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Abstract Background Common wheat (Triticum aestivum L.) is a worldwide cereal crop, which is an integral part of the diets of many countries. In addition, the MYB gene of wheat plays a role in the response to salt stress. Results “Y1805” is a Tritipyrum variety that is relatively tolerant to salt. We used transcriptome analysis to show that the “Y1805” MYB gene was both highly expressed and sensitive to salt stress. Compared with control roots, the level of MYB expression during salt stress was higher, which rapidly decreased to control levels during the recovery process. MYB gene relative expression showed the highest levels in “Y1805” roots during salt stress, with the stems and then leaves being the next highest stressed tissues. The novel MYB gene (TtMYB1) was successfully cloned from “Y1805”. It showed a coding sequence length of 783 bp with 95.79% homology with Tel2E01G633100 from Thinopyrum elongatum. TtMYB1 and MYB from Th. elongatum were clustered in the same branch using phylogenetic analysis, which indicated high similarities. The TtMYB1 gene is located in the nucleus. The coleoptile method was employed when a TtMYB1 overexpression vector was used during transformation into “1718” (common wheat). Under high salt stress, TtMYB1 leaves of overexpression lines had decreased wilting, when compared with wild-type (WT) plants. During normal conditions, salt stress, and recovery, the lengths of the roots and the heights of seedlings from the overexpression lines were found to be significantly greater than roots and seedlings of WT plants. In addition, during high salt stress, the overexpression lines showed that proline and soluble sugar levels were higher than that of WT plants, but with lower malondialdehyde levels. Forty-three proteins that interacted with TtMYB1 were identified using the yeast two-hybrid assay. Protein-protein interaction analyses indicated that most were SANT domain-containing and Wd repeat region domain-containing proteins. Among these proteins, ribosomal proteins were the main node. Abiotic stress-related terms (such as “carbonate dehydratase activity”, “protein targeting peroxisomes”, and “glutathione peroxidase activity”) were enriched in GO analysis. In KEGG analysis, “carbohydrate metabolism”, “environmental information processing”, “genetic information processing”, “signaling and cell precursors”, and “energy metabolism” pathways were enriched. Conclusion The TtMYB1 gene might enhance salt tolerance by increasing proline and soluble sugar content and antioxidase activity in transgenic wheat. It therefore has the potential to enhance high salt tolerance in plants.

SSR molecular markers were obtained based on abundant transcriptome data under different waterlogging conditions in order to develop appropriate biological tools and explore the molecular mechanism of hot pepper response to waterlogging stress in this experiment. The results were as follows: (1) A total of 128 939 Unigenes were obtained from transcriptome analysis of hot pepper. The total length, average length, and GC content were 55 082 725 bp, 1 101 bp and 40.57%, respectively. Compared with seven major functional databases, 102 123 (NR, 79.20%), 110 157 (NT, 85.43%), 70 203 (SwissProt, 54.45%), 73 539 (KOG, 57.03%), 77 646 (KEGG, 60.22%), 77 442 (GO, 60.06%) and 68 216 (Pfam, 52.91%) Unigenes obtained functional annotations. It was found that lipid metabolism, carbohydrate metabolism, amino acid metabolism, environmental adaptation, secondary metabolite biosynthesis, signal transduction and translation played important roles in the response to waterlogging stress. (2) A total of 26 574 SSR loci were found in 24 889 Unigenes from hot pepper transcriptome data. The frequency of SSR was 20.61%, of which single nucleotide repeat accounted for the highest ratio (37.26%), followed by tri-nucleotide (31.00%) and di-nucleotide (25.44%) repeat types, accounting for 93.70% of the total EST-SSR. The motifs A/T, AG/CT and TC/GA, followed by AT and TA, were the most abundant in mono-nucleotide and di-nucleotide. The most common types of tri-nucleotides were TTG/CAA and ACA/TGT. (3) 10 002 pairs of EST-SSR primers were designed with Primer 3. A total of 30 pairs of primers were randomly selected for amplification test, and all of them were effective. Seven pairs of primers could amplify the target bands in three hot pepper germplasms. To sum up, the motif structure of the most dominant SSR repeat type in hot pepper is basically similar to that of other varieties, and the molecular mechanism of hot pepper waterlogging stress response is preliminarily explored, and its EST-SSR markers are developed to provide reference for hot pepper waterlogging-tolerant genetic breeding.

Basic helix–loop–helix (bHLH) proteins are important in abiotic stress control. Here, a specific bHLH transcription factor gene, CabHLH18, from a strong waterlogging-tolerant pepper cultivar, ‘ZHC2’, was successfully cloned. The CabHLH18 gene presented a coding sequence length of 1,056 bp, encoding 352 amino acids, and the protein was the closest to Capsicum annuum XM016694561.2 protein. The CabHLH18 protein was located in the nucleus. The transformation of the CabHLH18 overexpression vector into the plumules of hot peppers, ‘DFZJ’ and ‘ZHC1’, exhibited 21.37% and 22.20% efficiency, respectively. The root length, plant height, and fresh weight of the ‘DFZJ’ overexpression lines were greater than those of wild-type (WT) plants under waterlogging conditions. Compared with the WT plants, the overexpression lines generally showed greater contents of water, the amino acid, proline, soluble sugar, root viability, and superoxide dismutase activity, but lower malondialdehyde content under waterlogging conditions. Plant fresh weight, amino acids, proline, and soluble sugar levels of the overexpression lines were 39.17%, 45.03%, 60.67%, and 120.18% greater, respectively, compared with the WT plants at 24 h after waterlogging stress. Therefore, the CabHLH18 gene could be implicated in conferring waterlogging tolerance in hot peppers and holds promise for enhancing their overall waterlogging tolerance.

Drought stress is one of the main factors influencing the growth and development of an organism. Auricularia fibrillifera has strong dessication resistance. In A. fibrillifera under dessication-stress, the melanin content of fruiting bodies elevated significantly by >10-fold compared with the control. Folate content also increased sharply but decreased significantly after rehydration, and amino acid and biotin levels increased by 40.11 and 22.14%, respectively. In proteomic analysis, 1,572 and 21 differentially abundant proteins (DAPs) were identified under dessication-stress and rehydration, respectively. A large number of DAPs were annotated in “amino acid metabolism,” “carbohydrate metabolism,” and “translation” pathways, and the DAPs related to osmotic regulation and antioxidant enzymes were significantly increased in abundance. Transcriptome-proteome association analysis showed that most DAPs (30) were annotated in the “biosynthesis of antibiotics” pathway. DAPs and corresponding differentially expressed genes were all up-regulated in the “biotin biosynthesis” pathway and associated with “folate biosynthesis” and “phenylalanine, tyrosine, and tryptophan biosynthesis.” In the analysis of protein–protein interactions, the DAPs annotated in the “phenylalanine, tyrosine, and tryptophan biosynthesis” pathway had the strongest interactions with other DAPs. These enriched pathways could enhance amino acid, folate, biotin, and melanin levels during desiccation stress, which is consistent with the physiological data (amino acid, folate, biotin, and melanin contents). In addition, many DAPs related to the cytoskeleton were significantly increased in abundance under dessication-stress. Physiological and transcriptome data were in agreement with proteomic results. This work provides valuable insight into the dessication-tolerant mechanisms of A. fibrillifera.