0, 60 and 120 kg/hm² MgO treatments (denoted by Mg0, Mg60, and Mg120, respectively) on a long-term wax gourd (Tiezhu No.2) magnesium (Mg) fertilizer gradient positioning experiment was conducted in 2022 and 2023 to investigate the physiological mechanism of Mg to improve the storage resistance of wax gourd fruits by regulating pectin metabolism by measuring indicators such as fruit hardness, weight loss rate, Mg content and morphology, pectin content and morphology, and pectin metabolic enzyme activity during fruit storage. Results showed that wax gourd yield increased by 8.5% to 16.9% after Mg fertilization, with the Mg60 treatment showing the greatest increase. Compared with the Mg0 treatment, the flesh hardness of the Mg60 treatment increased by an average of 12.9%, 11.7%, and 18.9% in the two years of 0, 30, and 60 d storage, while the Mg120 treatment showed a significant difference from the Mg0 only after 30 days of storage in 2022. Suitable Mg fertilization delayed the rise of the fruit storage weight loss rate. The fruit storage weight loss rate of Mg60 after 60 d was 34.4% and 35.1% lower than that of Mg0 and Mg120 treatment. Magnesium fertilization significantly increased fruit Mg content. Alcohol-soluble (Mg_Eth), water-soluble (Mg_Wat), and salt-soluble Mg (Mg_NaCl) were the main forms of Mg in the fruit. The content gradually increased with the prolongation of storage time. During fruit storage, the total pectin content gradually decreaseg. However, appropriate Mg fertilization (Mg60) delayed the decline in water-soluble (WSP), ion-bound (CSP), and covalently bound pectin (SSP) content, thereby maintaining the total pectin content. Suitable Mg fertilization (Mg60) inhibited the activity of polygalacturonase (PG) and β-galactosidase (β-Gal), thereby slowing down the degradation process of pectin. Concurrently, it increased pectin methylesterase (PME) activity and the content of free Mg²⁺ (MgEth and MgWat), enabling negatively charged pectin acid to bind with Mg²⁺, thereby increasing CSP and SSP. This slowed the rate of hardness decline and weight loss caused by pectin degradation during fruit storage. Comprehensively, suitable Mg (60 kg/hm²) fertilization can improve the storage resistance of wax gourd by regulating pectin metabolism, which is conducive to optimizing the Mg of wax gourd, improving the storage quality, and promoting the sustainable development of the industry.

The fruit of rambutan has a delicate and juicy taste, but it is not resistant to storage. It is prone to browning 2-3 days after harvest, which limits the market circulation of rambutan. Therefore, green, safe and convenient post-harvest preservation technology is very important for the development of the rambutan industry. The purpose of the study was to explore the effects of exogenous sodium nitroprusside (SNP) treatment on the browning of postharvest rambutan peel and its active oxygen metabolism, and to provide new ideas for the browning of postharvest rambutan. The Baoyan 7 rambutan was soaked with 200 μmol/L SNP, and the control was treated with distilled water. The weight loss rate, browning index and antioxidant enzyme activity of rambutan during storage were measured. The results showed that SNP treatment could effectively inhibit the increase of browning index of postharvest rambutan peel and maintain the peel color. Compared with the control group, the activity of reactive oxygen species (ROS) scavenging enzymes [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX)] was significantly increased in the peel of rambutan treated with SNP, which improved the scavenging ability of reactive oxygen species radicals in the peel. The activities of polyphenol oxidase (PPO) and peroxidase (POD) were lower than those of the control, which effectively inhibited the occurrence of enzymatic browning. In addition, compared with the control group, SNP treatment can also significantly inhibit the increase of membrane lipid degradation-related enzyme activity (lipoxygenase, LOX) and maintain the structural integrity of pericarp cells. At the same time, the expression levels of browning-related genes NlWRKY23 and NlWRKY57 was significantly up-regulated. This shows that SNP treatment can enhance the antioxidant capacity of the peel of rambutan, reduce the oxidative damage of reactive oxygen species (ROS), and delay the occurrence of peel browning. The results of this study can provide theoretical basis and practical basis for the application of SNP in postharvest rambutan.

