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The expression of stress related-genes against adverse environmental conditions has essential importance for plants. This study, using RT-qPCR, determined the expression of P5CS and PCS genes to investigate their roles in the leaves of tomato plants grown under heavy metal conditions. The expression of the PCS1 gene is significantly induced under such conditions. Transcript expression of P5CS1, a gene responsible for proline synthesis, changed depending on heavy metal doses; treatments of Cu (20 and 50 ppm), Cd and Pb (10 and 20 ppm) remarkably increased P5CS1 expression. However, the P5CS1 gene expression at 10 ppm dose of Cu and 50 ppm doses of Pb and Cd was not significantly different from that in control plants. The metal-chelating potency of the extract of tomato leaves exposed to Pb and Cd was higher than that of untreated plants. The proline content as assessed in the leaves of stressed plants was significantly increased by applications of 10 and 20 ppm of Cd and Pb, and high doses of Cu. In addition, the results showed that the proline content had a positive correlation with the P5CS1 gene expression in tomato leaves under application of these tree heavy metals and that there was a positive relation between the PCS1 gene expression and metal-chelating ability of Cd-stressed plants. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We compared three measures of birch leaf fluctuating asymmetry (FA). • A traditional and two landmark-based FA measures were poorly correlated. • FA in leaf shape was increased by experimental stress (control < drought < metals). • Even the shape-based measure of FA was not increased by severe industrial pollution. • Within-individual variation contributed over 90% to the total variation in leaf FA. Abstract Fluctuating asymmetry (FA), defined as the random deviations from symmetry in morphological traits, has repeatedly been suggested as a handy indicator of genetic and environmental stress experienced by organisms during their development. However, the value of FA for applied ecological and environmental research is now questioned by a growing number of studies that have found no increases in FA under stress. We used geometric morphometrics to test the hypothesis that FA measures based on naturally defined landmarks are better suited for detection of deviations from leaf symmetry than are traditional measures of FA. We compared two sets of mountain birch (Betula pubescens ssp. czerepanovii) leaves, obtained from trees growing in industrially polluted natural populations and from experimentally stressed seedlings, by examining three measures of FA: 1) a traditional distance-based measure calculated from the width of the left and right halves of a leaf at the middle of the lamina (FA width), 2) a distance-based measure reflecting differences in vein length calculated from three landmarks (FA veins), and 3) a multivariate FA measure describing asymmetry in leaf shape based on five landmarks (FA shape). These three FA measures were poorly (albeit positively) correlated with each other. The two distance-based measures reflected different parts of the multivariate measure FA shape , which had the highest sensitivity for detection of deviations from leaf symmetry. FA shape was also the only FA measure that weakly confirmed the expected increase in FA under experimental stress, and particularly under stress caused by application of heavy metals. However, very high levels of within-individual variation in asymmetry remain to be explained, and even FA shape did not show the expected effects of industrial pollution on leaf symmetry. We conclude that FA in birch leaves cannot be regarded as a reliable indicator of environmental stress, even when quantified using modern methods. [ABSTRACT FROM AUTHOR]

Human activities generate environmental stresses that can lead plant populations to become extinct. Population survival would require the evolution of adaptive responses that increase tolerance to these stresses. Thus, in pseudometallophyte species that have colonized anthropogenic metalliferous habitats, the evolution of increased metal tolerance is expected in metallicolous populations. However, the mechanisms by which metal tolerance evolves remain unclear. In this study, parent populations were created from non-metallicolous families of Noccaea caerulescens. They were cultivated for one generation in mesocosms and under various levels of zinc (Zn) contamination to assess whether Zn in soil represents a selective pressure. Individual plant fitness estimates were used to create descendant populations, which were cultivated in controlled conditions with moderate Zn contamination to test for adaptive evolution in functional traits. The number of families showing high fitness estimates in mesocosms was progressively reduced with increasing Zn levels in soil, suggesting increasing selection for metal tolerance. In the next generation, adaptive evolution was suggested for some physiological and ecological traits in descendants of the most exposed populations, together with a significant decrease of Zn hyperaccumulation. Our results confirm experimentally that Zn alone can be a significant evolutionary pressure promoting adaptive divergence among populations. [ABSTRACT FROM AUTHOR]

Developing strategies to tackle water stress in lawns in arid climate regions is significantly important. In such conditions, using growing media amendments as well as native plants can relieve drought stress in different growing stages of the plants. This study was carried out to investigate the effects of some types of soil amendments on the emergence and early seedling establishment of tall fescue (Festuca arundinecea Schreb 'GazBorkhar ecotype') under water stress conditions. The experiment was performed in a factorial trial based on a completely randomized design with three replications. The first factor, water stress, was applied based on field capacity (FC) at three levels (80% FC (control), 60% FC and 40% FC). The second factor, growing media amendments, was applied at nine levels of municipal solid waste (MSW), vermicompost (5% and 10% w/w), Stockosorb® (1% and 3% w/w) or zeolite superabsorbent (4% and 8% w/w) which were mixed with loam soil, and the loam soil was used as a control treatment. The results showed that using an irrigation system at 60% FC during seed emergence and early seedling growth did not reduce the quality of the turf grass, and also, in many cases, led to a higher quality lawn compared to the control, leading to water saving in turf grass management. Using MSW and manure vermicompost as soil amendments could maintain soil moisture and water supplement for the improvement of morphological, physiological and visual quality of this ecotype of Festuca arundinacea Schreb. [ABSTRACT FROM AUTHOR]

The current study was carried out with the aim of increasing the production of poly phenols in Coleus blumei plant using elicitation at the intact and cellular levels. The abiotic elicitor used to achieve this aim was sodium chloride (NaCl) at the concentrations 100, 200, or 300mM. Total phenols were estimated in the whole plant and compared with the total phenolic content in callus tissues. They were estimated by Folin-ciocalteu and spectrophotometric methods. Induction and maintenance of Coleus callus was carried out on the Gamborg medium (B5) for 21 days supplied with the growth regulators 0.8 mg.L-1 2,4 dichlorophenoxy acetic acid (2-4-D), 2 mg.L-1 Benzyl adenine (BA) and 0.5 mg.L-1 Naphthalene acetic acid (NAA) by using stem explants as a source for callus induction. Results showed a significant decrease in fresh and dry weights of the vegetative parts and roots in intact plants of Coleus in vivo after treatment with NaCl. The fresh weight decreased to 7.24 g at 300 mMNaCl compared with the control, which recorded 35.87g.while the fresh weight of the roots decreased to1.137g at 300 mMNaCl compared with the control, which recorded 3.73 g.Total phenols in callus cultures accumulated higher polyphenols compared with mother plants after treatment with NaCl. Phenols were also evaluated in both callus tissue and liquid medium and compared with the whole plant and control treatment. The highest value of total phenols was recorded in callus cultures supplied with NaCl which was 429.73 μg.L-1 at the concentration 200mMNaCl in both liquid medium and callus tissues. The intact plants recorded the highest mean in total phenols in plants grown in vivo (68.44) μg.L-1 for NaCl. [ABSTRACT FROM AUTHOR]

