Biochemical Aspects of the Soybean Response to Herbivory Injury by the Brown Stink Bug Euschistus heros (Hemiptera: Pentatomidae)

Plant defense response is an elaborate biochemical process shown to depend on the plant genetic background and on the biological stressor. This work evaluated the soybean biochemical foliar response to brown stink bug herbivory injury through an analysis of redox metabolism and proteomic 2DE profiles of susceptible (BRS Silvania RR) and resistant (IAC-100) varieties. The activity of lipoxygenase-3, guaiacol peroxidase, catalase and ascorbate peroxidase was monitored every 24 h up to 96 h. In the susceptible variety, injury caused an increase in the activities of lipoxygenase 3 and guaiacol peroxidase, no change in ascorbate peroxidase, and a decrease in catalase. In the resistant variety, injury did not cause an alteration of any of these enzymes. The proteomic profiles were evaluated after 24 h of injury and revealed to have a similar proportion (4–5%) of differential protein expression in both varieties. The differential proteins, identified by mass spectrometry, in the susceptible variety were related to general stress responses, to plant defense, and to fungal infections. However, in the resistant variety, the identified change in protein profile was related to Calvin cycle enzymes. While the susceptible variety showed adaptive changes in redox metabolism and expression of stress-responsive proteins, the resistant showed a defense response to circumvent the biological stressor.     

Rapid responses of C14 clone of Eucalyptus globulus to root drought stress: Time-course of hormonal and physiological signaling

The responses of juvenile plants of forest crops to drought stress are a key stage in the survival of forest populations. In this work, a suitable experimental system to study the early drought resistance mechanisms and signaling in a drought-tolerant clone (C14) of Eucalyptus globulus Labill is proposed. This system, using hydroponic culture and an osmotic agent, polyethylene glycol 8000, was demonstrated to induce severe stress in the root area, affecting the responses of the plantlets at the aerial level. These responses were very fast, beginning only 3 h after the induction of stress, and the results highlight the roles of xylematic abscisic acid (ABA) and pH changes over other signals, such as cytokinins, as early chemical signals in rapid water stress. The relationship between these chemical factors, ABA and pH, and the physiological and water parameters observed were significant, supporting their proposed principal role. This work aids our understanding of underlying responses to hydrological limitations of forest crops, and provides valuable information for further physiological and molecular studies of water stress in this and other tree species.     

Analysis of Natural Variation in Bermudagrass (Cynodon dactylon) Reveals Physiological Responses Underlying Drought Tolerance

Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H₂O₂ content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system.     

Physiological performance of two contrasting rice varieties under water stress

Two rice varieties PR-115 and Super-7 were imposed to water stress and different physiological traits were monitored to evaluate the performance of these varieties under drought. Under water stress condition although the relative water content, osmotic potential, chlorophyll content, photosynthesis rate, carbon discrimination and biomass decreased in both the varieties however, the reduction was more pronounced in Super-7 variety. Oryzanol a trans-ester of ferulic acid functions as antioxidant and it increased along with total phenolic and anthocyanin content in both the varieties under drought stress. However, gallic acid, 4 hydroxy benzoic acid, syringic acid and chlorogenic acid showed differential pattern in both of the varieties under water limiting conditions. Under drought, grain yield was penalized by 17 and 54% in PR-115 and Super-7 varieties, respectively in comparison to watered plants. Super-7 variety showed pronounced electrolyte leakage and MDA enhancement under water stress condition. High non photochemical quenching and reduction in Y(NO) and Y(II) indicated balanced energy management in tolerant PR-115 variety. The studies showed that PR-115 is a drought tolerant variety while Super-7 is drought sensitive in nature.     

