‘砀山酥梨’及其褐皮芽变果皮中多胺类物质含量和相关基因表达分析

为研究多胺类物质在‘砀山酥梨’芽变品系‘锈酥’果皮褐色形成中的作用,以‘砀山酥梨’和‘锈酥’花后不同时期果皮为试材,采用HPLC方法测定果皮中多胺类物质的含量,利用RACE技术克隆多胺合成过程中的关键基因,通过Protparam网站与MEGA5.0软件分析相关基因蛋白的理化性质及其系统进化,用荧光定量qRT-PCR方法分析不同时期果皮中相关基因的相对表达量。结果表明:(1)除花后50和150d外,其它时期‘砀山酥梨’果皮中腐胺含量均显著高于‘锈酥’,花后50d、75d、150d时,‘锈酥’果皮中的亚精胺、精胺含量显著高于‘砀山酥梨’果皮。(2)克隆出多胺合成的基因ADC、SPDS和SPMS(GenBank登录号分别为KM923903、KM923905和KM923906),预测ADC和SPMS均为水溶性蛋白、SPDS为疏水性蛋白,它们与苹果的亲缘关系最近。(3)荧光定量PCR结果显示,花后50d,多胺合成中ADC、SPDS和SPMS在‘锈酥’果皮中表达量均显著高于‘砀山酥梨’。研究推测,‘锈酥’果皮中多胺代谢及相关基因的上调表达可能与‘锈酥’的果皮褐色形成有关。     

Gas chromatography column as an ambient‐temperature volatile trap

Open‐tube volatile traps have largely been shunned in favor of solid adsorbent containing traps for the collection of volatile pheromones and attractants. Solid adsorbents require large solvent rinses and glass capillaries can be difficult to maneuver for the collection of volatiles from small or hard‐to‐reach odor sources. A gas chromatograph (GC) column (DB‐1), an open‐tube glass capillary, and a SuperQ^®‐containing capillary were compared for their collection efficiencies from rubber septa and live calling insects. All three traps captured similar ratios of test compounds from septa at airflows >10 ml per min. Eluting analytes from a packed adsorbent, SuperQ, required at least 30× more solvent than was required to collect all the pheromone from the open‐tube glass capillaries, and the GC column enjoyed an additional three‐fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted from the GC‐column trap and directly analyzed on GC without solvent evaporation. We placed glass wool ‘plugs’ in both GC columns and glass capillaries and found no volatiles in these plugs, indicating that breakthrough did not occur during 1‐h collections at 25 ml per min. We demonstrate here that at ambient laboratory temperatures, a DB‐1 GC column effectively collects Oriental fruit moth sex pheromone volatiles from a rubber septum and live pheromone‐releasing moths. Release ratios of pheromone from rubber septa are consistent with earlier reports from static air systems, whereas the release ratio of the (Z)‐8‐dodecenyl alcohol (Z8‐12:OH) from female Grapholita molesta Busck (Lepidoptera: Tortricidae) differed from published results and is likely due to different collection methods or moth‐strain origin.     

Oviposition behaviour and larval development of Anastrepha fraterculus from Argentina in citrus

Citrus peel physicochemical attributes are considered the main components conferring partial or even total resistance to fruit fly (Diptera: Tephritidae) infestation. Fruit fly females adapt their ovipositional strategies to overcome such resistance. Here, we explored the effects of citrus species (Rutaceae) on the ovipositional behaviour of the South American fruit fly, Anastrepha fraterculus (Wiedemann), and on its immature development. Particularly, we investigated the effects of (1) citrus species on oviposition behaviour and immature development, (2) citrus species on oviposition preference and on the location of the eggs at different depth in the citrus peel, and (3) harvest season and post‐harvest storage time on oviposition behaviour and immature development in lemon. Citrus species influenced ovipositional behaviour and affected survival of immature stages. Females laid eggs in lemon [Citrus limon (L.) Burm.], orange [Citrus sinensis (L.) Osbeck], and grapefruit (Citrus paradisi Macfadyen). In orange and lemon, larvae were found dead close to the oviposition areas, suggesting chemically mediated resistance mechanisms. Under choice conditions, females preferred grapefruit over lemon and bigger clutches were found in the layers where embryonic development is favoured. Unsuitability of lemon as a medium to complete development was neither affected by harvest season nor by storage time of the fruit after harvest. The physical and chemical characteristics of the peel were distinctive to each citrus species and may have affected the specific levels of resistance of these citrus species to infestation by A. fraterculus.     

