Induced synthesis of caffeoylserotonin in pepper fruits upon infection by the anthracnose fungus, Colletotrichum gloeosporioides

Caffeoylserotonin (CaS) is a serotonin derivative that belongs to the family of phenylpropanoid amides, but has not previously been identified in plants. In this study, pepper fruits challenged with the anthracnose fungus, Colletotrichum gloeosporioides, were found to synthesize CaS, which accumulated at concentrations of up to 2.3 μg/g fresh weight. The induction of CaS was accompanied by the upregulation of both 4-coumarate-CoA ligase (4CL) and serotonin N-hydroxycinnamoyl transferase (SHT) in unripe pepper fruits. However, no induction of SHT and 4CL was observed in ripe pepper fruits consistent with the lower level of CaS production.     

In vitro induction of the amphiploid in interspecific hybrid of blueberry (Vaccinium corymbosum × Vaccinium ashei) with colchicine treatment

Amphiploids were produced from pentaploid hybrids between Vaccinium corymbosum (4x) and Vaccinium ashei (6x) by colchicine treatment. Seeds of each parental species and those obtained by the interspecific crossing were treated with colchicine at 0, 500, 1000 and 2000 mg/l for 7 days, and the ploidy level of the seedlings was determined with flow cytometry. Either amphiploid (10x) or ploidy chimera (5x + 10x) was obtained from interspecific hybrid seeds treated with all colchicine concentrations, while no chromosome-doubled plants were obtained from both parents. Cross direction in interspecific hybridization affected the results of colchicine treatment and amphiploids were obtained only when V. corymbosum was used as the seed parent. In this cross, 17–25% of the seedlings turned to be amphidiploids or ploidy chimeras by treating with 500 mg/l colchicines for 7 days. These results indicate that susceptibility to colchicine may increase in the interspecific hybrid compared with the parental species but only when V. corymbosum was used as female parent.     

Relationship of leaf necrosis and defoliation to phosphorus and potassium concentrations in selected tissue and to certain fruit quality parameters of pecan

Pecan [Carya illinoinensis (Wangenh.) K. Koch] trees developed necrotic areas in the leaves late in the growing season. July samples indicated that leaf P (0.114% DW) and K (0.62% DW) were low, but other elements were within accepted sufficiency ranges. Relationships between leaf P and K concentrations with nut quality and return bloom were determined. Trees were rated for leaf necrosis 1 October using a 1 (none)–5 (severe) scale. Fruit were harvested and analyzed for weight/nut, kernel weight, and kernel grade. Leaflet pairs collected 1 October from fruit bearing shoots were analyzed for N, P and K. Return bloom was determined on branches that bore fruit the previous year. Necrosis ratings were positively related to leaf N and negatively correlated with weight/nut; kernel, shuck and leaf P concentrations; and kernel and leaf K concentrations. Leaf, kernel and shuck P concentrations were positively correlated with weight/nut and percentage number 1 kernels. Leaf K was positively correlated with return bloom and weakly negatively correlated to weight/nut. Phosphorus was the primary element limiting fruit development and K shortage substantially reduced return bloom. Data support minimum pecan leaf standards in July for fertility recommendations of 1.0% K and 0.14% P.     

Genetic characterization of different demes in Prunus persica revealed by RAPD markers

DNAs of 180 accessions in 10 demes in Prunus persica were amplified with twenty-two, 10-base primers selected from 200 arbitrary primers using Randomly Amplified Polymorphic DNA (RAPD) technology. One hundred and eighty loci were observed and recorded. With statistical analyses of the data from the study, genetic diversity of the demes was expressed as follow: yellow peach group > honey peach group > flat peach group > red leaf peach group > crisp peach group > bitao group and juicy peach group > nectarine group > shouxingtao group > weeping peach group. Genetic variations among and within groups by AMOVA analyses were 11.9, 88.1%, respectively. Demes clustered by UPGMA modified from NEIGHBOR procedure of PHYLIP Version 3.5, the edible peaches of which were combined as a section, while the ornamental species were classified into separate sections. Through analyses of genetic diversity and genetic structure, the results could provide molecular biological evidence for conservation and utilization of P. persica germplasm.     

