多效唑预处理对稻苗和原生质体耐冷性的影响（简报）

1/2 MS培养基中添加2.5mg/L MET后,稻苗生长显著延缓,根/冠比值提高、生长矮壮。低温下MET预处理的稻苗存活率显著提高,电解质外渗百分率降低,原生质体的得率、活力和存活率也显著提高。     

新型植物生长延缓剂和杀菌剂—优康唑简介

理化性质优康唑(Uniconazole)化学名称是(E)-1-对氯苯基-2-(1,2,4-三唑-1-基)-4,4-二甲基-1-戊烯-3-醇[(E)1-p-Chlorophenyl-2-(1,2,4-trizaol-1-yl)-4,4-dimethyl-1-penten-3-ol],结构式如下图,又名Pentefezol,实验代号S-3307, S-07和S-3270(为0.04％优康唑颗粒剂)是住友化学公司在80年代初推出的高效植物生长延缓剂和杀菌剂。优康唑纯品为白色结晶,熔点162～163℃,在水中的溶     

果树组织及土壤中PP333残留量的毛细管气相色谱测定法

PP_(333)[(2RS,3RS)-1-(4-氯苯基)-4,4-二甲基-2-(1H-1,2,4-三唑-1-基)戊醇-3]是一种高效低毒的植物生长延缓剂,对果树营养生长有很强的抑制作用。目前已试用于多种果树,均有一定的抑制营养生长的效果,而且土壤施用后残效长达三年以上。因此,在改善果树栽培方式、实现矮化密植栽培中,应用PP_(333)是提高果树生产率的又一条新途径。然而,PP_(333)在果实及土壤中的残留量始终是人们所关注的问题。从现有资料看,目前国外已有用气相色谱法测定植物组织中PP_(333)残留量的报道,但该方法前处理麻烦,操作繁琐,为此我们用毛细管气相色谱法测定植物组织中PP_(333)的残留量,简化了PP_(333)的定量分析技术。     

多效唑对水稻未成熟胚愈伤组织诱导,分化和壮苗培养的影响

多效唑(Mult-Effect Triazole,MET)是一种良好的植物生长延缓剂,具有多方面的生理效应。已在水稻、小麦、油菜等作物中应用。本文报道了多效唑对水稻未成熟胚愈伤组织诱导、分化以及对壮苗培养的影响,为植物试管苗的正常化生产提供了有效的化学调控措施。1.材料早粳“T53”未成熟胚,愈伤组织,再生绿芽;早籼87-5-0,“湘竹443”再生绿芽。多效唑由本所生理系提供。     

高效唑浸种对稻苗耐盐能力的影响（简报）

高效唑浸种的稻苗耐盐能力显著提高,稻苗矮壮,根系发达,绿叶数多。在0.5％NaCl胁迫下,存活率高,生长受阻较小,叶片叶绿素含量下降缓慢。高效唑浸种提高稻苗耐盐能力可能与其抑制地上部生长、稻苗根/冠此提高有关。     

新型植物生长延缓剂和杀菌剂——氯丁唑

氯丁唑(Paclobutrazol)是英国ICI有限公司在七十年代末推出的一个高效低毒的植物生长延缓剂和广谱性的杀菌剂。它具有延缓植物生长,抑制茎的伸长,促进植物分蘖的形成,提高植物的抗倒伏能力等效果;同时,它还是有效的杀真菌和杀细菌剂,可有效地防治许多农作物的病害;在农业和园艺等方面有广阔的应用前景。本文主要介绍氯丁唑的理化性质、生理效应和应用。     

多效唑提高水稻幼苗抗低温能力的机理初探

对植物生长延缓剂多效唑 ( PP333)影响水稻幼苗抗低温能力进行研究。结果表明 ,用PP333浸种后在水稻培养液中培养 1 0 d的幼苗 ,经 ( 4℃± 0 .5℃ )低温胁迫后 ,能有效地降低相对电导率 ,维持较高的 SOD活性 ,提高 CAT、POD活性 ,减缓 MDA的积累。PP333处理使低温下的水稻幼苗维持较高的游离脯氨酸含量 ,延缓幼苗生长 ,使幼苗生长健壮     

多效唑对金钗石斛试管苗生长的影响

多效唑是一种高效的植物生长延缓剂,通过不同浓度的多效唑对金钗石斛试管苗生长的影响进行研究。结果表明多效唑能明显提高金钗石斛试管苗再生芽分化的数量,促进再生苗根的分化,提高生根的数量;同时,多效唑能使再生苗的叶片变短,对再生植株有显著的矮化作用,使植株的茎段变粗,抑制根的伸长生长。多效唑对金钗石斛试管苗生长的影响具有明显的规律性,其作用效果均随着其使用浓度的升高而增强,并在3~4mg/L的范围处达到最强效果,再提高浓度则趋于饱和。     

