QTL hotspots in eggplant (Solanum melongena) detected with a high resolution map and CIM analysis

Fifty-eight F₂ individuals derived from an interspecific cross between cultivated eggplant, Solanum melongena, and its wild relative, S. linnaeanum, were phenotyped for 42 plant, leaf, flower, and fruit traits. Composite interval mapping analysis using genotypic data from 736 molecular markers revealed the positions of 71 statistically significant (P ≤ 0.05) quantitative trait loci (QTL) influencing 32 of the morphological traits. Although most QTL were location-specific, QTL governing three traits (leaf lobing, leaf prickles and prickle anthocyanin) were detected in both experimental locations. Analysis of three additional traits (stem prickles, fruit calyx prickles and fruit length) in both locations yielded QTL in similar but non-overlapping map positions. The majority (69 %) of the QTL corresponded closely with those detected in previous analyses of this data set. However the increased resolution of the linkage map combined with advances in QTL mapping permitted more precise localization, such that the average interval length of these QTL was reduced by 93 %. Thirty-one percent of the QTL were novel, suggesting that simple linear regression with a low density linkage map (the method used in previous studies of this population) missed a substantial portion of significant QTL. Hotspots of QTL affecting plant hairiness, prickliness, and pigmentation were identified on chromosomes 3, 6, and 10, respectively, and may reflect the pleiotropic activity of single structural or regulatory genes at these positions. Based on synteny between the eggplant, tomato, potato and pepper genomes, putative orthologs were identified for 35 % of the QTL suggesting strong conservation of gene function within the Solanaceae. These results should make it easier to target particular loci for map-based cloning and marker-assisted selection studies.     

Thiophanate-methyl sensitivity and fitness in Lasiodiplodia theobromae populations from papaya in Brazil

Stem-end rot, caused by Lasiodiplodia theobromae, is an important postharvest disease of papaya in Brazil. The use of fungicides is one of the main disease management measures. However, there are no data available on the sensitivity of L. theobromae to thiophanate methyl (methyl benzimidazole carbamate), the most common fungicide used in papaya orchards in northeastern Brazil. Thus, the effective concentration that results in 50 % of mycelial growth inhibition (EC₅₀) of 109 isolates, representing five populations of the pathogen was estimated in vitro. Seven components of fitness were measured for the 10 isolates with lower and high values of EC₅₀. Of the 109 isolates, 20.2 % were resistant to the fungicide with EC₅₀ values greater than 300 μg ml^?1, whereas the remaining 79.8 % were sensitive with an average EC₅₀ of 1.87 μg ml^?1. The EC₅₀ values for the resistant isolates were significantly (P?≤?0.05) higher than those for the sensitive isolates. When the fitness components were evaluated, only in relation to the spore production was significant difference among sensitive and resistant isolates, and resistant isolates showed sporulation capacity significantly lower than the S isolates, indicating a fitness cost.     

Physiological improvement in the copepod Eurytemora affinis through thermal and multi‐generational selection

As a major part of fish larval diet in nature, copepods constitute an appropriate live prey for aquaculture purposes. Considering the difficulty of mastering copepod mass production, studies on their growth performance at different environmental conditions are needed to improve their productivity. In this study a new selective approach based on temperature control is proposed to improve the physiological (body size, fecundity and lipid storage) performance of copepods. The estuarine copepod Eurytemora affinis known to have a high genetic variance in temperature tolerance was used as a biological model. First two different copepod lines were obtained after long‐term culture at constant cold (7°C) and warm (20°C) temperatures. Then both populations were transferred to a higher temperature of 24°C appropriate for aquaculture use and followed during five generations. During the first two generations (F1–F2) of a cold‐acclimated population, female body size and fecundity decreased significantly whereas the survival rate remained high. The high lipid content of this population was used by females to compensate the heat shock of more than 10°C. However, the survival rate decreased dramatically in F3 but allowed the selection of robust individuals which progressively improved their fitness during the following generations. So, compared to the warm acclimated population, the cold acclimated one showed larger body size, higher fecundity and better lipid storage. After only five generations at 24°C the cold‐acclimated population showed a significant genetic gain in prosome length compared to the warm acclimated one.     