A study was conducted to characterize marigold stress response to polycyclic aromatic hydrocarbons (PAHs) (oxidative stress inducers) with and without sulfuric acid (S.Acid; pH 3) (acid-stress inducer), and to evaluate reactive oxygen species (ROS) scavenging activity of mannitol (Mann). Marigold ( Calendula officinalis ) seedlings were grown in a greenhouse and fumigated with fluoranthene (FLU), phenanthrene (PHE), Mann, and S.Acid individually and in various combinations for 40 days. Various physiological and biochemical parameters among others were analyzed using standard methods. The results revealed that fumigation of FLU induced oxidative stress to the plants via ROS generation leading to negative effects on photosynthesis at near saturating irradiance (A max ), stomatal conductance (G s ), internal carbon dioxide concentration (C i ), leaf water relations and chlorophyll pigments. Significant per cent inhibition of A max (54%), G s (86%) and C i (32%), as well as per cent reductions in chlorophyll a (Chl.a) (33%), Chl.b (34%), and total chlorophyll (Tot. Chl) (48%) contents were recorded in FLU fumigated treatment in comparison to control. Combination of Mann with FLU scavenged the generated ROS and substantially lowered the oxidative stress on the plants hence all the measured parameters were not significantly different from control. PHE fumigation had varied effects on marigold plants and was not as deleterious as FLU. Combined fumigation of S.Acid with both the PAHs had significant negative effect on leaf water relations, and positive effect on fresh and turgid weight of the plants but had no effect on the other measured parameters. The lowest proline contents and highest catalase and ascorbate peroxidase activities in FLU fumigated plants further confirmed that oxidative stress was imposed via the generation of ROS. From the results, it is evident that Mann could be an efficient scavenger of ROS-generated by FLU in the marigold plants. We recommend Mann to be widely used for the protection of higher plants from FLU-generated stress in the urban areas. [ABSTRACT FROM AUTHOR]

Grindelia covasii is an endemic species of the Lihue Calel Sierras. In this semiarid enviroment soil water availability is a limiting factor for seedling establishment. This greenhouse experiment evaluated the growth and survival of juvenile G. covasii plants by exposing four plant sizes (G=large, M=medium, and P=small plant sizes) to three irrigation levels, simulating high (Rf), moderate (R7) and low soil water availability (R14). Plant growth and physiological measurements were taken during the experiment. Results showed that growth parameters were affected by increasing waterstress. Leaf senescence was high under severe water limitation (R14) with larger individuals showing highest drought tolerance. No changes were observed in resource allocation from aboveground parts to roots in response to water stress. Survival was also affected by reduced water availability, with smaller plants being the most affected. The lower tolerance of juvenile stages of G. covasii to severe water stress observed in this experiment, suggest that this species would require moist conditions for successful seedling establishment. This study provides useful information regarding G. covasii recruitment. [ABSTRACT FROM AUTHOR]

Electrophysiological signal in plant is a weak electrical signal, which can fluctuate with the change of environment. An amplification detection system was designed for plant electrical signal acquisition by using integrated op-amps (CA3140, AD620, and INA118), patch electrode, data acquisition card (NI USB-6008), computer, and shielded box. Plant electrical signals were also studied under pressure and flooding stress. The amplification detection system can make nondestructive acquisition for Aquatic Scindapsus and Guaibcn with high precision, high sensitivity, low power consumption, high common mode rejection ratio, and working frequency bandwidth. Stress experiments were conducted through the system; results show that electrical signals were produced in the leaf of Aquatic Scindapsus under the stress of pressure. Electrical signals in the up-leaf surface of Aquatic Scindapsus were stronger than the down-leaf surface. Electrical signals produced in the leaf of Guaibcn were getting stronger when suffering flooding stress. The more the flooding stress was severe, the faster the electrical signal changed, the longer the time required for returning to a stable state was, and the greater the electrical signal got at the stable state was. [ABSTRACT FROM AUTHOR]

This study was done to evaluate two sets of Egyptian cotton varieties (G. barbadense L.) for tolerance to late planting. The first set included 16 cultivated and obsolete varieties which evaluated for two seasons under early and late plantings. The second set included eight varieties selected from the first set for tolerance to late planting; four susceptible and four tolerant, and evaluated for three seasons. In the first set, mean squares of all the studied traits indicated significant (p ≤ 0.01) differences among varieties in separate and combined analyses under early and late plantings. Also, the combined analysis showed significant (p ≤ 0.01) differences between dates for all traits. However, the interactions of varieties × dates and varieties × dates × years were not significant. The mean square of varieties × years was significant only for lint percentage, boll weight and days of first flowers. Furthermore, the interaction mean squares of varieties x years under both of early and late planting was not significant indicating that the different traits were stable from year to year either for early or late planting. Late planting caused severe reduction in seed cotton yield reached 19.28, 19.14 and 19.21 % in the first, second year and combined date. Stress susceptibility index varied slightly from year to year. The highest stress susceptibility index was recorded for the varieties Giza 81 and Menoufi (1.19) followed by Giza 85 (1.20), Giza 88(1.20), Giza 69 (1.15), Giza 95 (1.15), Ashmouni (1.10) and Giza 92 (1.04). The highest yielding varieties (G90× Aus, Giza 90, Dandara, Giza 86 and Giza 80 were tolerant to late planting and scored stress susceptibility index less than unity. The highest varieties in lint yield were G90× Aus, followed by Giza 90, Giza 80, Giza 86 and Giza 95 under both planting dates. The reduction % in lint yield caused by late planting was very high and larger than that in seed cotton yield, and reached 22.88, 22.56 and 22.72 in the first, second year and combined data, respectively. The stress susceptibility index of the different varieties respect lint yield / plant showed the same picture as seed cotton yield /plant. The reduction in lint% for different varieties was low and averaged 4.53, 4.41 and 4.47 % in the first, second season and combined means, respectively. The reduction % in boll weight caused by delaying planting data was high and reached 21.79, 20.85 with an average of 21.31 %. The reduction% in boll weight was more than that in seed cotton yield. Therefore, number of bolls /plant increased under late planting. These results indicate that the stress of delay planting shortened the vegetative period of cotton growth. The results of the second set of varieties were in the same trend of the first one. These results indicate that the main cause of reduction in cotton yield is late planting date. This is due to that all the Egyptian cottons were bred to grow under full season and not for short season conditions. How ever, the stress susceptibility index indicated to the presence of tolerant varieties to late planting, and there is a chance to select for short season condition from the progenies of the crosses of such tolerant varieties. [ABSTRACT FROM AUTHOR]

