Methyl Jasmonate Reduces Water Stress in Strawberry

The effect of methyl jasmonate (MJ) on changes of oxygen-scavenging enzyme activities and membrane lipid composition was studied in strawberry leaves under water stress. Under water stress, MJ treatment reduced the increase of peroxidase (EC 1.11.1.7; POD) activity, maintained higher catalase (EC 1.11.1.6; CAT) and superoxide dismutase (EC 1.15.1.1; SOD) activities, and ascorbic acid content. In addition, MJ treatment reduced transpiration and membrane-lipid peroxidation as expressed by malondialdehyde (MDA) content, lessened the reduction of membrane lipids, glycolipids [monogalactosyl diglyceride (MGDG), digalactosyl diglyceride (DGDG)], and phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI)]. In water-deficit conditions, MJ treatment also alleviated the decline in the degree of fatty acid unsaturation and the ratio of linolenic (18:3) to linoleic acid (18:2). These results indicate that MJ treatment appears to alter the metabolism of strawberry plants rendering the tissue better able to withstand water stress. Received June 16, 1999; accepted October 1, 1999     

Moderate Salinity Stress Reduces Rice Grain Yield by Influencing Expression of Grain Number- and Grain Filling-Associated Genes

Journal of Plant Growth Regulation - Soil salinity is an environmental stress severely impacting on rice grain yield. However, limited information is available on how salinity affects expression...     

Opening of Rice Floret in Rapid Response to Methyl Jasmonate

Effects of methyl jasmonate (MeJA) on rice floret opening were investigated in seven cultivars or hybrid combinations covering various variety types. Intact or excised panicles, judged to have florets just before anthesis, were soaked in 4 × 10⁻⁵− 4 × 10⁻³M MeJA solutions for 2 min at different temperatures. The results indicated that MeJA significantly induced opening of rice florets within about 30 min, with the most rapid induction occurring just 6 min after treatment. Numbers of induced opening florets are correlated with MeJA concentrations. Higher concentrations of MeJA induced more florets. pH values had no influence on MeJA effect, but MeJA required less time and induced more florets at 34°C than at 25°C. As far as we know, this is the first evidence that floret opening is induced by plant hormones. CO₂ evolution from panicles was also increased by MeJA treatment. Field experiments revealed that perfect flowering synchrony between the cytoplasmic male sterile (CMS) and restorer lines in hybrid seed production could be obtained by spraying MeJA solution on CMS line plants at the rate of 25 mg/m². As a result, many more hybrid seeds were harvested. Received July 19, 1999; accepted September 30, 1999     

Response of Scenedesmus Incrassatulus to Salt Stress as Affected by Methyl Jasmonate

Exposure of the freshwater green alga Scenedesmus incrassatulus Bohl, strain R-83 to salt stress (175 mM NaCl) resulted in a reduction of its growth and ¹⁴CO₂ fixation and in an increase of accumulation of free proline and malondialdehyde (MDA). The accumulation of proline in the light was higher than in dark. NaCl significantly inhibited the Fe-induced release of organic chelators from the cells. Exogenously supplied 10^–4M methyl jasmonate (JA-Me) did not considerably change the ¹⁴CO₂ fixation, but increased proline and MDA accumulation in the cells and moderately inhibited the release of chelators from cells. JA-Me supplied simultaneously with NaCl helps the algae to counteract the salt stress.     

Regulation of Spikelet Development in Rice by Hormones

Four indica rice varieties belonging to two maturity groupswere cultivated in medium irrigated land during the wet seasonof 1989. In all varieties, the primary branches of the panicledeveloped basipetally. Poor development of spikelets on thebasal branches resulted in a high percentage (50–60%)of degeneration and sterility and, consequently, grain yieldwas poor. Application of gibberellic acid (GA3) and kinetin(6-furfuryl amino purine) improved development and grain yieldon all branches. The treatments were more effective on the proximalbranches and reduced the existing gradient in growth, developmentand yield between the distal and proximal branches. In contrastto this, 3-indole acetic acid (IAA) treatment increased spikeletgrowth and development in the distal branches, but suppressedthem in the proximal branches thus increasing the heterogeneityin primary branch growth and development. The soluble carbohydrateand amino acid content per unit dry weight of the primary branchesincreased at the time of anthesis following the applicationof growth regulators. The assimilate level declined rapidlyat the post-anthesis stage. Associated with the depressed growthand development in the lower branches of the panicle by IAAtreatment, was a significantly higher level of assimilates inthese branches in the post-anthesis period. The physiologicalmechanism of spikelet growth regulation is discussed. Key words: Rice, assimilates, development, spikelets, fertility, hormones     

