Nod factor [Nod Bj V (C(18:1), MeFuc)] and lumichrome enhance photosynthesis and growth of corn and soybean

The foliar application of Nod factor [Nod Bj V (C(18:1), MeFuc)] enhanced (P<0.05) the photosynthetic rate of corn; the increases were 36%, 23% and 12% for 10(-6), 10(-8) and 10(-10)M treated plants, respectively. Similarly, lumichrome at 10(-5) and 10(-6)M stimulated the photosynthetic rate of corn plants 1 and 2 days after application. Lumichrome (10(-5) and 10(-6)M) also increased the photosynthetic rates of soybean plants 3 days after treatment. Foliar applications of LCO (10(-6)M) to corn and soybean and of lumichrome (10(-5)M) to soybean increased leaf area, shoot dry mass and total dry mass relative to control plants. However, lumichrome treatments did not affect any growth variable of corn. Results of this study indicate that this signal compound can enhance the photosynthetic rate and growth of plants.     

Effect of Doubled CO2 Concentration on Leaf Chlorophyll-protein Complexes in Several Plants

The effect of doubled CO2 on the chlorophyll-protein complexes of the leaves of soybean ( Glycine max L., Ca plants), cucumber ( Cucumis sativus L., C3 plant), millet ( Setaria italica (L.) Beauv., not a very typical C4 plant) and corn (Zea mays L. ,C4 plant) was studied. Experi- mental plants were pot-cultured in polyethylene membrane (or glass) open top cultured chambers. After sowing, C02 was kept immediately either at ambient ( (350 ± 10) x 10-6) concentration for the control or at doubled CO2 ((700 ± 10) x 10-6) concentration for the treatment chambers. The chlorophyll-protein complexes of the thylakoid membrane of the plants were resolved by disk SDS- PAGE. The results showed that after doubled CO2 treatment,either in the soybean and cucmnber,or in the millet, the quantity of polymer state of PS Ⅱ light-harvesting chlorophyll a/b-protein complex (LHC Ⅱ ) had increased as the monomer state of LHC Ⅱ decreased. But such response to doubled CO2 was not found in corn, the C4 plant. The change of the state of LHC Ⅱ in soybean etc. might be an adaptive effect of plant photosynthetic mechanism to the long term elevated CO2. Thus it could increase the efficiency of the absorption, transfer and conversion of light energy in plant photosynthesis, and support the high efficiency of photosynthetic carbon assimilation.     

CO2浓度倍增对几种植物叶片的叶绿素蛋白质复合物的影响

研究了CO_2浓度倍增对大豆(Glycine max L.,C_3植物)、黄瓜(Cucumis sativus L.,C_3植物)、谷子(Setaria italica (L.) Beauv.,一种不很典型的C_4植物)和玉米(Zea mays L.,C_4植物)叶片的叶绿素蛋白质复合物的影响。实验植物盆栽于聚乙烯薄膜(或玻璃)的开顶式培养室中。播种后对照室的CO_2浓度立即保持在大气浓度(350±10)×10~(-6)中,CO_2浓度倍增处理室则保持在(700±10)×10~(-6)下。研究结果表明,对于大豆、黄瓜和谷子,CO_2浓度倍增均使其PSⅡ捕光叶绿素a/b-蛋白质复合物(LHCⅡ)的聚合体态的量增多,单体态的量减少。但C_4植物玉米对CO_2浓度倍增没有这样的反应。作者认为在大豆等植物中,LHCⅡ的上述状态变化可能是植物的光合机构对长期高CO_2浓度的一种适应效应,这样能提高光合作用中光能的吸收、传递和转换的效率,并支持高效的光合碳素同化作用。     

Jasmonate-dependent plant defenses mediate soybean thrips and soybean aphid performance on soybean

Insect herbivores from different feeding guilds induce different signaling pathways in plants. In this study, we examined the effects of salicylic acid (SA)- and jasmonic acid (JA)-mediated defenses on performance of insect herbivores from two different feeding guilds: cell-content feeders, soybean thrips and phloem feeders, soybean aphids. We used a combination of RT-qPCR analysis and elicitor-induced plant resistance to determine induction of SA and JA signaling pathways and the impact on herbivore performance. In the early interaction between the host plant and the two herbivores, SA and JA signaling seems to occur simultaneously. But overall, soybean thrips induced JA-related marker genes, whereas soybean aphids increased SA and ABA-related marker genes over a 24-h period. Populations of both soybean thrips and soybean aphids were reduced (47 and 25 %, respectively) in methyl jasmonate (MeJA)-pretreated soybean plants. SA treatment has no effect on either herbivore performance. A combination pretreatment of SA and MeJA did not impact soybean thrips population but reduced soybean aphid numbers which was comparable with MeJA treatment. Our data suggest that SA–JA antagonism could be responsible for the effect of hormone pretreatment on thrips performance, but not on aphid performance. By linking plant defense gene expression and elicitor-induced resistance, we were able to pinpoint the role for JA signaling pathway in resistance to two herbivores from different feeding guilds.     