The study was aimed to explore the changes of basic nutrients, active substances and antioxidant activity of the Macadamia flowers in the bud swelling period, early flowering, and full-flowering stages, and provide the basis for its development and utilization. The changes of basic nutrients, active substance content and antioxidant activity of the Macadamia flowers at the bud swelling period, early flowering stage and full-flowering stage were systematically analyzed. The results showed that among the basic nutrients of the Macadamia flowers at three flowering stages, the water content showed a decreasing trend [the highest at the bud swelling period was (70.99±2.58)%]. Soluble protein was the highest (0.054±0.009)% in the bud swelling period. Crude fat increased first and then decreased [the highest was (2.20±0.021)% at early flowering]. The total ash content decreased first and then increased [the highest was (3.73±0.02)% at full-flowering stage]. The early flowering stage of total sugar was the highest (1.65±0.19)%. It contained 16 abundant amino acids (7 essential amino acids and 9 non-essential amino acids), and the total amino acid content decreased with the development of flowering period. The proportion of essential amino acids and E/N value were close to the international high-quality protein standard, showing good protein nutritional value. In the Macadamia flowers at different flowering stages, the contents of five major elements in the three flowering stages showed the order of K>Ca>P>Mg>Na, highlighting the advantages of high K and low Na. The content of K at full-flowering stage was 5.2 times that of banana, and the content of Ca was 5.0 times that of milk. However, as a food development, it is necessary to pay attention to the risk of excessive As, Cr and other harmful elements. A total of 22 (the bud swelling period), 14 (early flowering stage) and 20 (full-flowering stage) volatile components were identified, mainly hexanal and d-limonene, which together constituted its unique floral characteristics. The analysis of active components showed that the content of total polyphenols decreased significantly with the prolongation of flowering period, and the bud swelling period was (18.47±2.3)mg/g. The content of total flavonoids increased first and then decreased, and the content was the highest in the early flowering stage, reaching (8.09±0.63)mg/g. The antioxidant activity evaluation showed that the DPPH and ABTS free radical scavenging rates were the highest in the bud swelling period, which were (89.96±0.61)% and (99.50±0.22)%, respectively, and the antioxidant capacity was strong. In summary, the Macadamia flowers are rich in amino acids, minerals and active substances from the bud swelling period to the full-flowering stage, and have high antioxidant capacity, which provides a scientific basis for their subsequent development and utilization.

Camellia oleifera is an important woody oil crop in southern China. Due to its generally weak disease resistance, it is susceptible to various diseases, among which southern stem blight is one of the major threats to its production. This study systematically screened and analyzed the non-volatile metabolites produced by Trichoderma semiorbis FJ059 with antagonistic activity against Sclerotium rolfsii, the causal agent of southern blight in C. oleifera, and identified the potential antifungal components. The antagonistic effects of non-volatile metabolites produced in different solid-state fermentation media were compared using the growth rate method of mycelia. Results indicated that rice was the optimal substrate, yielding the highest antagonistic effect (99.61%). The solid-state fermentation products in rice media were extracted using different solvents. The ethyl acetate extract exhibited significantly higher inhibition activity than the aqueous extract. When the concentration was 500 μg/mL, the inhibition rates was 98.84% and 44.18%, respectively, indicating that the solvent selection play a vital role in the extraction of active compounds. LC-MS analysis identified several key active substances in the ethyl acetate extract, including nootkatone, caryophyllene oxide, farnesol, pyrrole-2-carboxylic acid, and trans-ferulic acid, all of which demonstrated significant antagonistic effects against S. rolfsii. Notably, the inhibition rate of 200 μg/mL nootkatone and 300 μg/mL caryophyllene oxide were both 100%, while 400 μg/mL farnesol, 400 μg/mL pyrrole-2-carboxylic acid, and 400 μg/mL trans-ferulic acid were 78.30%, 69.38% and 69.77%, respectively. The results indicated that medium-polarity or hydrophobic small molecules in the solid-state fermentation products of T. semiorbis FJ059 were potential antifungal components. The results indicated that the medium-polarity or hydrophobic small molecules detected in the ethyl acetate extract of solid-state fermented T. semiorbis FJ059 were closely associated with antifungal activity, suggesting that the ethyl acetate extract may enrich certain compounds with antifungal potential. The findings would provide new theoretical support and bioactive compound resources for the development of novel and efficient biocontrol agents against southern blight in C. oleifera.

