Improving the soil structure and fertility of saline–alkali land is a major issue in establishing a sustainable agro-ecosystem. To explore the potential of different straw returning in improving saline–alkaline land, we utilized native saline–alkaline soil (SCK), wheat straw-returned saline–alkaline soil (SXM) and rapeseed straw-returned saline–alkaline soil (SYC) as our research objects. Soil physicochemical properties, fungal community structure and diversity of saline–alkaline soils were investigated in different treatments at 0–10 cm, 10–20 cm and 20–30 cm soil depths. The results showed that SXM and SYC reduced soil pH and total salinity but increased soil organic matter, alkali-hydrolyzable nitrogen, available phosphorus, total potassium, etc., and the enhancement effect of SYC was more significant. The total salinity of the 0–10 cm SCK soil layer was much higher than that of the 10–30 cm soil layers. Fungal diversity and abundance were similar in different soil layers in the same treatment. SXM and SYC soil had higher fungal diversity and abundance than SCK. At the genus level, Plectosphaerella, Mortierella and Ascomycota were the dominant groups of fungal communities in SXM and SYC. The fungal diversity and abundance in SXM and SYC soils were higher than in SCK soils. Correlation network analysis of fungal communities with environmental factors showed that organic matter, alkali-hydrolyzable nitrogen and available phosphorus were the main environmental factors for the structural composition of fungal communities of Mortierella, Typhula, Wickerhamomyces, Trichosporon and Candida. In summary, straw returning to the field played an effective role in improving saline–alkaline land, improving soil fertility, affecting the structure and diversity of the fungal community and changing the interactions between microorganisms.

Heat stress severely affects the yield and quality of maize. Melatonin (N-acetyl-5-methoxy-tryptamin, MT) plays an important role in various types of stress resistance in plants, including heat tolerance. Enolase (ENO, 2-phospho-D-glycerate hydrolyase) contributes to plant growth, development, and stress response. As of now, the molecular mechanisms by which MT and ENO1 affect heat tolerance are unknown. In our research, we have revealed that heat stress (H) and heat stress + MT (MH) treatment upregulate ZmENO1 expression levels by 15 and 20 times, respectively. ZmENO1 overexpression and mutant maize lines were created by transgenic and genome editing. These results illustrate that heat stress has a significant impact on the growth of maize at the seedling stage. However, ZmENO1-OE lines showed a lower degree of susceptibility to heat stress, whereas the mutant exhibited the most severe effects. Under heat stress, exogenous application of MT improves heat resistance in maize. The ZmENO1-OE lines exhibited the best growth and highest survival rate, while the zmeno1 mutants showed the least desirable results. Following treatment with H and MH, the level of MT in ZmENO1-OE lines exhibited the greatest increase and reached the maximum value, whereas the level of MT in the zmeno1 mutant was the lowest. Heat stress decreased the maize’s relative water content and fresh weight, although ZmENO1-OE lines had the highest and zmeno1 mutants had the lowest. Heat stress led to an increase in the levels of MDA, hydrogen peroxide, and superoxide in all plants. Additionally, the ionic permeability and osmotic potential of the plants were significantly increased. However, the levels of MT were decreased in all plants, with the greatest decrease observed in the ZmENO1-OE lines. Interestingly, the zmeno1 mutant plants had the highest expression levels of MT. Heat stress-induced upregulation of ZmSOD, ZmPOD, ZmAPX, ZmCAT, ZmP5CS, and ZmProDH in all plants. However, the ZmENO1-OE lines exhibited the greatest increase in expression levels, while the zmeno1 mutants showed the lowest increase following MT spraying. The patterns of SOD, POD, APX, and CAT enzyme activity, as well as proline and soluble protein content, aligned with the variations in the expression levels of these genes. Our findings indicate that MT can upregulate the expression of the ZmENO1 gene. Upregulating the ZmENO1 gene resulted in elevated expression levels of ZmSOD, ZmPOD, ZmAPX, ZmCAT, ZmP5CS, and ZmProDH. This led to increased activity of antioxidant enzymes and higher levels of osmoregulatory substances. Consequently, it mitigated the cell membrane damage caused by heat stress and ultimately improved the heat resistance of maize. The results of this study provide genetic resources for molecular design breeding and lay a solid foundation for further exploring the molecular mechanism of MT regulation of heat stress tolerance in maize.

TCP transcription factors are important during plant growth and stress responses. However, their role in the cold stress response of Brassica rapa L. remains poorly understood. In this research, we identified the TCPs gene family in B. rapa to learn the features of the BrTCP gene family, functionally annotating the interacting proteins of TCP4 and analyzing their expression levels. Our results illustrated the presence of 19 members of the BrTCPs family in B. rapa, exhibiting molecular weights ranging from 27,367.45 to 59,433.64 Da. All identified proteins were classified as unstable, with isoelectric points ranging from 5.5 to 9.48. Subcellular localization forecasted that TCP proteins were all positioned in the nucleus. The BrTCP gene structure is relatively simple, with only seven members possessing introns, and none of the members contain UTR regions. BrTCPs comprise hormone-, light-, and stress-responsive elements. We found that the frequency of photoresponsive elements was greatest in the promoter region, suggesting that BrTCP genes are regulated by light signals and function synergistically with plant growth and development. In addition, five candidate interaction proteins of BrTCP4 were identified using yeast two-hybrid screening. RNA-Seq and q-PCR analyses of the interacting genes revealed differential expression of BrTCP family genes across various tissues following cold stress. Significant responses were observed under low-temperature stress, drought stress, and rehydration treatment, suggesting that these genes play crucial roles as regulators of the molecular network mechanisms responding to stress. This study enhances our understanding of the BrTCP family and provides significant insights into the stress tolerance mechanisms of B. rapa.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Pepper (Capsicum annuum L.) represents a highly significant agricultural commodity worldwide. Heat stress (HS) poses a severe threat to pepper productivity and quality. However, our understanding of the molecular alterations triggered by HS remains insufficient. This study focused on characterizing P19055 and P17087 as heat-tolerant and heat-sensitive pepper lines, respectively. Through RNA sequencing, we quantified transcript abundance in pepper fruit to investigate the impact of HS on gene expression. A total of 41,793 differentially expressed genes (DEGs) was identified, encompassing 33,703 known genes and 8090 novel genes. Additionally, we obtained 89,821 expressed transcripts, including 52,726 known transcripts and 37,095 new transcripts. By comparing gene expression levels between P17087 and P19055 fruit, we pinpointed 2324 genes exhibiting differential expression across three time points (0.5 h, 2 h, 6 h). Leveraging the weighted correlation network analysis (WGCNA) approach, we constructed a co-expression network of DEGs in P19055 and P17087 based on transcriptomic data acquired at these time points. Notably, nineteen modules displayed significant correlations with the time points following HS during the fruiting stage in both genotypes. Functional enrichment analysis revealed that the DEGs were primarily associated with metabolic and cellular processes in response to stress, particularly photosynthesis at the 2 h and 6 h time points. Moreover, we identified and categorized 26 families of transcription factors, including ERF (19), WRKY (12), MYB (15), NAC (7), bHLH (7), MIKC (7), GRAS (6), and 40 others, which may potentially regulate the expression of key genes in response to HS. Our findings contribute to a comprehensive understanding of the molecular mechanisms governing HS during the fruiting stage of pepper cultivation.