Cucumber (Cucumis sativus L.), a widely cultivated and important crop, is susceptible to the Tobamovirus cucumber green mottle mosaic virus (CGMMV). CGMMV is known to reduce cucumber yield, yet little is known about its impact on the postharvest quality of the fruit. To examine the effect of CGMMV infection on the quality and storability of cucumber fruit after harvest, cucumber plants were inoculated with CGMMV at three different developmental stages: seedling infection, infection during the vegetative growth of the plants (along with trellis application), and infection during fruit set. Early-stage infections (seedling and trellising) led to significant reductions in yield and impaired fruit quality (shape, color, and weight). Conversely, infections during the fruit set stage produced marketable fruit that showed no apparent differences comparable to non-infected control fruit at harvest. Nevertheless, the quality of fruit after cold storage was significantly affected by CGMMV infection. Virus-infected fruit were more susceptible to chilling injuries, as evidenced by the degradation of fruit peel chlorophyll, increased ion leakage, elevated levels of Malondialdehyde, and higher values of auto-luminescence. Furthermore, CGMMV-infected fruits were more susceptible to gray mold disease caused by Botrytis cinerea. Transcriptomic profiling of infected fruit at harvest revealed upregulation of genes associated with phenylpropanoid and ethylene metabolism, ERF and WRKY transcription factors, suggesting the involvement of several pathways in mediating the differential physiological response of CGMMV-infected fruits to postharvest insults. These results indicate viral infection of fruit as an additional, previously unappreciated factor that affect quality and postharvest losses of fresh produce.

Acorn squash are a conveniently sized, inexpensive, nutritious vegetable, but the fruit quality of traditional cultivars is often unsatisfactory. New, sweet-tasting acorn squash were developed recently, but data on their fruit development and storability are limited. Our objective was to monitor the physical, carbohydrate, and antioxidant contents of 'Table Confection' sweet acorn squash fruits over the course of their development and after cold storage. Fruits were harvested at intervals spanning 15 to 60 days past anthesis (dpa) and assessed for various quality components. Maximum weight and dry matter content were attained at 40 dpa but 60-dpa fruits were firmer, with higher total soluble solids (TSS) (60 dpa: 18%; 40 dpa: 9%), sucrose, and antioxidant contents, and a more intense fruit-flesh colour. After long-term cold storage at either 10 degrees C-RH 70% or 15 degrees C-RH 95%, the fruits that had been harvested at 40 dpa had greatly increased TSS (17%), sucrose content, and flesh-colour intensity, but lost as much as 13% of their weight. The results indicate that if premature harvesting is forced by production or marketing considerations, sweet acorn squash can achieve high quality during cold storage, but at the expense of weight loss in accordance with the duration of storage.

Sweet pepper (Capsicum annuum) is a highly nutritious and economically important vegetable grown worldwide. Black mold, caused by mycotoxin-producing Alternaria spp., is a common postharvest disease during cold storage and transport, leading to significant produce losses. A better understanding of the infection process is essential for improving disease control. This study examined Alternaria alternata isolates infecting green (mature unripe) and red (ripe) pepper fruit. Findings indicate that black mold can infect fruit at both ripening stages, with differences in symptom progression, growth rates, and sporulation. Disease development was influenced by fruit ripeness in a temperature-dependent manner. At 7°C, lesion size and sporulation were similar on green and red fruit, but at 22°C, lesions were significantly larger on red fruit (P < 0.05). Microscopic studies revealed comparable conidial germination on both fruit stages; however, appressoria formation was less frequent on green fruit early in infection. Fungal penetration into the pericarp occurred 8 hours post-inoculation through cuticle wounds, with hyphae growing intercellularly among pericarp walls. By 24 hours post-inoculation, cell contents were disorganized, and cell walls had dissolved. In red fruit, vascular bundles were destroyed, whereas in green fruit, they remained intact. At 22°C, high levels of the mycotoxins altenuene, alternariol, and alternariol monomethyl ether were detected in both green and red infected fruit. The susceptibility of mature green fruit to black mold highlights the need for effective field treatments to prevent pathogen establishment and reduce postharvest disease.

Fusarium fruit rot caused by Fusarium solani f. sp. cucurbitae is an important postharvest disease impacting the global production and storage of pumpkins and winter squash (Cucurbita spp.). The pathogen infects fruit through wounds, causing water-soaked lesions that may become sunken, coalesce, and covered by fine mycelial growth. Fusarium solani is soilborne and can survive long term in soil and plant debris. Storage rots impact several Cucurbita species grown for long-term storage. F. solani f. sp. cucurbitae has two races and is the most commonly found Fusarium species infecting cucurbits. Identification includes morphologic and PCR-based methods. This guide outlines taxonomy, symptoms, isolation, and epidemiology and provides methods to identify the pathogen.