Glyphosate affects lignin content and amino acid production in glyphosate-resistant soybean

Farmers report that some glyphosate-resistant soybean varieties are visually injured by glyphosate. Glyphosate is the main herbicide that directly affects the synthesis of secondary compounds. In this work, we evaluated the effect of increasing rates of glyphosate on lignin and amino acid content, photosynthetic parameters and dry biomass in the early maturity group cultivar BRS 242 GR soybean. Plants were grown in half-strength complete nutrient solution and subjected to various rates of glyphosate either as a single or in sequential applications. All parameters evaluated were affected by increasing glyphosate rates. The effects were more pronounced as glyphosate rates increased, and were more intense with a single total application than sequential applications at lower rates.     

Effects of salicylic acid pre-treatment on cadmium and/or UV-B stress in soybean seedlings

The present study examined the effect of salicylic acid (SA) pre-treatment on soybean seedlings exposed to cadmium and/or UV-B stress. Dry mass, pigment content, net photosynthetic rate (P_N), stomatal conductance (g_s), and transpiration rate (E) were decreased by the Cd and/or UV-B stress. SA alleviated the adverse effects of Cd and/or UV-B on growth, pigment content, PN, and gs, but did not mitigate the inhibitory effect of Cd/UV-B on E, or that of Cd on chlorophyll fluorescence parameters. Cd and/or UV-B induced oxidative stress and increased lipid peroxidation that was significantly decreased by SA pre-treatment. The Cd and/or UV-B increased superoxide dismutase (SOD) activity, decreased peroxidase (POD) activity, and catalase (CAT) activity was mostly unaltered. SA might act as one of the potential antioxidants as well as a stabilizer of membrane integrity to improve plant resistance to the Cd and/or UV-B stress.     

Salicylic Acid Induces Salinity Tolerance in Tomato (Lycopersicon esculentum cv. Roma): Associated Changes in Gas Exchange, Water Relations and Membrane Stabilisation

The present study investigates the role of salicylic acid (SA) in inducing plant tolerance to salinity. The application of 0.1 mM SA to tomato [Lycopersicon esculentum Mill.] plants via root drenching provided protection against 150 mM or 200 mM NaCl stress. SA treated plants had greater survival and relative shoot growth rate compared to untreated plants when exposed to salt stress. At 200 mM salt, shoot growth rates were approximately 4 times higher in SA treated plants than untreated plants. Application of SA increased photosynthetic rates in salt stressed plants and may have contributed to the enhanced survival. Transpiration rates and stomatal conductance were also significantly higher in SA treated plants under saline stress conditions. SA application reduced electrolyte leakage by 44% in 150 mM NaCl and 32% in 200 mM NaCl, compared to untreated plants, indicating possible protection of integrity of the cellular membrane. Beneficial effects of SA in saline conditions include sustaining the photosynthetic/transpiration activity and consequently growth, and may have contributed to the reduction or total avoidance of necrosis. SA, when used in appropriate concentrations, alleviates salinity stress without compromising the plants ability for growth under a favourable environment.     

Antioxidative defense activation in soybean cells

Suspension-cultured, photoheterotrophically grown, green soybean cells ( Glycine max L.) were used to investigate alterations in the cellular contents of ascorbate and glutathione, as well as specific activities of antioxidative enzymes, elicited by salicylic acid (SA) and BTH [benzo(1,2,3)thiadiazole-7-carbothioic acid S -methylester]. Both antioxidants were positively regulated by 48-h incubations with SA and BTH, respectively, the latter induced a stronger increase in antioxidant levels compared to SA. The specific activities of glutathione reductase, monodehydroascorbate reductase and glutathione S -transferase increased strongly in soybean cells as a response to both SA and BTH. The enzyme activations observed were in the range of 2–8-fold. Catalase activity was also increased 2-fold by SA but decreased when cells were incubated with BTH. These results indicate an activation of the cellular antioxidative system at both the antioxidant and enzyme level. In addition, the effects of SA and BTH on phytotoxicity exerted by the peroxidizing herbicide oxyfluorfen were investigated. Both compounds protected soybean cells from herbicide-induced lipid peroxidation in a time- and concentration-dependent manner and strongly suppressed the herbicide-induced accumulation of protoporphyrin IX. SA as well as BTH antagonize the action of peroxidizing herbicides.     