Flow cytometry provides a tool to physically sort single algal cells in order to obtain clonal cultures. During sorting, cells are submitted to physical stress factors such as high fluidic pressure, exposure to the laser beam, electrostatic charges, deflection through high voltage fields, and collisions with container surfaces. All of these can damage the cells of interest and success rates for initiation of cultures from flow-sorted cells are generally very low. We found that the addition of bovine serum albumin in the culture medium into which cells were sorted drastically improved the success of initiation of pico- and nano-eukaryotic phytoplankton strains. Adding a mixture of antibiotics (Penicillin, Neomycin, Streptomycin) to the medium in order to slow down bacterial growth further improved culture development. This approach was successfully used to isolate taxonomically diverse strains, including novel taxa, from a fresh sample obtained in the English Channel and from enrichment cultures established during an Atlantic meridional transect cruise. We anticipate that these improvements will be useful to clone or purify existing cultures and to isolate novel cultures from oceanic samples. [ABSTRACT FROM AUTHOR]

Plant abundances and demography often vary along gradients of environmental stress, and neighboring plants can amplify or diminish such variation. We asked to what degree the effects of neighboring plants on a focal species can be explained by the traits and abundances of species in the surrounding community. We studied a common understory herb, Trientalis latifolia, across climatic gradients created by topography in the Siskiyou Mountains, southwestern Oregon. We compared Trientalis fitness along these gradients with and without neighbor removal, and asked whether the effects of neighboring plants could be predicted by their community-weighted trait values and abundances. Environmental conditions alone did not explain whether neighbors had competitive or facilitative effects on Trientalis. However, the environment interacted with neighbor traits and biomass to influence neighbor effects: at cool, higher elevations, high neighbor biomass was associated with stronger facilitative effects, while at warm, lower elevations, high neighbor dissimilarity from Trientalis was associated with stronger competitive effects. We suggest that covariation and interactions among environmental and community characteristics are key to understanding species performance along climatic gradients. [ABSTRACT FROM AUTHOR]

Digitaria eriantha Steudel is a forage species adapted to grazing areas but sensitive to low temperatures, water stress and salinity. The promoter's bacterial populations of plant growth PGPR (Plant growth-promoting rhizobacteria) have the ability to colonize the root system of plants and mitigate stresses.The aim of this work is to study the behavior of two cultivars of D. eriantha cv. Sudafricana and Mejorada INTA, in symbiosis with Azospirilum brasilense, strain Az39 and ipdC- (hyper production and low production of auxins, respectively) and their behavior in different abiotic stresses. Inoculated and uninoculated seeds were planted in pots and placed in chamber C 23:21 (day: night) with a photoperiod 16: 8 (day: night) with a photon flux density of 300 mol m-2 s-1. When the plants wereten cm high they were subjected to different types of stress (cold, drought and salinity). Finalized stress treatments, growth parameters were measured such as length of leaf and root; frombiomass parameters we measured: fresh and dry weight from root and leaf. The two cultivars of D. eriantha, made symbiosis with both bacteria and the best combination was obtained with the strain A. brasilense strain ipdC- with cv. Mejorada INTA, in which all measured parameters were increased expressing in this symbiosis the ability to mitigate all types of stresses that were studied. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is the most important food crop in the world and primary source of food for more than a third of the population. The low temperatures are among the main abiotic stresses that affect the yield of this cereal. The objective of this work was to determinate the response of different lines and cultivars of rice in seedling state to low temperature stress under controlled conditions. 172 lines and cultivars were studied. It were subjected to 5 °C for 24 hours, when the plants were about three to four leaves. The evaluations were conducted by measured of chlorophyll fluorescence and visually. A wide range of response was obtained, which indicated a high allelic diversity for the low temperatures sensitivity in the studied germplasm. A group of 30 cultivars responded more favorably to the cold and the most prominent cultivars showed Fv/Fm values between 0.80 and 0.89. A significant relationship between visual evaluation and chlorophyll fluorescence was found. The correlation coefficient revealed a moderately strong relationship between both variables. Tolerant plant materials were more consistently identified. However, the dispersion between methods increased to more susceptible cultivars. [ABSTRACT FROM AUTHOR]

El experimento se condujo en la Unidad Científico Tecnológica Los Palacios (UCTB Los Palacios), desde el año 2010 hasta el 2012, sobre un suelo Hidromórfico Gley Nodular Ferruginoso Petroférrico durante el período de noviembre a febrero en condiciones semicontroladas, en maceteros de 1 m2 de área. En cada macetero se sembraron 40 semillas de la variedad Delicia 364, con el objetivo de evaluar la respuesta del frijol sometido a diferentes intensidades de estrés de agua en la fase vegetativa y su efecto en el rendimiento. Los resultados demostraron que al cultivo de frijol en la fase vegetativa al someterlo a estrés hídrico permitió incremento en el rendimiento a favor de los tratamientos con estrés respecto al testigo que se mantuvo con riego normal. Diferentes intensidades de estrés de agua en la fase vegetativa incremento el rendimiento. [ABSTRACT FROM AUTHOR]

How species invasions impact ecosystem structure and function at important ecotones or boundaries is unknown, but may provide insight into the impacts of climate change and the mechanisms underlying community change. The dwarf bamboo, Sasa kurilensis, may be a good system to understand these issues, as the species impacts ecosystem features as it encroaches beyond treeline into alpine systems. We used remote sensing imagery spanning a 35 year period to quantify S. kurilensis expansion patterns across its range, measured growth and stress tolerances of S. kurilensis above and below treeline, and evaluated components of growth to reveal how shifts in light and water limitations influence the ontogeny of height, branching, and leaf production. We show that S. kurilensis more than doubled its abundance across its range, but more than tripled its abundance near and above treeline. Soil dry-down rates were a key driver of invasion above and below treeline, where growth rates decreased with more rapid rates of soil moisture dry-down. We found S. kurilensis responds to competition and climate stress by increasing allocation to belowground structures at high elevations. Further, it invests more carbon in fewer-yet taller and heavier-aboveground structures in low-light, low elevation environments. It appears this species' success is driven by considerable morphological and physiological flexibility, coupled with changes in water balance associated with snowmelt that in each habitat results in sites increasingly hospitable to bamboo. Overall, this study links resource allocation strategies and physiological responses to climate change and provides a mechanistic explanation of invasion success. [ABSTRACT FROM AUTHOR]

