Differences in body size and egg loads of Rhagoletis indifferens (Diptera: Tephritidae) from introduced and native cherries

The western cherry fruit fly, Rhagoletis indifferens Curran, infests introduced, domesticated sweet [Prunus avium (L.) L.], and tart cherries (Prunus cerasus L.) as well as native bitter cherry, Prunus emarginata (Douglas) Eaton. Bitter cherries are smaller than sweet and tart cherries and this could affect various life history traits of flies. The objectives of the current study were to determine 1) if body size and egg loads of flies infesting sweet, tart, and bitter cherries differ from one another; and 2) if any observed body size differences are genetically based or caused by the host fruit environment. Pupae and adults of both sexes reared from larval-infested sweet and tart cherries collected in Washington and Montana were larger than those reared from bitter cherries. In addition, flies of both sexes caught on traps in sweet and tart cherry trees were larger than those caught in bitter cherry trees and females trapped from sweet and tart cherry trees had 54.0-98.8% more eggs. The progeny of flies from naturally-infested sweet and bitter cherries reared for one generation in the laboratory on sweet cherry did not differ in size. The same also was true for progeny of sweet and bitter cherry flies reared in the field on bitter cherry. The results suggest that the larger body sizes of flies from sweet and tart cherries than bitter cherries in the field are caused by host fruit and not genetic factors.     

Cellulase gene expression in ripening avocado fruit: The accumulation of cellulase mRNA and protein as demonstrated by cDNA hybridization and immunodetection

Summary A cDNA library was constructed from poly(A)⁺RNA of ripe avocado fruit. Colony hybridization identified a number of ripening specific clones of which one, pAV5, was shown to be specific for cellulase. Hybrid selection with pAV5 provided a message from ripe fruit that on in vitro translation yielded a polypeptide of 53kD, comigrating with purified avocado cellulase on SDS polyacrylamide gel electrophoresis. The translation product was selectively immunoprecipitated by antiserum to purified avocado cellulase. Immunoblotting of unripe and ripe avocado fruit extracts following SDS-PAGE showed a plentiful immunoreactive polypeptide in ripe fruit, and essentially none in unripe fruit. Hybridization of pAV5 to poly(A)⁺-RNA from unripe and ripe avocado fruit demonstrated that there is at least a 50-fold increase in the cellulase message concentration during ripening. Thus, the expression of cellulase enzyme activity during ripening is regulated by the appearance of mRNA coding for cellulase rather than by either translational or post-translational control mechanisms.Abbreviations poly(A)⁺ polyadenylated - DS sodium dodecyl sulfate - D kilodalton - bp base pairs Supported by Research Grant GM 19807 from the United States Public Health Service and by additional funds from the University of California Research Council.     

Genetic structure of cherry fruit fly (Rhagoletis cingulata) populations across managed,unmanaged, and natural habitats

The cherry fruit fly (CFF), Rhagoletis cingulata Loew (Diptera: Tephritidae: Trypetini), is endemic to eastern North America and Mexico, where its primary native host is black cherry [Prunus serotina Ehrh. (Rosaceae)]. Cherry fruit fly is also a major economic pest of the fruit of cultivated sweet (Prunus avium L.) and tart (Prunus cerasus L.) cherries. Adult CFF that attack wild black cherry and introduced, domesticated cherries in commercial and abandoned orchards are active at different times of the summer, potentially generating allochronic isolation that could genetically differentiate native from sweet and tart CFF populations. Here, we test for host‐related genetic differences among CFF populations in Michigan attacking cherries in managed, unmanaged, and native habitats by scoring flies for 10 microsatellite loci. Little evidence for genetic differentiation was found across the three habitats or between the northern and southern Michigan CFF populations surveyed in the study. Local gene flow between native black cherry, commercial, and abandoned orchards may therefore be sufficient to overcome seasonal differences in adult CFF activity and prevent differentiation for microsatellites not directly associated with (tightly linked to) genes affecting eclosion time. The results do not support the existence of host‐associated races in CFF and imply that flies attacking native, managed, and unmanaged cherries should be considered to represent a single population for pest management purposes.     

Late dormant rapeseed oil treatment against black cherry aphid and cherry fruit moth in sweet cherries

Abstract:  Black cherry aphid [ Myzus cerasi (Fabricius)] and cherry fruit moth [ Argyresthia pruniella (Clerck)] are the main insect pests on sweet cherries in Norway. In this study, application of rapeseed oil alone and rapeseed oil mixed with pesticides were tested as a control method against overwintering eggs of both black cherry aphid and cherry fruit moth. Results showed that rapeseed oil applied at the late dormant stage significantly reduced damage by black cherry aphid. Efficiency of oil mixed with pesticides was higher, but only significant in three of seven trials. The efficiency of rapeseed oil against cherry fruit moth was low compared with what was achieved for black cherry aphid, but within the range that has been reported for other botanical pesticides. As for the black cherry aphid, adding pesticides to oil decreased damage by the cherry fruit moth. Timing of treatment and effect of temperature were discussed.     