大豆高光效育种研究进展

多年的研究证明,提高光合效率是提高大豆产量的重要途径.在高产条件下,高光效大豆(Glycine max L. Merr.)品种与一般品种相比可提高产量30%～40%,表明高光效育种有着广阔的发展前景.高光效育种虽然未能缩短育种时间,但为达到预定的高光效目标提供了"实时"监测,可免除目标的偏离,从而达到高光效与高产的同步提高.大豆叶片与豆荚均存在着高活性的有限的C4途径循环,因此,通过常规育种或基因工程技术提高C4途径酶的表达能力,可能是提高C3植物光合效率的新突破点.     

Changes in Oil Accumulation and Fatty Acid Composition of Soybean Seeds under Salt Stress in Response to Salicylic Acid and Jasmonic Acid

greenhouse experiment with factorial arrangement based on randomized complete block design with four replications was conducted in 2015 to evaluate the effects of salicylic acid (SA) (1 mM) and jasmonic acid (JA) (0.5 mM) on oil accumulation and fatty acid composition of soybean oil (Glycine max L.) under salt stress (Non-saline, 4, 7, and 10 dS/m NaCl). Oil percentage of soybean seeds declined, while oil content per seed enhanced with increasing seed filling duration. Foliar application of SA improved oil content per soybean seed at different stages of development under all salinity levels. Although JA treatment enhanced seed oil percentage, oil yield of these plants decreased as a result of reduction in seed yield per plant. In contrast, the highest oil yield was recorded for SA treated plants, due to higher seed yield. Salinity had no significant effects on percentage of palmitic acid and stearic acid, but treatment with JA significantly reduced stearic acid percentage. Oleic acid content of seeds increased, but percentages of linoleic acid, linolenic acid and unsaturation index (UI) of soybean oil decreased with increasing salinity. Foliar application of SA and JA improved oil quality of soybean seeds by reducing oleic acid and enhancing linoleic acid, linolenic acid contents and UI. Exogenous application of SA had the most beneficial effects on soybean seeds due to enhancing oil yield and quality under saline and non-saline conditions.     

大豆高光效育种研究进展

多年的研究证明 ,提高光合效率是提高大豆产量的重要途径。在高产条件下 ,高光效大豆 (GlycinemaxL .Merr.)品种与一般品种相比可提高产量 30 %～ 40 %,表明高光效育种有着广阔的发展前景。高光效育种虽然未能缩短育种时间 ,但为达到预定的高光效目标提供了“实时”监测 ,可免除目标的偏离 ,从而达到高光效与高产的同步提高。大豆叶片与豆荚均存在着高活性的有限的C4 途径循环 ,因此 ,通过常规育种或基因工程技术提高C4 途径酶的表达能力 ,可能是提高C3 植物光合效率的新突破点。     

The salicylic acid analog 2,6-dichloroisonicotinic acid has specific impact on the response of the halophyte plant species <Emphasis Type="Italic">Solanum chilense</Emphasis> to salinity

Salicylic acid (SA) is involved in the salt-resistance of the halophyte plant species Solanum chilense. The SA analog 2,6-dichloroisonicotinc acid (INA) is commonly used to elicit SA signal transduction in response to biotic stress and is frequently used to confirm the SA involvement in plant response to pathogens. Data are lacking concerning its impact on plant response to salinity, especially in the halophyte species. Solanum chilense was cultivated in the absence or presence of 125 mM NaCl in nutrient solution and exposed to 0.01 mM exogenous SA or sprayed with 0.5 mM INA. Exogenous SA increased the shoot dry weight while INA did not. Exogenous INA, in contrast to SA, increased the shoot Na⁺ concentration in NaCl-treated plants and decreased the root K⁺ concentration. In the absence of salt, both SA and INA induced an increase in H₂O₂ which was not due to ascorbate peroxidase (EC 1.11.1.11) inhibition. In salt-treated plants, SA stimulated the ascorbate peroxidase activity while INA did not. Exogenous SA increased the root putrescine and spermidine concentrations while INA significantly decreased the concentration of these protecting compounds. It is concluded that exogenous SA and INA do not have similar impacts on the plant behavior and that the difference between these compounds may be influenced by NaCl. The use of INA as a reliable SA analog should therefore be considered with caution in halophyte plant species.     