The impact of reed management on wildlife: A meta-analytical review of European studies

We reviewed European studies on the effect of reed management (harvesting, burning, mowing and grazing) on reedbed wildlife, and in addition, on the performance of re-growing reed (Phragmites australis). Our database consisted of 21 studies conducted on 10 plant species, 17 taxonomic groups of invertebrates and 11 bird species, and published between 1982 and 2006.We found that reed management modifies the structure of re-growing reed stands: reed stems were shorter and denser in managed sites than in unmanaged sites. However, harvesting does not have an impact on aboveground biomass. Plant species richness increased by 90% in managed stands in fresh water marshes, but not in saline water marshes.Overall, reed management had a significant negative impact on invertebrate community, but the duration of management was an important factor determining the magnitude of the effect. Short-term management (1-2 years) had no effect on invertebrates, whereas management for longer period significantly reduced invertebrate abundance. Reed harvesting and burning reduced abundance of passerine birds by about 60%. This was probably associated with food limitation as the numbers of butterflies, beetles and some spiders were reduced. Therefore, the optimal reed management regime to preserve number of birds and invertebrates in reedbeds could be a rotation of short-term management (1-2 years). However, the optimal interval between management applications should be established in future studies.     

Development and evaluation of a standard area diagram set for the severity of phomopsis leaf blight on eggplant

A standard area diagram set (SADs) with eight severity values ranging from 0.5 to 32% was evaluated as a tool to improve the accuracy of the estimates of Phomopsis leaf blight severity on eggplant by ten inexperienced raters. A first assessment in a 50-leaf dataset of digital images was performed unaided (UN, no SAD). Two further aided (A) assessments, conducted two (A1) and four weeks after the first (A2) unaided one were performed. The precision of the estimates, as indicated by the Pearson’s correlation coefficient (r), improved significantly when using the aid (A1: r = 0.96 and A2: r = 0.96) compared to unaided (UN: r = 0.79). However, the generalized bias (C _b) was not significantly affected because the unaided estimates were already quite accurate (C _b = 0.93). The overall concordance (ρ _c) was significantly improved due to the large gains in precision when using the SADs. The raters’ estimates were more uniform (ρ _c > 0.9) when using the aid, with progressive gains in the reliability of the estimates among them, indicated by the concordance correlation coefficient statistics. The SADs proposed in this study will be useful in severity estimation during field work involving multiple raters, especially as use of the SADs results in less variable estimates, improving accuracy and reliability among raters.     

Characterization of <Emphasis Type="Italic">Phaeoacremonium</Emphasis> isolates associated with Petri disease of table grape in Northeastern Brazil,with description of <Emphasis Type="Italic">Phaeoacremonium nordesticola</Emphasis> sp. nov.

Severe outbreaks of Alternaria leaf blotch and fruit spot were recently observed in cv. Pink Lady apples in northern Israel, especially on fruit. Such severe outbreaks have not been reported from other countries. Symptoms involved cracks and rot around the calyx and external rot of the fruit body. Up to 80 % of the fruit in some orchards were affected by the disease. Microscopic examinations, fulfillment of Koch’s postulates and molecular (genetic) analyses confirmed the causal agent as Alternaria alternata f. sp. mali. The incidence of Alternaria increased as the degree of calyx cracking increased, or if fruit were both cracked and rotted. Injecting spore suspensions into the fruit produced typical rot symptoms. Injection assays of detached fruit of eight apple cultivars showed that cvs. Pink Lady and Golden Delicious were susceptible whereas cv. Jonathan was resistant. Pink Lady and Golden Delicious produced more fruit rot as the inoculum concentration increased. Rot in all three cultivars was moderate close to the skin but more severe close to the seed locule. Aqueous extracts taken from Jonathan fruit peel inhibited germ tube elongation of A. alternata f. sp. mali in vitro. This is the first report on heavy infection of Pink Lady fruit in Israel caused by A. alternata f. sp. mali.     

Improving the performance of bread wheat genotypes by managing irrigation and nitrogen under semi-arid conditions

Wheat (Triticum aestivum L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors i) irrigation in main plots, ii) nitrogen in sub-plots, and iii) twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.     

Water stress effects on biochemical traits and antioxidant activities of wheat (Triticum aestivum L.) under In vitro conditions

Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of ?8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes.     

水资源不均等分配及其影响分析以簸箕李灌区为例

以簸箕李灌区为例,分析了该灌区水资源不均等分配及其所带来的对水资源利用方式和效率的影响。结果表明,在灌区内部从上游到下游,水资源可利用量很不均等,上游享用更多的水资源,地下水起到了调节水资源可用量年内波动的作用。上游地区地下水调节了春季水资源可用量的变异性,下游汛期储存的地下水在来年春季被重新利用,年平均利用量达到降雨灌溉总量的40.7%。下游农民应对水资源短缺的另2种途径是进行排水管理和减少种植面积,平均排水再利用量达到40 mm,因此下游地区具有更高的水资源利用效率。在水资源配置中应注意配置方案对水资源利用方式和效率的影响,同时要兼顾效率和公平。