Cassava (Manihot esculenta Crantz), a vital tropical food crop, exhibits significant sensitivity to low temperature, which severely restricts its cultivation range. Lignin is a key stress-resistant component in cell walls, playing a crucial role in plant adaptation to low temperature stress. However, the function of cinnamyl alcohol dehydrogenase (CAD), a pivotal enzyme in lignin biosynthesis, during low-temperature stress responses remains unclear. This study analyzed physiological phenotypes, CAD enzyme activity and lignin accumulation in cassava under low temperature stress. CAD enzyme activity was significantly increased by 66.7% and lignin content was also increased by 14.8% at the low temperature of 10 ℃. Transcriptome profiling identified MeCAD2 as the key gene responsive to low temperature stress. Heterologous expression of MeCAD2 confirmed that its encoded MeCAD2 protein possessed CAD enzymatic activity. Virus-induced gene silencing (VIGS) of MeCAD2 in cassava resulted in a 18.9% reduction in CAD enzyme activity and a 12.3%–22.4% decrease in lignin content. Furthermore, under low temperature stress, MeCAD2-silenced plants exhibited exacerbated leaf damage, a 172.5% increase in malondialdehyde (MDA) accumulation, and intensified reactive oxygen species (ROS) staining. The results indicate that MeCAD2 enhances cassava low-temperature tolerance by regulating lignin deposition. This study elucidated the critical role of MeCAD2 in cassava’s response to low-temperature stress, providing a novel candidate gene for molecular breeding.

This study was aimed to explore the impact mechanism of long-term different land use patterns on the physical and chemical properties and aggregate stability of tropical soils, thereby providing a scientific foundation for enhancing soil fertility and improving soil structure in tropical regions. For this purpose, three land use types with a history of nearly 30 years were selected as the research objects, namely artificially managed rubber plantation (MR), naturally managed rubber plantations (NR), and low human-disturbed longan orchards (NL). The basic physical and chemical properties of soil, the distribution of water-stable aggregates, and the characteristics of aggregate stability in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers were specifically analyzed. With the increase of soil depth, the soil pH in both MR and NL patterns showed a decreasing trend. In different profile layers, the pH of MR was lower than that of NL and NR. Under each soil layer, the contents of large soil aggregates (>2 mm, 1-2 mm) in the NR pattern were significantly higher than those in MR and NL. Conversely, the contents of small soil aggregates (<0.25 mm, 0.25-0.5 mm) were significantly lower than those in MR and NL patterns. Both the Mean Weight Diameter (MWD) and Geometric Mean Diameter (GMD) of soil water-stable aggregates in the NR pattern were significantly higher than those in MR and NL, and the fractal dimension (D) value was significantly lower than that in MR and NL. This indicates that the soil aggregates under the natural management pattern are more stable. Analysis of variance showed that land use patterns had an extremely significant impact on soil particle size distribution and aggregate stability. Soil depth significantly influenced the distribution of aggregates in the <0.25 mm, 0.25-0.5 mm, 0.5-1 mm, and 1-2 mm particle size fractions, with the intensity of the impact increasing as aggregate size decreased. The interaction effect between land use pattern and soil depth significantly affected soil aggregates (>2 mm, 1-2 mm) and the fractal dimension (D) value. Correlation analysis revealed that the soil aggregate stability indices (content of aggregates >2 mm, MWD, GMD) were negatively correlated with soil available phosphorus and positively correlated with soil organic matter (SOM); the fractal dimension (D) was negatively correlated with the content of soil aggregates (>2 mm) and significantly positively correlated with the content of soil aggregates (<0.25 mm). In conclusion, land use pattern is the most critical factor affecting soil aggregate stability. The naturally managed rubber plantation pattern can significantly increase the content of soil aggregates, enhance soil aggregate stability, and thereby improve soil structure.

Rubber tree (Hevea brasiliensis), an economically significant species, produces natural rubber, a strategic resource for China. Since rubber tree introduced from South America to Southeast Asia in the 19th century, rubber tree productivity has been substantially improved through sustained genetic improvement. This article comprehensively reviewed the botanical characteristics of the rubber tree, traced its history of introduction and domestication, and analyzed the current applications, achievements, challenges, and future research directions of both conventional breeding techniques (including hybrid breeding, polyploid breeding, mutagenesis breeding, etc.) and modern biotechnological breeding techniques (including molecular marker-assisted selection, genomic selection, genetic modification, gene editing, etc.) in rubber tree improvement. The review aims to provide a reference for researchers in rubber tree genetics and breeding, facilitate progress in this field, and promote the sustainable development of the natural rubber industry.