氮输入和水淹对短叶茳芏生长、养分及固碳的影响

外源氮输入显著改变河口湿地植物生长和固碳能力,进而影响河口湿地生态系统碳、氮循环过程。以闽江口湿地土著种短叶茳芏(Cyperus malaccensis)为研究对象,通过15个月的中型生态系实验,分析不同氮输入水平(CK,0 g N m~(-2)a~(-1);N8,8 g N m~(-2)a~(-1);N16,16 g N m~(-2)a~(-1))和2种水淹(T1,每天水淹时长2—3 h;T2,每天水淹时长11—12 h)处理对短叶茳芏生长、养分和固碳的影响,探讨短叶茳芏在环境变化下的生长、固碳特征。结果表明:T2处理株高极显著高于T1处理,N8、N16处理的植物株高显著高于CK处理,植物成熟季节的株高也极显著最高(P0.001)。水淹状况和植物生长期对短叶茳芏的密度有显著影响:T1处理密度极显著高于T2处理,植物成熟季节的密度也极显著最高(P0.001),但是氮输入没有显著提高植物密度。植物碳含量较为稳定,T2处理地上碳含量显著高于T1处理(P0.05),但是氮输入和植物生长期对地上碳含量影响不显著。氮输入水平、水淹状况和植物生长期则对植物地上氮含量都有显著影响(P0.05)。N8处理的植物地上生物量和固碳量极显著最高,CK处理极显著最低,植物成熟期的地上生物量和固碳量也极显著最大(P0.001),但是不同水淹处理植物生物量和固碳量无显著差异。闽江口湿地短叶茳芏具有较强的环境适应能力,在持续氮输入环境下,闽江口湿地的短叶茳芏可能向高潮滩拓展。     

肉桂醛调控不结球白菜多胺氧化酶-过氧化氢系统缓解硒胁迫的机理研究北大核心CSCD

硒(Se)胁迫通常引发植物细胞生理损伤,进而抑制植物生长。肉桂醛(CA)是一种具有抗氧化特性的天然化合物。该研究以不结球白菜(Brassica rapa)幼苗根为研究材料,采用多种生理生化以及原位荧光检测手段,研究了多胺氧化酶-过氧化氢(PAO-H_(2)O_(2))系统参与肉桂醛缓解硒胁迫的作用方式。结果表明:(1)硒胁迫显著抑制不结球白菜幼苗根的生长,并呈现浓度效应,而肉桂醛能显著缓解硒胁迫导致的生长抑制。(2)肉桂醛能够显著缓解硒胁迫诱导的根细胞氧化损伤和细胞死亡。(3)硒胁迫导致根内PAO活性和H_(2)O_(2)水平显著升高,而加入肉桂醛后可显著抑制PAO活性并降低H_(2)O_(2)水平。(4)在不结球白菜体内6个BrPAOs家族基因(BrPAO1-6)中,硒胁迫能够诱导BrPAO3、BrPAO5和BrPAO6表达量显著上调,而肉桂醛可显著抑制硒胁迫的这种诱导效应。研究发现,肉桂醛可通过抑制PAO-H_(2)O_(2)系统有效缓解不结球白菜的硒胁迫伤害,为外源调控作物耐受硒胁迫提供了新证据。     

Effect of Putrescine, 4-PU-30, and Abscisic Acid on Maize Plants Grown under Normal, Drought, and Rewatering Conditions

The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N¹-(2-chloro-4-pyridyl)-N²-phenylurea (4-PU-30), and abscisic acid (ABA) at concentrations of 10⁻⁵ m. Twenty-four hours later the plants were subjected to a water deficit program, induced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient solution for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf pigment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide content, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plant damage provoked by PEG stress. At the end of the water shortage program the plants treated with these PGRs possessed higher fresh weight than drought-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulation of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results provided further information about the influence of putrescine, 4-PU-30, and ABA on maize plants grown under normal, drought, and rewatering conditions. Received September 25, 1997; accepted August 10, 1998     

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.     

Proline accumulation: A parameter for evaluation of sensitivity of tomato varieties to drought stress?

