Effects of Trichosporon sp. in Combination with Calcium and Fungicide on Biocontrol of Postharvest Diseases in Apple Fruits

The capability of yeast Trichosporon sp., an antagonist isolated from peach fruit, in biological control was evaluated in apple ( Malus domestica Borkh. cv. Fuji) fruits, when inoculated with different concentrations of Botrytis cinerea Pers. and Penicillium expansum (Link) Thom, as well as in combination with calcium and fungicide. The concentrations of the yeast cells and pathogen spores obviously influenced disease incidence and lesion development in apples. There was a significant negative correlation between concentrations of the yeast cells and infectivity of the pathogens. When the yeast cell suspensions reached the concentration of 10 8 colony_forming units (CFU) /mL, there was no infection caused by B. cinerea and P. expansum with spore concentrations below 10 6 spores/mL in apple fruits. The yeast at concentrations of 10 6-10 7 CFU/mL in combination with fungicide (iprodione at 50 μL/L) provided control of decay caused by B. cinerea and P. expansum better than separate application. Effect of controlling gray mould and blue mould rots was enhanced when Trichosporon sp., even at low concentration of 10 5 CFU/mL, was applied in the presence of 1%-2% CaCl 2 in an aqueous suspension.

Biocontrol Efficacy of Two Antagonistic Yeasts Against Postharvest Diseases in Peach Fruits During Storage Periods

Two antagonistic yeasts, Thichosporon pullulans and Cryptococcus laurentii, were investigated for their biocontrol potential to blue mold rot and rhizopus rot on harvested peach fruits(Prunus persica L. Batsch, cv. Okubao), alone or in combination with a low dose of iprodione(50 μg ml-1). The results indicated that T. pullulans and C. laurentii were effective at reducing disease incidence and severity of blue mold rot and rhizopus rot in peach fruits. Biocontrol efficacy of C. laurentii and T. pullulans were significantly enhanced by combination with a low dose of iprodione(50 μg ml-1)against blue mold and rhizopus rot in peach fruits. T. pullulans and C. laurentii combined with a low dose of iprodione(50 μg ml-1)resulted in better disease control than either iprodione or the yeasts used alone. Dipping fruits in suspensions of antagonist cells showed the similar control effect as the treatment with iprodione(500μg ml-1).

Physiological and Biochemical Characteristics of Yeast 3SJ and Its Inhibitory Effect on Postharvest Diseases of Apple

The physiological and biochemical characteristics of the yeast 3SJ with resistance against three species of postharvest diseases were identified in the pa- per, and the inhibitory effects of the yeast 3SJ on Penicillium expansum, Botrytis cinerea and Colletotrichum gloeosporioides during storage period was preliminarily studied. The control effects of the yeast on postharvest diseases caused by P. expansum, B. cinerea and C. gloeosporioides were measured in vivo and in vitro condi- tions. The results showed that the yeast had best control effect against P. expansum and B. cinerea at 20 ~C ; followed by the control effect against C. gloeospori- oides. Inoculation of spore suspension of yeast in apple wound could effectively inhibit rot of apple, while supematant filtrate and sterilized liquid could not inhibit rot of apple. This simultaneously indicated that the action mode of the yeast mainly was nutrition competition. The yeast was conducted traditional classification and identification based on physiological and biochemical characteristics of the yeast, and preliminarily identified to be Kloechera spp. The yeast could survive for at least one month in apple wound at 4 ~C low temperature conditions, with increased amounts. The tolerance to low temperature laid the foundation for application of yeast in low-temperature refrigeration of fruits.

Postharvest Treatment with β-Aminobutyric Acid Induces Resistance Against Dry Rot Caused by Fusarium sulphureum in Potato Tuber

The effectiveness ofpostharvest β-aminobutyric acid （BABA） treatment was studied for inducing resistance against dry rot caused by Fusarium sulphureum in tubers and slices of two potato cultivars （resistant cultivar Shepody and susceptible cultivar Xindaping）. The results showed that BABA at 100 mmol L-1 significantly reduced lesion diameter in inoculated both tubers and slices. The chemical at 100 mmol L-1 showed an effective reduction in infection ability ofF. sulphureum inoculated 48 and 72 h after treatment in slices of resistant cultivar, and 72 and 96 h in susceptible ones. BABA increased the activitives of peroxidase （POD）, polyphenoloxidase （PPO） and phenylalanine ammonialyase （PAL）, and accumulated the contents of lignin, flavonoids and phenolics in slices. The resistant cultivar had a stronger resistant response than the susceptible one. These findings suggest that the BABA treatment can induce the resistance in potato tubers, however, the inducing degree depends on the original level of resistance present in each cultivar.

