Investigation of the role of AcTPR2 in kiwifruit and its response to Botrytis cinerea infection

Comparative transcriptomic and physiological analyses reveal the key role of abscisic acid in hydrangea macrophylla responding to Corynespora cassiicola

BACKGROUND

Bigleaf hydrangea (Hydrangea macrophylla) is a widely cultivated ornamental plant species. Leaf spot disease, caused by Corynespora cassiicola, poses a significant threat to the ornamental quality and economic value of hydrangeas. However, the disease resistance breeding of hydrangea is limited due to the lacking of resistant varieties and genes.

RESULTS

This study evaluated ten hydrangea varieties for their resistance to leaf spot disease. Among them, 'White Angel' and 'Ocean Heart' were screened out as representative varieties for resistance and susceptibility, respectively, on the basis of evaluation. Physiological and biochemical indices, phytohormones, and transcriptomic changes were measured in the leaves of both varieties at 0 and 24 h post inoculation with C. cassiicola. The results showed that C. cassiicola infection significantly increased abscisic acid (ABA) contents in both varieties; however, the increase was significantly higher in the susceptible variety 'Ocean Heart' compared to the resistant variety 'White Angel' (p < 0.05). Moreover, exogenous ABA (100 µM) decreased the leaves' resistance to C. cassiicola of both varieties, underscoring its key role in reduced disease resistance. Transcriptome profiling revealed 17,087 differentially expressed genes (DEGs) responding to C. cassiicola between the two varieties. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated significant enrichment of DEGs in "Plant hormone signal transduction", particularly related to ABA signaling (HmPP2C and HmABFs). In addition, the expression of ABA biosynthesis genes (HmZEP3, HmABA2, and HmAAO3) was upregulated in both varieties. Meanwhile, the ABA catabolism gene (HmCYP707A4) exhibited significantly upregulated expression in the resistant variety 'White Angel' and downregulated expression in the susceptible variety 'Ocean Heart'. Intriguingly, the expression of HmCYP707A4 was 15-fold higher in 'White Angel' than in 'Ocean Heart'.

CONCLUSION

In summary, these findings highlight the crucial role of ABA in the resistance of bigleaf hydrangea to leaf spot disease and provide valuable genetic resources for breeding programs to enhance the disease resistance in hydrangeas.

Eco-friendly managements and molecular mechanisms for improving postharvest quality and extending shelf life of kiwifruit: A review

Kiwifruit (Actinidia spp.) is a commercially important horticultural fruit crop worldwide. Kiwifruit contains numerous minerals, vitamins, and dietary phytochemicals, that not only responsible for the flavor but can also serve as adjuncts in the treatment of diabetes, digestive disorders, cardiovascular system, cancer and heart disease. However, fruit quality and shelf life affect consumer's acceptance and production chain. Understanding the methods of fruit storage preservation, as well as their biochemical, physiological, and molecular basis is essential. In recent years, eco-friendly (comprehensive and environmentally friendly) treatments such as hot water, ozone, chitosan, quercetin, and antifungal additive from biocontrol bacteria or yeast have been applied to improve postharvest fruit quality with longer shelf life. This review provides a comprehensive overview of the latest advancements in control measures, applications, and mechanisms related to water loss, chilling injury, and pathogen diseases in postharvest kiwifruit. Further studies should utilize genome editing techniques to enhance postharvest fruit quality and disease resistance through site-directed bio-manipulation of the kiwifruit genome.

Virus-Induced Gene Silencing (VIGS) in Chinese Jujube

Virus-induced gene silencing (VIGS) is a fast and efficient method for assaying gene function in plants. At present, the VIGS system mediated by Tobacco rattle virus (TRV) has been successfully practiced in some species such as cotton and tomato. However, little research of VIGS systems has been reported in woody plants, nor in Chinese jujube. In this study, the TRV-VIGS system of jujube was firstly investigated. The jujube seedlings were grown in a greenhouse with a 16 h light/8 h dark cycle at 23 °C. After the cotyledon was fully unfolded, Agrobacterium mixture containing pTRV1 and pTRV2-ZjCLA with OD₆₀₀ = 1.5 was injected into cotyledon. After 15 days, the new leaves of jujube seedlings showed obvious photo-bleaching symptoms and significantly decreased expression of ZjCLA, indicating that the TRV-VIGS system had successfully functioned on jujube. Moreover, it found that two injections on jujube cotyledon could induce higher silencing efficiency than once injection. A similar silencing effect was then also verified in another gene, ZjPDS. These results indicate that the TRV-VIGS system in Chinese jujube has been successfully established and can be applied to evaluate gene function, providing a breakthrough in gene function verification methods.

Transgene-free genome editing and RNAi ectopic application in fruit trees: Potential and limitations

For the past fifteen years, significant research advances in sequencing technology have led to a substantial increase in fruit tree genomic resources and databases with a massive number of OMICS datasets (transcriptomic, proteomics, metabolomics), helping to find associations between gene(s) and performance traits. Meanwhile, new technology tools have emerged for gain- and loss-of-function studies, specifically in gene silencing and developing tractable plant models for genetic transformation. Additionally, innovative and adapted transformation protocols have optimized genetic engineering in most fruit trees. The recent explosion of new gene-editing tools allows for broadening opportunities for functional studies in fruit trees. Yet, the fruit tree research community has not fully embraced these new technologies to provide large-scale genome characterizations as in cereals and other staple food crops. Instead, recent research efforts in the fruit trees appear to focus on two primary translational tools: transgene-free gene editing via Ribonucleoprotein (RNP) delivery and the ectopic application of RNA-based products in the field for crop protection. The inherent nature of the propagation system and the long juvenile phase of most fruit trees are significant justifications for the first technology. The second approach might have the public favor regarding sustainability and an eco-friendlier environment for a crop production system that could potentially replace the use of chemicals. Regardless of their potential, both technologies still depend on the foundational knowledge of gene-to-trait relationships generated from basic genetic studies. Therefore, we will discuss the status of gene silencing and DNA-based gene editing techniques for functional studies in fruit trees followed by the potential and limitations of their translational tools (RNP delivery and RNA-based products) in the context of crop production.

Redox and Hormonal Changes in the Transcriptome of Grape (Vitis vinifera) Berries during Natural Noble Rot Development

Noble rot is a favorable form of the interaction between grape (Vitis spp.) berries and the phytopathogenic fungus Botrytis cinerea. The transcriptome pattern of grapevine cells subject to natural noble rot development in the historic Hungarian Tokaj wine region has not been previously published. Furmint, a traditional white Tokaj variety suited to develop great quality noble rot was used in the experiments. Exploring a subset of the Furmint transcriptome redox and hormonal changes distinguishing between noble rot and bunch rot was revealed. Noble rot is defined by an early spike in abscisic acid (ABA) accumulation and a pronounced remodeling of ABA-related gene expression. Transcription of glutathione S-transferase isoforms is uniquely upregulated, whereas gene expression of some sectors of the antioxidative apparatus (e.g., catalases, carotenoid biosynthesis) is downregulated. These mRNA responses are lacking in berries exposed to bunch rot. Our results help to explain molecular details behind the fine and dynamic balance between noble rot and bunch rot development.