Moringa oleifera seed oil was extracted using an aqueous enzymatic method following microwave pretreatment of M. oleifera seed power. The antioxidant activity of M. oleifera seed oil was evaluated by its ability to scavenge hydroxyl radical. Single-factor experiments were initially conducted to evaluate the effects of key parameters, raw material particle size, microwave power, and microwave duration. Based on the findings, an orthogonal experimental design was employed to optimize the microwave pretreatment conditions, ultimately determining the most effective pretreatment parameters. The results showed that the optimal microwave pretreatment conditions were raw material crushing particle size of 60 mesh, microwave power of 800 W, and microwave time of 7 min. Under these conditions, the hydroxyl radical (·OH) scavenging rate of the obtained M. oleifera seed oil (at a concentration of 0.5 mg/mL) was 43.98%. Compared to the sample without microwave pretreatment, the antioxidant activity increased by 15.16% (an absolute increase of 5.79%). This demonstrated that microwave pretreatment effectively enhanced the antioxidant capacity of M. oleifera seed oil extracted via the aqueous enzymatic method. The antioxidant activity tests revealed that M. oleifera seed oil extracted using microwave pretreatment combined with the aqueous enzymatic method possessed significant hydroxyl radical (·OH) scavenging ability, with a half inhibitory concentration (IC₅₀) of 0.14 mg/mL. Additionally, the oil showed certain reducing ability toward Fe³⁺. Furthermore, compared to samples without microwave pretreatment, microwave pretreatment increased the acid value, iodine value, and the levels of polyphenols, total flavonoids, squalene, and phytosterols in Moringa oleifera seed oil extracted via the aqueous enzymatic method. Therefore, microwave pretreatment is a suitable pretreatment method for the enzymatic extraction of M. oleifera seed oil. Compared with the conventional aqueous enzymatic method, it can significantly improve the antioxidant activity of M. oleifera seed oil, increase the concentrations of bioactive compounds such as polyphenols, flavonoids, squalene, and plant sterols. However, it also results in higher acid and iodine values, which may slightly compromise the overall quality of the oil. The results of this study could provide technical insights and references for the comprehensive development and high-value utilization of M. oleifera resources.

After intercropping pepper with areca nut, the growth of pepper is restored and the intercropping barrier is alleviated. This is related to the increase in soil microbial diversity by the root exudates of areca nut. However, the specific components that play a role and the effects are still unclear. Three specific components of areca nut root exudates identified were added them to the deionized water for cultivation as the control and the differences in soil microbial carbon source utilization ability among different treatment groups were analyzed using the Biolog microplate method. This was done to clarify the effects of the specific component on the functional diversity and community structure of the rhizosphere soil microorganisms of intercropped pepper and to analyze the correlation between the treatment groups and related indicators using the PCA method. The average absorbance values (AWCD) of the three specific components treatments reached the maximum and were stable significantly higher than those of the deionized water control. The Shannon index and Shannon evenness of the treatments containing flavonoids and phenolic acids were significantly higher than those of the deionized water control, while the Shannon index of the organic acid treatment was only significantly different. The Simpson dominance index of the deionized water control was significantly higher than that of other treatments, while the yellowing acid treatment was significantly lower than that of other treatments. The number of carbon sources changed in the Biolog culture plates caused by the addition of organic acids, phenolic acids, flavonoids and deionized water was 17, 18, 15 and 12 respectively, and the carbon sources decomposed by the three specific component treatments were mainly carbohydrates. With the addition of specific components, the soil microbial community structure also changed significantly. The changes in the yellowing acid treatment were the most obvious, followed by organic acids and phenolic acids, and the soil nutrient indicators also changed with the addition. In summary, the addition of the three specific components of areca nut root exudates significantly enhanced the carbon utilization activity of soil microorganisms in the rhizosphere of intercropped pepper and increased the functional diversity of the soil community. The three treatment groups mainly increased the utilization of carbon sources by microorganisms to enhance diversity and maintained the stability of the community structure, thereby improving the nutrient status of the pepper rhizosphere and alleviating the harm of pepper intercropping barrier.