The plant holobiont extends the plant's capacity for nutrient acquisition and stress protection. Recent studies show that under biotic stress plants can promote the acquisition of certain beneficial bacteria to their rhizosphere. Active emission of volatile organic compounds (VOCs) is a newly identified mechanism utilized by plants for this process. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is one of the main pollutants in paddy fields, and its accumulation in rice ( Oryza sativa L.) and subsequent transfer to food chain is a global environmental issue. This paper reviews the toxic effects, tolerance mechanisms, and management of Cd in a rice paddy. Cadmium toxicity decreases seed germination, growth, mineral nutrients, photosynthesis, and grain yield. It also causes oxidative stress and genotoxicity in rice. Plant response to Cd toxicity varies with cultivars, growth condition, and duration of Cd exposure. Under Cd stress, stimulation of antioxidant defense system, osmoregulation, ion homeostasis, and over production of signaling molecules are important tolerance mechanisms in rice. Several strategies have been proposed for the management of Cd-contaminated paddy soils. One such approach is the exogenous application of hormones, osmolytes, and signaling molecules. Moreover, Cd uptake and toxicity in rice can be decreased by proper application of essential nutrients such as nitrogen, zinc, iron, and selenium in Cd-contaminated soils. In addition, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce Cd stress in rice. Selection of low Cd-accumulating rice cultivars, crop rotation, water management, and exogenous application of microbes could be a reasonable approach to alleviate Cd toxicity in rice. To draw a sound conclusion, long-term field trials are still required, including risks and benefit analysis for various management strategies. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the accumulation of proline in stressed plants by exploring an analogy between what happens in animals with lactic fermentation and proline accumulation in plants.

Drought is one of the most important abiotic stresses, since it limits the production and growth of Stevia rebaudiana (Bertoni) Bertoni. The objective of the present work was to determine the effect of water stress induced by polyethylene glycol on the in vitro growth of ‘KH-IAN / VC-142’ S. rebaudiana plants. Growth variables were evaluated on in vitro plants subjected to simulated conditions of hydric stress with PEG 6000 at concentrations of 10 000, 1 000, 100, 10 and 1 ppm. In addition, a control without PEG was included. The variables plant height, root length, fresh and dry mass were negatively affected as the concentration of PEG increased. These results demonstrated the low tolerance of S. rebaudiana ‘KH-IAN / VC-142’ cultivar to hydric stress and make possible the future application on in vitro selection systems for the discrimination of cultivars genetically improved based on their tolerance to hydric stress. [ABSTRACT FROM AUTHOR]

NADPH oxidases (NOXs), also known as respiratory burst oxidase homologs (RBOHs), are the major source of reactive oxygen species (ROS), and are involved in many important processes in plants such as regulation of acclimatory signaling and programmed cell death (PCD). Increasing evidence shows that NOXs play crucial roles in plant immunity and their functions in plant immune responses are not as separate individuals but with other signal molecules such as kinases, Rac/Rop small GTPases and hormones, mediating a series of signal transmissions. In a similar way, NOX-mediated signaling also participates in abiotic stress response of plants. We summarized here the complex role and regulation mechanism of NOXs in mediating plant immune response, and the viewpoint that abiotic stress response of plants may be a kind of special plant immunity is also proposed. [ABSTRACT FROM AUTHOR]

One of the factors limiting the growth of crops is water deficit. A split plot factorial experiment was conducted in Qazvin (Iran) to determine the effects of water deficit stress on three Brassica species at different growing stages and application of zeolite in 2010-12 growing seasons. In these experiments factorial combination of different levels of water deficit stress (regular irrigation (I0), withholding irrigation from flowering stage to end of plant life cycle (I1), and withholding irrigation from pod stage to end of plant life cycle (I2) and zeolite were applied (0 and 10 t.ha-1), in main plot units, and different species (B. napus, B. rapa and B. junceu) were placed in sub plot units. Results showed that interactions among water deficit stress and different species, different water deficit stress and two zeolite amounts were significant for number of branches per plant, length of main, sub and total plant pod, and seed oil yield. Application of zeolite in all water deficit regimes increased the seed oil percent and seed oil yield and in interaction between these two factors, I1 without zeolite reduced the seed oil yield, in comparison to I0 and zeolite application. [ABSTRACT FROM AUTHOR]

The author reflects on the aspects of strain signaling, adaptation, and stress in abiotic plants considering the concerns on plants' food production under climate change. Topics include the discipline associated with the study on abiotic stress, the clarification of the definition of the terms and its essence to plant stress researches, and the analogy of the association between constitutive properties of beam strain tolerance and biological system allows for adaptive strain tolerance.

Seed collection and storage of wild species in ex-situ seed banks should be continued as an integrated tool for the conservation of plants in their habitats. Although seed-bank facilities are widely used today, their seed samples often suffer low genetic diversity. Consequently, reintroduced seeds and plant material may not have the resilience to cope with future environmental stress so leading to complete wastage of seeds. Molecular techniques allow the benefit of quantification of the genetic diversity of a seed collection in comparison with that of the natural population. In this study we focus on ex-situ seed bank samples and living collections of Ranunculus peltatus subsp. baudotii . We compare their genetic diversity and structure with that of the natural population before and after undertaking a restoration project on a natural pond in the Tuscan Archipelago National Park. ISSR analyses, carried out on a total of five sampling groups, shows a relatively high level of genetic diversity for the ex-situ cultivated groups. The analysis of molecular variance, in agreement with clustering obtained in the neighbour-joining dendrogram and with the pattern from cluster analysis, suggests dividing the samples analysed into two groups: one formed by individuals sampled before the pond restoration and the other formed by the subsequent pond population. The results highlight the importance of planning mixed propagation lines which can be obtained through the use of a range of germination conditions to exploit a novel source of genetic variability which may otherwise remain hidden within the seed collection. [ABSTRACT FROM AUTHOR]

