Effects of NaCl on Root Growth and Cell Wall Composition of Two Soya bean Cultivars with Contrasting Salt Tolerance

Our objectives were to determine the influence of salinity on root cell wall composition in soya beans and the possible mechanism of salt tolerance. Two soya bean cultivars, Touzan 69 (salt sensitive) and Dare (salt tolerant), were selected as experimental material for comparison. Root growth was clearly inhibited by salinity in both cultivars, but Touzan 69 showed more severe reductions in root length than Dare. In the 0–5 mm root segment (from root tip), the total cell wall sugar content of Touzan 69 decreased considerably due to salinity as were the pectin, hemicellulose and cellulose fractions. In Dare, NaCl treatments only caused a slight decrease in the pectin fraction and no marked change in hemicellulose and cellulose fractions. Without salt treatment, the pectin fraction accounted for about 40 % and cellulose for 30 % of cell wall composition in the 0–5 mm root segment; in the 5–10 segment (from root tip), pectin and cellulose accounted for 27 % and 45 % in Touzan 69, and 34 % and 38 % in Dare. The percentage of pectin decreased and that of cellulose increased in the 5–10 mm root segment compared with the 0–5 mm segment. This indicates that pectin largely regulates cell growth, as the 0–5 mm region is considered the elongation zone of soya bean roots. Salt treatment decreased the percentage of pectin, but increased that of cellulose across root zones of the two cultivars, suggesting that salt presence may increase cell wall rigidity, and thus, inhibits root growth. Dare was able to maintain its main root cell wall substances, an apparent advantage for root cell growth that may overall improve its salt tolerance. Also, the less reduction in cell wall uronic acid was of some benefit in the positive regulation of root cell growth in Dare. The changes in cell wall composition, especially the pectin content had a close relation with the regulation of root growth. The difference in salt tolerance between the two tested cultivars can partly be explained on the basis of these changes in response to salinity. Sugar compounds in each cell wall constituent and their functions in ion transport as well as the relationship between root cell wall and soya bean salt tolerance need to be further investigated.     

NaCl胁迫对水稻品种中花11幼苗根系生长发育的影响

以水稻中花11幼苗为材料,探讨高浓度NaCl处理对其根系生长发育的影响。结果表明,200 mmol/L NaCl胁迫下,幼苗胚根生长受到抑制,不定根数目减少,根毛数量减少长度变短;幼苗根系出现褐化,且根系木质素含量增加,根系过氧化物酶(POD)活力显著上升;半定量RT-PCR检测显示,盐胁迫应答基因OsCDPK7表达显著下降,P 5 CS 1表达上升,OsHKT 1;5、OsNHX 1在处理初期表达上升,其后随处理时间延长而下降。     

不同磷效率大豆基因型根形态构型对低磷胁迫的响应

探讨大豆根系形态构型指标在低磷胁迫下的适应性反应,研究根系形态构型指标与磷效率的关系。本试验选用3个“磷低效”大豆基因型D3、D17和D18及“磷高效”大豆基因型D34、D37和D38,采用田间试验,设高、低磷两个处理,对大豆基因型磷效率与根形态构型指标的关系进行了研究。结果表明,在高磷处理下,供试大豆根系各形态构型指标和根干生物量均无显著差异,在低磷处理下,各基因型间差异达到显著水平。相关分析表明,根长、根表面积和根生物量与地上部干生物量达到显著或极显著正相关,根直径与磷效率相关系数未达到显著水平。低磷胁迫时,根长、根表面积与根生物量影响植物的磷效率,而根直径对磷效率的影响较小。因此可以把根长、根表面积作为大豆磷效率筛选的重要指标,把根生物量作为辅助筛选指标。     

三江平原地区大豆根腐病调查报告

为了明确三江平原地区大豆根腐病发生的严重程度,于2014年对该地区所属县、市及农场内大豆进行病害调查,计算发病率及病情指数。采集大豆根腐病样本,对病株样本进行真菌的分离及鉴定,共分离获得相关致病真菌3个属10个种。镰孢菌为优势菌群,其分离频率为29.92%。镰孢菌中,尖孢镰孢菌为优势种,其占分离镰孢菌总量的65.75%。调查结果表明,含水量大及重茬地块,大豆根腐病发病率及病情指数较高。     

Protective Effects of Polyamines against Oxidative Stress Induced by Water and Cold Stress in Chickpea