Acorn squash (Cucurbita pepo) have been a familiar item at produce stands for decades in the United States and Canada, but little known or appreciated elsewhere. Following the breeding and development of sweet-fleshed acorn squash in Israel and its commercial introduction in 2007, acorn squash became a high-priced, popular produce item there. Scarcity of supply in winter has led to attempts to fill the consumer demand by using available protected cultivation infrastructure in the relatively mild area of southwestern Israel for production. Such production has proven feasible but it was not determined whether it would be preferable to allow the plants to simply grow sprawling on the ground or vertically, using trellises to train the plants to grow erect. Two sweet acorn squash hybrid cultivars differing in fruit size were compared, growing on the ground or on trellises, for yield, quality, and storability of the fruits. The hybrids bore fully ripe fruits from December through February, producing 56% higher yields when trellised rather than when allowed to grow on the ground. The fruits of trellised plants of both hybrids were more uniformly black-green and firmer than those of ground-grown plants. Their dry matter content at harvest and after 78 days of storage was very high, averaging 28% and 25%, respectively. Total soluble solids content of the fruit flesh from trellised plants was 19% at harvest and an extraordinary 20% after storage at 10°C, 70% RH. The fruit flesh of trellised plants was also more highly colored and had higher carotenoid, ascorbate, and anti-oxidant contents. Overall, trellising of sweet acorn squash during the winter under protected cultivation resulted in significantly higher yields and the finest fruit quality.

Intra-canopy illumination using light-emitting diodes (LEDs) is a technique used to supplement the inside of the canopy of intensively grown crops with light. Bell pepper grown in double-row beds using 'Spanish' trellis systems during the winter suffers from considerable shading of the inner canopy. Moreover, under passive growth conditions, limited light availability and low temperature over the winter may attenuate photosynthetic efficiency and result in non-optimal fruit set and therefore less yield. In our studies, we found that intra-canopy illumination operated during daytime or edge-of-daytime in passive growth tunnels increased the spring fruit yield of the bell pepper cultivar 'Cannon'. In this paper, we report on a study with daytime intra-canopy illumination carried out with the cultivar 'Gilad' in the Jordan Valley. Along the growth season, we studied the effect of the added illumination on physiological parameters, fruit yield and quality. Our results show that the LED illumination significantly increased gas exchange activity and photosynthetic assimilation of the inner canopy without causing any light or heat stress. The fruit yield increased by similar to 20% in spring in the illuminated plots, with the majority of the yield increase (higher fruit number) arising from western-facing plants of the double-row beds. Postharvest quality parameters differed for different harvests along the season, yet no considerable differences were found between fruit from illuminated or non-illuminated plants per harvest. Thus, the supplemental illumination resulted in an increase to the yield without compromising fruit quality.

Cladosporium rot ( Cladosporium cladosporioides ) is a common disease affecting sweet pepper postharvest. Rots are frequently observed in Mediterranean growing regions, and conidia produced during refrigerated transport and storage can spread readily in air currents or by direct contact with healthy fruits. There are limited management strategies that are used to control Cladosporium rot that include protecting fruits from physiological disorders and limiting wounding. The objective of our research was to characterize C. cladosporioides isolates from sweet pepper in Israel and to determine isolate sensitivity to the fungicide fludioxonil. Isolates collected from multiple regions in Israel were slow growing and formed olivaceous-grey to brown colonies on PDA. The conidia measured 5.1 × 3.1 µm and ramoconidia measured 15.4 × 3.3 µm. The optimum temperature was 20 °C for mycelial growth and conidial germination, and limited fungal growth occurred at 1 and 30 °C. Fruit extracts enhanced conidial germination, while there was no effect of fruit surface exudates. In histological sections from diseased pepper, hyphae had ramified through the inner pericarp layer by 24 h post inoculation (hpi) and dissolution of the cytoplasm occurred by 72 h. Sporulation from the hyphal layer and diseased tissue was observed 96 hpi. On fludioxonil amended media the average EC 50 was 0.19 ppm for the isolates tested, suggesting this fungicide could be beneficial in disease management programs.

