Cryopreservation can reduce the risk of genetic variation in the long-term subculture of rubber tree anther callus tissue, and is an effective method for long-term preservation of callus tissues. To evaluate the effects of dehydration duration on physiological parameters during cryopreservation, rubber tree anther calli were treated with plant vitrification solution PVS2 for 0, 10, 20 and 40 min and then cryopreserved for 24 h in this study. Physiological parameters related to stress resistance were analyzed, including soluble protein content, malondialdehyde (MDA) content, and activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) during cryopreservation. Dehydration duration had a significant effect on soluble protein content, MDA content, SOD and POD activities in callus tissues after cryopreservation, while showing no significant impact on CAT activity. All physiological parameters (except MDA) exhibited higher values after cryopreservation compared to pre-preservation levels across all dehydration durations. After 40 min of dehydration and cryopreservation, the soluble protein content, CAT, SOD and POD activities of anther callus reached the maximum value, which was 129.63 μg/mL, 627.30 U/g, 290.38 U/g and 25 643.33 U/g, with the lowest MDA content of 41.31 nmol/g. The findings indicate that dehydration for 40 min significantly enhances water retention capacity and antioxidant level in cryopreserved callus cells. Post-thawing viability tests revealed that 40 min dehydrated callus maintained over 70% survival rate and could induce fragile embryogenic callus formation with an average induction rate of 13.33%. This study establishes a physiological foundation for the regeneration of cryopreserved rubber tree anther callus.

Anthracnose caused by Colletotrichum gloeosporioides occurs extensively during the post-harvest storage of papaya (Carica papaya L.), significantly affecting fruit quality and yield. In this study, the excellent antagonistic bacteria J-11 agaist C. gloeosporioides were screened from the rhizosphere soil of papaya, and the antagonistic characteristics and biological control ability were explored. The size of biocontrol bacterium J-11 was about 1.5 μm×3.3 μm (growing for 3 d), Gram-positive (G⁺), rod-shaped or oval, common single arrangement, and its morphological characteristics were consistent with Bacillus velezensis. The sequences of 16S rRNA, gyrA and gyrB genes of strain J-11 were 99.28%, 97.57% and 98.79% consistent with those of B. velezensis model strain OOT-47, respectively. Phylogenetic tree analysis showed that the tested strain J-11 and Bacillus velezensis LB4 were clustered into one branch. According to the results of morphological, molecular biological and physicochemical analysis, it was confirmed that the microbial antagonistic pathogen of papaya C. gloeosporioides in Zhanjiang area of Guangdong was B. velezensis. Strain J-11 demonstrated a broad-spectrum antifungal ability, inhibiting the growth of three pathogenic fungi of C. gloeosporioides, C. siamense and Botryosphaeria dothidea, with antagonism indices of 0.48, 0.41 and 0.40, respectively. The control testing showed that the inhibition rate of strain J-11 against the C. gloeosporioides on papaya leaves was 89.96%, and the inhibition rate of strain J-11 against the C. gloeosporioides on papaya fruits in vitro was 84.92%. Strain J-11 screened in this study has a certain control effect on papaya anthracnose, which could provide a theoretical basis for in-depth study of the antibacterial mechanism of plant biocontrol bacteria and will lay a foundation for its development and utilization.

In this study, three pitaya varieties, Spineless Yellow Dragon, Fuguihong, and Jindu No. 1, were selected as rootstocks. Through systematic observation and analysis of key indicators such as the growth potential of cuttings, grafting survival rate, fruit traits and quality, the most suitable rootstock variety was determined. Combined with the environmental conditions in Hainan, corresponding cultivation and management suggestions were put forward, aiming to provide solid technical support for the development of the pitahaya industry. Rootstock Fuguihong performed the best in the comprehensive survival rate of cuttings and grafting. The promoting effect of growth potential on pitahaya was significantly better than that of other rootstocks. Therefore, Fuguihong was determined as the optimal rootstock. Meanwhile, different rootstocks had a significant impact on the fruit traits of pitahaya (including 10 traits such as single fruit weight, peel weight, pulp weight, soluble solids, and total sugar). During the cultivation and management process, the suitable cultivation conditions for pitahaya in Hainan were summarized. Before cultivation, the field should be prepared and ridged first. 17 tons/667 m² of decomposed sheep manure and earthworm manure in a ratio of 3∶1 were spread over the whole garden. After rotary tillage and deep plowing, ridges with a width of 1m, a height of 25–30 cm, a row spacing of 2 m, and a ditch depth of 30 cm were built. Appropriate branches were selected as rootstocks. After treatment, they were planted at a density of 7 plants per meter in early September. In the first and second ten days of October, the “two-bud side flat grafting method” was used for grafting, and paper bags were put on. At the same time, a “丰” -shaped scaffold was built. Field management included soil covering or planting white clover and laying ground cloth, adjusting water and fertilizer according to the growth status, bending branches and leaving buds when the main branches exceeded the scaffold by 1 m, and closely monitoring common diseases such as sooty mold to ensure the orderly progress of all work, thus promoting the growth and development of pitahaya. This study would lay an important technical foundation for the vigorous development of the pitahaya industry in Hainan, effectively promote the progress of the domestic pitahaya cultivation industry, and significantly enhance its market competitiveness.