Combined heat and controlled atmosphere quarantine treatments for control of western cherry fruit fly in sweet cherries

Nonchemical quarantine treatments, using a combination of short duration high temperatures under low oxygen, elevated carbon dioxide atmospheric environment were developed to control western cherry fruit fly, Rhagoletis indifferens Curran, in sweet cherries, Prunus avium (L.). The two treatments developed use a chamber temperature of 45 degrees C for 45 min and a chamber temperature of 47 degreesd C for 25 min, both under a 1% oxygen, 15% carbon dioxide, -2 degrees C dew point environment. Both these treatments have been shown to provide control of all life stages of western cherry fruit fly while preserving commodity market quality. There was no definitive egg or larval stage, which was demonstrated to be the most tolerant to either controlled atmosphere temperature treatment system treatment. Efficacy tests for both treatments resulted in 100% mortality of >5000 western cherry fruit flies in each treatment. These treatments may provide, with further study, quarantine security in exported sweet cherries where western cherry fruit fly is a quarantine concern and fumigation with methyl bromide is not desired.     

Detection of Rhagoletis indifferens (Dipt., Tephritidae) larvae using brown sugar flotation and hot water methods

The brown sugar flotation and hot water methods are accepted procedures for detecting larval western cherry fruit fly, Rhagoletis indifferens Curran, in sweet cherry [Prunus avium (L.) L.] and could be included in a systems approach, a combination of all steps involved in cherry production, for showing the absence of larvae in fruit. The methods require crushing cherries and then submerging them in brown sugar solution or hot water to extract the larvae. Larvae are visually detected when they float to the surface of the brown sugar solution or sink in the hot water. The objective of this study was to test the efficacy of these two methods. Both methods detected at least one larva in all 288 moderately to heavily infested cherry samples. The brown sugar flotation and hot water methods detected 89.6–94.7% and 83.0–85.9% of total larvae, respectively, from cherry samples on each of three dates. Significantly higher percentages of 1st instars were detected using the brown sugar than hot water method on two dates, of 3rd instars on one date and of total larvae on two dates. Percent detection of 3rd instars was higher than that of 1st instars using both methods. For both methods, greater percentages of split whole cherries with seeds and non‐split cherries had larvae than split whole cherries with no seeds and halved cherries. Results show that both methods were equally efficacious in detecting the presence of R. indifferens larvae in cherry samples, but brown sugar flotation was more efficacious than the hot water method in detecting a higher percentage of total larvae present and could be integrated into a systems approach for R. indifferens.     

Evaluation of the glycoside hydrolase activity of a Brettanomyces strain on glycosides from sour cherry (Prunus cerasus L.) used in the production of special fruit beers

The glycoside hydrolase activity of Saccharomyces cerevisiae and Brettanomyces custersii was examined on sour cherry (Prunus cerasus L.) glycosides with bound volatile compounds. Refermentations by the beta-glucosidase-negative S. cerevisiae strains LD25 and LD40 of sour cherry juice-supplemented beer demonstrated only a moderate increase of volatiles. In contrast, the beta-glucosidase-positive B. custersii strain LD72 showed a more pronounced activity towards glycosides with aliphatic alcohols, aromatic compounds and terpenoid alcohols. Important contributors to sour cherry aroma such as benzaldehyde, linalool and eugenol were released during refermentation as shown by analytical tools. A gradually increasing release was observed during refermentations by B. custersii when whole sour cherries, sour cherry pulp or juice were supplemented in the beer. Refermentations with whole sour cherries and with sour cherry stones demonstrated an increased formation of benzyl compounds. Thus, amygdalin was partially hydrolysed, and a large part of the benzaldehyde formed was mainly reduced to benzyl alcohol and some further esterified to benzyl acetate. These findings demonstrate the importance and interesting role of certain Brettanomyces species in the production of fruit lambic beers such as 'Kriek'.     

A study of ethylene in apple, red raspberry, and cherry

High ethylene levels were associated with flower abscission in apple (Malus sylvestris) and cherry (Prunus avium and Prunus cerasus), “June drop” of immature cherries, and harvest drop of apple and red raspberry (Rubus idaeus). However, an increase in ethylene content was not associated with June drop of apples and harvest drop of cherries. During the period of fruit ripening on the plant, the largest increases in ethylene occurred in apple flesh and red raspberry receptacular tissue. Ethylene remained low throughout the period of sweet and tart cherry ripening. The data obtained indicated marked ethylene gradients between adjacent tissues. Increases of ethylene in some tissues may have resulted from ethylene diffusion from adjacent tissues containing high levels of ethylene.     

