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.

Areca palm leaf yellowing virus disease, caused by Areca palm velarivirus 1 (APV1), is a fatal disease for which no effective control measures currently exist. Breeding resistant or tolerant varieties is the key approach to addressing this issue, while the collection of superior germplasm resources is an essential foundation for breeding efforts. This study focused on three major affected areas in Hainan Province (Tunchang, Qionghai, and Wanning) and systematically conducted research activities including germplasm collection, phenotypic observation, pathogen detection, and long-term monitoring. The results revealed that among the 200 areca palm germplasm materials collected, 84 out of 100 resistant/susceptible materials did not show the presence of APV1, while 92 out of 100 susceptible materials tested positive for APV1. This finding confirmed a close association between APV1 infection and plant yellowing symptoms, and demonstrated that the screened resistant/tolerant materials are representative. Through continuous observation and correlation analysis, a significant negative correlation was found between tree age and resistance/tolerance to the disease. This study successfully identified a group of betel palm germplasm resources with resistance/tolerance traits, laying a crucial foundation for the development of disease-resistant varieties in future breeding programs.

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.

Plant rhizosphere bacteria play a crucial role in plant nutrient uptake and utilization, and the active functional microbial communities in the rhizosphere are closely associated with high yield of crops. This study aimed to isolate, screen and identify functional bacteria from the rhizosphere soil of super high-yield rubber trees to identify beneficial strains that could potentially enhance rubber tree productivity. Using gradient dilution plating and selective medium, 60 strains of functional bacteria were isolated from the rhizosphere soil of super high yield rubber trees in Mengla Farm, Yunnan province. The isolated strains were characterized for the abilities to solubilize phosphate and potassium, fix nitrogen, and for the plant growth-promoting traits, including the production of indole-3-acetic acid (IAA), siderophores, ACC deaminase, and acetoin (3-hydroxy-2-butanone). 16S rDNA sequence analysis showed that the isolates could be classified into 12 genera, including Burkholderia, Paraburkholderia, Caballeronia, Cupriavidus, Dyella, Pseudomonas, Silvania, Enterobacter, Escherichia, Raoultella, Pantoea and Bacillus. Among these, Burkholderia was the dominant genus, comprising 40 strains (66.67%). Pot experiments with rubber seedlings demonstrated that the strain Enterobacter sp. SYK24 exhibited significant growth-promoting effects, with increases in whole plant fresh weight, aboveground dry weight, belowground dry weight and root length by 12.89%, 23.24%, 22.81% and 28.30%, respectively, compared to the control. The SYK24 treatment showed 5.01% and 18.98% reductions in total phosphorus and available potassium, respectively, compared to the control, while no statistically significant differences were observed in other soil nutrient contents. The strain Burkholderia sp. SYN37 did not promote biomass growth in rubber seedlings during the experimental period. SYN37 inoculation substantially depleted soil nutrients, resulting in reductions of soil organic matter by 31.39%, total nitrogen by 22.73%, and available potassium by 13.03% compared to the control. This study preliminarily established a small-scale functional bacterial strain library from the rhizosphere of super high-yield rubber trees, validated the growth-promoting effects of two functional strains through pot experiments, and would provide a scientific basis for the further development and application of microbial inoculants specifically tailored for rubber trees.

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.

The fruits of Qiongdong No. 9 Camellia oleifera at five developmental stages were taken as the experimental materials to ascertain the basic characteristics of the growth and development in Hainan and the changes in the content of antioxidant active substances. The morphological characteristics were observed, the crude fat and six main active ingredient contents of the seeds at different developmental stages were measured, and four antioxidant activity indicators of the seeds at different developmental stages were detected. The results demonstrated that the growth changes of each part of the fruit generally followed a logistic curve, presenting a slow increase in the initial stage, a rapid growth in the middle stage, and eventual stabilization. During the whole growth period, changes in crude fat content continued to accumulate, with S₃-S₅ being the period of rapid oil accumulation; the changing trends of the contents of flavonoids, total polysaccharides, vitamin E, ABTS radical scavenging ability and total antioxidant activity (FRAP) in seed kernels were consistent, experiencing a process of rapid decrease-significant increase-slow decrease. The content of carotenoids and the ability to scavenge hydroxyl radicals showed a significant increasing trend at all stages. The content of total phenols, total saponins, and total antioxidant activity (DPPH) showed a gradually decreasing trend. Through Pearson correlation analysis, the content of six active ingredients was significantly correlated with four antioxidant capacity indicators to varying degrees, and each ingredient had a different degree of response to different antioxidant capacities. S₁–S₃ were the rapid swelling stages of the fruit, accompanied by significant fluctuations in the content of active ingredients. S₃–S₄ were the key stages of substance transformation, and S₄–S₅ were the steady-state accumulation stages of contents; In the early stages of fruit development (S₁–S₃), water-soluble antioxidant components such as phenols, saponins, and polysaccharides dominated, while in the middle and late stages (S₃–S₅), they shifted towards lipid soluble components (carotenoids) and lipids. This competitive process was an important reason for the decrease in the content of the main active components. This research revealed the growth and development characteristics of C. oleifera fruits in tropical areas, which would have theoretical reference value for formulating corresponding cultivation and management measures for quality breeding purposes.