Macrophyte and fish chemicals suppress Daphnia growth and alter life-history traits

Daphnids undergoing diel horizontal migration (DHM) to seek daytime refuge in the littoral zones of shallow lakes are likely to confront chemical cues from littoral-associated predators and macrophytes. In field experiments, we investigated how the natural suite of chemicals occurring in a wholly vegetated lake as well as within plant-free mesocosms with artificial macrophytes and epiphytes (either fishless or containing small fish) influenced individual daphnid growth. In laboratory experiments, we further examined how water containing chemicals from either a submerged macrophyte (waterweed, Elodea canadensis ), a planktivorous fish (roach, Rutilus rutilus ) or both impacted daphnid growth and life-history traits. In the field, we found the greatest suppression of daphnid growth in vials containing water from the wholly vegetated lake relative to growth of daphnids housed in vials containing spring water. Water from the mesocosm with fish also suppressed daphnid growth. Daphnid growth in water from the fishless mesocosm, which contained plastic plants colonized by epiphytes, did not differ from that of daphnids grown in spring water. In the lab experiment, daphnids exposed to Elodea chemicals took longer to mature and possessed fewer eggs than daphnids in media without Elodea chemicals. Daphnids exposed to chemicals from both Elodea and roach reproduced the earliest and at a smaller size. Daphnids exposed to only roach chemical cues did not significantly differ from daphnids in control media for age or size at first reproduction although they did possess fewer eggs. Daphnia responses to chemicals from either roach or Elodea alone did not predict how Daphnia responded to the combined influence of multiple chemical cues. Our results suggest that prolonged exposure to macrophyte chemicals incurs costs for Daphnia .     

Genotypic variation in drought stress response and subsequent recovery of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Three wheat (Triticum aestivum L.) genotypes, Sadovo, Katya and Prelom, with different tolerance to drought were comparatively evaluated in terms of leaf respiratory responses to progressing dehydration and consecutive rewatering. Under drought stress, the respiration of all varieties gradually decreased, as the drought-tolerant Katya showed the most pronounced decline at earlier stages of dehydration. When water stress intensified, this genotype gave relatively stable respiration rates compared with the drought-sensitive varieties. Additionally, dehydrated Katya leaves displayed lower stomatal conductance and higher photosynthesis values, which resulted in greater water use efficiency during the dehydration period. Combination of drought stress and short-term changes in leaf temperature also induced genotype-specific response that differed from the response to drought only. Over the whole temperature range, the leaves of Katya exposed to dehydration for 14 days, showed higher respiration rates compared to the drought-sensitive varieties. The sensitive varieties maintained higher respiration rates under control conditions and mild dehydration, and very low rates under severe drought. In Katya, respiration and photosynthesis were fully restored from the stress within the first day of rewatering. The drought-sensitive genotypes displayed a considerably slower recovering capacity. The results are discussed in terms of possible physiological mechanisms underlying plant tolerance to drought.     

辽宁省水稻品种品质性状及亲缘关系变化分析

为了解辽宁省水稻品种品质性状及亲缘关系的演变情况,对1991-2015年审定的257份水稻品种进行品质性状分析,并通过亲缘系数、系谱分析了解品种间的亲缘关系和骨干亲本的应用。结果表明,25年来辽宁省水稻品种随着时间的推进表现出子粒变长、变宽,垩白度减少,透明度、直链淀粉含量、胶稠度下降的趋势。总体上随着时间的推进,品种品质性状的相似度和优质率逐步提高。但由于品质性状在不同年份的变异程度有所不同,品质性状的综合表现差异依然较大。随着时间的推进,水稻品种间亲缘系数表现出先下降后上升的特点,每个亲本直接育成品种数呈现出上升趋势。257份水稻品种共形成22个骨干亲本,利用的骨干亲本也越来越集中,丰锦、辽粳5号、辽粳326、辽粳454、辽粳294、辽星1号是辽宁省水稻育种中重要的优质骨干亲本。今后辽宁省水稻优质品种选育过程中应在利用现有骨干亲本的基础上,拓宽品种遗传基础,将外观品质、加工品质的优化作为品质改良的主要方向。     