Ethylene plays important roles in plant growth, development, and stress responses. The ethylene signaling pathway has been studied extensively, mainly in Arabidopsis (Arabidopsis thaliana). However, the molecular mechanism of ethylene signaling is largely unknown in rice (Oryza sativa). Previously, we have isolated a set of rice ethylene-response mutants. Here, we characterized the mutant maohuzi6 (mhz6). Through map-based cloning, we found that MHZ6 encodes ETHYLENE INSENSITIVE3-LIKE1 (OsEIL1), a rice homolog of ETHYLENE INSENSITIVE3 (EIN3), which is the master transcriptional regulator of ethylene signaling in Arabidopsis. Disruption of MHZ6/OsEIL1 caused ethylene insensitivity mainly in roots, whereas silencing of the closely related OsEIL2 led to ethylene insensitivity mainly in coleoptiles of etiolated seedlings. This organ-specific functional divergence is different from the functional features of EIN3 and EIL1, both of which mediate the incomplete ethylene responses of Arabidopsis etiolated seedlings. In Arabidopsis, EIN3 and EIL1 play positive roles in plant salt tolerance. In rice, however, lack of MHZ6/OsEIL1 or OsEIL2 functions improves salt tolerance, whereas the overexpressing lines exhibit salt hypersensitivity at the seedling stage, indicating that MHZ6/OsEIL1 and OsEIL2 negatively regulate salt tolerance in rice. Furthermore, this negative regulation by MHZ6/OsEIL1 and OsEIL2 in salt tolerance is likely attributable in part to the direct regulation of HIGH-AFFINITY K+ TRANSPORTER2;1 expression and Na+ uptake in roots. Additionally, MHZ6/OsEIL1 overexpression promotes grain size and thousand-grain weight. Together, our study provides insights for the functional diversification of MHZ6/OsEIL1 and OsEIL2 in ethylene response and finds a novel mode of ethylene-regulated salt stress response that could be helpful for engineering salt-tolerant crops. [ABSTRACT FROM AUTHOR]

The gaseous hormone ethylene profoundly affects plant growth, development, and stress responses. Ethylene perception occurs at the endoplasmic reticulum membrane, and signal transduction leads to a transcriptional cascade that initiates diverse responses, often in conjunction with other signals. Recent findings provide a more complete picture of the components and mechanisms in ethylene signaling, now rendering a more dynamic view of this conserved pathway. This includes newly identified protein-protein interactions at the endoplasmic reticulum membrane, as well as the major discoveries that the central regulator ETHYLENE INSENSITIVE2 (EIN2) is the long-sought phosphorylation substrate for the CONSTITUTIVE RESPONSE1 protein kinase, and that cleavage of EIN2 transmits the signal to the nucleus. In the nucleus, hundreds of potential gene targets of the EIN3 master transcription factor have been identified and found to be induced in transcriptional waves, and transcriptional coregulation has been shown to be a mechanism of ethylene cross talk. [ABSTRACT FROM AUTHOR]

Excessive heavy metals (HMs) in agricultural lands cause toxicities to plants, resulting in declines in crop productivity. Recent advances in ethylene biology research have established that ethylene is not only responsible for many important physiological activities in plants but also plays a pivotal role in HM stress tolerance. The manipulation of ethylene in plants to cope with HM stress through various approaches targeting either ethylene biosynthesis or the ethylene signaling pathway has brought promising outcomes. This review covers ethylene production and signal transduction in plant responses to HM stress, cross talk between ethylene and other signaling molecules under adverse HM stress conditions, and approaches to modify ethylene action to improve HM tolerance. From our current understanding about ethylene and its regulatory activities, it is believed that the optimization of endogenous ethylene levels in plants under HM stress would pave the way for developing transgenic crops with improved HM tolerance. [ABSTRACT FROM AUTHOR]

A priority in many crop improvement programs for a long time has been to enhance the tolerance level of plants to both abiotic and biotic stress. Recognition that the root system is the prime determinant of a plant's ability to extract both water and minerals from the soil implies that its architecture is an important variable underlying a cultivar's adaptation. The density and/or length of the root hairs (RHs) that are formed are thought to have a major bearing on the plant's performance under stressful conditions. Any attempt to improve a crop's root system will require a detailed understanding of the processes of RH differentiation. Recent progress in uncovering the molecular basis of root epidermis specialization has been recorded in the grasses. This review seeks to present the current view of RH differentiation in grass species. It combines what has been learned from molecular-based analyses, histological studies, and observation of the phenotypes of both laboratory- and field-grown plants. [ABSTRACT FROM AUTHOR]

Common bean Phaseolus vulgaris L. has been shown to be a recalcitrant plant to induce somatic embryogenesis (SE) under in vitro conditions. We used an alternative strategy to induce SE in common bean based upon the use of a cytokinin (BAP) coupled with osmotic stress adaptation instead of SE response that is induced by auxins. Explants derived from zygotic embryos of common bean were subjected to osmotic stress (sucrose 12 % w/v, 0.5 M) in the presence of BAP 10 mg/L and adenine free base 40 mg/L to induce somatic embryos from specific competent cells of the apical meristem and cotyledonary node. Somatic embryos were obtained from the competent cells in a direct response (direct SE). In a secondary response (secondary SE), those somatic embryos formed proembryogenic masses (PEM) that originated/developed into secondary somatic embryos and showed the SE ontogeny. Maturation of somatic embryos was achieved by using different osmolality media and converted to plants. Full-visible light spectrum was necessary to achieve efficient plant regeneration. Long-term recurrent SE was demonstrated by propagation of PEM at early stages of SE. This protocol is currently being applied for stable genetic transformation by means of Agrobacterium tumefaciens and bioballistics as well as for basic biochemical and molecular biology experiments. [ABSTRACT FROM AUTHOR]

Melatonin (N-acetyl-5-methoxytryptamine) functions as a ubiquitous modulator in multiple plant developmental processes and various stress responses. However, the involvement of melatonin in natural leaf senescence and the underlying molecular mechanism in Arabidopsis remain unclear. In this study, we found that the endogenous melatonin level was significantly induced in a developmental stage-dependent manner, and exogenous melatonin treatment delayed natural leaf senescence in Arabidopsis. The expression level of AUXIN RESISTANT 3 ( AXR3)/ INDOLE-3- ACETIC ACID INDUCIBLE 17 ( IAA17) was significantly downregulated by exogenous melatonin treatment and decreased with developmental age in Arabidopsis. Further investigation indicated that At IAA17-overexpressing plants showed early leaf senescence with lower chlorophyll content in rosette leaves compared with wild-type plants, while At IAA17 knockout mutants displayed delayed leaf senescence with higher chlorophyll content. Notably, exogenous melatonin-delayed leaf senescence was largely alleviated in At IAA17-overexpressing plants, and At IAA17-activated senescence-related SENESCENCE 4 (SEN4) and SENESCENCE- ASSOCIATED GENE 12 ( SAG12) transcripts might have contributed to the process of natural leaf senescence. Taken together, the results indicate that At IAA17 is a positive modulator of natural leaf senescence and provides direct link between melatonin and At IAA17 in the process of natural leaf senescence in Arabidopsis. [ABSTRACT FROM AUTHOR]