Sweet pepper (Capsicum annuum L.) is an important vegetable crop grown in Israel for local and export markets. Bell pepper 'Dinamo' and sweet bite pepper exhibiting fruit spotting were observed in postharvest storage of commercial farms in Giv'at Ko'ah (32°02'21″ N; 34°56'41″ E) and Arava (30°46'41″ N; 35°14'28″ E) in July, 2021. Fruit with lesions were sporadic at each facility, however, limited numbers of packaged boxes were discarded due to a high percentage of symptomatic fruit. The spots appeared as slightly sunken dark brown or black lesions, coated by a fine velvety layer of olive-grey conidia (Suppl. Fig. 1). A fungus was routinely isolated from the fruit onto potato dextrose agar amended with 50 ppm chloramphenicol (PDAC) and was tentatively identified as a Cladosporium spp. based on colony morphology and conidial appearance (Suppl. Fig. 1). Isolates (n = 6) of the fungus were cultured on malt extract agar (MEA) and PDA for morphological observation. On MEA, the pathogen sporulated profusely and conidia measured 4.5 (3 - 7) × 3.5 (2 - 4) µm and were smooth and globose or sub-globose. Ramoconidia had 0 or 1 septations and measured 13.4 (10 - 18) × 3.9 (3 - 6) µm. Conidiophores were solitary, straight or flexous, usually unbranched, and measured 60 - 350 µm. Both macro- and micronematous conidiophores were present. Hyphae were flat and immersed, olivaceous-grey, septate and rope-like. The fungus was slow growing, reaching 41.0 mm after 10 d incubation at 20°C. To confirm species identity, the isolates were grown in potato dextrose broth and DNA was extracted from the mycelium using MasterPure DNA Purification Kit (EpiCentre, Madison, WI, USA) following the manufacturer's instructions. The internal transcribed spacer (ITS) region was amplified using primers ITS 1 and ITS 4, and elongation factor-1 and actin gene regions with EF1-728F/986R and ACT-512F/783R, respectively (Carbone and Kohn, 1999). The PCR products were sequenced and a BLASTn search showed 99-100% similarity to Cladosporium cladosporioides (GenBank accession nos. MW255614.1, MK416093.1, MK306457.1), a common fungal species found worldwide as a plant pathogen and saphrophyte (Bensch et al., 2012). The ITS gene sequences for a representative isolate from each location were deposited in GenBank (accession nos. OK104139.1 and OL672241.1). To confirm pathogenicity, red bell pepper fruits (n = 8) were wounded with a sterile needle and a 12 µl drop of conidial suspension (4 x 105/ml) of each isolate was pipetted onto the wound. Control fruit received sterile water. The fruit were incubated at 100% RH in sealed containers at 20-22°C. After 7-10 d incubation small dark sunken spots developed, and by 14 d lesions formed with velvety conidial growth similar to the ones originally observed. The fungus was successfully isolated again from the lesions onto PDA and confirmed as C. cladosporioides based on colony and conidial morphology. No symptoms developed on fruit inoculated with sterile water. The pathogenicity test was repeated two times with similar results. C. cladosporioides is a cosmopolitan pathogen and has been cited causing disease on numerous crops worldwide (Bensch et al., 2012). This species was reported causing tomato leaf spot in Mexico (Robles-Yerena et al., 2019) and black mould of tomato fruit in Australia (Ma et al., 2020). Cladosporium herbarum was found causing fruit rot of bell pepper in the U.S. (Ramsey and Heiberg, 1952). Sweet peppers are widely grown in Israel, and have high economic value as an export crop. Control measures to limit losses from C. cladosporioides postharvest may be necessary if conditions are favorable for disease during prolonged storage and refrigerated transport.

Acorn squash (Cucurbita pepo) is a familiar fruit vegetable in North America, appreciated for its attractive appearance, good flavor, nutritional content and long storage life. A breeding program in Israel has produced three new acorn squash hybrids of enhanced sweetness and flavor. Presently, we evaluated productivity, quality, and storability of these new cultivars in fall plantings. The plants were grown trellised, in an insect-proof greenhouse, for fruit production during the winter to meet consumer demand. The plants were highly productive and bore fruits of superb quality, but there was a high incidence of fungal rots during postharvest cold storage. Pre-treating the fruits with hot water brushing and rinsing before storage was found effective in reducing rot incidence of the fruits stored at 15 °C, but only for one cultivar. Storing the fruits at 10 °C with reduced humidity (Rh 70%) enabled a 3-month shelf life with significantly reduced fruit-rot incidence and minimal effect on fruit quality of all three cultivars. Storage at 20 °C with reduced humidity was suitable for a 1-month period. These protocols for prolonging storage life will help attain controlled, gradual year-round marketing of quality acorn squash at uniform, reasonable price levels for farmers and consumers, and could facilitate overseas export.

Penicillium expansum is a major postharvest pathogen that infects different fruits, mainly through injuries inflicted during harvest or subsequent handling after harvest. Several effectors were suggested to mediate pathogenicity of P. expansum in fruit tissue. Among these effectors Nep1-like proteins (NLPs), produced by various microorganisms with different lifestyles, are known for their ability to induce necrosis in dicot plants and were shown to be involved in virulence of several plant-related pathogens. This study was aimed at the identification and functional characterization of two NLP genes found in the genome of P. expansum. The genes were designated Penlp1 and Penlp2 and were found to code type1 and type3 NLP respectively. Necrosis-inducing activity of the two proteins was demonstrated by transient expression in Nicotiana benthamiana leaves. While Penlp1 expression was induced during apple infection and in liquid culture, the highest level of Penlp2 expression was found in ungerminated spores. Deletion of Penlp1, but not Penlp2, resulted in reduced virulence on apples manifested by reduced rate of lesion development (disease severity).

