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The flowering of Amorphophallus bulbifer (A. bulbifer) plays an important role in its reproduction. The flowers and leaves of A. bulbifer cannot grow at the same time. However, the physiological and molecular mechanisms involved in flower bud and leaf bud formation are still unclear. In this study, the flower buds and leaf buds of A. bulbifer in the early stage of growth were used as research materials, transcriptome and metabolome analyses were carried out, and the soluble sugar and starch contents of A. bulbifer corms were determined. Transcriptome analysis revealed 5542 differentially expressed genes (DEGs) between flower buds and leaf buds, 3107 of which were upregulated and 2435 of which were downregulated. Enrichment analysis of the KEGG pathway showed that these differential genes were enriched mainly in the plant hormone signal transduction, DNA replication and fatty acid elongation pathways. A total of 5296 significant differentially abundant metabolites were screened out by nontargeted metabolomics analysis. The differentially abundant metabolites were functionally classified in the HMDB, and 118 were successfully matched, including 17 that were highly expressed in flower buds. The differentially abundant metabolites in the flower buds were mainly enriched in pathways such as amino acid metabolism, isoquinoline alkaloid biosynthesis and pyrimidine metabolism. Targeted metabolomics analysis revealed that the contents of ABA, ZT and iPA in flower buds were significantly greater than those in leaf buds, while the opposite trend was observed for IAA. The analysis of soluble sugar and starch contents showed that the starch and soluble sugar contents in flower buds were significantly greater than those in leaf buds. The results of this study showed that flower bud development in A. bulbifer was regulated by amino acids, starch, ABA, ZT, iPA, IAA and other hormones. These findings could lead to valuable genetic resources for further study of A. bulbifer flowering and provide a deeper understanding of the molecular basis of A. bulbifer flowering.

Salinity is a prominent environmental stressor that significantly impacts plant growth and development. Here, we conducted research on the physiological and transcriptomic mechanism of a wild cucumber, Cucumis hystrix Chakr, under NaCl stress. Physiological data showed that contents of malondialdehyde, peroxide (H2O2), proline, soluble sugar, and activities of antioxidant enzymes of superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione reductase in wild cucumber plants were increased significantly after NaCl treatment. Transcriptomic analysis revealed that 3509 transcripts were differentially expressed in leaves and 5516 transcripts in roots after NaCl treatment. Numerous genes were related to the signal transduction, transcription factor, ion transport, osmotic metabolism, and reactive oxygen species scavenging. Moreover, the thioredoxin H type gene of Cucumis hystrix Chakr (ChTrxh) was isolated and characterized. Our study demonstrated that the transgenic tobacco plants overexpressing ChTrxh exhibited enhanced tolerance to NaCl stress compared to wild-type plants. These findings contribute valuable insights into the functional characteristics of important genes in wild cucumber under NaCl stress.

Nitric oxide (NO) modulates plant response by post-translationally modifying proteins, mainly through S-nitrosylation. Ascorbate peroxidase (APX) in the ascorbate-glutathione (AsA-GSH) cycle participates in the removal of hydrogen peroxide (H2O2). However, the relationship between S-nitrosylation and the role of tomato APX (SlAPX) under nitrate stress is still unclear. In this study, the enzyme activity, mRNA expression, and S-nitrosylation level of SlAPX were significantly increased in tomato roots after nitrate treatment. SlAPX protein could be S-nitrosylated by S-nitrosoglutathione in vitro, and APX activity was significantly increased after S-nitrosylation. The SlAPX overexpressed tobacco plants grew better than the wild type (WT) plants under nitrate stress. Meanwhile, the transgenic plants showed lower reactive oxygen species and malondialdehyde content, higher APX, monodehydroascorbate reductase, glutathione reductase activities, ascorbic acid/dehydroascorbic acid, and reduced glutathione/oxidized glutathione ratio, proline, and soluble sugar contents than those in the WT plants under nitrate treatment. Moreover, overexpressed transgenic seeds showed higher tolerance to methyl viologen induced oxidative stress compared with the WT. The NO accumulation and S-nitrosylation APX level were higher in transgenic plants than in WT plants after nitrate stress treatment. Our results provide novel insights into the mechanism of SlAPX modulation excess nitrate stress tolerance involving the S-nitrosylation modification.

Myelocytomatosis (MYC) transcription factors are crucial mediators of the jasmonate signaling pathway, which mediates the growth and developmental processes of plants. However, the function of MYC genes in tomato, Solanum lycopersicum (SlMYC), remains poorly understood. In this study, we have identified 14 non-redundant SlMYC genes across the genome of tomatoes. Six of the twelve chromosomes included these genes, and four syntenic pairs of SlMYC were identified. According to the results of phylogenetic analysis, 14 SlMYC genes were clustered into classes I, II, III, and IV, and their functional domains were predicted. The SlMYC upstream promoter region contained a variety of light-, stress-, and hormone-response regulatory elements. The expression of the 14 SlMYC genes differed significantly across organs. SlMYCs primarily showed an upregulation trend after methyl jasmonate (MeJA) treatment. In contrast, after treatment with sodium chloride (NaCl), SlMYCs showed a trend of downregulation. However, there were differences in the expression patterns of SlMYCs after mannitol treatment. Using clustered regularly interspaced short palindromic repeats/Cas 9 (CRISPR/Cas 9) technology, the loss-of-function of SlMYC1 (slmyc1) was obtained. The slmyc1 tomato plants demonstrated reduced resistance to NaCl and mannitol stress compared to wild-type plants due to their shorter root length and higher reactive oxygen species (ROS) content. In brief, this study provides valuable information about the taxonomy of the SlMYC genes in tomato. It establishes a foundation for future research on the mechanism by which SlMYC influences plant development and stress response.

Manganese peroxidases (MnPs), gene family members of white-rot fungi, are necessary extracellular enzymes that degrade lignocellulose and xenobiotic aromatic pollutants. However, very little is known about the diversity and expression patterns of the MnP gene family in white-rot fungi, especially in contrast to laccases. Here, the gene and protein sequences of eight unique MnP genes of T. trogii S0301 were characterized. Based on the characteristics of gene sequence, all TtMnPs here belong to short-type hybrid MnP (type I) with an average protein length of 363 amino acids, 5–6 introns, and the presence of conserved cysteine residues. Furthermore, analysis of MnP activity showed that metal ions (Mn2+ and Cu2+) and static liquid culture significantly influenced MnP activity. A maximum MnP activity (>14.0 U/mL) toward 2,6-DMP was observed in static liquid culture after the addition of Mn2+ (1 mM) or Cu2+ (0.2 or 2 mM). Moreover, qPCR analysis showed that Mn2+ obviously upregulated the Group I MnP subfamily (T_trogii_09901, 09904, 09903, and 09906), while Cu2+ and H2O2, along with changing temperatures, mainly induced the Group II MnP subfamily (T_trogii_11984, 11971, 11985, and 11983), suggesting diverse functions of fungal MnPs in growth and development, stress response, etc. Our studies here systematically analyzed the gene structure, expression, and regulation of the TtMnP gene family in T. trogii, one of the important lignocellulose-degrading fungi, and these results extended our understanding of the diversity of the MnP gene family and helped to improve MnP production and appilications of Trametes strains and other white-rot fungi.