Seasonal variations in nutritional components of green asparagus using the mother fern cultivation

Harvesting season for green asparagus can be extended by the use of the mother fern method and greenhouse cultivation. To evaluate seasonal variations in nutritional quality of green asparagus, the compositional profiles of fresh spears (Asparagus officialis L. cv. UC157 F1) harvested each month from March to October were compared in two locations of China using mother fern method. During the harvest season, dry matter content, soluble sugar, crude fiber, rutin and total soluble phenol in spears exhibited marked variation. Although there was no significant difference in total amino acid contents among most of months throughout the season, but quantitative changes in some specific amino acids occurred. Fresh spears harvested in warm season (from June to July) contained lower level of soluble sugars, dry matter, ascorbic acid and higher nitrate, crude fiber, total phenolics and rutin contents compared with those in cooler months. Asparagus harvested in spring accumulated relatively higher level of soluble sugar, carotenoid and chlorophyll contents than those in autumn, but total phenol and rutin contents were higher in autumn than in spring. The relationships between weather data and nutritional quality parameters of asparagus spear during harvest season were also discussed.     

Development of a simple thermal time method for describing the onset of morpho-anatomical features related to sweetpotato storage root formation

A thermal time-based approach using growing degree days was used to describe the onset of morpho-anatomical features associated with storage root developmental stages in the sweetpotato cultivar ‘Beauregard.’ Initially, we calculated accumulated growing degree days corresponding to adventitious root initiation, the onset of storage root formation (appearance of anomalous cambium), and appearance of visible storage roots with localized thickening and pigmentation in sweetpotatoes grown under greenhouse conditions. Subsequently, we performed field calibration of this approach to verify the timing of these storage root developmental stages under natural growing conditions. Under field conditions, transplants required relatively fewer calendar days to achieve the thermal time corresponding to each developmental stage in comparison to greenhouse-grown plants. Further calibration of this approach for ‘Beauregard’ and other sweetpotato varieties grown in diverse environments will help enhance our understanding of the effects of management and agroclimatic variables on sweetpotato yield determination. This study demonstrates the advantage of using thermal time vs. calendar days in estimating storage root development in sweetpotatoes.     

Comparison of SSR polymorphisms using automated capillary sequencers,and polyacrylamide and agarose gel electrophoresis: Implications for the assessment of genetic diversity and relatedness in almond

In this work we have performed a comparative study of the utilization of three electrophoresis separation methods for the analysis of peach SSR polymorphism in almond and its implications in the assessment of genetic diversity and relatedness. Automated SSR detection and polyacrylamide gel electrophoresis were the most efficient methods and would be able to resolve allelic variation at a finer scale than the electrophoresis in MetaPhor^® agarose. Moreover, automated electrophoresis detection is much more expensive in terms of cost of equipment and cost of the analysis. In addition, SSR detection using polyacrylamide gel electrophoresis showed similar results than automated sequencing, although it is more time-consuming and toxic than electrophoresis in agarose gels. Discrepancies among polyacrylamide and automated capillary, and MetaPhor^® were observed when differences in SSR polymorphisms were between 1 and 5 bp. While the use of MetaPhor^® agarose appears less indicated for genotype characterization, this technique may be the most convenient in other applications, i.e. mapping of population, due to its lower cost and easier routine application. The utilization MetaPhor^® agarose produced a slightly different clustering of genotypes in spite of the big differences observed in the DNA fingerprinting. However, bootstrap values using MetaPhor^® agarose were lower indicating a lower accuracy of this SSR polymorphism analysis method.     