Molecular genetic diversity and differentiation of populations of ‘somnus’ passion fruit trees (Passiflora setacea DC): Implications for conservation and pre-breeding

The ‘somnus’ passion fruit tree (Passiflora setacea) is native to the ‘Cerrado’ and ‘Caatinga’ biomes in Brazil and possesses agrobiological and commercial traits of interest. Studies examining the nature of genetic variability in natural populations are important for the utilization of these traits in conservation and breeding programs. In this study, we analyzed 12 populations of P. setacea from different locations distributed in three agro-ecological zones within the Bahia state of Brazil. Eleven ISSR primers and four pairs of RGA primers were used to assay 109 and 49 unique and reproducible loci, of which 108 (99%) and 49 (100%) were polymorphic. Although the level of genetic diversity in ‘somnus’ passion fruit trees was greater than that observed for other species of the same genus, preferential collection of certain populations, such as those located in the cities of Vitória da Conquista and Licinio de Almeida, is important when considering the fact that ‘somnus’ passion fruit trees occur in areas that are highly disturbed. This disturbance is primarily due to the deployment of pasture, predatory extraction and accelerated urban expansion. An analysis of molecular variance revealed a balance between the estimated genetic variation within and among populations. These data may be useful for developing strategies for preservation of this species in the Cerrado.     

Physiology of pepper fruit and the metabolism of antioxidants: chloroplasts,mitochondria and peroxisomes

Background and Aims Pepper (Capsicum annuum) contains high levels of antioxidants, such as vitamins A and C and flavonoids. However, information on the role of these beneficial compounds in the physiology of pepper fruit remains scarce. Recent studies have shown that antioxidants in ripe pepper fruit play a key role in responses to temperature changes, and the redox state at the time of harvest affects the nutritional value for human consumption. In this paper, the role of antioxidant metabolism of pepper fruit during ripening and in the response to low temperature is addressed, paying particular attention to ascorbate, NADPH and the superoxide dismutase enzymatic system. The participation of chloroplasts, mitochondria and peroxisomes in the ripening process is also investigated.Scope and Results Important changes occur at a subcellular level during ripening of pepper fruit. Chloroplasts turn into chromoplasts, with drastic conversion of their metabolism, and the role of the ascorbate–glutathione cycle is essential. In mitochondria from red fruits, higher ascorbate peroxidase (APX) and Mn-SOD activities are involved in avoiding the accumulation of reactive oxygen species in these organelles during ripening. Peroxisomes, whose antioxidant capacity at fruit ripening is substantially affected, display an atypical metabolic pattern during this physiological stage. In spite of these differences observed in the antioxidative metabolism of mitochondria and peroxisomes, proteomic analysis of these organelles, carried out by 2-D electrophoresis and MALDI-TOF/TOF and provided here for the first time, reveals no changes between the antioxidant metabolism from immature (green) and ripe (red) fruits.Conclusions Taken together, the results show that investigation of molecular and enzymatic antioxidants from cell compartments, especially chloroplasts, mitochondria and peroxisomes, is a useful tool to study the physiology of pepper fruit, particularly in the context of expanding their shelf-life after harvest and in maintaining their nutritional value.     

Variation in pollen limitation and floral parasitism across a mating system transition in a Pacific coastal dune plant: evolutionary causes or ecological consequences?

