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Grey mould caused by Botrytis cinerea leads to severe economic loss on commercial tomato production. Application of beneficial microorganism offers an eco-friendly alternative for mitigation of tomato fungal disease damage, considering negative influences of fungicides. In the present study, an antagonistic Trichoderma afroharzianum isolate TM24 was evaluated for its biocontrol potential on tomato grey mould. The isolate TM24 showed obviously antagonistic effect on B. cinerea mycelium growth and production of glucanase and chitinase. Leaf spraying with spore suspension of isolate TM24 showed a biocontrol efficiency of over 54% against tomato grey mould in greenhouse pot experiment. The activities of plant defense-related enzymes including polyphenol oxidase, phenylalanine ammonialyase, superoxide dismutase, and peroxidase were all increased to varying degrees in tomato leaves after isolate TM24 treatment. Transcriptome analysis showed that, a total of 1941, 1753 and 38 differentially expressed genes (DEGs) were obtained at 24, 48 and 72 hpi, respectively, in tomato leaves pretreated with T. afroharzianum TM24, and then challenged with B. cinerea inoculation. The DEGs were mainly enriched in MAPK signaling pathway and plant hormones signal transduction pathway. Multiple genes that regulated crucial nodes of defense-related pathways, like flavonoid, phenylpropanoid, jasmonic acid and ethylene metabolisms were also identified, which may have positive correlations with the biocontrol potential of isolate TM24 in tomato plants. These promising results provided valuable information on using T. afroharzianum TM24 as a beneficial biocontrol agent in tomato grey mould management.

Camellia chrysantha is cultivated as rare genetic resource of the family Theaceae, which mainly distributed in the South of Guangxi Zhuang Autonomous Region in China. Rhizosphere microbiota may play important roles in C. chrysantha growth and homeostasis through interaction of the plant and soil ecosystem. In order to investigate the bacterial community composition in the rhizosphere soil of three C. chrysantha cultivars under different growing conditions, Illumina MiSeq high-throughput sequencing and real-time quantitative PCR methods were used in this study. Results indicated that Proteobacteria, Acidobacteria, Chloroflexi, Actinobacteria, Bacteroidetes, and Gemmatimonadetes were the top six phyla across all the six rhizosphere soil samples. The richness and diversity of bacterial community in the rhizosphere soil from cultivar “Fangpu” grown understorey (LF) in retail planting area were significantly different from the other samples. Principal coordinate analysis revealed that bacterial community composition of the rhizosphere soil from cultivar “Fangpu” grown understorey (LF) and perennial grown undershed (PFC) was obviously separated from each other as well as the other four rhizosphere soil samples. The growing conditions displayed more influences on the bacterial community composition than plant cultivars, and close correlations were found between the soil physicochemical characters of the geographical origins and the bacterial communities. This work improves understanding of the rhizosphere bacterial community composition and the influencing soil physicochemical factors, and provides basic information for cultivation and protection of the C. chrysantha plants in China.

Grey mould of tomato caused by Botrytis cinerea is a highly damaging disease worldwide. This study was aimed at identifying fungal strain QF05, which was isolated from the sandy soil collected in the Qinghai-Tibet Plateau in China and to evaluate its biocontrol potential on grey mould and growth promotion effect on tomato plants. On the basis of morphological observation and a multigene phylogeny based on the ITS, β-tubulin and calmodulin genes, QF05 was identified as Aspergillus tubingensis. An in vitro dual culture test indicated obvious antagonistic activity by strain QF05 against B. cinerea. Strain QF05 distinctly reduced grey mould in assays on tomato fruits and plants. Treatments with the culture filtrate of strain QF05 and a tenfold dilution of the filtrate gave disease biocontrol efficacy of 34.5 and 31.0% on tomato plants, respectively. QF05 also promoted seed germination and plant growth of tomato. Length and total fresh and dry mass of tomato plants were all significantly increased by 17.8, 25.7 and 56.8%, respectively, after treatment with the tenfold dilution of the culture filtrate. QF05 also had positive biocontrol attributes such as indoleacetic acid and siderophore production, phosphate solubilization, and rhizosphere colonization. All these results indicated the good performance of A. tubingensis QF05 for the biocontrol of tomato grey mould and growth promotion of tomato plants.

Brown rot caused by Monilinia spp. is among the most important postharvest diseases of commercially grown stone fruits, and application of antagonistic yeasts to control brown rot is one promising strategy alternative to chemical fungicides. In this research, new yeast strains were isolated and tested for their activity against peach brown rot caused by Monilinia fructicola. Three yeast strains were originally isolated from the surface of plums (cv Chinese Angelino) collected in the north of China. In artificially wounded inoculation tests, the yeast reduced the brown rot incidence to 20 %. The population of the yeast within inoculated wounds on peaches significantly increased at 25 °C from an initial level of 5.0×10(6) to 4.45×10(7) CFU per wound after 1 day. The antagonistic strains were belonging to a new species of the genus Candida by sequence comparisons of 26 S rDNA D1/D2 domain and internal transcribed spacer region. The strains are most closely related to C. asparagi, C. musae and C. fructus on the basis of the phylogenetic trees based on the D1/D2 region of 26S rDNA. However, the strains are notably different from C. asparagi, C. musae and C. fructus, in morphological and physiological characteristics. Therefore, the name Candida pruni is proposed for the novel species, with sp-Quan (=CBS12814T=KCTC 27526T=GCMC 6582T) as the type strain. Our study showed that Candida pruni is a novel yeast species with potential biocontrol against brown rot caused by M. fructicola on peaches.