Cologne as a pungency control in tests of chemical discrimination: effects of concentration,brand, and simultaneous and sequential presentation

Cologne has been used extensively as a pungency control in experiments on chemosensory behavior to assess responses to an odorous, readily detectable stimulus that is irrelevant to the adaptive response being studied. However, undiluted cologne may be aversive, its effects might differ among brands, it might suppress responses to simultaneously presented chemical stimuli, and might affect subsequent responsiveness to other stimuli. We present experimental data showing that undiluted cologne can be aversive, but that aversion can be eliminated by dilution. We also show that the utility of cologne as a pungency control varies among brands, that cologne does not suppress responses to food chemicals in some species, but does in others, and that prior exposure to cologne does not affect later response to food chemicals. In 60 s swab trials with the Balearic lizard (Podarcis lilfordi), the main chemosensory responses were unaffected by cologne concentration. However, one-fourth of lizards exhibited slight to moderate aversion to undiluted cologne and 3:1 water:cologne, but not to a readily detected lower concentration (9:1). Two cologne brands did not affect responses, but a third brand induced increased tongue-flick rates. Colognes that stimulate increased tongue-flicking might mask real experimental effects. Cologne presented simultaneously with cricket chemicals did not affect tongue-flicking and biting responses in two species, but caused increased tongue-flicking in a third species and weaker response to cricket chemicals in a fourth. Prior testing with cologne did not affect responsiveness to cricket chemicals in a subsequent trial. Although cologne is a useful pungency control, pilot tests are needed to verify its utility for unstudied cologne types and animal species. Electronic Publication     

Age,Experience, and the Response of Streamside Salamander Hatchlings to Chemical Cues from Predatory Sunfish

Previous work has shown that streamside salamander larvae (Ambystoma barbouri; Ambystomatidae) exhibit an adaptive ‘sink to the bottom’ response to chemical cues from predatory green sunfish (Lepomis cyanellus; Centrarchidae), that is, larvae sink to the bottom more quickly (thus minimizing exposure time to sunfish predation) when they are dropped into water with sunfish chemicals (as compared to Ashless controls). Here, we examined this anti-predator behaviour in early hatchlings and the effects of age and experience on subsequent expression of this behaviour. Hatchlings responded significantly to fish chemical cues within the first 18 h after hatching. Age did not significantly influence this response, i.e. regardless of age (1, 7, or 14 days after hatching) larvae showed a significant response during their first exposure to fish chemical cues. Experience also did not significantly influence the larval response to fish chemicals i.e., repeated exposures over 2 weeks did not significantly influence the magnitude of the response. Finally, comparisons of 3 siblingships detected significant variation among siblingships that might reflect genetic variation in this behaviour.     

Physiological and morphological traits associated with adaptation of lucerne (Medicago sativa) to severely drought‐stressed and to irrigated environments

Adaptation to severe drought and to irrigated cropping can both contribute to increased water use efficiency of lucerne, but knowledge on the relevant adaptive traits is limited. Five cultivars featuring contrasting adaptive responses for 3‐year forage yield across 10 agricultural environments of the western Mediterranean basin were currently studied, to identify physiological and morphological traits associated with specific and wide‐adaptation responses. The landraces Mamuntanas, Demnat 203 and Erfoud 1, and the varieties SARDI 10 and Prosementi, were grown in replicated metal containers (55 cm long × 12 cm wide × 75 cm deep; 21 plants per container) under irrigation (weekly restoring soil field capacity) and under moderate and severe drought stress (implying decreased irrigation for 30 days followed by withheld irrigation for 33 and 58 days, respectively). Cultivar post‐stress survival reflected the known cultivar adaptation to drought‐prone agricultural environments. Demnat 203, specifically adapted to irrigated, frequently mown environments, displayed higher amounts of starch, soluble proteins and total nitrogen in the crown and the root under irrigation. This was due to outstanding organ size and, for starch, higher concentrations. Mamuntanas, specifically adapted to drought‐prone environments, exhibited high water‐soluble carbohydrate concentration in storage organs under severe stress, along with a water‐conservation strategy implying less water used in initial drought‐stress phases due to limited early root development that resulted in more water available under severe stress. Drought‐tolerant germplasm also displayed lower wilting under early stress, more plants with green tissues under severe stress, and more stems per plant in stress or favourable conditions. Multivariate patterns of cultivar variation for physiological and morphological traits were strictly associated with cultivar variation for adaptation pattern. Our results highlighted the difficulty to combine some traits of environment‐specific adaptive value into a unique widely adapted variety, supporting the selection of varieties specifically adapted to irrigated or severely drought‐prone environments.     