Reasonable fertilization is of great significance for increasing the yield of oil-tea Camellia, and the application of bio-organic fertilizers is superior to the current practice of using farm manure as the main fertilizer for oil-tea Camellia in many aspects. In order to develop and value the specialized bio-organic fertilizers suitable for the soil conditions of oil-tea Camellia plantations in tropical regions, the nutrient contents of oil-tea Camellia leaves, the physical and chemical properties, and enzyme activities of oil-tea Camellia forest soil were determined. The results showed that the application of bio-organic fertilizers and conventional compound fertilizer could significantly increase the water content, relative chlorophyll content (SPAD value), and nutrient elements of oil-tea Camellia leaves. The soil moisture contents and field capacities of different fertilization treatments were higher than those without fertilization, but there were no significant differences in soil bulk density and porosity between the treatments and the control group. All four types of bio-organic fertilizers could increase the contents of soil organic matter, alkaline nitrogen, available phosphorus, available potassium, and soil enzyme activity in different soil layers. T₁ and T₄ bio-organic fertilizer improved the chemical properties of oil-tea Camellia soil more, which is of great significance for the targeted improvement of the fertility and available potassium content of Hainan oil-tea Camellia forest land. The results would provide data for screening specialized bio-organic fertilizers suitable for tropical oil-tea Camellia, laying a scientific foundation for the subsequent large-scale application of bio-organic fertilizers for tropical oil-tea Camellia.

Phytophthora capsici is a damaging pathogen with a wide host range, causing devastating diseases such as root rot, stem rot, leaf and fruit rot in plants from diverse families like Solanaceae, Cucurbitaceae, and Legumes. The diseases pose a significant threat to the sustainability of related agricultural industries. In this study, we identified a key RXLR effector, Pc13306, from the RXLR effector repertoire of P. capsici. The coding region of Pc13306 comprised 888 nucleotides, encoding 295 amino acids, with a conserved RXLR motif residing at positions 34-37 in the N-terminal region. Utilizing a yeast secretion system, we confirmed that the signal peptide of Pc13306 exhibited robust secretory activity. Quantitative real-time PCR (qRT-PCR) analysis revealed that Pc13306 was specifically upregulated during the late stages of P. capsici infection. Through agrobacterium-mediated transient transformation of Nicotiana benthamiana Pc13306 was demonstrated to significantly enhance lesion expansion and pathogen biomass accumulation, thereby improving infection efficiency. Moreover, Pc13306 induced reactive oxygen species (ROS) bursts and hypersensitive response (HR). Further exploration into the regulatory mechanism of Pc13306 in plant immunity revealed that it activated the salicylic acid (SA) signaling pathway and autophagy processes. Notably, Pc13306 markedly upregulated the expression of core genes involved in pattern-triggered immunity (PTI), indicating its role in modulating plant immune responses. The findings would provide insights into the interaction mechanisms between P. capsici and its host, and facilitate the development of targeted disease control strategies focusing on effectors.

The study developed a new fresh-eating sweet potato variety Guishu No. 13 and established its virus-free seedling breeding technology system to meet the market demand for fresh-eating sweet potato varieties and healthy seedlings. Guishu No. 13 was bred from seeds by open pollinated using Guizhu No. 10 as mother. The variety has purple red skin, orange yellow flesh, and a high rate of medium to large storage roots. The content of β-carotene, protein and reducing sugar was 1790 mg/100 g, 1860 mg/100 g and 1200 mg/100 g, respectively. In the production experiment, the starch storage roots yield was 29 786.40 kg/hm² and starch yield was 4675.10 kg/hm², which increased by 5.52% and 17.52% respectively compared to Guishu No. 2 (CK). Guishu No. 13 has moderate resistance to Fusarium wilt, black rot, and stem nematode. The best culture medium for callus differentiation and germination rate of Guishu No. 13 was MS+0.10 mg/L NAA+1 mg/L 6-BA and MS+0.20 mg/L NAA+2 mg/L 6-BA, respectively. Guishu No. 13 has good yield and stability, high fresh storage root yield, and the establishment of a virus-free breeding system would lay the foundation for the development and application of the Guishu No. 13.