Thermal Stress Impacts on Reproductive Development and Grain Yield in Grain Legumes

Temperature stress (cold, heat) during reproductive development is one of the serious constraints to the productivity of grain legumes as their cultivation is expanding to warmer environments and temperature variability is increasing due to climate change. Grain legumes exposed to temperature below 10-15°C or above 30°C show flower abortion, pollen and ovule infertility, impaired fertilization, and reduced seed filling, leading to substantial reduction in grain yield. For managing these effects of temperature extremes, it is important to improve the resistance of grain legumes by using improved breeding and genetic engineering tools. In this review article, the impact of both high and low temperature stress on different phases of the reproductive stage, from meiosis to grain filling, and the sensitivity of different reproductive organs to temperature extremes are discussed. The review also covers the management options to improve resistance to temperature stress in grain legumes. Furthermore, innovative breeding, genetic and molecular strategies in grain legumes against temperature stress are also discussed.     

茉莉酸甲酯与水杨酸在诱导黑麦草颖花开放中的拮抗效应

在意大利黑麦草完全没有开颖的情况下,１mmol.L^-1MeJA处理体穗２min,１１h内可使其单穗颖花开放数达２５左右,表现出明显的诱导效应,滞后期约为１６０min;10mmol.L^-1和１mmol.L^-1的ＳＡ对MeJA诱导的开颖效应均有抑制作用,这种抑制作用可被MeJA处理解除。     

Spikelet Sterility and Flowering Response of Rice to Water Stress at Anthesis

Water deficits at the anthesis stage of rice (Oryza sativa L.)induce a high percentage of spikelet sterility and reduce grainyield. This study attempted to elucidate the direct effectsof water stress on panicle exsertion, spikelet opening, andspikelet desiccation leading to spikelet sterility. A well-wateredtreatment and two water stress levels were imposed in pot-grownplants of IRAT 13 (upland cultivar) and IR20 (lowland cultivar)at the time of flowering under greenhouse conditions A cultivar difference was observed in the flowering responseto water stress with a high sensitivity in IR20. The time courseof panicle exsertion showed an inhibitory effect due to thelow panicle water status. Low panicle water potentials significantlyreduced the number of opened spikelets. Spikelet opening wascompletely inhibited at panicle water potentials below –1·8MPa and –2·3 MPa in IR20 and IRAT 13, respectively.However, the peak spikelet opening time in a day was not influencedby the stress treatment. Spikelets in stressed panicles wereobserved to remain open for a longer period than in the well-wateredpanicles. The role of turgor in spikelet opening is also discussedin the study. At low panicle water potentials, severe desiccationof spikelets and anthers was noted. The deleterious effectsof water deficits on spikelet opening and spikelet water losscontributed to reduced spikelet fertility Oryza sativa L., rice, spikelet sterility, flowering, water stress, panicle water potentials, turgor potentials, desiccation     

Stimulated Accumulation of Lectin mRNA and Stress Response in Helianthus tuberosus Callus by Methyl Jasmonate

Callus from Helianthus tuberosus expresses a mannose-specific lectin (HTA). The level of HTA mRNA significantly increased one hour after treatment of the callus with 20 mg/l methyl jasmonate. Following this, fragmentation of the callus DNA at regular intervals was observed together with strong self-fluorescence emission in the callus cells.     

Effects of Strigolactones on Grain Yield and Seed Development in Rice

Journal of Plant Growth Regulation - Strigolactones (SLs) are well known as a class of endogenous phytohormones that regulate tiller bud outgrowth. Reduction of inorganic phosphate (Pi) induces the...     