The pattern of proline accumulation and the growth response were followed in several tomato ( Lycopersicon esculentum Mill.) varieties which were exposed to 7 days of drought stress followed by a 15-day period of rewatering. During dehydration, water potential and leaf elongation rates decreased more in var. 'Hosen' and 'S-5' than in 'LX-11', '1970', 'Pakmor', 'Faculty-16', 'Alcobaca' and '475'. Proline accumulation during stress was greatest in the first two varieties. In 'Hosen' and 'S-5' rewatering resulted in a decrease of proline to control levels, whereas in the other varieties accumulation of proline continued long after turgor had been regained. The extent of this continued accumulation was not correlated with the degree to which each variety was dehydrated. Upon rewatering of the plants the rate of leaf elongation was increased, but the final leaf size as well as whole shoot and root fresh weight of the recovered plants were not colated with the degree of "suffering" that each variety experienced during the drought period. Incubation of detached young tomato leaves in polyethylene glycol solution for 48 h resulted in a substantial accumulation of proline. The varietal differences observed under these conditions were reminiscent of the differential responses in proline accumulation obtained in the intact plants. It is concluded that proline accumulation at the time of dehydration signals drought stress in tomato plants but does not correlate with the overall varietal sensitivity to transient dehydration in recovered plants.     

Influence of Exogenous Glycine Betaine and Abscisic Acid on Papaya in Responses to Water-deficit Stress

The effects of exogenous foliar glycine betaine (GB) and abscisic acid (ABA) on papaya responses to water stress were investigated under distinct water regimes. Papaya seedlings (Carica papaya L. cultivar “BH-65”) were pretreated with GB or ABA and subsequently subjected to consecutive periods of drought, rehydration, and a second period of drought conditions. Results indicated that water stress induced ABA, jasmonic acid (JA), and proline accumulation but did not modify malondialdehyde (MDA) concentration. In addition, water deprivation reduced photosynthetic rate, stomatal conductance, relative water content (RWC), leaf fresh weight, and increased leaf abscission. GB applied prior to drought imposition decreased the impact of water stress on ABA, JA, proline accumulation, leaf water status, growth, and photosynthetic performance. However, ABA-pretreated plants did not show alteration of most of these parameters under water stress conditions when compared with non-pretreated plants except a clear induction of JA accumulation. Taken together, the data suggest that GB may modulate ABA, JA, and proline accumulation through the control of stomatal movement and the high availability of compatible solutes, leading to improvement of leaf water status, growth, and photosynthetic machinery function. In contrast, exogenous ABA did not stimulate papaya physiological responses under drought, but interestingly ABA in combination with drought could induce progressive JA synthesis, unlike drought alone, which induces a transitory JA increase and may trigger endogenous ABA accumulation. The data also suggest that irrespective of the pretreatments, papaya did not suffer oxidative damage.     

Abscisic acid, indole-3-acetic acid and mineral–nutrient changes induced by drought and salinity in longan (Dimocarpus longan Lour.) plants

Longan species (Dimocarpus longan Lour.) exhibit a high agronomic potential in many subtropical regions worldwide; however, little is known about its responses to abiotic stress conditions. Drought and salinity are the most environmental factors inducing negative effects on plant growth and development. In order to elucidate the responses of longan to drought and salinity, seedlings were grown under conditions of drought and salt stresses. Drought was imposed by suspending water supply leading to progressive soil dehydration, and salinity was induced using two concentrations of NaCl, 100 and 150 mM in water solution, for 64 days. Data showed that salt concentrations increased foliar abscisic acid (ABA) and only 150 mM NaCl reduced indole-3-acetic acid (IAA) and increased proline levels. NaCl treatments also increased Na⁺ and Cl^? content in plant organs proportionally to salt concentration. Drought increased leaf ABA but did not change IAA concentrations, and also increased proline synthesis. In addition, drought and salt stresses reduced the photosynthesis performance; however, only drought decreased leaf growth and relative leaf water content. Overall, data indicate that under severe salt stress, high ABA accumulation was accompanied by a reduction of IAA levels; however, drought strongly increased ABA but did not change IAA concentrations. Moreover, drought and high salinity similarly increased (or maintained) ion levels and proline synthesis. Data also suggest that ABA accumulation may mitigate the impact of salt stress through inducing stomatal closure and delaying water loss, but did not mediate the effects of long-term drought conditions probably because leaves reached a strong dehydration and the role of ABA at this stage was not effective to detain leaf injuries.     