Chickpea (Cicer arietinum L.) yields are drastically reduced by water and cold stress that occur individually or simultaneously in northern region of India. The comparative effects of both the stresses were investigated at the metabolic level by examining the endogenous status of polyamines (PAS), active oxygen species and antioxidants. Chickpea plants (15‐day old) growing hydroponically under controlled conditions (light/ dark; 24/21 °C, 16/8 h; irradiance 250 μmol m^?2 s^?1) were subjected to water deficit stress (Ψ_s of ?0.2 to ?1.0 MPa) and cold stress (5–25 °C) for 4 days. LD₅₀ in terms of root growth rate (RGR), electrolyte leakage and triphenyl tetrazolium chloride (TTC) reduction activity was observed at ?0.6 MPa and 10 °C for water and cold stress, respectively. In a subsequent experiment, 15‐day‐old plants were exposed to these stress levels under the above‐mentioned growth conditions for 7 days and analysed for various parameters. In cold‐stressed plants (CS), putrescine (PUT) was observed to be relatively higher while water‐stressed plants (WS) had more of spermidine (SPD). Spermine (SPM) levels increased more rapidly in WS and declined on the fourth day of stress while in CS, a gradual increase occurred that decreased on the seventh day. The accumulation of PAs was short‐lived under the combined presence of both the stresses. Hydrogen peroxide elevated abruptly in WS and remained higher than CS while the latter showed a marked increase in malondialdehyde content. Ascorbic acid increased sharply in WS that decreased on the fourth day while CS showed a relatively gradual increase that reached its maximum on the fourth day and declined subsequently. Glutathione was significantly higher in CS plants in comparison with WS and CS + WS plants. The activity levels of superoxide dismutase were higher up to 4 days and declined subsequently while those of WS stayed higher till the last day of stress. Ascorbate peroxidase levels were significantly higher in CS plants while catalase activity was comparatively more in WS. Exogenous application of PAs reduced the level of hydrogen peroxide, malondialdehyde content and raised the level of antioxidants. Put caused 44 and 32 % increase in RGR in CS and WS, respectively, while SPD resulted in 110 and 25 % enhancement in WS and CS, respectively. Under combination of stresses, RGR increased by 21, 53 and 10 % by Put, SPD and SPM, respectively. The effects of PAs could be reversed largely by their biosynthetic inhibitors. α‐difluoromethylornithine (a biosynthetic inhibitor of putrescine) caused more damage to CS while cyclohexylamine (inhibitor of SPD and SPM biosynthesis) was more inhibitory in WS.     

外源蔗糖，Vc对铬诱导的拟南芥主根生长抑制和过氧化物积累的缓解作用

通过水培实验研究重金属铬胁迫下拟南芥主根生长和过氧化物积累情况,以及外源施加蔗糖和维生素C对毒害的缓解作用。结果发现随着铬浓度的升高,植物主根生长受到了明显的抑制,胎盘兰染色表明高剂量的铬造成了主根的根尖细胞的死亡。进一步DAB染色发现铬胁迫诱导植物根尖大量积累过氧化氢,而在胁迫培养基中加入蔗糖和维生素C都可显著改善植物根的生长、减低过氧化氢的积累,并减少铬诱导的根尖细胞的死亡。上述结果表明铬胁迫诱导的拟南芥主根生长的抑制很可能是由于根尖细胞过氧化物积累所致。     

三江平原主栽大豆品种对大豆根腐病尖孢镰孢菌的抗性分析

明确三江平原地区主栽大豆品种对主要大豆根腐病致病菌尖孢镰孢菌的抗性。收集了该地区主栽大豆品种13 个,对其同时进行盆栽接种和大田接种尖孢镰孢菌的抗性分析试验,大田接种试验设不接种对照。‘垦丰16’和‘合丰55’的抗性最好,盆栽试验中均表现为抗病,平均病情指数分别为15.33%和20.67%,大田接种试验中表现为抗病,病情指数分别为25.55%和22.89%,与未接种对照相比,减产率最低,分别为3.55%和3.77%,差异达到显著水平。‘垦丰16’和‘合丰55’是适宜三江平原地区种植的抗尖孢镰孢菌根腐病的抗病品种。     

Root and Rhizosphere Colonization of Soybean [Glycine max (L.) Merr.] by Plant-Growth-Promoting Rhizobacteria at Low Root Zone Temperatures and under Short-Season Conditions

