条件下的抗寒性及相关生理生化指标的变化。结果表明:(1)经平均5.76℃连续15 d的自然低温胁迫后,不育系L23A和P3A的抗寒性明显强于其对应的保持系;在L23A/福红992杂交F2代植株中,不育株的抗寒性也明显强于可育株;(2)不育系L23A和P3A茎皮中可溶性糖、可溶性蛋白质、脯氨酸含量及超氧化物歧化酶活性等生理指标均高于保持系,而L23A和P3A的相对电导率比相应的保持系都小;(3)在L23A/福红992杂交F2代植株中,不育株茎皮中可溶性糖、脯氨酸含量及超氧化物歧化酶活性等高于可育株,相对电导率低于可育株,其抗寒性相关生理生化指标表现出与不育系、保持系相同的变化规律。     

茶鲜叶可溶性糖和氨基酸含量与低温的相关性

为评价茶树抗冻物质基础和品种间抗冻性差异,选择乌牛早和茂绿品种的栽培茶园,从2013年10月20日到翌年4月5日逐日调查供园气温;每月5、15、25日采集茶树成叶,以比色法检测鲜叶可溶性糖含量,以HPLC检测脯氨酸等17种游离氨基酸含量。结果发现：①在2013年10月20日至12月27日气温持续下降、2013年12月28日至翌年2月10日持续低温、2014年2月11日至4月5日气温日渐升高的3个时段,可溶性糖含量相应地持续增加、继续增加、逐渐减少,整个试验期间温度与可溶性糖含量显著负相关;②脯氨酸含量和17种游离氨基酸总量在这3个阶段相应的缓慢增加、明显增加、显著提升。研究结果表明：①可溶性糖、脯氨酸、游离氨基酸,这3类都是茶树抗寒物质,且可溶性糖含量与温度相关性大于其他两类物质;②这3类抗冻物质的含量,乌牛早鲜叶相应地大于茂绿鲜叶,乌牛早冻害指数小于茂绿冻害指数,因此乌牛早抗冻性更强。