China is currently the largest sweet potato producer globally. The postharvest starch and soluble sugar (glucose, fructose, and sucrose) contents in storage roots not only influence sweet potato utilization and commercial value (including taste, nutritional quality, and food processing properties), but also affect sprouting, weight loss, and decay during storage and transportation. Studies on tubers/roots such as potato and carrot have demonstrated that vacuolar invertase (VIN) serves as the primary sucrose-cleaving enzyme determining postharvest sugar composition and content. However, the key sucrose-cleaving enzyme regulating postharvest sugar metabolism in sweet potato storage roots remains unclear. This study systematically investigated sugar metabolism characteristics in storage roots of ‘Kokei 14’, a major sweet potato cultivar in Hainan Province, under room temperature storage (25 ℃) and low-temperature storage (15 ℃), aiming to identify the principal sucrose-cleaving enzymes affecting postharvest sugar composition and content. Low-temperature storage enhanced preservation quality by reducing dry matter loss and sprouting rate through suppression of hexokinase (HK) activity and respiratory intensity. Compared with room temperature storage, low-temperature treatment induced greater increases in soluble sugar (glucose, fructose, and sucrose) content and more pronounced starch degradation, accompanied by significantly higher β-amylase activity, indicating that low-temperature storage promotes starch hydrolysis into soluble sugars. During room temperature storage, cell wall invertase (CWIN) and sucrose synthase (Sus) activities generally declined, while VIN activity initially increased before returning to baseline levels. Notably, cytoplasmic invertase (CIN) activity exhibited a continuous upward trend, suggesting CIN as the key sucrose-cleaving enzyme responsible for hexose accumulation under ambient conditions. Conversely, low-temperature storage induced continuous declines in all three invertase activities but progressively increased Sus activity, indicating Sus as the predominant enzyme mediating hexose accumulation under cold storage. Transcriptional analysis identified IbCIN4 as the key gene family members regulating CIN activity elevation at room temperature, while IbSus6 was determined as the primary regulator of Sus activity enhancement under low-temperature conditions. This study reveals that different postharvest storage temperature induces shifts in the predominant sucrose-cleaving enzymes governing hexose accumulation in sweetpotato storage roots. Notably, our findings contrast with previous reports on potato tubers under cold storage, demonstrating that Sus rather than VIN serves as the key enzyme regulating hexose content in sweetpotato roots under low-temperature conditions. The results would establish a theoretical foundation for future genetic engineering approaches to improve postharvest quality of sweetpotato storage roots.

A comprehensive evaluation of agronomic traits of 70 varieties of fresh food tomato germplasms was conducted. Genetic diversity analysis of 28 morphological traits of the germplasms was carried out using methods such as variance analysis, principal component analysis, cluster analysis and calculation of comprehensive evaluation scores. The analysis results of genetic variability of 13 quantitative traits indicated that the variation degree of the germplasms was relatively high and the variation was rich. The variation range was 21.68%‒99.08%, and the genetic diversity index was relatively high, suggesting that the phenotypic diversity of germplasms was relatively rich and there was a significant degree of variation among the traits, indicating excellent selection potential. Among these, the traits such as single fruit weight, number of chambers, sugar-acid ratio, and transverse diameter exhibit relatively high genetic variation. The correlation analysis results showed that the traits significantly corelated with fruit firmness were the greateast in number, and fruit firmness were extremely significantly positively correlated with fruit surface ridges, fleshiness, single fruit weight, number of chambers, flesh thickness, and acidity. Sugar content was significantly negatively correlated with fruit color before maturity, and it was extremely significantly negatively correlated with fruit surface ridges, single fruit weight, number of chambers, and flesh thickness, and significantly positively correlated with plant height, and extremely significantly positively correlated with fruit shape index and soluble solids content. Single fruit weight was significantly positively correlated with leaf type, significantly negatively correlated with fruit peel color, extremely significantly positively correlated with flower sequence type and fruit surface ridges, and extremely significantly negatively correlated with fruit top shape and fruit shape. The principal component analysis results indicated that the 28 phenotypic traits could be classified into nine factors. The eigenvalues were all above 1.0, and the cumulative contribution rate reached 78.143%, which could reflect most of the information of all indicators and highlight the basic characteristics of the germplasms. Cluster analysis further divided the germplasms into five groups. The first and fourth groups had smaller tomato fruits and stronger edible properties, which could be important materials for cultivating cherry tomato varieties with good taste and high quality. The fifth group had higher hardness and larger fruits, and could be used to cultivate economic tomato varieties suitable for long-distance transportation. The comprehensive evaluation results showed that the top five germplasms were XH20-48, XH20-35, XH20-37, XH20-34 and XH20-30. In conclusion, this research achievement is dedicated to discovering and exploring the excellent tomato germplasm resources retained by the research group, laying a foundation for the next step of creating core parents and breeding new high-quality tomato varieties with characteristics unique to Xinjiang.