Co-inoculation of plant-growth-promoting rhizobacteria (PGPR) with B. japonicum has been shown to increase soybean [ Glycine max (L.) Merr.] nodulation, nitrogen fixation, growth and physiological activity at suboptimal root zone temperatures (RZTs). We studied the survival and growth of seven PGPR inoculated on soybean in a sterile rooting medium at three RZTs (25, 17.5 and 15 °C) on a growth bench. The survival of the two most promising strains ( Serratia liquefaciens 2-68 and S. proteamaculans 1-102) was studied under field conditions in methyl bromide fumigated and non-fumigated soils. In general, population densities varied with temperature. PGPR strains generally colonized the rhizosphere and root surface effeciently at higher RZTs; however, S. proteamaculans 1-102 colonized best at a low RZT (15 °C). The population of PGPR applied to the rhizosphere either with or without addition of B. japonicum increased over time in fumigated soil as compared to non-fumigated soil, indicating that the PGPR survive and proliferate better under fumigated conditions. S. liquefaciens 2-68 had higher population densities both on the root and in the rhizosphere, demonstrating, their ability to colonize under short-season conditions. The possible interactions between the two cultivars (Maple Glen and AC Bravor) and the PGPR were generally not significant, despite observations that growth and yield of AC Bravor respond more strongly to PGPR inoculation.     

Root Growth of a Salt Susceptible and a Salt Resistant Rice (Oryza sativa L.) During Seedling Establishment Under NaCl Salinity

The salt susceptible rice ( Oryza sativa L.) cv. Jaya and salt resistant cv. Damodar seed germination and seedling growth rates were studied in laboratory and field conditions. The effect of salinity on seed germination, shoot and root length, seedling vigour index (SVI) and increase in the root: shoot length ratio in the laboratory was relatively more in cv. Jaya than in cv. Damodar. The relative susceptibility to salinity was more in cv. Jaya than in cv. Damodar in the field also. However, their responses varied with growth period. The root: shoot length and fresh and dry weight ratios increased with salinity at 15 days in cv. Jaya. The root: shoot fresh and dry weight ratio decreased with salinity at 15 days in cv. Damodar. However, the root: shoot fresh weight ratio decreased with salinity at 25 days in the susceptible cv. Jaya. The root and shoot length fresh and dry weight of cv. Damodar was enhanced at 0.5% (w/v) NaCl treatment compared to the control seedlings at 25 days. SVI in cv. Jaya decreased with salinity in the laboratory and field conditions. SVI in cv. Damodar, SVI showed little change at 15 days but decreased with salinity of 1–3% NaCl with an enhancement at 0.5% NaCl level in the laboratory and at 25 days in field conditions.     

黑龙江省大豆根腐病致病病原种类分布及抗病种质鉴定

为了明确黑龙江省大豆根腐病菌种类并筛选抗病种质资源,2008年以来,从黑龙江省大豆产区100个地点采集根腐病株,通过采用PDA培养基分离镰刀菌、立枯丝核菌、腐霉菌,选择培养基分离疫霉菌的方法。分离结果表明,各主要致病菌出现频率为：镰刀菌42.7%,腐霉菌25.2%,立枯丝核菌7%,疫霉菌25.2%。对1249份大豆材料在自然发病条件下鉴定的结果表明,病情指数15%以下的材料有471份,占鉴定材料的37.7%;对471份材料人工接种出现频率最高的镰刀菌的结果表明,病情指数15%以下的材料69份,占供试材料的14.6%。通过试验研究明确了大豆根腐病致病病原菌种类;明确了现行大豆品种和资源中有抗根腐病的材料。     

银川大豆根腐病病原鉴定及种衣剂对其防治效果

为明确宁夏银川地区大豆根腐病病原及种衣剂对其防治效果,于2018—2019年从宁夏银川贺兰、兴庆和永宁地区大豆产区采集大豆根腐病病样,采用组织分离法分离病原菌,通过形态学鉴定并结合ITS和TEF序列分析确定病原菌的分类地位;通过田间试验明确6种种衣剂对大豆根腐病的防治效果。分离纯化获得126株镰刀菌,属于4个种,分别为茄病镰刀菌(Fusarium solani)、尖孢镰刀菌(F. oxysporum)、木贼镰刀菌(F. equiseti)和短肥镰刀菌(F. brachygibbosum),占比分别为51.59%、24.60%、13.49%和10.32%。4种镰刀菌对大豆均有致病作用,造成根腐病症状。供试6种种衣剂在播种后20天的防治效果均在65%以上,60天后防治效果均在60%以下。造成宁夏银川地区大豆根腐病的病原菌为茄病镰刀菌、尖孢镰刀菌、木贼镰刀菌和短肥镰刀菌。供试种衣剂对大豆根腐病均有一定的防治效果,但在大豆成株期防治效果下降。     