An antagonistic bacterium, denoted as strain Z01, was isolated from suppressive soils and identified using fatty acid profile analysis and molecular tools. Its efficacy to control Fusarium oxysporum f. sp. conglutinans on rockets (cv. Eruca sativa) was investigated in the presence of the pathogen, and its effects on the growth and pigment contents of rockets, including the plant biomass and chlorophyll and carotenoid contents, were evaluated in the absence of the pathogen. Z01 was identified as Pantoea agglomerans (GenBank accession number is JX257179). Rockets were grown under greenhouse conditions for 21 days at 25 °C and 95 % relative humidity. When the antagonist suspension was applied at 108, 107 and 106 cells/ml by root-dipping for 20 min before transplanting, the disease incidence was 23.5 %, 28.5 % and 60.0 %, respectively. The disease incidence of rockets treated with carbendazim was 22.5 %, and in the inoculated control, the disease incidence was 82.0 %. In the absence of the pathogen, compared with the average plant biomass (10.7 g/4 plants) of the uninoculated control, application of the antagonist at 108 or 107 cells/ml significantly increased the biomass of the rockets by 40.9 % and 39.1 %, respectively, suggesting that Z01 had an additional ability to promote plant growth beyond its role in Fusarium wilt control. This study indicated that P. agglomerans Z01 has a potential to control Fusarium wilt in rockets. This report is the first to describe the application of P. agglomerans to control Fusarium wilt.

The efficacy of the antagonistic yeasts Pseudozyma fusiformata AP6, Metschnikowia fructicola AP47 and Aureobasidium pullulans PL5 were investigated, in combination with hot water dipping (HWD), to control brown rot of peaches caused by Monilinia laxa. The effects on postharvest fruit quality were also evaluated under semi-commercial conditions. In potato dextrose broth, HWD at 50°C for more than 40 s or at 55-60°C for more than 10 s completely suppressed M. laxa spore germination and germ tube elongation. In fruits inoculated by wounding, HWD at 55°C for 50 s significantly reduced brown rot decay and maintained fruit quality. This treatment would be optimal for commercial application. The harvested fruits were dipped in HW at 55°C for 50 s, cooled to 1°C for 10 min, dipped in the selected yeast cell suspension (108 cells ml−1) for 60 s, and then stored at 1°C and 95% relative humidity (RH). After 21 days, the disease incidence was measured and the postharvest quality parameters of the fruits, including firmness, total soluble solids, ascorbic acid and titratable acidity, were measured. When used alone, the antagonists AP6, AP47 and PL5 reduced brown rot incidence on the peaches to 28.3%, 30.0% and 25.8%, respectively, compared with 74.2% for the untreated control. However, when applied together with HWD, AP6, AP47 and PL5 reduced brown rot incidences to 16.7%, 15.8% and 17.5%, respectively, while when HWD was used alone, disease incidence was 30.0%, suggesting that HWD greatly increased the effectiveness of the antagonists. In combination with HWD, the efficacies of AP6, AP47 and PL5 signifi-cantly increased from 61.8%, 59.6% and 65.2% to 77.5%, 78.7% and 76.4%, respectively, and they were similar to the efficacy of tebuconazole (77.5%). Analysis of postharvest quality indicated that none of the treatments damaged fruit quality. Our results showed that the three antagonists combined with HWD at 55°C for 50 s exhibited potential for commercial use, as an effective alternative to fungicides in controlling postharvest brown rot of peaches. This appears to be the first report on combined application of yeast strains M. fructicola or P. fusiformata with HWD to control M. laxa on peaches.

The permafrost soil of Mo-he in Northeast China presents a typical cold environment colonized by psychrophilic microorganisms. This study is aimed at assessing the bacterial communities of permafrost soil of Mo-he in China by sequencing the 16S rRNA genes and Mothur analysis. PCR products with universal 16S rRNA gene primers were cloned and partially sequenced, and bacterial identification at the species was performed by comparative analysis with the GenBank/EMBL/DDBJ database. A total of 266 clones were obtained with the average length of 1,050 bp. Mothur analysis showed that the coverage value of clone library was 53.78 %, Shannon diversity (H) was 4.03, Simpson diversity value was 0.018, and 74 operational taxonomic units were generated. Through phylogenetic assignment using BLASTN by more than 97 % similarity, a total of 87 tentative taxa were identified. The majority of bacterial sequences recovered in this study belonged to the Acidobacteria, Proteobacteria, Verrucomicrobia, Bacteroidetes, Chloroflexi and Chlorobi. Among them, Acidobacteria are dominant community, accounting for 30.1 % of total bacteria, followed by Proteobacteria which accounted for 22.2 %. This result reflected the acidic characteristics of the permafrost soil of which pH value was 6.0. Our study indicated that the permafrost soil of Mo-he in China has a high diversity of bacteria and represents a vast potential resource of novel bacteria. As far as we knew, this is the first report on bacterial diversity of permafrost soil of Mo-he in China.