The major Nod factor of Bradyrhizobium japonicum promotes early growth of soybean and corn

Greenhouse experiments were conducted to evaluate the effect of Nod factor Nod Bj-V (C18:1, MeFuc) of Badyrhizobium japonicum on the growth of soybean and corn. Three-day-old seedlings of soybean and corn were grown in hydroponic solutions containing four concentrations (0, 10(-7), 10(-9) or 10(-11) M) of Nod factor. After 7 d of treatment, Nod factor enhanced soybean and corn biomass. Nod factor elicited profound effects on root growth resulting in 34-44% longer roots in soybean. More detailed analyses of the roots, using a scanner based image analysis system, revealed that Nod factor increased the total length, projected area and surface area of the roots and decreased the diameter of soybean roots, while it increased the total length of corn roots. Stem injection of soybean plants with 10(-7) M Nod factor resulted in increased dry matter accumulation. These results suggest that Nod factor, besides mediating early stages of nodulation, has more general plant growth-promoting effects.     

Effect of salicylic acid pretreatment on drought stress responses of zoysiagrass (Zoysia japonica)

The present study was carried out to examine the effects of exogenous salicylic acid (SA) on growth, activities of antioxidant enzymes, and some physiological and biochemical characteristics of zoysiagrass (Zoysia japonica Steud.) plants subjected to drought. Aqueous 0.1, 0.5, or 1.0 mM SA solution was sprayed on the leaves of zoysiagrass for 3 days. Drought was induced by withholding watering for 16 days after SA application. Biomass, chlorophyll content, net photosynthetic rate (P _n), activities of antioxidant enzymes (e.g., superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), MDA and proline contents were determined. Pretreatments with 0.1 and 0.5 mM SA significantly increased fresh and dry weights and chlorophyll content, while 1 mM SA pretreatment did not show significant change compared to controls. SA pretreatments showed a marked increase in P _n compared with controls from the 7th to 16th day after drought start. Activities of SOD, POD, and CAT were increased by SA pretreatments. MDA and proline contents after 0.1 and 0.5 mM pretreatments were lower than those of controls from the 6th to 12th day of drought, while 1 mM SA pretreatment did not show significant change from the 0th to 9th day of drought. This work suggests that suitable exogenous SA (0.5 mM) helps zoysiagrass to perform better under drought stress by enhancing the net photosynthetic rate and antioxidant enzyme activities while decreasing lipid peroxidation as compared to the controls. SA could be used as a potential growth regulator for improving plant growth under drought stress.     

Salicylic acid induced changes on antioxidant capacity,pigments and grain yield of soybean genotypes in water deficit condition

Salicylic acid (SA) plays an important role in the regulation of plant growth and development in response to water deficit. The effect of SA (0, 0.4 and 0.8?mM) on some physiological parameters of three soybean genotypes was investigated in three irrigation schedules included (85%, 65% and 45% of field capacity) during 2014–2015. Results showed that water deficit decreased stomatal conductance, leaf area index, relative water content, membrane stability index, yield components and grain yield particularly in L17 genotype. Activities of superoxide dismutase, ascorbate peroxidase and concentration of hydrogen peroxide, proline and total protein were increased in response to water deficit as well as SA applications. SA inhibited catalase activity resulting in increased hydrogen peroxide accumulation in soybean genotypes. Application of 0.4?mM SA decreased the adverse effects of water deficit in soybean genotypes by elevation of antioxidant enzymes activity and reducing malondialdehyde formation especially in Williams genotype.     

Biological aspects of Bemisia tabaci biotype B and the chemical causes of resistance in soybean genotypes

In Brazil, the silverleaf whitefly (SLW), Bemisia tabaci biotype B, is a serious soybean pest. SLW management is difficult and new control strategies, such as host–plant resistance, are required. Herein, we aimed to evaluate the biology of SLW, from eggs to adults, on seven soybean cultivars. The emergence of adult insects was monitored daily. Defense-related compounds were identified and quantified from the V3 to the V8 stages in SLW-infested and non-infested plants. The rates of emergence of SLW adults were lower in cultivars ‘IAC 17,’ ‘IAC 19’, and ‘IAC 24’ compared with the susceptible cultivar ‘IAC Holambra Stwart’. Rutin, genistin, genistein, and salicylic acid were identified and quantified in plant extracts. The rutin, genistin, and genistein levels decreased after SLW infestation. Rutin concentrations increased in infested plants of ‘IAC 17’ (V6) and ‘IAC 19’ (from V5 to V8). ‘Barreiras’ showed the highest genistein content in non-infested plants; from V5 growth stage, it was not detected in cultivars Doko (infested), Vencedora, ‘IAC 17’, and ‘IAC 24’ (non-infested). High levels of salicylic acid were observed in ‘IAC ‘19’-infested plants (at V3 and V5). The results suggest that rutin can be related to SLW adults’ emergence only when the feeding source was ‘IAC 19’. Consequently, further studies are needed to access the associated gene expressions and the effect of other secondary metabolites, mainly volatile compounds from SA pathway, including its consequences on feeding preference and mostly in relation to IAC cultivars.     

