A Comparative Analysis of the Microbiome of Kiwifruit at Harvest Under Open-Field and Rain-Shelter Cultivation Systems

Climate Change Impacts on and Response Strategies for Kiwifruit Production: A Comprehensive Review

Climate change, a pressing global concern, poses significant challenges to agricultural systems worldwide. Among the myriad impacts of climate change, the cultivation of kiwifruit trees (Actinidia spp.) faces multifaceted challenges. In this review, we delve into the intricate effects of climate change on kiwifruit production, which span phenological shifts, distributional changes, physiological responses, and ecological interactions. Understanding these complexities is crucial for devising effective adaptation and mitigation strategies to safeguard kiwifruit production amidst climate variability. This review scrutinizes the influence of rising global temperatures, altered precipitation patterns, and a heightened frequency of extreme weather events on the regions where kiwifruits are cultivated. Additionally, it delves into the ramifications of changing climatic conditions on kiwifruit tree physiology, phenology, and susceptibility to pests and diseases. The economic and social repercussions of climate change on kiwifruit production, including yield losses, livelihood impacts, and market dynamics, are thoroughly examined. In response to these challenges, this review proposes tailored adaptation and mitigation strategies for kiwifruit cultivation. This includes breeding climate-resilient kiwifruit cultivars of the Actinidia species that could withstand drought and high temperatures. Additional measures would involve implementing sustainable farming practices like irrigation, mulching, rain shelters, and shade management, as well as conserving soil and water resources. Through an examination of the literature, this review showcases the existing innovative approaches for climate change adaptation in kiwifruit farming. It concludes with recommendations for future research directions aimed at promoting the sustainability and resilience of fruit production, particularly in the context of kiwifruit cultivation, amid a changing climate.

Characteristics of Corynespora cassiicola, the causal agent of tobacco Corynespora leaf spot, revealed by genomic and metabolic phenomic analysis

Corynespora cassiicola is a highly diverse fungal pathogen that commonly occurs in tropical, subtropical, and greenhouse environments worldwide. In this study, the isolates were identified as C. cassiicola, and the optimum growth and sporulation were studied. The phenotypic characteristics of C. cassiicola, concerning 950 different growth conditions, were tested using Biolog PM plates 1-10. In addition, the strain of C. cassiicola DWZ from tobacco hosts was sequenced for the using Illumina PE150 and Pacbio technologies. The host resistance of tobacco Yunyan 87 with different maturity levels was investigated. In addition, the resistance evaluation of 10 common tobacco varieties was investigated. The results showed that C. cassiicola metabolized 89.47% of the tested carbon source, 100% of the nitrogen source, 100% of the phosphorus source, and 97.14% of the sulfur source. It can adapt to a variety of different osmotic pressure and pH environments, and has good decarboxylase and deaminase activities. The optimum conditions for pathogen growth and sporulation were 25-30 °C, and the growth was better on AEA and OA medium. The total length of the genome was 45.9 Mbp, the GC content was 51.23%, and a total of 13,061 protein-coding genes, 202 non-coding RNAs and 2801 and repeat sequences were predicted. Mature leaves were more susceptible than proper mature and immature leaves, and the average diameter of diseased spots reached 17.74 mm at 12 days. None of the tested ten cultivars exhibited obvious resistance to Corynespora leaf spot of tobacco, whereby all disease spot diameters reached > 10 mm and > 30 mm when at 5 and 10 days after inoculation, respectively. The phenotypic characteristics, genomic analysis of C. cassiicola and the cultivar resistance assessment of this pathogen have increased our understanding of Corynespora leaf spot of tobacco.

Kiwifruit resistance to gray mold is enhanced by yeast-induced modulation of the endophytic microbiome

The influence of endophytic microbial community on plant growth and disease resistance is of considerable importance. Prior research indicates that pre-treatment of kiwifruit with the biocontrol yeast Debaryomyces hansenii suppresses gray mold disease induced by Botrytis cinerea. However, the specific underlying mechanisms remain unclear. In this study, Metagenomic sequencing was utilized to analyze the composition of the endophytic microbiome of kiwifruit under three distinct conditions: the healthy state, kiwifruit inoculated with B. cinerea, and kiwifruit treated with D. hansenii prior to inoculation with B. cinerea. Results revealed a dominance of Proteobacteria in all treatment groups, accompanied by a notable increase in the relative abundance of Actinobacteria and Firmicutes. Ascomycota emerged as the major dominant group within the fungal community. Treatment with D. hansenii induced significant alterations in microbial community diversity, specifically enhancing the relative abundance of yeast and exerting an inhibitory effect on B. cinerea. The introduction of D. hansenii also enriched genes associated with energy metabolism and signal transduction, positively influencing the overall structure and function of the microbial community. Our findings highlight the potential of D. hansenii to modulate microbial dynamics, inhibit pathogenic organisms, and positively influence functional attributes of the microbial community.