连作大豆苗期根际土壤根腐病病原真菌菌群结构分析

连作障碍是限制黑龙江地区大豆产质量提高的主要因素。本项研究的主要目的是探究连作大豆根腐病发病期病原真菌菌群结构,为生物防治大豆根腐病奠定基础。采用PCR-DGGE技术,分析不同连作年限苗期大豆土壤中的3个大豆品种根系以及根际土壤根腐病病原真菌菌群结构。试验结果表明：随着连作年限的延长,3个大豆品种苗期根系以及根际土壤根腐病病原真菌丰度值以及多样性指数随之增加;并且不同大豆品种间根腐病病原真菌菌群结构也存在差异;聚类分析结果验证了连作年限、大豆品种均对根腐病病原真菌菌群结构产生影响。     

Effect of Salinity Stress on Growth and Nutrient Composition of Three Soybean (Glycine max L. Merrill) Cultivars

Soil salinity is a major limitation to legume production in many areas of the world. The salinity sensitivity of soybean was studied to determine the effect of salinity on seed germination, shoot and root dry weights, and leaf mineral contents. Three soybean cultivars, Lee, Coquitt, and Clark 63, were planted in soils of different salinity levels. The electrical conductivity (EC) of the soils used in this experiment was 0.5 dS m^?1. The soil salinity treatments were 0.5, 2.5 4.5, 6.5 and 8.5 dS m^?1. Saline drainage water from a drainage canal with an EC of 15 dS m^?1 was used to treat the soil samples in order to obtain the desired salinity levels. Germination percentages were recorded 10 days after planting. Shoot and root dry weights of 45‐day‐old plants were measured. Nutrient concentrations for Na⁺, K⁺, Ca²⁺, Mg²⁺ and Cl^? were determined. Germination percentages were significantly reduced with increasing salinity levels. The cultivar Lee was less affected by salinity stress than Coquitt and Clark 63. At 8.5 dS m^?1 a significant reduction in plant height was found in all three cultivars. However, Lee plants were taller than plants of the other two cultivars. Salinity stress induced a significant increase in leaf sodium (Na⁺) and chloride (Cl^?) in all cultivars. However, the cultivar Lee maintained lower Na⁺ and Cl⁺ concentrations, a higher potassium (K⁺) concentration and a higher K⁺/Na⁺ ratio at higher salinity levels than Coquitt and Clark 63. Saline stress reduced the accumulation of K⁺, calcium (Ca²⁺) and magnesium (Mg²⁺) in the leaves of the cultivars studied. This study suggests that Lee is the most tolerant cultivar, and that there is a relationship between the salt tolerance of the cultivar and macronutrient accumulation in the leaves.     

Comparative Growth Responses and Ionic Relations of Four Cereals during Salt Stress

Four varieties, one each of triticale, wheat, rye and barley were grown in nutrient solution without and with the addition of 75 and 150 mM NaCl. Plants were exposed to salinity for two weeks and growth and ionic relations of plants were measured. Growth of four cereals varieties was affected to different degrees with salinity and shoot fresh weight/dry weight ratios decreased with increase in salt concentration in root medium. Shoots of barley variety accumulated high content of Na and Cl which were primarily due to higher rates of net ion transport from root to shoot. Higher accumulation of Na and Cl in barley variety shoot accompanied by better relative growth rates indicated plant's ability to compartmentalize ions in vacuoles.     