Productivity of soybean-rhizobium symbiosis after modification of root nodule bacteria activity with exogenous proteins

Plant growth experiments were conducted to assess symbiotic efficiency, photosynthetic rates, and the development of soybean (Glycine max (L.) Merrill) seedlings after seed inoculation with active and inactive strains of root nodule bacteria Bradyrhizobium japonicum preincubated in the presence homologous and heterologous proteins. The properties of active and inactive symbiotic strains were differentially modulated by homologous soybean lectin, which had a marked influence on plant physiological condition. The incubation of active rhizobia with a homologous lectin, i.e., lectin of the respective plant, increased the nitrogen-fixing activity of nodules and, consequently, elevated photosynthetic rates and weight increments in soybean plants. At the same time, the homologous lectin suppressed the symbiotic properties of inactive strain of nodule bacteria. The preincubation of rhizobia with a heterologous pea lectin had virtually no effect on functioning of symbiotic apparatus and photosynthetic rate, whereas the preincubation of root nodule bacteria with human albumin exerted an effect similar to that induced by a homologous lectin on symbiotic productivity.     

Effects of foliar applications of nitric oxide and salicylic acid on salt-induced changes in photosynthesis and antioxidative metabolism of cotton seedlings

Nitric oxide (NO) is a plant signaling compound known to mitigate key physiological processes and salicylic acid (SA) is considered to be a signaling molecule that plays a key role in growth, development, and defense responses in plants under stress conditions. This work investigated the effects of sodium nitroprusside (SNP, a donor of NO) and SA on salt-tolerance of cotton (Gossypium hirsutum L.) seedlings by examining growth, photosynthetic performance, total osmoregulation substance content, antioxidative enzymes and H⁺-ATPase enzyme subjected to 100 mM NaCl. Addition of 100 mM NaCl inhibited the growth and photosynthetic parameters of cotton seedlings, and dramatically increased the electrolyte leakage, the plant contents of proline, lipid peroxidation (malondialdehyde), hydrogen peroxide (H₂O₂) and Na. Furthermore, antioxidant enzyme activities were restrained. Foliar applications of 0.1 mM SNP or/and 0.1 mM SA led to increase in the growth rate and photosynthesis, including photosystem II, net photosynthetic rate and transpiration rate, improvement of reactive oxygen species-scavenging enzymes activities and reduction of H₂O₂ accumulation in cotton seedlings induced by NaCl. In addition, membrane transport and function were facilitated by decreasing leaf electrolyte leakage, improving ion absorption and activating the osmotic-regulated substances metabolic. Further investigation also showed that SNP and SA alleviated the inhibition of H⁺-ATPase in plasma membrane induced by NaCl. The present study showed that foliar application of SNP and SA alone mitigated the adverse effect of salinity, while the combined application proved to be even more effective in alleviating the adverse effects of NaCl stress.     

Anatomy ofZea mays andGlycine max seedlings treated with triazole plant growth regulators

Soil drenches containing 250 μg of paclobutrazol or uniconazol (50 ml of a 17 μM solution) reduced the height of both corn (Zea mays L. cv. How.Sweet It Is) and soybean (Glycine max (L.) Merr. cv. A2) seedlings. With corn, uniconazol was considerably more active than paclobutrazol in reducing height whereas with soybean both compounds had similar dwarfing effects. The compounds increased foliar chlorophyll content and leaf thickness in soybean but had no effect on these parameters in corn. The increase in leaf thickness with soybean was due primarily to an increase in the thickness of the palisade cell layer. Chloroplast size and ultrastructure of both species were unaffected by the compounds. The growth regulators increased root diameter in both corn and soybean because of increased size of cortical parenchyma cells and particularly in soybean because of radial rather than longitudinal growth of the first few layers of the cortical parenchyma.