Drought resistances of 4 different flue-cured tobacco cultivars were studied under drought stress conditions in pot experiments. Some indexes, including the main agronomic botanical characters, accumulation of the plant, leaf relative water content, water-holding capacity, MDA content and proline content, were screened out, and the drought resistance of each type was comprehensively analyzed by membership function to clear the differences of drought resistance of flue-cured tobacco varieties. The results showed that under drought stress, their main agronomic botanical characters, both plant fresh and dry mass and leaf relative water content were decreased obviously, but the decreasing range of ‘ Yunyan 87 ' was the most less ， ‘ Bina 1 ' was relatively less, and ‘ Qianxi 1 ' was the largest. Leaf water holding strength was in order of ‘ Yunyan 87 ' > ‘ Bina 1 ' > ‘ Qianxi 1 ' > ‘ Jiucaiping 2 ' . The content of MDA and proline in flue-cured tobacco roots increased significantly, the MDA content of ‘ Yunyan 87 ' and ‘ Bina 1 ' had smaller increase, their proline content increased greatly, while ‘ Jiucaiping 2 ' and ‘ Qianxi 1 ' was on the contrary. The results of membership function analysis indicated that the drought resistance strength order was ‘ Yunyan87' > ‘ Bina 1 ' > ‘ Jiucaiping 2 ' > ‘ Qianxi 1 ' . [ABSTRACT FROM AUTHOR]

Phleum sardoum is an endemic psammophilous species of Sardinia, growing exclusively on coastal sandy dunes. The effect of glumes on seed germination, germination requirements at constant (5-25° C) and alternating (25/10° C) temperatures, both in the light (12/12 h) and in the dark were evaluated, as well as the effect of a dry after-ripening period (90 days at 25° C), the salt stress effect (0-600 mmol NaCl) and its recovery on seed germination. The presence of glumes reduced final germination percentages. For fresh naked seeds, high germination percentages were observed at 10° C. Dry after-ripening increased germination rate at low temperatures, but did not affect final germination percentages. NaCl determined a secondary salt-induced dormancy which recovery interrupted only partially. Our results highlighted that this species has its optimum of germination during autumn-winter when, under a Mediterranean climate, water availability is highest and soil salinity levels are minimal. [ABSTRACT FROM AUTHOR]

Characterizing the spatial variability in water status across vineyards is a prerequisite for precision irrigation. The crop water stress index (CWSI) indicator was used to map the spatial variability in water deficits across an 11-ha 'Pinot noir' vineyard. CWSI was determined based on canopy temperatures measured with infrared temperature sensors placed on top of well-watered and water-stressed grapevines in 2009 and 2010. CWSI was correlated with leaf water potential (Ψ) ( R = 0.83). This correlation was also tested with results from high resolution airborne thermal imagery. An unmanned aerial vehicle equipped with a thermal camera was flown over the vineyard at 07:30, 09:30, and 12:30 h (solar time) on 31 July 2009. At about the same time, Ψ was measured in 184 grapevines. The image obtained at 07:30 was not useful because it was not possible to separate soil from canopy temperatures. Using the airborne data, the correlation between CWSI and Ψ had an R value of 0.46 at 09:30 h and of 0.71 at 12:30 h, suggesting that the latter was the more favorable time for obtaining thermal images that were linked with Ψ values. A sensitivity analysis of varying pixel size showed that a 0.3 m pixel was needed for precise CWSI mapping. The CWSI maps thus obtained by airborne thermal imagery were effective in assessing the spatial variability of water stress across the vineyard. [ABSTRACT FROM AUTHOR]

Abstract: Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction modules that play essential roles in plant growth, development and stress response. MAPK kinases (MAPKKs), which link MAPKs and MAPKK kinases (MAPKKKs), are integral in mediating various stress responses in plants. However, to date few data about the roles of poplar MAPKKs in stress signal transduction are available. In this study, we performed a systemic analysis of poplar MAPKK gene family expression profiles in response to several abiotic stresses and stress-associated hormones. Furthermore, Populus trichocarpa MAPKK4 (PtMKK4) was chosen for functional characterization. Transgenic analysis showed that overexpression of the PtMKK4 gene remarkably enhanced drought stress tolerance in the transgenic poplar plants. The PtMKK4-overexpressing plants also exhibited much lower levels of H2O2 and higher antioxidant enzyme activity after exposure to drought stress compared to the wide type lines. Besides, some drought marker genes including PtP5CS, PtSUS3, PtLTP3 and PtDREB8 exhibited higher expression levels in the transgenic lines than in the wide type under drought conditions. This study provided valuable information for understanding the putative functions of poplar MAPKKs involved in important signaling pathways under different stress conditions. [Copyright &y& Elsevier]

Contents [ABSTRACT FROM AUTHOR]

Potato yield and quality are highly dependent on an adequate supply of water. In this study, 3 years of information from thermal and RGB images were collected to evaluate water status in potato fields. Irrigation experiments were conducted in commercial potato fields (Desiree; drippers). Two water-deficit scenarios were tested: a short-term water deficit (by suppressing irrigation for a number of days before image acquisition), and a long-term cumulative water deficit. Ground and aerial images were acquired in various phenological stages along the potato growing season. Effects of irrigation treatments were recorded by thermal indices and biophysical measurements of stomatal conductance (SC), leaf water potential, leaf osmotic potential and gravimetric water potential in soil. Canopy temperature was delineated from the thermal images with and without fused information from the RGB image. Crop water stress index (CWSI) was calculated, using three forms of minimum baseline temperature: empirical, theoretical and statistical. An empirical evaluation of maximum baseline temperature of Tair + 7 °C was used in all CWSI forms examined. Statistical tests and comparison of CWSI with biophysical measurements were performed to evaluate the responses to irrigation treatments. The results indicated a high correlation of CWSI with SC from tuber initiation to maturity based on ground and aerial data (0.64 ≤ R ≤ 0.99). Similar trends of increasing CWSI from well to deficit-irrigated treatments were found in all three growing seasons. The results also showed that CWSI may be calculated based merely on thermal imagery data. [ABSTRACT FROM AUTHOR]

In the course of evolution, plants have developed different responses and adaptations allowing them to survive under water deficit. These adaptation strategies can occur at physiological, cellular and molecular levels. At the latter one, gene expression modification would produce different proteins whose function may be: a) acting as protective molecules which contribute to water deficit tolerance, or b) acting as carriers of regulatory signals. Knowledge of these proteins and their functions can be used by Molecular Biology and Genetic Engineering to obtain plants tolerant to water limitations, as an important aid to agricultural production in regions with low hydric availability. [ABSTRACT FROM AUTHOR]