Organic fertilizer can effectively improve soil fertility and microbial diversity, as well as metabolic activity, in facility cultivation. It can also alleviate problems such as water-heat imbalance, soil secondary salinization, acid-base imbalance, reduced microbial diversity, and insufficient nutrient supply in facility greenhouses. Currently, however, research on organic fertilizers mostly focuses on open fields and field crops, and most studies use animal manure as the organic fertilizer. This study selected Hainan coir organic fertilizer and bio-enzyme-active bacterial fertilizer as bottom fertilizers. High-throughput sequencing technology was used to study how different bottom fertilizers and their dosages affect soil nutrient and microbial changes in facility greenhouses. The goal was to identify effective fertilization methods for improving soil. The results showed that: (1) The application of 14 286 kg/hm² of coir organic fertilizer effectively improved soil pH, organic matter, total nitrogen, effective phosphorus, and quick-acting potassium. The bio-enzyme-activated bacterial fertilizer improved the soil's total nitrogen, effective phosphorus, and quick-acting potassium levels, but the effect was weaker than that of the coir organic fertilizer. The CK indicators were generally lower than the pre-planting levels. (2) The number of soil bacterial OTUs generally decreased after planting. However, organic fertilizer treatments, especially bioenzyme treatments, could partially restore or enhance microbial diversity. Coconut coir organic fertilizer was more conducive to the proliferation of beneficial bacterial flora, such as Rhizobiales and Paecilomyces spp. WSH L07. Bioenzyme-activated bacterial fertilizers had an effect on Sphingomonadales, Rhodospirillales, and Aspergillus terreus.

Albino plants lacking photosynthetic pigments are ideal materials for studying photosynthesis. In this study, albino Artocarpus heterophyllus seedlings (AAS) were found during the preliminary investigation. AAS have larger leaves, longer survival time and stable phenotypic traits, so it is a rare woody plant albino material. The expression of photosynthesis-related genes were analyzed through transcriptome sequencing technology and found that the expression of many genes in photosynthetic pigment synthesis, photosynthesis-antenna protein, photoreaction and carbon fixation reaction pathways were down-regulated in AAS leaf, also the expression of genes encoding heat shock protein 70 (HSP70), heat shock protein 90 (HSP90) and HSP70-HSP90-organizing protein 3 (HOP3), which are considered to be key regulators in the plastid-nuclear signaling pathway, were up-regulated. This study discussed the cause of AAS from the synthesis pathway of photosynthetic pigment, and also discussed the expression of photosynthesis-related genes from the aspect of plastid-nuclear signal, which can provide reference for the research of this retrograde signaling pathway.

Plant fructokinase (FRK) specifically catalyzes fructose phosphorylation into glycolysis pathway, which is a key enzyme for fructose metabolism and soluble sugar accumulation. This study elucidated the expression pattern and enzyme characteristics of red pitaya HpFRK2 gene, which would provide a theoretical basis for understanding the molecular mechanism of fruit soluble sugar accumulation and improving fruit quality. HpFRK2 was cloned from red pitaya ‘Zihonglong’, and its expression pattern was analyzed by real-time fluorescence quantitative PCR. Subcellular localization was performed by transiently expressing in tobacco mesophyll cells, and the recombinant protein was obtained by prokaryotic expression and its enzyme activity was detected. The open reading frame (ORF) was 1026 bp, encoding 341 amino acids. The relative molecular weight of HpFRK2 was 36.95 kDa, and the theoretical isoelectric point was 5.94. Phylogenetic analysis showed that HpFRK2 was closely related to cassava MeFRK2, tomato SlFRK1, apple MdFRK1 and Arabidopsis AtFRK1. HpFRK2 contained a conserved domain of the phosphofructokinase type B (pfkB) family. The expression level of HpFRK2 was the highest at 20 days of fruit development, gradually decreased with fruit development, and the expression level was the lowest at 30 days. In addition, the expression of HpFRK2 in stems was significantly lower than that in fruits. Subcellular localization results showed that HpFRK2 was mainly located in the cytoplasm. A prokaryotic expression vector was constructed and expressed in Escherichia coli, and recombinant protein was successfully induced. The results of enzyme activity characteristics showed that HpFRK2 specifically catalyzed fructose phosphorylation, fructose did not have the substrate inhibition on its enzyme activity, and the Km value for fructose phosphorylation was 1.84 mmol/L. The results showed that HpFRK2 was located in the cytoplasm, specifically catalyzed fructose phosphorylation, was mainly expressed during the veraison period (20-23 d after flowering) of red pitaya fruit, and may negatively regulate fructose accumulation in fruit.