Genotypic variation in the response of pepper to salinity

Using 102 pepper (Capsicum annuum) genotypes, a greenhouse experiment has been conducted to study genotypic variation in tolerance to 100 mM sodium chloride (NaCl) in nutrient solution. Based on the severity of leaf symptoms caused by the NaCl treatment there was a substantial genotypic variation in salt tolerance. From this screening experiment, six sensitive and six tolerant genotypes were chosen to study dry matter production and root and shoot concentrations of sodium (Na), potassium (K) and calcium (Ca) in a growth chamber experiment in a nutrient solution with and without 150 mM NaCl. The genotypes selected as sensitive were highly damaged and developed severe chlorosis and necrosis under NaCl treatment, while the genotypes selected as tolerant were slightly affected. On average, decreases in shoot dry matter production caused by NaCl were greater in the sensitive than the tolerant genotypes. Application of salt increased shoot Na concentration at greater amount in the sensitive than the tolerant genotypes. Of the tolerant genotypes, the genotype Cac (Capsicum annuum var. cerasiforme) and 1245 F1 had around 2.45% Na in shoot while the sensitive genotypes Kandil and Pazarcik contained, on average, 5.4% Na. All sensitive and tolerant genotypes exhibited more or less similar shoot concentrations of K and Ca. There was very significant and positive correlation between severity of leaf symptoms and shoot Na concentration, but no correlation could be found in the case of K or Ca concentrations with the severity of leaf symptoms. The results indicate existence of substantial genotypic variation in tolerance to NaCl stress in pepper. It seems very likely that exclusion of Na from roots into growth medium plays a critical role in expression of high Na tolerance in pepper.     

Using a gestalt to measure the quality of in vitro responses

Overall “quality” of in vitro responses can sometimes be difficult to assess using measured response variables (e.g., shoot number and height, and callus fresh weight). Gestalt Theory is the idea that the whole is perceived to be greater than the sum of the individual parts. To determine if a gestalt assessment could be used to assess quality of in vitro responses two plant tissue culture systems were examined—Brugmansia x candida shoot multiplication and sweet orange nonembryogenic callus growth. The gestalt assessment of each system was compared to measured responses—shoot number, leaf length and width for Brugmansia x candida, and fresh weight accumulation for citrus. The gestalt analysis modeled as precisely as the measured response variables for both in vitro systems while satisfying the statistical assumptions necessary for a valid analysis. We concluded that the gestalt response is a valid response as it was indistinguishable, in terms of statistical quality, from the measured responses.     

Photosynthesis of field-grown Arracacha (Arracacia xanthorriza Bancroft) cultivars in relation to root-yield

There has been limited research on measuring potential differences in leaf gas exchange of Arracacha (Peruvian parsnip, Arracacia xanthorriza Bancroft) cultivars, as affected by different environments, as well as its relation to storage root-yield. The present paper reports field measurements of leaf CO₂ assimilation rates (A) for five contrasting cultivars grown at two different high-altitude locations. Using a design of plots chosen at random with three repetitions, commercial root production was determined in the two locations at different altitude (1580 and 1930 m). Daily leaf gas exchange was repeatedly monitored with a portable open-mode infrared gas analyzer at different times in both locations during the growth cycle. Root-yield, leaf area and dry weight were measured. Significant differences in leaf photosynthetic rate and in specific leaf area (SLA) were observed among cultivars. Cultivars with high SLA, had high CO₂ assimilation. Mean (A_n) and total (A_tot) of CO₂ assimilation and SLA were significantly correlated with storage root-yield across cultivars and locations. The three cultivars with the greatest commercial root production also had the highest maximum values for A and the highest specific leaf area, indicating that these two parameters can be used to select for highly productive cultivars of A. xanthorriza.     

Chitinase and β-1,3-glucanase enzymatic activities in response to infection by Alternaria alternata evaluated in two stages of development in different tomato fruit varieties