This research was conducted with the aim to among forty-one tested tomato (Lycopersicon esculentum Mill) populations distinguish those tolerant to limited water supply. Tolerance assessments were performed by using sixteen drought stress selection indices calculated on the basis of tomato shoot and root dry weight yields determined at water stress and non-stress conditions. Populations were differentiated in groups using the method of cluster analysis. The pot experiment was set in controlled greenhouse conditions and comprised optimally irrigated control and drought treatment (35.0 and 20.9% volumetric soil water content, respectively), imposed at the phase of intensive vegetative growth. The experiment was conducted at the Institute for Vegetable Crops in Smederevska Palanka, Serbia. The analyzed tomatoes exhibited significant differences in terms of response to limited irrigation, which had more pronounced effect on shoot dry weight than on the roots (average decrease of 64.4 and 35.7%, respectively). Consequently, root fraction in the total dry weight increased at drought for 68.2% on average. Shoot and root dry weights were positively correlated at optimal irrigation but not in drought, implying genotypic differences in terms of root adjustments to stress conditions. As for the calculated selection indices, substantial variation was found among the populations enabling their ranking in terms of drought tolerance. Since ranking was not the same in all cases, clustering the populations was performed taking into account all sixteen selection indices. The results of this analysis indicate that populations designated with numbers 126, 124, 131, 125, 128, 105, 101, 138, 110, 132 and 109 in Institute for Vegetable Crops germplasm collection exhibit satisfactory level of drought tolerance at vegetative phase and therefore may be used as parents in breeding +programs. [ABSTRACT FROM AUTHOR]

Fourier transform infrared spectroscopy was used to characterise highland and lowland populations of Polygonum minus Huds. grown in different controlled environments. A thermal perturbation technique of two-dimensional correlation infrared spectroscopy (2D-IR) correlation spectra was applied to establish differences between the populations. The absorption peaks at 3,480 cm (hydroxyl group), 2,927 cm (methyl group), 1,623 cm (carbonyl group), and 1,068 cm (C-O group) were particularly powerful in separating the populations. These peaks, which indicate the presence of carbohydrate, terpenes, amide and flavonoids were more intense for the highland populations than lowland populations, and increased in environments with a higher temperature. Wavenumbers (1,634, 669 cm) and (1,634, 1,555 cm) in the 2D-IR correlation spectra provided fingerprint signals to differentiate plants grown at different temperatures. This study demonstrates that IR fingerprinting, which combines mid-IR spectra and 2D-IR correlation spectra, can directly discriminate different populations of P. minus and the effects of temperature. [ABSTRACT FROM AUTHOR]

Abstract: Posidonia oceanica meadows are sensitive to disturbance often associated with highly human-impacted coasts. A recent anthropogenic impact is due to hypersaline water produced by desalination plants of seawater that severely affects growth rate, induces necrotic lesions and enhances meadow mortality. To define the early effects directly correlated to salt regime variation on leaf tissue, we focused on aquaporins, water channel proteins of intracellular and plasma membranes. PIP aquaporins localization was carried out in leaf cross sections, using an antibody raised against the evolutionarily conserved N-terminal amino acid sequence of Arabidopsis thaliana PIP1;1 (which showed 84% of identity with P. oceanica PIP1;1 aquaporin), both in leaves kept in natural seawater and in leaves subjected to hypersaline treatment. In natural seawater conditions, the antibody was localized mainly in epidermis and weakly in vascular bundles and mesophyll tissues of leaves. A widespread increase of fluorescence was observed in leaves subjected to hypersaline regime. Hence, our results showed histological evidence of PIP1;1 peptide increase following salt stress. Our data also suggest that aquaporins are involved in osmotic balance maintenance in seagrasses. [Copyright &y& Elsevier]

Wilt disease of soybean caused by a very common soil-borne fungus, Fusarium oxysporum is one of the most destructive diseases of the crop. The aim of the present study was to characterize plant growth-promotion activities and induced resistance of a rhizobacterial strain for the soybean plant against F. oxysporum. Rhizobacterium strain SJ-5 exhibited plant growth-promotion characteristics and antagonistic activity against the test pathogen on dual plate assay. It was identified as a Carnobacterium sp. A 950 bp PCR product was amplified from Carnobacterium sp. strain SJ-5, using zwittermicin A self-resistance gene-specific primers ( zmaR). The strain produced indole 3-acetic acid (19 μg/ml) in the presence of salt stress and exhibited growth in Dworkin and Foster salt medium amended with 1-aminocyclopropane-1-carboxylate (ACC) through ACC deaminase activity (277 nmol/mg/h) as compared to the control. Strain seeds treated with the strain significantly enhanced the quorum of healthy plants after challenge inoculation at 14 days after seeding. An increase in the activity of stress enzymes after challenge inoculation with the test pathogen is reported. Treatment with the bacterium resulted in an increase in the chlorophyll content in the leaves in comparison with challenge-inoculated plants. [ABSTRACT FROM AUTHOR]

Antioxidant enzyme mechanisms are important for protecting crop productivity against stressful environmental conditions. Therefore, the current study was designed to evaluate lipid peroxidation (via malondialdehyde (MDA)) levels, superoxide dismutase (SOD) gene expression profiles, and SOD enzyme activities in tomato (Lycopersicum esculentum L.) plants subjected to different concentrations (100 and 150 mM) and time periods of NaCl and polyethylene glycol (PEG) stress (3 h, 6 h, 9 h, 12 h, and 48 h). Enhancement of lipid peroxidation in plants may be attributed to the increased accumulation of reactive oxygen species (ROS). Results indicated the antioxidant responses of tomato plants could be reflected as changes in gene transcripts and enzyme activities of SOD, but SOD gene expression patterns and changes in SOD enzyme activity revealed no positive correlation. As a result, stressful conditions led to stress in tomato plants (indicated by increased MDA levels) and triggered the expression levels of the SOD gene. The antioxidative response of tomato plants to PEG stress was found to be more vigorous than the response to NaCl stress. All these results pointed to the importance of SOD for stress defense in tomato. The overexpression and silencing of the SOD gene in tomato plants under NaCl and PEG stresses remain to be identified in further studies. [ABSTRACT FROM AUTHOR]

