Trichoderma spp. are widely used in plant disease control and growth promotion due to their high efficacy and multiple biocontrol mechanisms. Trichoderma koningiopsis T-51 is an effective biocontrol agent against gray mold disease by direct contact. However, the indirect physical contact biocontrol potential of Trichoderma spp. is not clear. In this study, the volatile organic compounds (VOCs) produced by T-51 showed high inhibitory activity against plant pathogenic fungi Botrytis cinerea and Fusarium oxysporum. The percentage of B. cinerea and F. oxysporum mycelial growth inhibition by T-51 VOCs was 73.78% and 43.68%, respectively. In both B. cinerea and F. oxysporum, conidial germination was delayed, and germ tube elongation was suppressed when exposed to T-51 VOCs, and the final conidial germination rate of B. cinerea decreased significantly after T-51 treatment. The VOCs from T-51 reduced the Botrytis fruit rot of tomato compared with that noted when using the control. Moreover, the T-51 VOCs significantly increased the size and weight of Arabidopsis thaliana seedlings. Twenty-four possible compounds, which were identified as alkenes, alkanes, and esters, were detected in VOCs of T-51. These results indicate that T. koningiopsis T-51 can exert biological control by integrating actions to suppress plant disease and promote plant growth.

Mycoviruses widely exist in filamentous fungi and sometimes cause phenotypic changes in hosts. Trichoderma harzianum hypovirus 1 (ThHV1) and its defective RNA ThHV1-S were found in T. harzianum and exhibited high transmissibility. In our previous study, ThHV1 and ThHV1-S were transferred to an excellent biological control agent T. koningiopsis T-51 to form a derivative strain 51-13. In this study, we assessed the metabolic changes in strain 51-13 and antifungal activity of its culture filtrate (CF) and volatile organic compounds (VOCs). The antifungal activity of CF and VOCs of T-51 and 51-13 was different. Compared with the CF of T-51, that of 51-13 exhibited high inhibitory activity against B. cinerea, Sclerotinia sclerotiorum, and Stagonosporopsis cucurbitacearum but low inhibitory activity against Leptosphaeria biglobosa and Villosiclava virens. The VOCs of 51-13 exhibited high inhibitory activity against F. oxysporum but low inhibitory activity against B. cinerea. The transcriptomes of T-51 and 51-13 were compared; 5531 differentially expressed genes (DEGs) were identified in 51-13 with 2904 up- and 2627 downregulated genes. In KEGG enrichment analysis, 1127 DEGs related to metabolic pathways (57.53%) and 396 DEGs related to biosynthesis of secondary metabolites (20.21%) were clearly enriched. From the CF of T-51 and 51-13, 134 differential secondary metabolites (DSMs) were detected between T-51 and 51-13 with 39 up- and 95 downregulated metabolites. From these, 13 upregulated metabolites were selected to test their antifungal activity against B. cinerea. Among them, indole-3-lactic acid and p-coumaric acid methyl ester (MeCA) exhibited strong antifungal activity. The IC₅₀ of MeCA was 657.35 μM and four genes possibly related to the synthesis of MeCA exhibited higher expression in 51-13 than in T-51. This study revealed the mechanism underlying the increase in antifungal activity of T-51 because of the mycovirus and provided novel insights in fungal engineering to obtain bioactive metabolites via mycoviruses.