Sequencing and identification of a cDNA clone for tomato polygalacturonase.

The 2a isoenzyme of tomato polygalacturonase was purified from ripe fruit and characterised. The N-terminal amino acid sequence of the protein was determined in order to identify polygalacturonase cDNA clones. The nucleotide sequence of a ripening-related cDNA (pTOM 6) was determined and found to encode the N-terminal sequence of mature polygalacturonase 2a. The complete open reading frame encodes a polypeptide of molecular weight 50,051, including a putative pre-sequence of 71 amino acids.     

Assessment of cultivated cherry germplasm in Iran by multivariate analysis

Key message

This work is an important step in the conservation of genetic cherry resources, which showed distinctive and interesting agronomical characters. Also it introduces suitable genotypes for cultivation and breeding studies.

Abstract

The purpose of this study was to characterize cherry germplasm that is cultivated in Iran. Thirty-three morphopomological parameters were studied in this germplasm, consisting of 70 cherry genotypes (41 sweet cherry, 24 sour cherry and 5 duke cherry genotypes). A wide variation was found in blooming time, ripening time, fruit weight, fruit color, anthocyanin, total soluble solids (TSS), titratable acidity (TA), fruit dimensions and flesh firmness and stone size. There were close positive correlations between fruit weight and fruit dimensions, and between fruit weight and fruit stalk weight, fruit flesh firmness and cracking and also a negative correlation between pH and TA. Dendrogram gave a clear separation between the sour, duke and sweet cherry species and also showed existing intraspecific morphological variation. Based on fruit size and organoleptic properties, the sweet cherry genotypes ‘Siah-Mashhad’, ‘Takdaneh-Mashhad’, ‘Shabestar’, ‘Siah-Daneshkade’, ‘Ghazvin’ and ‘Droongezna’ are recommended for fresh consumption. Good fruit chemical composition and late-ripening time stands out genotypes ‘Dirres-Italia’, ‘Dirres-Pardis’, ‘Maremoot’, ‘Abardeh’ and ‘Rorshon’ and make them suitable for processing. Also, ‘Gilas46’ and ‘Gilas49’ were substantially late-ripening, a characteristic that makes these genotypes highly suitable for breeding studies in case of ripening time. Furthermore, sour cherries ‘Hashtgerd2’ and ‘Hashtgerd3’ and duke cherries ‘Pardis1’ and ‘Pardis3’ were the best genotypes. This work is an important step in the conservation of genetic cherry resources in Iran, which showed distinctive and interesting agronomical characters such as low susceptibility to fruit cracking, high levels of total soluble solids, early fruit maturity and high fruit quality.     

都江堰林区取食樱桃果实(种子)的鸟类及其种子扩散作用

樱桃(Prunus pseudocerasus)是广泛分布于我国亚热带常绿阔叶林内的一种重要核果植物。为了解食果鸟类在樱桃种群更新中的作用,于2007年和2008年在四川都江堰亚热带常绿阔叶林内研究了取食樱桃果实(种子)的鸟类及其种子扩散作用。研究表明,樱桃成熟果实的下落高峰发生在4月下旬至5月上旬;2007年的种子扩散率为4.0%±1.0%,明显低于2008年(27.7%±5.7%)。在研究地内,发现至少有16种鸟取食樱桃果实或种子,根据其对果实和种子的处理方式分为3个功能群:白头鹎(Pycnontus sinensis)、领雀嘴鹎(Spizixos semitorques)、黑鹎(Hypisipetes leucocephalus)、白颊噪鹛(Garrulax snnio)、红嘴蓝鹊(Urocissa erythorhyncha)等10种鸟吞食樱桃果实,而种子通过消化道末端排出并将种子携至远离母树的地方,是重要的种子扩散者;暗绿绣眼鸟(Alcippe morrisonia)和灰眶雀鹛(Zosterops iaponicus)等4种鸟主要啄食果肉而将种子丢弃在母树下,为啄食果肉者;而普通朱雀(Carpopacus erythrinus)和灰头鸦雀(Paradoxornis gularis)则主要取食种子,为纯粹的种子捕食者。在吞食樱桃果实的食果鸟中,3种鹎科鸟类访问频次所占的比例达55.3%(2007年)和35.3%(2008年),说明鹎科鸟类是都江堰林区樱桃种子的主要扩散者,对樱桃种群的空间格局和自然更新可能有重要影响。     

Molecular cloning of a ripening-specific lipoxygenase and its expression during wild-type and mutant tomato fruit development.