Methyl Jasmonate and Nitrogen Interact to Alleviate Cadmium Stress in Mentha arvensis by Regulating Physio-Biochemical Damages and ROS Detoxification

Journal of Plant Growth Regulation - We examined effects of methyl jasmonate (MeJ), with and without N, for the alleviation of the adverse effects of 150 mg kg−1 CdCl2...     

Enhanced Sucrose Loading Improves Rice Yield by Increasing Grain Size

Yield in cereals is a function of grain number and size. Sucrose (Suc), the main carbohydrate product of photosynthesis in higher plants, is transported long distances from source leaves to sink organs such as seeds and roots. Here, we report that transgenic rice plants (Oryza sativa) expressing the Arabidopsis (Arabidopsis thaliana) phloem-specific Suc transporter (AtSUC2), which loads Suc into the phloem under control of the phloem protein2 promoter (pPP2), showed an increase in grain yield of up to 16% relative to wild-type plants in field trials. Compared with wild-type plants, pPP2::AtSUC2 plants had larger spikelet hulls and larger and heavier grains. Grain filling was accelerated in the transgenic plants, and more photoassimilate was transported from the leaves to the grain. In addition, microarray analyses revealed that carbohydrate, amino acid, and lipid metabolism was enhanced in the leaves and grain of pPP2::AtSUC2 plants. Thus, enhancing Suc loading represents a promising strategy to improve rice yield to feed the global population.Rice (Oryza sativa) is a staple food for nearly one-half of the global population. Given the rapid growth of the world’s population, there is an urgent need to increase rice yield. Rice yield is a complex trait that is directly associated with grain size, panicle number, and the number of grains per panicle (Xing and Zhang, 2010). Increasing grain size is a prime breeding target, and several genes known to control rice grain size, such as GRAIN SIZE3 (GS3), GS5, GW2 QTL for rice grain width and weight (GW2), GW8, and rice seed width5, have been identified (Fan et al., 2006; Song et al., 2007; Shomura et al., 2008; Li et al., 2011a; Wang et al., 2012). However, our knowledge of the mechanisms that control rice yield is limited. Thus, further improving rice yield remains a challenge for breeders (Sakamoto and Matsuoka, 2008). Identifying and characterizing unique genes or targets that regulate yield traits would improve our understanding of the molecular mechanisms that regulate yield traits and facilitate the breeding of new rice varieties with higher yields.The carbohydrates in rice grains originate from photosynthesis that is carried out predominantly in leaves (sources). Therefore, grain filling and rice yield depend on the efficient transport of carbohydrates from the leaves to seeds (sinks). In most plants, Suc is the main carbohydrate transported long distance in the veins to support the growth and development of roots, flowers, fruits, and seeds (Baker et al., 2012; Braun, 2012). Recently, the entire pathway for the export of Suc from leaves has been elucidated (Baker et al., 2012; Braun, 2012). Suc is synthesized in leaf mesophyll cells and diffuses from cell to cell through plasmodesmata until it reaches the phloem parenchyma cells (Slewinski and Braun, 2010). The SWEET transporters mediate Suc efflux from the phloem parenchyma cells into the apoplast, where Suc is subsequently loaded into the phloem sieve element-companion cell (SE/CC) complexes by Suc transporters (SUTs; Braun and Slewinski, 2009; Ayre, 2011; Chen et al., 2012). The resultant accumulation of Suc in sieve elements produces a hydrostatic pressure gradient that results in the bulk flow of Suc through a conduit of contiguous sieve elements, leading to its arrival and unloading in sink tissues (Lalonde et al., 2004; Baker et al., 2012).Genetic evidence has demonstrated that apoplastic Suc phloem loading is critical for growth, development, and reproduction in Arabidopsis (Arabidopsis thaliana). AtSWEET11 and AtSWEET12 are localized to the plasma membrane of the phloem and are expressed in a subset of phloem parenchyma cells in minor veins. These transporters mediate Suc efflux from phloem parenchyma cells into the apoplast prior to Suc uptake by SE/CC (Chen et al., 2012). The atsweet11 or atsweet12 single mutants exhibit no aberrant phenotypes, possibly due to genetic redundancy. However, atsweet11;12 double mutants are mildly chlorotic and display slower growth and higher levels of starch and sugar accumulation in the leaves than do wild-type plants (Chen et al., 2012). Arabidopsis phloem-specific sucrose transporter (AtSUC2) is a phloem-specific SUT that is expressed specifically in companion cells (Stadler and Sauer, 1996). AtSUC2 plays an essential role in phloem Suc loading and is necessary for efficient Suc transport from source to sink tissues in Arabidopsis (Stadler and Sauer, 1996; Gottwald et al., 2000; Srivastava et al., 2008). The atsuc2 mutants show stunted growth, retarded development, and sterility. Furthermore, these mutants accumulate excess starch in the leaves and fail to transport sugar efficiently to the roots and inflorescences (Gottwald et al., 2000).The proper control of carbohydrate partitioning is fundamental to crop yield (Braun, 2012). It has been reported that increasing sink grain strength by improving assimilate uptake capacity could be a promising approach toward obtaining higher yield. For example, seed-specific overexpression of a potato (Solanum tuberosum) SUT increased Suc uptake and growth rates of developing pea (Pisum sativum) cotyledons (Rosche et al., 2002). In addition, the Suc uptake capacity of grains and storage protein biosynthesis was increased in transgenic wheat (Triticum aestivum) plants expressing the barley (Hordeum vulgare) SUT HvSUT1 under the control of an endosperm-specific promoter (Weichert et al., 2010). Moreover, it was recently found that these transgenic wheat plants had a higher thousand grain weight and grain width and length, as well as a 28% increase in grain yield (Saalbach et al., 2014).Since the carbohydrates in rice grains originate from photosynthesis in source leaves, and carbohydrate partitioning from source leaves to heterotrophic sinks (e.g. seeds) is mediated by Suc transport in plants (Lalonde et al., 2004; Ayre, 2011), enhancing the capacity for Suc transport from leaves to seeds theoretically could increase crop yield. However, until now, enhancing Suc transport from leaves to seeds has not been shown to improve yield (Ainsworth and Bush, 2011).Here, we tested the hypothesis that enhancing Suc transport from leaves to seeds would increase rice yield. We expressed Arabidopsis SUC2 under control of the phloem protein2 promoter (pPP2) in rice and found that enhancing Suc loading did indeed increase rice yield. The pPP2::AtSUC2 plants produced larger grain than the wild type and showed grain yield increases of up to 16% in field trials. Our results suggest that manipulating phloem Suc transport is a useful strategy for increasing grain yield in rice and other cereal crops.     