An antimicrobial peptide (SAMP) derived from Microcitrus australasica can not only reduce the concentration of Candidatus Liberibacter asiaticus (CLas) in the infected trees and reduce the symptoms of the diseased trees, but also induce innate immunity and prevent the infection of Huanglongbing in healthy trees that are not infected with Huanglongbing. MaSAMP was analyzed by functional structure, subcellular localization and phylogeny. The results showed that the open reading frame (ORF) of MaSAMP was 201 bp in length, encoding 67 amino acids. The molecular weight of the corresponding protein was 7.59959 kDa, the theoretical isoelectric point was 5.38, and the instability index (Instability index (II)) was 33.22. The aliphatic index was 87.16%, and the grand average of hydropathicity was -0.09, indicating that the protein was a hydrophilic one. The protein contained one Dabb domain and was predominantly structured by α-helices and random coils. In terms of evolution, MaSAMP was phylogenetically close to the stress-response A/B barrel domain-containing protein CISIN_1g033887mg from Citrus sinensis and the A/B barrel domain protein HS1 from Citrus×clementina, with protein similarity of 97.01% and 91.04%, respectively. Subcellular localization results indicated that MaSAMP was localized in chloroplasts. Furthermore, through homologous recombination, a pCAMBIA1300-35S::MaSAMP-EGFP overexpression vector fused with an EGFP fluorescent tag was successfully constructed, and transgenic citrus plants were obtained using agrobacterium-mediated in planta transformation technology. This study would provide a material basis for subsequent research on the biological functions of MaSAMP.

STAY-GREEN (SGR) is a key gene that regulates chlorophyll degradation in plants and plays an important role in controlling plant senescence. To investigate the regulatory role of the SGR gene in the fruit coloration process of pepper, the homologous gene cloning method was employed to amplify the CaSGR gene from pepper fruit cDNA using PCR technology in this study. Bioinformatics analysis was conducted on its protein sequence, and a virus-induced gene silencing (VIGS) vector was constructed to preliminarily verify the gene function. The results showed that ORF of CaSGR was 792 bp, encoding 263 amino acids. Bioinformatics analysis revealed that SGR was relatively conserved among Solanaceae crops, and SGR had a closer evolutionary relationship with SGR from tomato and potato. CaSGR VIGS vector was constructed and injected into pepper leaves, successfully obtaining silenced plants. The silenced plants exhibited leaf whitening, fruit color changed, and CaSGR expression levels reduced significantly. Additionally, the chlorophyll and β-carotene content in the fruits of the silenced plants increased markedly. This study would provide a foundation for further elucidating the molecular regulatory mechanisms of CaSGR in pepper fruit coloration and offer theoretical support for breeding new pepper varieties with high carotenoid content.

Meloidogyne enterolobii is a pathogen causing significant damages to pepper production. Utilization of resistant cultivars is the most economical and environmentally friendly method to control this disease. A deeper understanding of the regulatory mechanisms of resistance to root-knot nematodes could facilitate the breeding process of disease-resistant cultivars. In previous studies, analysis of transcriptomic data of Hainan local M. enterolobii-resistant pepper germplasm CF25 before and after inoculation were carried out to explore metabolic pathways closely related to nematode resistance. In order to further explore the regulatory mechanisms of resistance, sRNA libraries of CF25 before and after inoculation with M. enterolobii were sequenced to identify a total of 133 differentially expressed miRNAs. Based on the criteria of P≤0.05 and |log₂(FC)|≥3, 33 significantly differentially expressed miRNAs were identified, including 19 known miRNAs and 14 newly discovered miRNAs. Target gene prediction for the 33 miRNAs yielded a total of 373 target genes, with miR5658-z having the highest number of predicted target genes. GO and KEGG analyses showed that the target genes were mainly enriched in pathways related to plant-pathogen interactions and signal transduction. It is speculated that miRNA-mediated signal transduction and plant defense responses might be important reasons for the resistance of CF25 to M. enterolobii. To preliminarily verify the regulatory relationships between differentially expressed miRNA and the target genes, six differentially expressed miRNA and the target genes were selected for qRT-PCR validation. The results showed that the differential expression trends of miRNA and target genes were consistent with the high-throughput sequencing results and generally conformed to the negative regulation pattern between miRNA and the target genes. The results of this study suggest that miRNA may play significant roles in the defense response to root-knot nematodes and lay the foundation for furtherly elucidating the mechanisms of miRNA-mediated nematode resistance in pepper.