Blue mold caused by Penicillium expansum is a major postharvest disease of pome fruit Several mechanisms possibly involved in P. expansum pathogenicity and virulence. However, factors that mediate pathogenicity and virulence are largely not yet characterized. In this work we analyzed P. expansum predicted secretome to reveal potential genes that have a role in host-pathogen interaction. A prediction pipeline was designed using an approach that combines common effector features, transcriptomic data and homology to proteins reported to be involved in pathogenicity of other pytopathogenic fungi. Among 297 genes predicted in P. expansum secretome, 103 genes (35%) were found to code for hydrolytic enzymes. The majority of the secreted enzymes are carbo-hydrate-degrading enzymes among which five coding for pectin-degrading enzymes are highly induced during the infection and decay of apple fruit by P. expansum, indicating that they may represent an important aspect of pathogenicity and virulence. Applying the pipeline we have predicted 17 candidate genes coding for proteins that are most likely involved in pathogenicity and virulence. One of the top candidates is a subtilisin-related peptidase, S8 (PePRT), proteolytic enzyme highly expressed in planta, and potentially involved in authophagy process. Deletion of PePRT-coding gene resulted in reduced virulence of P. expansum on apples. Moreover, Delta Peprt exhibited decreased sporulation as well as affected mycelial morphology and internal mycelial cell structure.

P. expansum is regarded as one of the most important postharvest rots of apple fruit and is also of great concern to fruit processing industries. Elucidating the pathogenicity mechanism of this pathogen is of utmost importance for the development of effective and safe management strategies. Although, many studies on modification of the host environment by the pathogen were done, its interactions with fruit during the early stages of infection and the virulence factors that mediate pathogenicity have not been fully defined. Effectors carrying LysM domain have been identified in numerous pathogenic fungi and their role in the first stages of infection has been established. In this study, we identified 18 LysM genes in the P. expansum genome. Amino acid sequence analysis indicated that P. expansum LysM proteins belong to a clade of fungal-specific LysM. Eleven of the discovered LysM genes were found to have secretory pathway signal peptide, among them, 4 (PeLysM1 PeLysM2, PeLysM3 and PeLysM4) were found to be highly expressed during the infection and development of decay of apple fruit. Effect of targeted deletion of the four putative PeLysM effectors on the growth and pathogenicity was studied. Possible interactions of PeLysM with host proteins was investigated using the yeast-two-hybrid system.

A pomegranate peel extract (PGE) was evaluated as a natural antifungal preparation for the control of postharvest rots. In vitro trials revealed a strong fungicidal activity against germination of conidia of Botrytis cinerea, Penicillium digitatum and Penicillium expansum. Almost complete inhibition of all fungal spore germination was achieved after 20 h of incubation with PGE. PGE was very effective in inhibiting decay following artificial inoculations of lemons by P. digitatum and Penicillium italicum, grapefruits by P. italicum and apples by P. expansum. At concentrations of 1.2 and 12 g/l complete inhibition of infection was achieved in the majority of host pathogen combinations. Furthermore, it was also effective in reducing natural rots under semi-commercial conditions on both sweet cherries and lemons: on cherries Monilinia laxa and B. cinerea rots were reduced by 61.0% (cv. Bigarreau Moreau) and 95.6% (cv. Giorgia), respectively, and on lemons 87.8% reduction of total rot was achieved. PGE treatment showed residual effect as it was effective in inhibiting infections made at 6,12, and 24h after the application of the extract in fruit wounds. Additionally, PGE exhibited curative activity and reduced the incidence of rots when it was applied 6 and 24h after inoculation. Considering that PGE was extracted and stabilized using safe chemicals (food grade ethanol and citric acid) and that it did not have any apparent phytotoxic effect on treated fruit, PGE proved to be effectively eco-friendly and safe control mean for postharvest rots of fruit. (C) 2015 Elsevier B.V. All rights reserved.

To gain a better understanding of the molecular changes taking place in citrus fruit tissue following the application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. Using a cut-off of P < 0.05 and a 1.5-fold change difference as biologically significant, the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. Microarray results of selected genes were validated by reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). The data indicated that yeast application induced the expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. Moreover, suppression was correlated with significantly higher levels of hydrogen peroxide, superoxide anion and hydroxyl radical production in yeast-treated surface wounds. Interestingly, large amounts of hydrogen peroxide were detected inside yeast cells recovered from wounded fruit tissue, indicating the ability of the yeast to activate reactive oxygen species when it is in contact with plant tissue. This study provides the first global picture of gene expression changes in grapefruit in response to the yeast antagonist M. fructicola.