Quality Changes and Fungal Microbiota Dynamics in Stored Jujube Fruits: Insights from High-Throughput Sequencing for Food Preservation

Postharvest rot is an urgent problem affecting the storage of winter jujube. Therefore, the development of new technologies for efficient and safe preservation is very important. This study aimed to elucidate the fungal microbiota found on the epidermis of jujube during the storage period using high-throughput sequencing, as well as to monitor the changes in quality indexes throughout this period. Through internal transcribed spacer (ITS) sequencing, we identified two phyla (Basidiomycota and Ascomycota) and six genera (Cryptococcus, Bulleromyces, Sporidiobolus, Alternaria, Pseudozyma, and Sporobolomyces), which potentially contribute to the spoilage and deterioration of jujube, referred to as "core fungal taxa". A high correlation was further found between preservation indices (including decay rate, firmness, and total soluble solids) and the growth of multiple core fungi over time. These findings will provide insights and a theoretical basis for further research on preservation techniques related to biological control during date fruit storage.

Pathogenic fungi shape the fungal community, network complexity, and pathogenesis in kiwifruit

Kiwifruit decay caused by endophytic fungi is affected by exogenous pathogens that trigger changes in fungal community composition and interact with the endophytic fungal community. Four fungal pathogens of kiwifruit were identified. These were Aspergillus japonicus, Aspergillus flavus, Botryosphaeria dothidea, and Penicillium oxalicum. Except for P. oxalicum, the remaining three species represent newly described pathogens of kiwifruit. All four fungal species caused disease and decay in mature kiwifruit. Results of the fungal community analysis indicated that three pathogens that A. japonicus, A. flavus and P. oxalicum were the most dominant, however, other fungal species that did not cause disease symptoms were also present. Positive interactions between fungal species were found in asymptomatic, symptomatic, and infected kiwifruit. The ability of all four pathogens to infect kiwifruit was confirmed in an inoculation experiment. The presence of any one of the four identified pathogens accelerated decay development and limited the postharvest longevity of harvested kiwifruit. Results of the study identified and confirmed the ability of four fungal species to infect and cause decay in harvested kiwifruit. Changes in the structure and composition of the kiwifruit microbiome during the decay process were also characterized. This provides a foundation for the further study of the microbiome of kiwifruit and their involvement in postharvest diseases.

Effect of Different Pre-Growth Temperatures on the Survival Kinetics of Salmonella enterica and Listeria monocytogenes in Fresh-Cut Salad during Refrigerated Storage

The effect of the pre-growth temperature of bacterial cultures on their subsequent survival kinetics in fresh-cut produce during refrigerated storage was investigated in this study. Three-strain cocktails of Listeria monocytogenes and Salmonella enterica, cultured at different growth temperatures (4, 21, and 37 °C) were inoculated on fresh-cut mixed salad and on individual produce in the mixed salad. The inoculated samples were stored at 4 °C and 80 ± 2% relative humidity (RH) for up to 72 h and the growth, survival, or death kinetics were determined at regular intervals. The results indicate that depending upon the type of pathogen tested, the pre-growth temperature(s) and the type of produce showed a significant (p ≤ 0.05) effect on the survival kinetics. Among the tested produce, mixed salad showed the highest reduction in L. monocytogenes pre-grown at 37 °C (1.33 log CFU/g) followed by red cabbage (0.56 log CFU/g), iceberg lettuce (0.52 log CFU/g), and carrot (-0.62 log CFU/g), after 72 h, respectively. In the case of Salmonella, carrot showed the highest reduction (1.07 log CFU/g for 37 °C pre-grown culture) followed by mixed salad (0.78 log CFU/g for 37 °C pre-grown culture), cabbage (0.76 log CFU/g for 21 °C pre-grown culture), and lettuce (0.65 log CFU/g for 4 °C pre-grown culture), respectively. Among the tested ComBase predictive models, the Baranyi-Roberts model better fitted the experimental data. These findings indicate that the appropriate selection of pre-growth environmental conditions is critical to better understand the kinetics of foodborne pathogens.

High-Quality Genome Resource of Gilbertella persicaria Causing Peach Soft Rot

Peach soft rot caused by Gilbertella persicaria is an economically important disease. Here, we report a high-quality complete and annotated genome sequence of G. persicaria strain TFLB-J, isolated from peach fruit in Yuanyang county of Henan Province, China. The assembly consists of 91 scaffolds with an estimated genome size of 33.59 Mb and N₅₀ length of 0.92 Mb, encoding 13,296 predicted protein-coding genes. The whole-genome sequence could provide gene resources for further study of pathogenic effectors and comparative genomics of peach soft rot pathogens.