植物激素ABA调控侧根生长发育的研究进展

侧根构型直接影响植物根系形态建成,是植物整个根系的重要组成部分,在植物抗逆反应中起着重要作用。为了研究植物激素脱落酸(ABA)调控侧根生长发育的分子机制,本研究归纳了ABA在侧根发育中的信号传递,揭示了ABA在侧根起始中的双重作用和ABA对侧根分生组织活性的抑制作用。并分析了在侧根发育过程中ABA与其他调控因素包括活性氧(ROS)、生长素、细胞分裂素、碳和氮信号,以及盐胁迫间的交叉对话机制,指出ABA通过诱导根中ROS的产生,拮抗生长素和协同细胞分裂素的作用从而达到抑制侧根生长发育;ABA还参与了复杂的碳和氮信号调控的侧根发育过程;此外,ABA信号介导了盐胁迫对侧根发育起始的抑制。ABA调控侧根生长发育的分子机制的揭示可以为改善植物根系性状,提高作物抗逆性提供指导作用,然而,ABA对根生长调控的分子机制还不是很清楚,根系形成也十分复杂,因此需要更多的努力。     

Influence of Root-Applied Epibrassinolide and Carbenoxolone on the Nodulation and Growth of Soybean (Glycine max L.) Seedlings

24-Epibrassinolide belongs to the brassinosteroid family of plant hormones, and carbenoxolone is a synthetic analogue of glycyrrhizic acid that inhibits enzymes important in steroid and prostaglandin action in animals. The effect of these compounds on root nodulation, root growth and shoot growth of Glycine max (L.) Merr. cv. Tracy M was examined. Epibrassinolide reduced total nodulation, plant wet weight, root length, shoot length, first internode length and number of lateral roots. Effects were observed at concentrations as low as 0.1 μ M . Carbenoxolone reduced lateral root formation, but did not reduce nodule numbers, root length or weight, nor stem length or weight.     

水分胁迫对大豆生长与产量的影响及应对措施

在大豆生长发育过程中,非生物胁迫严重影响理化进程并降低产量,其中水分胁迫是所有其他非生物胁迫（高温、低温、土地瘠薄、盐碱等）损失的总和。为了提高大豆在水分胁迫中的抗逆性,通过归纳水分胁迫对大豆生长发育及产量的研究现状,总结干旱和淹水胁迫对大豆形态结构、生理指标及产量指标的影响,分析抵御水分胁迫的应对措施和有效方法。指出目前抗旱防涝存在的问题,并提出解决方案,以期降低水分胁迫对大豆生产造成的损失。     

Penetration Resistance,Root Growth,and Water Content in a Subsoiled Claypan1

Penetration resistance, root length density, and water content of soil with maize (Zea mays L.), soybean (Glycine max [L.] Merr.), or a mixture of alfalfa (Medicago sativa L.) and fescue (Festuca arundinacea Schreb.) were measured during two summers, one of which was dry. Plants grew on a silt loam (Mollic Albaqualfs; fine, mixed, thermic), 0.25 m deep overlying a claypan, 1.75 m thick. Half of the plots were subsoiled before planting in the first year of the study and the other half were not subsoiled. During both years, subsoiling had no measurable effect in lowering the penetration resistance in the claypan. Root length density was greater in the claypan than in the topsoil. Subsoiling did not increase root length density in either year. Water content in plots that had been subsoiled was usually similar to that in plots that had not been subsoiled. In the dry year, roots of maize proliferated more in the claypan than did roots of soybean or alfalfa + fescue.     

盐胁迫诱导的棉花叶片细胞程序性死亡

为明确盐胁迫是否可以诱导棉花叶片发生细胞程序性死亡,用0.5%的NaCl溶液对棉花叶片进行胁迫处理,在DNA琼脂糖凝胶电泳图谱上观察到明显的DNA拖尾现象,即NaCl处理诱发了DNA核小体间的断裂,从而表现出典型的细胞程序性死亡的生化特征。表明NaCl诱导棉花叶片死亡过程中,存在一个明显的细胞程序性死亡阶段。     

Effect of PEG Stress and Mycorrhiza on Growth and Mineral Uptake of Barley and Soybean

Two cultivars of barley ( Hordeum vulgare L.), Giza-119 and Sahrawy , and one of soybean ( Glycine max [L.] Merr.), Clark were subjected to osmotic stress caused by polyethylene glycol (PEG) 6000 and inoculated with ectomycorrhizal fungus; Cenococcum graniforme. PEG had stimulated growth of each barley cultivar, but not soybean. Inoculation resulted in increased shoot fresh and dry weights of soybean, either with or without PEG, and those of PEG-stressed barley. PEG displayed a synergistic effect with mycorrhizal fungus in barley by enhancing the uptake of N, Na, K, Ca and Mg by shoots.