Chitinase of Trichoderma longibrachiatum for control of Aphis gossypii in cotton plants

Expression of endochitinase and exochitinase in lettuce chloroplasts increases plant biomass and kills fungal pathogen Candida albicans

Lettuce (Lactuca sativa) is a popular leafy vegetable with global production of ~28 million Mt, cultivated >1 million hectares, with a market value of US$ 4 billion in 2022. However, lettuce is highly susceptible to fungal pathogens that drastically reduce biomass and quality due to spoilage/rot. Therefore, in this study, we investigated the expression of chitinase genes via the lettuce chloroplast genome to enhance biomass and disease resistance. Site-specific integration of the expression cassette into chloroplast genomes was confirmed using two sets of PCR primers. Homoplasmy in transplastomic lines was confirmed in Southern blots by the absence of untransformed genomes. Maternal inheritance of transgenes was confirmed by the lack of segregation when seedlings were germinated in the selection medium. Chitinases expressed in chloroplasts are active in a broad range of pH (5-9) and temperatures (20-50 °C). Exochitinase expression significantly increased the number of leaves, root or shoot length and biomass throughout the growth cycle. Endochitinase expression reduced root/shoot biomass at early stages but recovered in older plants. Plant extracts expressing endochitinase/exochitinase showed activities as high as purified commercial enzymes. Antifungal activity in Candida albicans cultures inhibited growth up to 87%. A novel Carbotrace 680™ Optotracer binding to the ß-1,4 linkages of chitin, evaluated for the first time in plant systems, is highly sensitive to measure chitinase activity. To the best of our knowledge, this is the first report of chitinase expression via the chloroplast genomes of an edible plant, to confer desired agronomic traits or for biomedical applications.

Function of chitinase in Penicillium ochrochloron Q-3-1 and its insecticidal and antifungal mechanism and biological control against citrus pests and diseases

The biocontrol potential strain of Penicillium ochrochloron Q-3-1 was isolated from Hepialus armoricanus larvae. However, the insecticidal and antifungal mechanisms of Q-3-1 are still unclear. Eleven chitinase genes (Poch1-Poch11) were isolated for functional identification. During Q-3-1 infection, Poch1, Poch2, and Poch11 were upregulated in Galleria mellonella, whereas Poch4, Poch6, and Poch11 were upregulated in Diaphorina citri. Chitinase activity was determined based on the expression of the chitinase genes in an in vitro prokaryotic expression system and an analysis of the p-nitrophenol (pNP) degradation ability of recombinant chitinase. They exhibit excellent degradation activities for chitin, citrus pectin, D-cellobiose, and G. mellonella epidermis. The exonuclease activity of Poch1 can effectively degrade insect chitin and pectin. The insect chitin utilization rate of Poch11 is higher than that of pectin, and it can randomly degrade different pNP substrates. In addition, the present study found that exogenous chitinase proteins showed significant antagonistic ability against citrus pathogens. The special antifungal and insecticidal character of Q-3-1 may lead to its potential application in agriculture as a biological control agent.

Potential Role of Malassezia restricta in Pterygium Development

Pterygium is a condition affecting the ocular surface, marked by a triangular-shaped growth of fibrotic tissue extending from the nasal conjunctiva toward the corneal center, potentially causing visual impairment. While ultraviolet (UV )light exposure is the primary risk factor for pterygium, its underlying cause remains unclear. In order to better understand the true genesis of pterygium development, we investigated pterygium tissue and compared it with healthy conjunctiva controls. Given the eye's direct environmental exposure, we analyzed the microbiota composition using metagenomic sequencing of pterygium tissue to identify microbes potentially associated with this condition. Metagenomic sequencing revealed a higher prevalence of the fungus Malassezia restricta in five pterygium samples, confirmed by in situ hybridization. The CHIT1 gene, which plays a role in antifungal defenses, displayed the highest expression in five pterygium tissue samples compared to healthy conjunctiva controls, suggesting the potential involvement of Malassezia restricta in pterygium development. Gene expression profiling of pterygium highlighted an IL-33 and IL-4 gene expression signature, along with an increased presence of M2 macrophages, emphasizing their role in promoting fibrosis-a hallmark feature of pterygium. The detection of Malassezia restricta in the pterygium samples and associated molecular changes provides novel insights into the ocular microbiome and raises the possibility of Malassezia's involvement in pterygium pathology.

Identification of mycoparasitism-related genes in Trichoderma harzianum T4 that are active against Colletotrichum musae

Trichoderma harzianum is a well-known biological control agent (BCA) that shows great potential in controlling many pathogenic fungi. To screen for genes associated with mycoparasitism, we sequenced and analyzed the transcriptome of T. harzianum T4 grown in dual culture with Colletotrichum musae. We analyzed differentially expressed genes (DEGs) of Trichoderma harzianum T4 in three different culture periods: before contact (BC), during contact (C) and after contact (AC). A total of 1453 genes were significantly differentially expressed compared to when T. harzianum T4 was cultured alone. During the three periods of double culture of T. harzianum T4 with C. musae, 74, 516, and 548 genes were up-regulated, respectively, and 11, 315, and 216 genes were down-regulated, respectively. The DEGs were screened using GO and KEGG enrichment analyses combined with differential expression multiples. Six gene categories related to mycoparasitism were screened: (a) pathogen recognition and signal transduction, (b) hydrolases, (c) ribosomal proteins and secreted proteins, (d) multidrug-resistant proteins and transporters, (e) heat shock proteins and detoxification, and (f) oxidative stress and antibiotics-related genes. The expression levels of 24 up-regulated genes during T. harzianum T4's antagonistic interaction with C. musae were detected via real-time fluorescence quantitative PCR (RT-qPCR). This study provided information on the transcriptional expression of T. harzianum T4 against C. musae. These results may help us to further understand the mechanism of mycoparasitism, which can provide a potential molecular target for improving the biological control capacity of T. harzianum T4.