Chitinase (ChA) and β-1,3-glucanase (GA) activity had been related with plant defense mechanism against pathogen attack in vegetative tissues. Scarce information is available about the behavior of these enzymes in response to different stages of development and fungi infection in fruits. The changes in ChA and GA activities in response to Alternaria alternata infection were evaluated in mature green (MG) and red ripe (RR) developmental stages of Sunpride, Geronimo and Charleston varieties of tomato fruit. Tomato fruits were inoculated with a conidial suspension of A. alternata and stored for 10 days at 25 °C and 90–92 H.R.%. The degree of fruit infection was measured by a hedonic scale every 2 days. ChA activity was determined fluorometrically by quantifying the release of 4-methylumbelliferyll (4-MU) from 4-methylumbelliferyll β-d-N,N′N″-triacetylchitotrioside, and GA activity was measured quantifying the release of glucose from β-1,3-glucan (laminarin) by HPLC. Tomato fruit in RR stage was more susceptible to fungi infection than MG stages. Geronimo was the most resistant variety, whereas Sunpride was the most susceptible for both stages of development (MG and RR). Higher levels of ChA and GA activities were observed for mature green stage in Charleston variety at the end of the storage period. An induction in ChA and GA in response to infection by A. alternata was observed in all varieties. Particularly high levels of ChA were found for inoculated Geronimo in RR stage and inoculated Charleston in MG stage which correlated with low levels of fungi infection. Higher levels of GA induction in response to fungi infection were recorded for Sunpride variety in RR stage, whereas no substantial induction was observed for Geronimo and Charleston varieties at the same stage of development. This GA induction correlated negatively with the resistance showed by the different varieties to fungi infection. We concluded that chitinase and β-1,3-glucanase induction are part of the tomato fruit defense mechanism against A. alternata infection with a different behavior depending upon stage of development and variety.     

Feathering of ‘Doyenné du Comice’ pear in the nursery using repeat sprays of benzyladenine and gibberellins

This work sets out to examine the effectiveness of a number of cytokinins or products with cytokinin-like activity, with and without additional sprays of gibberellins or leaf plucking, on the production of feathers (sylleptic shoots) on trees of the European pear cultivar ‘Comice’ in a fruit tree nursery. It covers the results from three successive years experimentation.     

Content levels of various fruit metabolites in the ‘Conference’ pear response to branch bending

The response of ‘Conference’ pear subjected to branch bending in the content levels of various metabolites in its fruit was investigated. The fruits in commercial maturity were sampled in 2004 and 2005 from branches bent in the late summer of 2003 (the summer treatment), from branches bent in the late spring of 2004 (the spring treatment) and from control branches. The content levels of carbohydrates, organic acids and phenolic compounds were compared among treatments in two successive years. The fruit revealed various responses in content levels of metabolites. In the first year after bending, no significant differences were found in the content of each carbohydrate, but in 2005 by far the highest content level of glucose and fructose and the lowest content level of sucrose were found in fruits from the control. The control fruit showed significantly higher content levels of malic acid and lower content levels of some phenolics (chlorogenic and vanillic acid) in the first year after bending, but in the next year the opposite reaction occurred—the control fruit had the lowest content level of malic acid and the highest content level of epicatechin, quercetin-3-d-galactoside and quercetin-3-β-d-glucoside. The comparison of the two bending treatments alone in 2004 showed that the summer treatment often produced a slightly higher value of each phenolic in comparison to the spring treatment. However, in 2005 the significantly highest content of chlorogenic acid was in fruit from the spring treatment. Sorbitol, as well as citric acid, catechin and sinapic acid showed no clear tendency among treatments, neither in 2004 nor in 2005. It is suggested that these variations of ‘Conference’ fruit subjected to different bending treatments could not be the result of bending alone, but that they could be indirectly affected by other physiological responses of the fruit tree. However, it seemed that variations are affected by the time of bending and by the year-to-year, and such responses can be attributed to the ‘Conference’ genotype only.     

Dry weight and carbohydrate distribution in different tree parts as affected by various fruit-loads of young persimmon and their effect on new growth in the next season