Background and Aims Evolutionary transitions from outcrossing to self-fertilization are thought to occur because selfing provides reproductive assurance when pollinators or mates are scarce, but they could also occur via selection to reduce floral vulnerability to herbivores. This study investigated geographic covariation between floral morphology, fruit set, pollen limitation and florivory across the geographic range of Camissoniopsis cheiranthifolia, a Pacific coastal dune endemic that varies strikingly in flower size and mating system.Methods Fruit set was quantified in 75 populations, and in 41 of these floral herbivory by larvae of a specialized moth (Mompha sp.) that consumes anthers in developing buds was also quantified. Experimental pollen supplementation was performed to quantify pollen limitation in three large-flowered, outcrossing and two small-flowered, selfing populations. These parameters were also compared between large- and small-flowered phenotypes within three mixed populations.Key Results Fruit set was much lower in large-flowered populations, and also much lower among large- than small-flowered plants within populations. Pollen supplementation increased per flower seed production in large-flowered but not small-flowered populations, but fruit set was not pollen limited. Hence inadequate pollination cannot account for the low fruit set of large-flowered plants. Floral herbivory was much more frequent in large-flowered populations and correlated negatively with fruit set. However, florivores did not preferentially attack large-flowered plants in three large-flowered populations or in two of three mixed populations.Conclusions Selfing alleviated pollen limitation of seeds per fruit, but florivory better explains the marked variation in fruit set. Although florivory was more frequent in large-flowered populations, large-flowered individuals were not generally more vulnerable within populations. Rather than a causative selective factor, reduced florivory in small-flowered, selfing populations is probably an ecological consequence of mating system differentiation, with potentially significant effects on population demography and biotic interactions.     

Dyeing Insects for Behavioral Assays: the Mating Behavior of Anesthetized Drosophila

Mating experiments using Drosophila have contributed greatly to the understanding of sexual selection and behavior. Experiments often require simple, easy and cheap methods to distinguish between individuals in a trial. A standard technique for this is CO₂ anaesthesia and then labelling or wing clipping each fly. However, this is invasive and has been shown to affect behavior. Other techniques have used coloration to identify flies. This article presents a simple and non-invasive method for labelling Drosophila that allows them to be individually identified within experiments, using food coloring. This method is used in trials where two males compete to mate with a female. Dyeing allowed quick and easy identification. There was, however, some difference in the strength of the coloration across the three species tested. Data is presented showing the dye has a lower impact on mating behavior than CO₂ in Drosophila melanogaster. The impact of CO₂ anaesthesia is shown to depend on the species of Drosophila, with D. pseudoobscura and D. subobscura showing no impact, whereas D. melanogaster males had reduced mating success. The dye method presented is applicable to a wide range of experimental designs.     

Role of foliar hemibiotrophic and fruit resistance in anthracnose‐resistant strawberry genotypes for annual hill plasticulture systems

Anthracnose fruit rot (AFR) caused by Colletotrichum acutatum is one of the most devastating diseases of strawberry (Fragaria × ananassa) in plasticulture systems in the Southeast US. Host resistance offers the best option to limit crop losses in both nursery and fruiting fields. To evaluate levels of anthracnose resistance and elucidate the role of foliar and fruit resistance in overall field AFR resistance, we tested 14 strawberry genotypes including numerous selections from the North Carolina State University strawberry breeding programme. Inoculations of plug plants with three representative C. acutatum isolates prior to field‐set indicated that the commercially standard cultivar Chandler was highly susceptible, with an average fruit rot incidence of over 72% the following spring. In contrast, breeding lines such as NC C99‐13 and NC C02‐63 showed superior resistance with AFR incidence values of 23.6% and 11.1%, respectively, and showed superior marketable yields. An average hemibiotrophic infection (HI) severity on foliage (percent leaf area covered with acervular growth after paraquat treatment and incubation) did not correlate (r = 0.57) well with in vitro AFR severity on detached fruit, indicating different mechanisms may be operative for resistance to foliar HI and fruit rot resistance. Multiple regression analysis indicated that in vitro fruit rot resistance expressed by lesion diameter and severity of foliar hemibiotrophic infections may be utilized to predict field AFR incidence. Strawberry genotypes bred for resistance against both fruit rot and foliar HI could be effectively selected by using rank‐sum classification methods and this process offers an effective strategy to advance selections for superior AFR field resistance.