Molecular diversity analysis of eggplant (Solanum melongena) genetic resources

Eggplant (Solanum melongena), a vegetable that is cultivated worldwide, is of considerable importance to agriculture in China. We analyzed the diversity of this plant using inter-simple sequence repeat (ISSR) and RAPD procedures to subdivide 143 Chinese-cultivated eggplants based on coefficient of parentage, genetic diversity index (GDI) and canonical discriminant analysis. ISSR markers were more effective than RAPD markers for detecting genetic diversity, which ranged from 0.10-0.51, slightly lower than what is known from other crops. Our ISSR/RAPD data provide molecular evidence that coincides with morphological-based classification into three varieties and further subdivision into eight groups, except for two groups. Intensive use of elite parents and extensive crossing within groups have resulted in increased coefficient of parentage and proportional contribution but decreased GDI during the past decades. The mean coefficient of parentage and proportional contribution increased from 0.05 to 0.10% and from 3.22 to 6.46% during 1980-1991 and 1992-2003, respectively. The GDI of landraces was 0.21, higher than the 0.09 and 0.08 calculated for the hybrid cultivars released during the two periods. The recent introduction of alien genotypes into eggplant breeding programs may broaden the genetic base.     

Cytokine fingerprinting: characterization of chemical allergens.

Chemical allergy is a common and important occupational health issue. Allergic sensitization induced by chemicals may take a variety of forms, including allergic contact dermatitis (skin sensitization) and allergic asthma and rhinitis (sensitization of the respiratory tract). There is a need to identify and characterize chemicals that have the potential to cause such sensitization reactions. Although a number of methods are available for the prospective analysis of skin sensitizing activity, there are currently no widely accepted tests for the identification of chemical respiratory allergens. We here describe a novel approach, cytokine fingerprinting, that has the potential to distinguish between chemical contact and respiratory allergens. The pattern of cytokine production by draining lymph node cells (LNCs) is evaluated following repeated topical exposure of mice to test chemicals. Experience to date reveals that contact allergens stimulate the selective development of type 1 immune responses associated with the secretion by draining LNCs of interferon gamma (IFN-gamma), but little interleukin-4 (IL-4) or interleukin-10 (IL-10). In contrast, chemical respiratory allergens are found to induce the appearance of preferential type 2 immune responses characterized by IL-4 and IL-10 production, but comparatively low levels of IFN-gamma. It is proposed that cytokine fingerprinting may permit the simultaneous identification and characterization of those chemicals that have the potential to cause allergic sensitization.     

Solute Heterogeneity and Osmotic Adjustment in Different Leaf Structures of Semi-Leafless Pea (Pisum sativum L.) Subjected to Water Stress

Abstract: Semi-leafless varieties of pea have considerable agronomic importance and it has been suggested that they may have a superior response to water deficits than conventional varieties. However, these varieties are poorly characterized from a physiological point of view and there is lack of a physiological basis for their supposed better performance under conditions of water deficit. Here, we describe the solute distribution in the different leaf structures of a semi-leafless pea variety ( Pisum sativum L.) under non-limiting water conditions and under water stress. A conventional variety was subjected to the same conditions for comparative purposes. A detailed study was carried out both at the tissue level and at the single cell level. In control conditions, epidermal vacuoles of tendrils showed a different ion distribution of those of the laminar leaf structures. However, under water deficit, only stipules of the semi-leafless variety showed a significantly higher capability to increase osmolarity. This occurred by accumulating potassium, magnesium and chloride to a higher extent than other leaf structures. The inability of performing an adequate osmotic adjustment in tendrils may be the cause of the lack of a better response to water deficit.     