A 94-kD protein that accumulates predominately in tomato (Ly-copersicon esculentum) fruit during ripening was purified, and antibodies specific for the purified protein were used to isolate cDNA clones from a red-ripe fruit cDNA library. A sequence analysis of these cDNAs and cross-reactivity of the 94-kD-specific antibodies to the soybean lipoxygenase (LOX) L-1, L-2, and L-3 proteins and soybean LOX L-1-specific antibodies to the 94-kD protein identified it as a member of the LOX gene family. Maximum levels of the 94-kD LOX mRNA and protein are present in breaker to ripe and red-ripe stages, respectively. Expression of 94-kD LOX in different tissues from mature green and red-ripe tomato fruits was found to be greatest in the radial walls of ripe fruit, but immunocytolocalization using tissue printing suggests that the highest accumulation of its protein occurs in locular jelly. None of 94-kD LOX is expressed in nonripening mutant fruits of any age. Never-ripe mutant fruit accumulate the 94-kD LOX mRNA to levels similar to those obtained in wild-type fruit, but fail to accumulate the 94-kD LOX protein. Collectively, the results show that expression of 94-kD LOX is regulated by the ripening process, and ethylene may play a role in its protein accumulation.     

Apple beta-galactosidase. Activity against cell wall polysaccharides and characterization of a related cDNA clone.

A beta-galactosidase was purified from cortical tissue of ripe apples (Malus domestica Borkh. cv Granny Smith) using a procedure involving affinity chromatography on lactosyl-Sepharose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that two polypeptides of 44 and 32 kD were present in the fraction that showed activity against the synthetic substrate p-nitrophenol-beta-D-galactopyranoside. The enzyme preparation was incubated with polysaccharide extracts from apple cell walls containing beta-(1-->4)-linked galactans, and products of digestion were analyzed by gas chromatography. Small amounts of monomeric galactose were released during incubation, showing that the enzyme was active against native substrates. Amino acid sequence information was obtained from the purified protein, and this showed high homology with the anticipated polypeptide coded by the ethylene-regulated SR12 gene in carnation (K.G. Raghothama, K.A. Lawton, P.B. Goldborough, W.R. Woodson [1991] Plant Mol Biol 17: 61-71) and a harvest-related pTIP31 cDNA from asparagus (G. King, personal communication). Using the asparagus cDNA clone as a probe, an apple homolog (pABG1) was isolated. This clone contains a 2637-bp insert, including an open reading frame that codes for a polypeptide of 731 amino acids. Cleavage of an N-terminal signal sequence would leave a predicted polypeptide of 78.5 kD. Genomic DNA analysis and the isolation of other homologous apple clones suggest that pABG1 represents one member of an apple beta-galactosidase gene family. Northern analysis during fruit development and ripening showed accumulation of pABG1-homologous RNA during fruit ripening. Enzyme activity as measured in crude extracts increased during fruit development to a level that was maintained during ripening.     

Influence of the interaction of temperature and water activity on the production of ochratoxin A and the growth of Aspergillus niger, Aspergillus carbonarius and Aspergillus ochraceus on coffee-based culture medium

In the present study, the effect of temperature and water activity on fungal growth and ochratoxin production on coffee-based medium was assessed. Optimal growth of three Aspergillus strains was observed in the same ecological conditions, namely 30 degrees C and 0.99 water activity. Maximal daily growth is 11.2, 6.92, and 7.22 mm/day for Aspergillus niger, Aspergillus carbonarius, and Aspergillus ochraceus, respectively. However, ecological conditions for optimal ochratoxin production vary according to the toxinogenic strain, with water activity as a limiting factor. Such an ochratoxin A production is inhibited at 42 degrees C and 0.75 water activity. Correspondence between laboratory tested water activity and that measured on a sun-dried ripe cherry batch shows that the first 5 days of drying are critical for fungal growth and ochratoxin A production. Accordingly, artificial drying of cherries at temperatures above 42 degrees C will impede not only fungal growth but also contamination with ochratoxin A.     

Identification of tomato bushy stunt virus in cherry and plum trees showing fruit pitting symptoms

The fruit pitting symptoms on cherries, plums and prunes were investigated from the standpoint of their etiology. Tomato bushy stunt virus (TBSV) was isolated from pitted fruits of these plants and from their leaves and identified by means of biological and serological methods. Both isolates reacted with antisera againstPetunia and artichoke strain of this virus. In addition, the etiology of pseudopox disease of plum and that of cherry detrimental canker is discussed.     

Purification and characterization of tomato polygalacturonase converter

Extracts of ripe tomatoes contain two forms of polygalacturonase (PG I and PG II). A heat-stable component that binds PG II to produce PG I has been isolated from tomato fruit. This component has been named polygalacturonase converter (PG converter). The PG converter has been purified by gel filtration, ion-exchange chromatography and chromatofocusing. It appears to be a protein with a relative molecular mass of 102000. It was readily inactivated by papain and pronase. The converter was labile at alkaline conditions, and treatment of PG I at pH 11 released free PG II. A similar factor with a lower molecular mass was extracted from tomato foliage.