Arabidopsis LOS5/ABA3 overexpression in transgenic tobacco (Nicotiana tabacum cv. Xanthi-nc) results in enhanced drought tolerance

Drought is a major environmental stress factor that affects growth and development of plants. Abscisic acid (ABA), osmotically active compounds, and synthesis of specific proteins, such as proteins that scavenge oxygen radicals, are crucial for plants to adapt to water deficit. LOS5/ABA3 (LOS5) encodes molybdenum-cofactor sulfurase, which is a key regulator of ABA biosynthesis. We overexpressed LOS5 in tobacco using Agrobacterium-mediated transformation. Detached leaves of LOS5-overexpressing seedlings showed lower transpirational water loss than that of nontransgenic seedlings in the same period under normal conditions. When subjected to water-deficit stress, transgenic plants showed less wilting, maintained higher water content and better cellular membrane integrity, accumulated higher quantities of ABA and proline, and exhibited higher activities of antioxidant enzymes, i.e., superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, as compared with control plants. Furthermore, LOS5-overexpressing plants treated with 30% polyethylene glycol showed similar performance in cellular membrane protection, ABA and proline accumulation, and activities of catalase and peroxidase to those under drought stress. Thus, overexpression of LOS5 in transgenic tobacco can enhance drought tolerance.     

Physiological Evaluation of Drought Stress Tolerance and Recovery in Cauliflower (Brassica oleracea L.) Seedlings Treated with Methyl Jasmonate and Coronatine

Coronatine (COR) is a chlorosis-inducing phytotoxin that mimics some biological activities of methyl jasmonate (MeJA). Although MeJA has been reported to alleviate drought stress, it is unclear if COR has the same ability. Our objective was to determine the influence of exogenously applied MeJA and COR on the growth and metabolism of cauliflower seedlings under drought stress and recovery. Both MeJA and COR enhanced the growth and accumulation of dry matter in cauliflower seedlings during drought-stressed and rewatering conditions. Treatment with MeJA or COR enhanced tolerance of drought stress through increased accumulation of chlorophyll and net photosynthetic rate. Enzymatic (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione reductase) and nonenzymatic antioxidant (proline and soluble sugar) systems were activated, and lipid peroxidant (malondialdehyde and hydrogen peroxide) was suppressed by MeJA and COR under drought stress. MeJA and COR also increased leaf relative water content and endogenous abscisic acid level under drought-stressed conditions. After rewatering, the contents of leaf water, chlorophyll, abscisic acid, and photosynthetic characteristics as well as enzymatic and nonenzymatic antioxidant systems showed nearly complete recovery. Both MeJA and COR can alleviate the adverse effects of drought stress and enhance the ability for water stress resistance through promotion of defense-related metabolism in cauliflower seedlings.     

The Association between Soil and Xylem Water Potential, Leaf Resistance, and Abscisic Acid Content in Droughted Seedlings of Douglas-fir (Pseudotsuga menziesii)

During progressive stages of drought and subsequent recovery through rewatering, foliage of 2-year-old seedlings of Douglas-fir was sampled for water potential, stomatal resistance, and abscisic acid content (ABA). Simultaneous measurements of soil matric potential were also made. There was a rapid rise in stomatal resistance in the range of 1500–2000 ng ABA g^?1 dry weight of foliage corresponding with a plant water potential of –10 to –12 bars. Soil matric potential seemed more closely associated with ABA increase than did plant water potential. After rewatering, seedlings returned to normal ABA levels within 6 days.     

Physiology of rice tungro virus disease: Proline accumulation due to infection

Tungro virus infection stimulates proline accumulation in leaves of rice ( Oryza sativa L.), especially in a sensitive cultivar, Taichung Native 1. Disease-induced proline accumulation increases with the severity of the disease. Proline also accumulates in senescing, detached healthy rice leaves. The magnitude of proline accumulation in these leaves was further accentuated by ABA and retarded by kinetin. In the absence of drought stress, virus infection induces severe symptoms (stunting) in a drought tolerant cultivar (Lalnakanda 41) when compared to cultivars with intermediate (MW 10) and high sensitivity (Cauvery) to drought. Thus tungro virus mimics water stress in inducing proline accumulation in rice leaves. In both cases a common factor, ABA, may mediate proline accumulation. In drought stress, proline accumulation is associated with tolerance, while in virus stress, proline accumulation is connected with sensitivity. It is, therefore, clear that proline cannot always act to relieve physiological stress.     

Cell Shape in Leaves of Drought-stressed Barley Examined by Low Temperature Scanning Electron Microscopy

Cells in leaves of well-watered and slowly drought-stressedbarley seedlings were examined by low temperature scanning electronmicroscopy, when the leaves were turgid, when just wilting,and when sufficiently stressed to prevent either regain of turgor(leaf blades) or regrowth (leaf sheath bases) after rewatering.Deformation of the cell surface was a major response to cellvolume reduction during stress. Folds occurred in the wallsof cells in leaf blades which were just wilting. In severelystressed and damaged plants a range of cell shapes and deformationsoccurred characteristic of a particular cell type and oftenunlike the control cell shape. Cell shape, drought, frost, barley, Hordeum