Preservation Effect of Prochloraz-manganese Chloride Complex on Postharvest ‘Shatangju'( Citrus reticulata)Fruits

[ Objective ] The paper was to solve the weakness of heavy postharvest diseases and non-endurable storage of ＇ Shatangju＇, to improve the preservation effect of ＇ Shatangju＇. [ Method ] Fruits were dipped in different concentrations of procbloraz-manganesc chloride complex solutions. The postharvest weight loss rate, soluble solids content and decay rate of fruits were determined, and the safety of chemical agents was observed and evaluated. [ Result ] Prochloraz-manganese chloride complex had significant preservation effect on postharvest ＇ Shatangju＇ fruits, and the appropriate concentration was 0.15% -0.20% （effective content） ; the decay rates of fruits stored at room temperature for 15, 30, 45, 60 and 90 d were 0, 5%, 〈 10%, 〈 10% and 〈 30% ; there was no specific changes in smell and flavor of non-decayed fruits. [ Conclusion ] Prochloraz-manganese chloride complex solution had significant preservation effect on ＇ Shatangju＇ by inhibiting and reducing the growth and development of pathogenic bacteria, and the effect was much better under refrigeration condition.

Identification of Postharvest Pathogens of Amorphophallus muelleri and Indoor Screening of Fungicides

Konjac （Amorphophallus muelleri）, a genus of tuberous plants in the Araceae family, is one of high-value crops in Southwest China. This study aimed at identifying the main pathogens causing tuber rot during storage ofA. muelleri and screening the effective fungicides, so as to prolong the storage period ofA. muelleri and decrease the losses. Isolation and identification, as well as pathogenicity test and retro-inoculation experiments were made for the pathogen causing tuber rot during storage ofA. muelleri in Kunming city, Yunnan province, China. The effective fungicides for the main pathogens were also screened in the laboratory. Six fungi were identified as the pathogens causing tuber rot of A. muelleri, which were Fusarium solani （Mart,） Sacc., Fusarium oxysporum Schlecht., Botrytis cinerea Pers., Alternaria alternata （Fr.） Keissl., Rhizopus nigricans Ehrenb., Penicillium ulaiense Hsieh, Su ＆ Tzean. The main pathogens causing postharvest diseases ofA. muelleri were F. solani, F. oxysporum and B. cinerea. The isolation frequencies of them were 33.9%, 10.5% and 19.4%, respectively. After artificial inoculation, the incidence of tubers infected by F. solani, F. oxysporum and B. cinerea was 100%, 83% and 95%, respectively. The results of chemical screening showed that, in potato dextrose agar （PDA） media plate, the compounds Fludioxonil （50% WP） and Boscalid （50% WG） were the most effective in controlling the three main pathogens, and the average effect reached more than 97%. The test of fungicidal antisepsis on tubers consisted ofA. muelleri being dipped in the 9,000x diluted solution of Fludioxonil （50% WP） or in the 3,500x diluted solution of Boscalid （50% WG） for 3 min and stored at room temperature （25 ℃） for 7 d and 15 d, respectively. The fungicidal effects of Fludioxonil against F. solani, F. oxysporum and B. cinerea for 7 d and 15 d were 88.6%/83.2%, 90.1%/84.7% and 93.0%/91.5%, respectively, whereas the fungicidal effects of Boscalid were 87.0%/85.3%, 89.0%/85.6% and 89.2%/89.1%, respectively. The results may provide useful information for the control ofpostharvest diseases ofA. muelleri.

Hot air treatment activates defense responses and induces resistance against Botrytis cinerea in strawberry fruit

The effect of hot air（HA, 45°C, 3.5 h） treatment on reducing gray mold caused by Botrytis cinerea in strawberry fruit and the possible mechanisms were investigated. The results showed that HA treatment significantly reduced lesion diameter and enhanced activities of chitinase（CHI）, β-1,3-glucanase and phenylalanine ammonia-lyase（PAL） in strawberry fruit. Total phenolic contents were also increased by HA treatment. The activities of antioxidant enzymes including superoxide dismutase（SOD）, catalase（CAT） and ascorbate peroxidase（APX） were higher in HA treated strawberry fruit than those in control. Expression of three defense related genes such as CAT, CCR-1 allele and PLA6 was greatly induced in HA treated strawberry fruit with or without inoculation by B. cinerea. In addition, the in vitro experiment showed that HA treatment inhibited spore germination and tube growth of B. cinerea. These results suggested that HA treatment directly activated disease resistance against B. cinerea in strawberry fruit without priming response and directly inhibiting growth of B. cinerea.