Effects of 1-Methylcyclopropene on Rice Growth Characteristics and Superior and Inferior Spikelet Development Under Salt Stress

Journal of Plant Growth Regulation - Salinity stress hampers rice growth and development due to its osmotic, ionic, and hormonal (ethylene) stresses. High ethylene production affects inferior and...     

Gum Formation by Methyl Jasmonate in Tulip Shoots is Stimulated by Ethylene

The promotive effect of methyl jasmonate (JA-Me) on the induction of gum in tulip shoots (Tulipa gesneriana L. cvs. Gudoshnik and Apeldoorn) was studied in the presence of ethylene. Gum formation in the stem and the basal part of the leaves was induced by JA-Me (1% w/w in lanolin) and stimulated strongly by the simultaneous application of 1 or 5 mm 1-aminocyclopropane-1-carboxylic acid (ACC). JA-Me at a concentration of 0.1% did not induce gum, but that together with ACC at a concentration of 1 or 5 mm induced it substantially. Although JA-Me stimulated ethylene production substantially in the stem of intact tulips, ethephon (1% w/w) or ACC (1 or 5 mm) did not induce gum formation in tulip shoots. JA-Me induced gum formation in tulip shoots even in the presence of aminooxyacetic acid or cobalt ions. Moreover, gum formation was also observed in the cut shoot applied with JA-Me as a solution at concentrations of 0.23 mm or more. These results strongly suggest that JA-Me is required for gum formation in tulip shoots, and ethylene probably makes the tissues of shoots sensitive to JA-Me. Received March 23, 1998; accepted June 10, 1998     