Seed shattering is the main reason for the continuous self-reproduction and spread of weedy rice in rice fields. Genes SH4 and qSH1 are considered to be the main genes controlling rice seed shattering. The aim of this study was to determine the genotype of the seed shattering SNP locus at SH4 and qSH1 of weedy rice in Hainan. Using weedy rice from rice fields in Lingao and Yazhou District as research materials, this study collected weedy rice and corresponding cultivated rice seeds from 13 rice fields. 144 Weedy rice seeds with different phenotypes and 13 corresponding cultivated rice seeds were selected for germination and planting, and the seed shattering rates were measured. PCR amplification and sequence analysis were performed on the seed shattering SNP locus at SH4 and qSH1. The results showed that there were 77 wild type (G) weedy rice plants, 48 mutant type (T) weedy rice plants, and 19 heterozygous type (G/T) weedy rice plants with the locus at SH4 gene; Seed shattering SNP locus of SH4 gene in all cultivated rice samples were T. The determination of seed shattering rate found that 96 weedy rice samples with G and G/T genotype seed shattering SNP at SH4 gene had extremely high seed shattering rates, while among 48 weedy rice samples with T genotype seed shattering SNP locus at SH4 gene, 40 weedy rice samples had moderate seed shattering rates and 8 weedy rice samples had low seed shattering rates. Seed shattering SNP locus of qSH1 in all weedy rice and cultivated rice samples were wild-type seed shattering G genotype. The above results indicate that the difference in seed shattering rate between Hainan weedy rice and cultivated rice is not related to the seed shattering SNP locus at qSH1 gene, but significantly correlated with the seed shattering SNP locus at SH4 gene. The difference in seed shattering rate between weedy rice and cultivated rice with T genotype SNP locus at SH4 gene may be caused by differences in other unknown genes or locus. This study would provide a molecular basis for the seed shattering mechanism of weedy rice in Hainan.

Bok choy (Brassica campestris ssp. chinensis) is an important vegetable crop native to China and is also one of the leafy vegetables favored by people in Hainan. The high temperature and intense sunlight in Hainan’s summer greatly affect the normal growth and development of bok choy, reducing its yield and quality. At present, research on the growth of bok choy under abiotic stress is mostly focused on heat tolerance, while study on the response of bok choy to strong light stress is relatively scarce. To investigate the molecular regulatory mechanisms of bok choy in response to strong light, this study used the variety ‘Aijiao Huang’ as the research object. We compared and analyzed the physiological indicators, photosynthetic characteristics, and expression levels of response genes in the leaves of bok choy under normal light [300 μmol/(m²·s)] and strong light [1500 μmol/(m²·s)]. Under strong light, dry weight of bok choy significantly increased, and the R/S ratio gradually increased from day 0 to day 10, followed by a significant decrease on day 15. The chlorophyll content significantly decreased in the later stages. Pn, Tr, and Gs significantly increased on day 5 under strong light, and then gradually decreased, while Ci remained relatively stable. Using RNA-seq technology for transcriptome sequencing, a total of 2324 differentially expressed genes (DEGs) were identified. GO and KEGG enrichment analyses revealed 14 DEGs related to photosynthesis and photoprotection mechanisms, and 6 DEGs associated with antioxidant enzyme activity. 8 DEGs were selected for qRT-PCR validation, which were consistent with the transcriptome sequencing results, confirming the reliability of the transcriptome analysis. Strong light had a certain impact on the antioxidant enzyme activity of bok choy. During days 0-5, the activity of SOD, POD, and CAT was induced to increase, while from days 5-15, the activity of SOD and POD gradually decreased, and CAT showed an upward trend. In summary, bok choy may rapidly respond to photosynthesis-related mechanisms and regulate antioxidant enzyme activity under strong light conditions, thereby alleviating the inhibitory effects of strong light on growth and enhancing the seedlings adaptability to strong light.