Molecular basis of pathogenesis of postharvest pathogenic Fungi and control strategy in fruits: progress and prospect

The disease caused by pathogenic fungi is the main cause of postharvest loss of fresh fruits.The formulation of disease control strategies greatly depends on the understanding of pathogenic mechanism of fungal pathogens and control strategy.In recent years,based on the application of various combinatorial research methods,some pathogenic genes of important postharvest fungal pathogens in fruit have been revealed,and their functions and molecular regulatory networks of virulence have been explored.These progresses not only provide a new perspective for understanding the molecular basis and regulation mechanism of pathogenicity of postharvest pathogenic fungi,but also are beneficial to giving theoretical guidance for the creation of new technologies of postharvest disease control.Here,we synthesized these recent advances and illustrated conceptual frameworks,and identified several issues on the focus of future studies.

What are the common anthracnose pathogens of tropical fruits?

t Species of Colletotrichum are associated with anthracnose of a wide range of host plants including cultivated and wild tropical fruits.The genetic and ecological diversity of species associated with wild fruits are poorly explored,as compared to those associated with pre and postharvest diseases of cultivated fruits.In the present study,isolates of Colletotrichum were obtained from commercially available cultivated fruits,wild fruits(from native trees in natural habitats)and a few herbaceous hosts collected in northern Thailand.These isolates were initially characterized based on analysis of complete sequences of nuclear ribosomal internal transcribed spacer(ITS),into the genetically defined species complexes of Colletotrichum gloeosporioides,C.acutatum,C.boninense and C.truncatum.The isolates were primarily identified in the C.gloeosporioides species complex,based on a strongly supported clade within the ITS gene tree and were further characterized using multi-gene phylogenetic analyses and morphology.Phylogenetic analyses of ITS,partial sequences of actin(ACT),calmodulin(CAL),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),glutamine synthetase(GS)andβtubulin(TUB2)genetic markers were performed individually and in combination.Colletotrichum gloeosporioides sensu stricto was identified from lime(Citrus aurantifolia)and rose apple(Syzygium samarangense).Colletotrichum fructicola was isolated from dragon fruit(Hylocerous undatus)and jujube(Ziziphus sp.).Colletotrichum endophytica was found only from an unknown wild fruit.We observed a considerable genetic and host diversity of species occurring on tropical fruits within the clade previously known as Colletotrichum siamense sensu lato.The clade consists of isolates identified as pre and postharvest pathogens on a wide range of fruits,including coffee(Coffea arabica),custard apple(Annona reticulata),Cerbera sp.,figs(Ficus racemosa)mango(Mangifera indica),neem(Azadirachta indica)and papaya(Carica papaya)and was the dominant group of species among most wild fruits studied.With the exception of one isolate from banana,which grouped in the C.siamense clade,all the other isolates were identified as Colletotrichum musae.A new species,Colletotrichum syzygicola,associated with Syzygium samarangense in Thailand,is introduced with descriptions and illustrations.This study highlights the need to re-assess the evolutionary relationships of Colletotrichum species occurring on cultivated and wild fruits with emphasis on their ecology and cryptic diversification including sampling at regional and global scales.

Molecular basis for optimizing sugar metabolism and transport during fruit development

Sugars are fundamental metabolites synthesized in leaves and further delivered to fruit in fruit crops.They not only provide"sweetness"as fruit quality traits,but also function as signaling molecules to modulate the responses of fruit to environmental stimuli.Therefore,the understanding to the molec-ular basis for sugar metabolism and transport is crucial for improving fruit quality and dissecting responses to abiotic/biotic factors.Here,we provide a review for mol ecular components involved in sugar metabolism and transport,crostalk with hormone signaling and the roles of sugars in responses to abiotic and biotic stresses.Moreover,we also envisage the strategies for optimizing sugar metabolism during fruit quality maintenance.