内源茉莉酸甲酯的积累改变了大豆叶片与根的发育

茉莉酸甲酯是一种调节植物形态发生、诱导防御相关基因的植物信号转导分子。为了解内源茉莉酸甲酯在植物发育中的作用,将编码茉莉酸甲基转移酶的NTR1基因与CaMV 35S启动子连接并导入大豆植株。PCR及Northern杂交结果表明,NTR1基因稳定整合在大豆基因组并得到过量表达。与野生型植株相比,转基因大豆叶片与根的形态发生了显著的变化。大部分转基因大豆叶片变得细长,初生根生长受到抑制而侧根的生长却受到促进。定量分析结果表明,转基因大豆植株叶片中茉莉酸甲酯的含量比对照高出 2～2.5 倍。这些结果表明,内源茉莉酸甲酯的积累参与了大豆形态发生的调控。     

Two Methyl Jasmonate-Insensitive Mutants Show Altered Expression of AtVsp in Response to Methyl Jasmonate and Wounding

Jasmonates are plant signal molecules that are derived from lipids through the action of lipoxygenase. Jasmonates regulate gene expression during plant development and in response to water deficit, wounding, and pathogen elicitors. The signal transduction chain that mediates jasmonate action was investigated by isolating and studying two methyl jasmonate (MeJA)-insensitive mutants of Arabidopsis thaliana. The recessive mutants, jin1 and jin4, are nonallelic and neither corresponds to coi1, a previously identified MeJA-insensitive mutant. Both mutants showed reduced sensitivity to MeJA-mediated root growth inhibition as well as reduced MeJA induction of AtVsp in leaves. Expression of AtVsp in flowers was not altered in the mutants. Furthermore, MeJA modulation of the jasmonate-responsive lipoxygenase and phenylalanine ammonia lyase genes was not altered in the mutants. jin4 plants exhibited increased sensitivity to abscisic acid in seed germination assays, whereas jin1 plants showed wild-type sensitivity. Neither mutant showed altered sensitivity to ethylene in hypocotyl growth inhibition assays. jin1 and jin4 identify genes that modulate the response of AtVsp to MeJA in leaves of A. thaliana.     

Effect of Methyl Jasmonate on the Germination and the Degradation of Storage Reserve in Rice Seed

The effects of methyl jasmonate (MeJA, Nippon Zeon Co., Ltd, Tokyo, Japan) on germination and the degradation of storage reserve in rice （Oryza sativa L.） seeds were studied. There were dual effects of MeJA on seed germination and seedling growth of rice, low concentration of MeJA promoted germination and seedling growth whereas high concentration of MeJA inhibited germination and seedling growth. The optimal concentration of promotion was 5×10-7 mol/L. The acid phosphatase activity, α-amylase activity, degradation of starch and salt-soluble proteins were affected same as germination by MeJA. MeJA inhibited the degradation of glutelins, the higher the concentration, the higher the extent of inhibition above 5×10-7 mol/L.The results showed that either promotion or inhibition of germination by MeJA was very close to the effect on the activity of α-amylase. The mechanisms between abscisic acid and MeJA affection on seed germination and seedling growth were compared.     

茉莉酸甲酯对水稻种子萌发和贮藏物质降解的影响

茉莉酸甲酯 (methyljasmonate ,MeJA)对水稻 (OryzasativaL .)种子萌发及幼苗生长的作用表现出“双重性”效应 ,低浓度促进种子萌发和幼苗生长 ,最适浓度为 5× 10 -7mol/L ,高浓度作用相反。MeJA对水稻萌发胚乳酸性磷酸酶、α_淀粉酶、淀粉和盐溶蛋白降解作用也如此 ,但它抑制谷蛋白降解。实验结果表明 ,MeJA促进和抑制水稻种子萌发都与α_淀粉酶活性有关。讨论了MeJA对种子萌发作用与ABA作用的异同