Phospholipid changes in wheat and barley leaves under water stress

Total phospholipid content of leaves of wheat and barley increased and phospholipid components changed under water stress. Notable among these were the absence of phosphatidyl serine in barley varieties, decrease in phosphatidyl glycerol content in a less drought-tolerant variety of wheat (S-308) and barley (BG-25), and appearance of phosphatidic acid in both crops. The phospholipid content and its components did not return to normal upon release of the stress by subsequent irrigations. Such observations are indicative of water stress effected alterations in membranes.     

Variation in the Fatty‐Acid Content in Seeds of Various Black,Red, and White Currant Varieties

Currant seeds, a by‐product of juice production, are recognized as a valuable source of oil rich in polyunsaturated fatty acids. We have evaluated 28 currant varieties for their oil content and fatty‐acid composition. The oil content in the seeds ranged from 18.2–27.7%, and no statistical difference between varieties of different fruit color were recorded. Furthermore, the estimated oil yields in the field production ranged from 26.4–212.4 kg/ha. The GC and GC/MS chemical profiles of the seed oils extracted from all examined varieties were common for currants. Linoleic acid (LA) was the major component, with contents ranging from 32.7–46.9% of total fatty acids, followed by α‐linolenic acid (ALA; 2.9–32.0 %), oleic acid (OA; 9.8–19.9%), γ‐linolenic acid (GLA; 3.3–18.5%), palmitic acid (PA; 4.4–8.1%), stearidonic acid (SDA; 2.2–4.7%), and stearic acid (SA; 1.2–2.4%). Quantitative differences in the fatty‐acid profiles between varieties of different fruit color were observed. Blackcurrant varieties showed significantly higher contents of LA, GLA, and PA than red and white currant varieties, whereas significantly higher amounts of ALA and OL were detected in the red and white varieties. Cluster analysis based on the chemical oil profiles joined the blackcurrants in one group, while most of the red and white cultivars joined in a second group at the same linkage distance.     

Effect of aspartic acid on physiological characteristics and gene expression of salt exclusion in Tartary buckwheat under salt stress

Salt-tolerant variety Chuanqiao No. 1 and salt-sensitive variety Chuanqiao No. 2 of Tartary buckwheat were used as experimental materials. The effect of aspartic acid on seed germination, physiological characteristics of seedlings and gene expression of salt exclusion in Tartary buckwheat were studied under NaCl stress of 150 mM. The results showed that the aspartic acid treatment could restore the seed germination rate and root vigor of seedlings to the control with non-damage level in salt-tolerant Tartary buckwheat variety under salt stress, and the salt-sensitive variety was increased greatly. Spraying aspartic acid had some protective effects on cell membrane of leaves in Tartary buckwheat under salt stress, and the protective effects were more obviously on salt-sensitive variety, and that could restore the activity of SOD and CAT of leaves to the control level in salt-tolerant Tartary buckwheat variety under salt stress, and the activity of antioxidant enzymes in salt-sensitive variety was increased significantly. The relative expression of FtNHX1 and FtSOS1 genes was increased significantly under salt stress, and that of FtNHX1 gene in salt-tolerant and salt-sensitive varieties was reached the maximum expression level at 12 h and 24 h respectively, while that of FtSOS1 gene in salt-tolerant and salt-sensitive varieties was reached the maximum expression level at 12 h, and the salt-tolerant variety was increased greatly. After spraying aspartic acid, the relative expression of FtNHX1 and FtSOS1 genes was increased more obviously. The relative expression of FtNHX1 gene in salt-tolerant and salt-sensitive varieties was reached the maximum expression level at 12 h, while that of FtSOS1 gene was reached the maximum expression level at 12 h and 24 h respectively, and that in salt-tolerant variety was increased especially more, indicating that spraying aspartic acid on gene expression of salt exclusion in salt-tolerant variety of Tartary buckwheat has a better effect under salt stress.     