Miniature inverted-repeat transposable elements (MITEs), as active mobile elements in eukaryotic genomes, provide novel molecular markers for germplasm genetic diversity analysis through the insertion polymorphisms. This study systematically identified hAT family MITE transposons in pitaya using bioinformatics approaches based on the whole-genome data of the Guanhua Bai cultivar. A total of 2350 candidate elements with complete terminal inverted repeats (TIRs) and target site duplications (TSDs) were screened, with an average of 213 elements per chromosome pair. Through sequence specificity and polymorphism analysis, 110 highly divergent loci (10 per chromosome pair) were selected for primer design, ultimately yielding 41 stable polymorphic hAT-MITE markers after PCR validation. Genome-wide scanning of 48 pitaya germplasms using the 41 primer pairs detected 81 polymorphic loci (polymorphism rate: 97.59%) via agarose gel electrophoresis. UPGMA cluster analysis revealed substantial genetic variation and diversity among the 48 accessions, with genetic similarity coefficients ranging from 0.57 to 0.91. At a genetic similarity threshold of 0.63, the germplasm resources were categorized into four genetically distinct groups. A digital fingerprinting system covering all germplasm resources was constructed using four core primer pairs (HU-MIT-02/06/26/75) based on the primer-band pattern combination method, achieving 100% cultivar identification accuracy. This study established the first hAT-MITE molecular marker system for pitaya, providing an efficient toolkit including a marker library and standardized identification protocols for precise germplasm classification, cultivar identification and varieties property protection of pitaya. The advancements is of significant application value for intellectual property protection in the pitaya seed industry.

Sri Lankan cassava mosaic disease, caused by Sri Lankan cassava mosaic virus (SLCMV), is a recently emerging dangerous disease in China. Existing detection methods of SLCMV are constrained by low sensitivity and poor efficiency, impeding related research and applications. Primers and probes were designed according to the gene sequences of the SLCMV, and a positive plasmid standard was prepared. The TaqMan fluorescence quantitative detection technology for SLCMV was established, and its application effect was verified. The method only generated specific fluorescence signals for SLCMV DNA samples, and the minimum detectable amount of the positive plasmid standard was 4.5×10¹ copies/μL. The standard curve showed that there was a good linear relationship between the C_t value and the logarithm of the copy number. The slope of the curve was –3.1312, the correlation coefficient R² was 0.9969, the amplification efficiency (E) was 97.9%, and the equation of the standard curve was y=–3.1312x+34.599. Using this technology to detect the tested samples from two cassava plantations in Guangxi and Fujian, the positive detection rate of leaves was 95.45% and 78.57%, respectively, and the minimum detectable copy number was 1.45×10⁵ copies/g. The virus-carrying rate of Bemisia tabaci in the field was 86%, and the minimum virus-carrying amount was 9.42×10⁴ copies/B. tabaci. This technology has good sensitivity, specificity, and repeatability, and could provide effective technical support for the monitoring and control work such as field identification, early diagnosis, and evaluation of virus-free stem cuttings of the disease.