Areca palm velarivirus 1 (APV1) is identified as a causative agent of yellow leaf disease (YLD), which emerges as a prominent threat to betel palm plantation. Developing methods for rapid detection of APV1 is necessary for preventing and controlling YLD in betel palm cultivation. In this work, APV1 virions were extracted from APV1-infected Nicotiana benthamiana by using polyethylene glycol (PEG) precipitation, ultracentrifugation, sucrose density gradient centrifugation, and affinity magnetic beads. The purified APV1 virions were identified by transmission electron microscopy (TEM), SDS-PAGE and Western blotting. The purified APV1 virions were used to immunize BALB/c mice to produce polyclonal antiserum for detection of APV1. APV1 virions were precipitated from N. benthamiana homogenates by applying 5% PEG6000 and 0.6% NaCl. After resuspension and ultracentrifugation with 55% sucrose cushion, APV1 virions were distributed in the lower part of the sucrose layer or precipitated at the bottom of the centrifuge tube. APV1 was purified by 30%, 40%, 50%, 60% and 70% discontinuous sucrose density gradient centrifugation at 140 000×g for 2 h, and the results showed that APV1 was enriched in 60% and 70% sucrose layers. Affinity magnetic beads could efficiently purify APV1 virions. The purified virions were elongated, about 650–2200 nm in length and 10–13 nm in diameter. BALB/c mice were immunized with the extracted APV1 virions to obtain antiserum with high specificity for APV1 and titer of 1∶25 600. The results would provide a new idea for the separation and purification of APV1, and an important technical support for rapid detection of APV1.

Lignin serves a crucial defensive function in cassava's resistance to harmful organisms. Among the genes involved in lignin biosynthesis, shikimate hydroxycinnamoyl transferase (HCT) and caffeoyl coenzyme A-O-methyltransferase (CCoAOMT) are of particular importance. Yet, their specific roles in cassava's resistance to the insect pest P. marginatus remain to be fully elucidated. To elucidate the anti-insect defense mechanisms of cassava against P. marginatus, we conducted comparative studies using insect-resistant cultivar C1115 and susceptible cultivar KU50. Life table analysis revealed significant cultivar-dependent effects on pest developmental biology. Specifically, C1115-fed females exhibited significantly prolonged developmental duration (38.50 days in C1115 vs. 28.86 days in KU50), significantly reduced fecundity (221 eggs in C1115 female vs. 331 eggs in KU50 female), and significantly shortened adult longevity (4.30 days in C1115 vs. 8.83 days in KU50). Notably, population growth parameters demonstrated significant comprehensive suppression in C1115 cohorts: net reproductive rate (R₀=224.13 in C1115 vs. 330.67 in KU50), intrinsic growth rate (r_m=0.10 d^‒1 in C1115 vs. 0.12 d^‒1 in KU50), and finite growth rate (λ=1.11 d^‒1 in C1115 vs. 1.12 d^‒1 in KU50). Furthermore, extended generation time (T=50.25 in C1115 vs. 49.98 days in KU50) and doubling time (Dt=6.44 in C1115 vs. 5.97 days in KU50) were observed, indicating multilevel inhibition of pest population dynamics by C1115. Molecular characterization showed progressive downregulation of lignin biosynthesis genes HCT and CCoAOMT post-infestation in C1115. Although both cultivars exhibited suppression patterns, C1115 maintained significantly lower expression levels (52.99%, 66.81% of KU50) and enzymatic activities (74.42%, 73.91% of KU50) across timepoints. Using Spearman correlation analysis, it was found that both HCT and CCoAOMT gene expression levels and the activity of their encoded enzymes were negatively correlated with cassava resistance to P. marginatus. This suggests that the downregulation of these two genes may affect lignin accumulation in cassava leaves and the level of insect resistance defense responses. This study has laid a solid preliminary work foundation for in-depth analysis of the molecular mechanisms by which lignin regulates cassava's defense responses against P. marginatus

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.

Guangdong and Guangxi are the major production regions of pitaya and the common area for pitaya canker. Understanding the genetic diversity of Neoscytalidium dimidiatum is of great significance for the disease prevention and control. This research focused on four geographical population of N. dimidiatum mainly collected from Guangxi and Guangdong. To obtain the genetic fingerprints of N. dimidiatum, the isolates were amplified using ISSR genetic molecular markers and further analyzed the genetic diversity. The tested N. dimidiatum isolates were amplified with eight ISSR primers, resulting in 203 bands and the percentage of polymorphic sites was 31.7%, with the genetic similarity coefficient for any two germplasm resources ranged from 0.7619-1.0000. When the genetic similarity coefficient was 0.90 on the UPGMA cluster, all isolates could be divided into three groups, but the genetic groups were not closely related to the geographical distribution. The results of principal component analysis indicated considerable overlap between the four geographical groups and there were no relatively independent geographical poputation. This study proved that there existed lower level of genetic polymorphism in the isolates and there was frequent exchange of inoculum source between different places. The study would provide the scientific basis for researching the genetic architecture and pathogen surveillance of pitaya canker pathogen N. dimidiatum.