Electroantennogram responses of the potato tuber moth, <Emphasis Type="Italic">Phthorimaea operculella</Emphasis> (Lepidoptera; Gelichiidae) to plant volatiles

Electroantennograms (EAGs)were recorded from males and females of the potato tuber moth,Phthorimaea operculella in response to a broad range of plant volatile compounds belonging to diverse chemical classes.The responses to 27 compounds were evaluated,which indicated significant differences in EAGs between chemicals as well as between sexes.The fatty acid derivatives comprising essentially green leaf volatile components elicited significantly greater responses in females.The response profile of males was,in general,lower than that of females.EAG responses to the oxygenated and hydrocarbon monoterpenes were lower in both males and females.Dose -response studies indicate differences in response between the sexes and concentrations,suggesting the existence of sexual dimorphism. Compounds belonging to the fatty acid derivatives class appear to be important for an oligophagous pest such as the potato tuber moth and the findings are discussed in relation to host plant selection in this species.     

Biology and biotype determination of greenbug, Schizaphis graminum (Hemiptera: Aphididae), on seashore paspalum turfgrass (Paspalum vaginatum)

Greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), was first discovered damaging seashore paspalum (Paspalum vaginatum Swartz) turfgrass in November 2003 at Belle Glade, FL. Inquiries to several golf courses with seashore paspalum turf across southern Florida indicated infestation was wide spread by April 2004. Damage symptoms progress from water soaked lesions surrounding feeding sites within 24 h to chlorosis and necrosis of leaf tips within 96 h. Problems caused by greenbug feeding were initially misdiagnosed as fertilizer, disease, other insects, or water management problems because aphids were not previously found on warm season turfgrasses. Greenbug development and fecundity studies were conducted on six seashore paspalum varieties: 'Aloha,' 'SeaDwarf,' 'SeaGreen,' 'SeaIsle,' 'SeaWay,' and 'SeaWolf.' Greenbug did not survive on 'SeaWolf.' Development rates (mean +/- SEM) ranged from 7.6 +/- 0.2 to 8.2 +/- 0.2 d on the remaining varieties. Greenbug longevity and fecundity on 'Aloha' were significantly less than on the other varieties. The estimated intrinsic rate of natural increase (r(m)) for greenbug ranged from 0.24 to 0.26 across tested varieties. Values for net reproductive rate (R(o)) ranged from 12.3 on 'Aloha' to 40.4 on 'SeaWay.' In feeding trials on indicator plants, the Florida isolate of greenbug exhibited a unique biotypic profile most commonly found on noncultivated grass hosts. It was virulent on the wheat variety GRS1201 that is resistant to the principal agricultural biotypes attacking small grains and to all currently available resistant sorghum varieties.     

Studies on plant growth-regulating substances: Water uptake by discs from inulin-storing roots and tubers in response to growth-substance treatment

Discs of tissue cut from chicory and dandelion roots are shown to take up large amounts of water when treated with solutions of the auxin 2,4-dichlorophenoxyacetic acid. The effects of disc size, concentration of auxin and cold-storage of the roots on the magnitude of the response have been studied. A range of plant growth-regulating chemicals has been examined for the capacity to promote water uptake in chicory root discs. The results are considered both in relation to chemical structure and to the growth responses induced by these compounds in the wheat cylinder and pea segment tests. The evidence indicates that the water uptake response by chicory root tissues provides a useful method for assessing plant growth-promoting activity.