The study was aimed to explore the physiological response and gene expression differences of cassava seedlings under waterlogging stress and to provide theoretical basis for disaster prevention and reduction of cassava northward migration cultivation in Hunan Province. Seedlings of cassava NZ199 were used, and two waterlogging levels of moderate (W1) and severe (W2) were set. The normal water supply (CK) was used as the control. The photosynthetic characteristics and antioxidant enzyme activities of the seedlings were measured after 14 days of stress and after rewatering, and transcriptome sequencing analysis was performed on the leaves after 14 days of stress. The results showed that with the aggravation of stress, the net photosynthetic rate decreased, and the stomatal conductance, intercellular CO₂ concentration and transpiration rate showed an overall upward trend. The activities of superoxide dismutase, catalase and peroxidase were significantly higher than those of CK under waterlogging stress, the content of malondialdehyde increased, and the degree of accumulation was positively correlated with the degree of stress, indicating that the plant initiated the antioxidant mechanism when suffering from waterlogging, but still suffered a certain degree of oxidative damage. After rewatering treatment, the photosynthetic index decreased significantly compared with that before stress. Antioxidant enzyme activity and malondialdehyde content also decreased, indicating that although the plant had a certain recovery ability, it did not fully recover to the normal level before stress. The results of transcriptome sequencing showed that 900, 1542 and 575 differentially expressed genes were identified in the three comparison groups of W1 vs CK, W2 vs CK and W2 vs W1, respectively, of which 1594 were up-regulated and 1423 were down-regulated. The pathways significantly enriched by KEGG included flavonoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, etc. In summary, cassava seedlings have certain waterlogging resistance, but the waterlogging resistance has a threshold value. Timely drainage after waterlogging helps to reduce plant damage. In this study, the physiological and gene expression changes of cassava under different degrees of waterlogging stress in Hunan were systematically analyzed, and several differentially expressed genes and pathways related to waterlogging resistance were identified, which would lay a theoretical foundation for screening candidate genes of cassava in response to waterlogging stress, and also provide a new direction for further research on the molecular mechanism of cassava waterlogging resistance and the cultivation of waterlogging resistant varieties.

The yield of tropical crops is highly sensitive to climate conditions, and accurately modeling the meteorological-driven mechanisms is crucial for improving tropical agricultural productivity and climate adaptability. This study systematically compared the prediction performance of six machine learning models, including LGBM, RF, XGBoost, AdaBoost, SVM and MLR based on natural rubber, mango, pineapple and banana in Hainan. The SHAP method was used to quantify the contribution and non-linear response characteristics of meteorological factors. The LGBM model demonstrated the best prediction performance, with an average R² of 0.945 for the test set (the R² of rubber, mango, pineapple and banana were 0.942, 0.902, 0.954 and 0.983, respectively), and average RMSE and MAE of 1.436 t/hm² and 1.150 t/hm², significantly outperforming the other models (the R² of RF, XGBoost, AdaBoost, SVM, MLR were 0.773, 0.563, 0.589, 0.368 and 0.508, respectively). The meteorological-driven mechanisms exhibited significant crop-specific differences. Rubber yield was mainly driven by solar radiation (the contribution was 14.7%) and temperature factors (the contribution of monthly minimum temperature and monthly maximum temperature were 14.4% and 11.7%, respectively). Mango yield was highly sensitive to monthly maximum temperature (the contribution was 19.0%) and vapor pressure deficit (the contribution was 18.5%). Pineapple and banana yield were dominated by soil moisture (the contribution was 18.9%) and relative humidity (the contribution was 23.6%), respectively. Based on the findings, differentiated agronomic management recommendations for each crop type were proposed. This study demonstrates that machine learning, combined with explainability methods, can effectively elucidate the climate response mechanisms of tropical crops, providing theoretical support for regional agricultural precision management.

Transcriptional regulation is one of the pivotal mechanisms governing biological activities. Natural rubber (NR), a crucial industrial raw material, is predominantly derived from rubber trees. The transcriptional regulation of NR biosynthesis has emerged as a focal point in the fundamental research of rubber tree in recent years. Mevalonate diphosphate decarboxylase (MVD) is a key enzyme in the biosynthetic pathway of NR, yet its transcriptional regulation remains poorly understood. In this study, a 1500 bp promoter region of the HbMVD1 gene from rubber tree was cloned. Sequence analysis revealed the presence of various cis-acting elements, including the responsive to jasmonic acid, ethylene, mechanical wounding, light, and MYC binding. A gradient assay for autoactivation suppression demonstrated that the transcriptional autoactivation of the pAbAi-pHbMVD1 bait vector was effectively inhibited at an AbA concentration of 100 ng/mL. 13 non-redundant proteins from a rubber tree latex yeast cDNA library that interact with the HbMVD1 promoter, including one WRKY transcription factor (HbWRKY1), one heat shock transcription factor, and one G-box binding factor were identified utilizing yeast one-hybrid screening. Tissue-specific expression analysis indicated that the genes encoding the proteins exhibited distinct expression patterns across different tissues. Transcriptional regulation analysis showed that HbWRKY1 activated the expression of HbMVD1 in vivo. Molecular docking revealed that HbWRKY1 bound to the mechanical wounding element of the HbMVD1 promoter, and 11 potential amino acid binding sites were identified. This study would lay the groundwork for further elucidating the transcriptional regulatory network of HbMVD1 in rubber tree.