Soil salinisation has become one of the major abiotic stresses limiting crop growth in the world. To enhance soybean productivity on saline lands, understanding its salt-stress response and underlying mechanisms is necessary. In this study, the salt-tolerant soybean Kefeng 1 and the salt-sensitive soybean Qihuang 1 were used to elucidate the synergistic regulatory networks underlying soybean salt tolerance. After 12 days of 150 mM NaCl treatment, both varieties were subjected to phenotypic evaluation, physiological measurements, and integrated transcriptomic and metabolomic analysis. The results showed that the salt tolerance in Kefeng 1 primarily originated from its root. Under salt stress, Kefeng 1 maintained Na⁺/K⁺ ion homeostasis by up-regulating Cation/H⁺ Exchanger 15 (CHX15) and Cation Exchanger 3 (CAX3), and down-regulating Cyclic Nucleotide-Gated Channel 13 (CNGC13). Furthermore, Kefeng 1 stabilised auxin (IAA) homeostasis by inhibiting IAA biosynthesis and regulating concentrations through PIN-FORMED 3 (PIN3)-mediated efflux. It also scavenged reactive oxygen species (ROS) by employing enhanced enzymatic antioxidant systems, specifically aldo-keto reductase 1 (AKR1), glutathione S-transferase (GST), and catalase (CAT), alongside non-enzymatic antioxidants like the isoflavone genistein. Gene–metabolite correlation network analysis identified Glyma.09G117900 (PIN3) and Glyma.19G244200 (AKR1) as two hub genes. These two genes were specifically up-regulated in Kefeng 1 root under NaCl stress, and the proteins they encoded played important roles in salt tolerance in Kefeng 1 root as described above. Accordingly, these two genes were identified as candidate genes for salt tolerance in Kefeng 1. This study offered a theoretical framework and genetic resources for developing salt-tolerant soybean cultivars.

Watermelon is one of the most important edible plants worldwide. Owing to its special cultivation conditions, watermelon is exposed to many biological and abiotic stresses during its development. Lectin receptor-like kinases (LecRLKs) are plant-specific membrane proteins that play important roles in sensing and responding to environmental stimuli. Although the LecRLK gene family has been identified in a variety of plants, a comprehensive analysis has not yet been undertaken in watermelon. In this study, 61 putative LecRLK genes were identified in watermelon, consisting of 36 G-type, 24 L-type, and 1 C-type LecRLK genes. They were distributed in clusters on chromosomes, and members from the same subfamily were mostly clustered together. The analysis of the phylogenetic tree and conserved motif indicated that there were obvious differences among three ClaLecRLK subfamilies, and there was also rich diversity in the C-terminal within subfamilies. A collinear analysis revealed that the evolution of the ClaLecRLK gene family in different Cucurbitaceae crops was asynchronous. Furthermore, the analysis of the ClaLecRLK protein structure showed that not all proteins contained signal peptides and a single transmembrane domain. A subcellular localization assay confirmed that the number and position of transmembrane domains did not affect ClaLecRLK protein localization in cells. Transcriptome data revealed distinct expression patterns of LecRLK genes of watermelon in various tissues, and their responses to different fungi infection were also significantly different. Finally, the potential binding sites of the ClaLecRLK genes targeted by miRNA were predicted. This study enhances the understanding of the characteristics and functions of the LecRLK gene family in watermelon and opens up the possibility of exploring the roles that LecRLK genes may play in the life cycle of Cucurbitaceae plants.

Shanghai-native vegetable soybean (Glycine max [L.] Merril) landraces are valuable germplasms, but their systematic evaluation for agronomic and nutritional traits remains insufficient. This study aimed to assess their phenotypic and nutritional diversity to explore their potential for breeding and meeting dietary needs. Twenty-nine local landraces and one control cultivar (‘Qingsu 7’) were evaluated for key agronomic traits, yield components, nutritional traits, and isoflavone profiles, using hierarchical clustering, principal component analysis (PCA), and correlation analysis. Substantial phenotypic diversity was found, with the germplasm classified into four groups. First pod height and effective pods per plant were highly variable. Nutritional traits showed low variability for crude protein but high diversity for crude fat, soluble sugars (dominated by sucrose), vitamin C, and free amino acids. Total isoflavone content in dry seeds varied widely, with genistin, daidzin, and daidzein as the main forms. ‘Xiangshui Maodou’ had high free amino acids and vitamin C, ‘Heiyan Susudou’ showed superior soluble sugar content, and two landraces exceeded 1500 μg/g DW total isoflavones. The landraces possess rich phenotypic diversity and nutritional diversity. This germplasm represents a valuable resource for breeding programs to enhance crop quality and address global nutritional demands.