Salinity and Orobanche or Phelipanche spp. infection are important crop stress factors in agricultural areas. In this study, we investigated the effect of salt stress on Phelipanche ramosa seed germination and its attachment onto Arabidopsis thaliana roots. We also evaluated the effect of both stresses on the expression of genes regulated by abiotic and biotic stresses. According to our results, high concentration of NaCl delayed P. ramosa seed germination in the presence of a strigolactone analogue ( GR24). A similar pattern was observed in the presence of A. thaliana plants. Furthermore, we found that salt-treated A. thaliana seedlings were more sensitive to P. ramosa attachment compared with the untreated plants, indicating that there was a positive correlation between salt sensitivity and the ability of P. ramosa to infect A. thaliana plants. At the molecular level, a synergystic effect of both salt and P. ramosa stresses was observed on the cold-regulated ( COR) gene expression profile of treated A. thaliana seedlings. Our data clarify the interaction between parasitic plants and their hosts under abiotic stress conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Stress triggers production of ROS family-reactive molecules. [•] ROS function as a stress sensory hub and an initiator of stress responses. [•] ROS regulate production of a myriad of retrograde signaling molecules. [•] The blend of retrograde signals determines the nature of the adaptive responses. [Copyright &y& Elsevier]

Drought stress is a major limiting factor for crop production. Cuticular wax plays an important role in preventing water loss from drought stress. However, the genetic control of cuticular wax deposition under drought stress conditions has not been characterized. Here, we identified a rice gene Drought-Induced Wax Accumulation 1 (DWA1) encoding a very large protein (2,391 aa in length) containing multiple enzymatic structures, including an oxidoreductase-like domain; a prokaryotic nonribosomal peptide synthetase-like module, including an AMP-binding domain; and an allene oxide synthase-like domain. This previously unreported putative megaenzyme is conserved in vascular plants. A dwa1 KO mutant was highly sensitive to drought stress relative to the WT. DWA1 was preferentially expressed in vascular tissues and epidermal layers and strongly induced by drought stress. The dwa1 mutant was impaired in cuticular wax accumulation under drought stress, which significantly altered the cuticular wax composition of the plant, resulting in increased drought sensitivity. The mutant had reduced levels of very-long-chain fatty acids, and plants overexpressing DWA1 showed elevated levels of very-long-chain fatty acids relative to the WT. The expression of many wax-related genes was significantly suppressed in dwa1 under drought conditions. The AMP-binding domain exhibited in vitro enzymatic activity in activating long-chain fatty acids to form acyl-CoA. Our results suggest that DWA1 controls drought resistance by regulating drought-induced cuticular wax deposition in rice. This finding may have significant implications for improving the drought resistance of crop varieties. [ABSTRACT FROM AUTHOR]

In plants, stress signals propagate to trigger distant responses and thus stress acclimation in non‐exposed organs. We tested here the hypothesis that leaves submitted to photooxidative stress may influence the metabolism of nearby fruits and thus quality criteria. Leaves of orange trees (Citrus sinensis (L.) Osbeck cv. ‘Navelate’) were acclimated to shade for 1 week and then submitted to full (FL) and medium light (ML) conditions. As expected, photoinhibition was detected in leaves of both FL and ML treatments as revealed by stress indicators (Fv/Fm, Performance Index) for at least 99 h after treatments. In the fruits near the stressed leaves, we then determined the activities of enzymes related to oxidative stress, superoxide dismutase, catalase and the enzymes of the ascorbate (AA)/glutathione cycle, as well as the contents in sugars, organic acids and carotenoids. Ascorbate peroxidase and monodehydroascorbate reductase activities in the pulp of fruits were dramatically higher in both treatments when compared to the control. AA and total sugars were not affected by the photooxidative stress. However, the FL treatment resulted in a 16% increase in total organic acids, with succinic acid being the major contributor, a shift towards less glucose + fructose and more sucrose, and a 15% increase in total carotenoids, with cis‐violaxanthin being the major contributor. Our observations strongly suggest the existence of a signal generated in leaves in consequence of photooxidative stress, transmitted to nearby fruits. Exploiting such a signal by agronomic means promises exciting perspectives in managing quality criteria in fruits accumulating carotenoids. [ABSTRACT FROM AUTHOR]

This study was conducted to identify quantitative trait loci (QTLs) for drought tolerance in sorghum ( Sorghum bicolor (L.) Moench) by association mapping using a simple sequence repeat (SSR)-marker-based diversity research set. Genotypic data for 98 SSR marker loci on ten chromosomes were used for the association analysis. The experiment was conducted under control (well-watered) and drought stress conditions, and the phenotypic values of 23 morphological traits were recorded. Drought tolerance was assessed by using a leaf drying score as a parameter of the tolerance/susceptibility: scores were assigned on a scale from 1 (most tolerant) to 9 (most susceptible). Under the control conditions, 17 QTLs associated with 12 traits were identified on chromosomes 1, 2, 4, 8, 9, and 10, with −Log ( P) ranging from 2.5 to 7.6 and explaining 9.5-57.5 % of the total phenotypic variance for the traits. Under the drought stress conditions, nine QTLs associated with 8 traits were identified on chromosomes 1, 2, 3, and 10 that explained 9-61.2 % of the total phenotypic variance for the traits, with −Log ( P) ranging from 2.5 to 3.5. QTLs for some traits were detected only under the drought stress condition, suggesting that these traits are important in drought tolerance. These QTLs could be used to further dissect the genetic and physiological basis of drought tolerance in sorghum. [ABSTRACT FROM AUTHOR]

Abstract: The increasing rate of human-induced environmental changes on coastal marine ecosystems has created a demand for effective descriptors, in particular for those suitable for monitoring the status of seagrass meadows. Growing evidence has supported the useful application of biochemical and genetic descriptors such as secondary metabolite synthesis, photosynthetic activity and genetic diversity. In the present study, we have investigated the effectiveness of different descriptors (traditional, biochemical and genetic) in monitoring seagrass meadow conservation status. The Posidonia oceanica meadow of Monterosso al Mare (Ligurian sea, NW Mediterranean) was subjected to the measurement of bed density, leaf biometry, total phenols, soluble protein and photosynthetic pigment content as well as to RAPD marker analysis. This suite of descriptors provided evidence of their effectiveness and convenient application as markers of the conservation status of P. oceanica and/or other seagrasses. Biochemical/genetic descriptors and those obtained by traditional methods depicted a well conserved meadow with seasonal variability and, particularly in summer, indicated a healthier condition in a portion of the bed (station C), which was in agreement with the physical and sedimentological features of the station. Our results support the usefulness of introducing biochemical and genetic approaches to seagrass monitoring programs since they are effective indicators of plant physiological stress and environmental disturbance. [Copyright &y& Elsevier]