This study was conducted to determine the changes in the accumulation of dry weight (DW) and the distribution of carbohydrates in different parts of young persimmon (Diospyros kaki) as affected by various fruit-loads. The effects of such changes were monitored with regard to the abundance of new growth in the following year. On June 15, the fruit-load was adjusted to a leaf–fruit (L/F) ratio of 10, 20, and 30, and some trees were completely defruited. Between June 15 and November 11, the increase in DW was less in the defruited and more in the higher L/F-ratio trees. Among the various tree parts, the DW increased the most in the fruits during the same period. It was observed that the lower the L/F ratio, the more the DW in the fruits: the fruits accounted for 78.7% of the total DW in the 10-L/F, 57.6% in the 20-L/F, and 49.7% in the 30-L/F ratio trees. In contrast, as the L/F ratio increased, the DW distribution to the roots increased to 3% in the 10-L/F, 13% in the 20-L/F, and 26% in the 30-L/F ratio trees and 61% in the defruited trees. During this period, carbohydrates were distributed mostly to the fruits, but as the L/F ratio decreased, their distribution to permanent tree parts decreased. The distribution of soluble sugars and starch to the permanent parts was 1% and 14% in the 10-L/F, 3% and 48% in the 20-L/F, 9% and 57% in the 30-L/F ratio trees, and 71% and 93% in the defruited trees, respectively. Maintaining a lower L/F ratio resulted in a decrease in the shoot and fruit numbers in the following year: there were zero and four fruits in those trees with an L/F ratio of 10 and 20, respectively. The carbohydrates decreased in the roots of both the 30-L/F ratio trees and the defruited trees, whereas the defruited trees showed more new shoot growth in the following year. In the roots of the trees with the L/F ratio of 30, soluble sugars and starch decreased by 7.6 g and 1.8 g, respectively, during the spring growth, whereas, in the roots of the defruited trees soluble sugars and starch decreased by 33.3 g and 94.6 g, respectively.     

Canopy profiles of starch and leaf mass per area in greenhouse tomato and the relationship with leaf area and fruit growth

Better knowledge of patterns of carbon allocation in plants growing in CO₂-supplemented atmospheres may help to guide more efficient management of CO₂ applications in tomato greenhouses. Leaf starch and LMA (leaf mass per unit area) were investigated in commercially grown greenhouse tomato plants to determine the distribution and influence of leaf area and fruit load on these measures.     

Fruit nutrient content and lipoxygenase activity in relation to the production of malformed and button berries in strawberry (Fragaria × ananassa Duch.)

Fruit nutrient content and lipoxygenase (LOX) activity were determined in strawberry fruit to establish a relationship, if it exists, between nutrients, and LOX activity with the fruit malformation and nubbins or button berry disorders. Nearly 17% fruit were affected by malformation and 10% by nubbins in open-field-grown strawberries. ‘Etna’ produced higher proportion of malformed (22.7%) as well as button berries (16.9%) and ‘Sweet Charlie’ the lowest (8.9% and 3.3%, respectively). Dry matter content (%) was lower in malformed (5.2%) and button berries (3.23%) than normal berries (7.41%). The concentration of P and Mg did not differ significantly, but that of N and K was notably higher and of Ca and B was lower in malformed and button berries than normal berries. Consequently, the N/Ca and K/Ca ratios were higher in malformed and button berries. LOX activity was significantly higher in malformed as well as button berries than normal berries, with significant differences among cultivars. The correlations between N, K and malformed and button berries were positive and between Ca and B, and malformed and button berries were negative. Similarly, the correlation between LOX activity and malformed, and button berries were also positive, indicating that excess of N and K, and deficiency of Ca and B are related to the production of malformed and buttons or nubbins in strawberry.     

Dissemination of Phytophthora cactorum, cause of crown rot in strawberry,in open and closed soilless growing systems and the potential for control using slow sand filtration

Closed (recirculating) growing systems provide a greater potential for the dispersal of water-borne plant pathogens and disease expression compared to open (run-to-waste) systems. Here we studied the effects of three soilless growing systems (open, closed, and closed with slow sand filtration) on the dispersion of Phytophthora cactorum propagules and the severity of the crown rot disease in strawberry (Fragaria × ananassa Duch.). The plant-growth medium used was coir fiber. The three growing systems showed the same density of P. cactorum propagules in the water drained from the growing media. However, propagules of this pathogen were not detected by the baits in the filtered solution recovered from slow sand filtration. In all systems Phytophthora propagules dispersed from the inoculated plant to adjacent uninoculated plants. At the end of the first crop no differences in the severity of crown rot were found between the different systems of crop culture. However, at the end of the second crop cycle, crown rot in the closed soilless system without slow sand filtration was more severe than in the other two systems. These results demonstrated that the commercial potential of slow sand filtration to prevent propagule dispersal and hence suppress crown rot in strawberry crops grown in a closed culture system.