The study was aimed to explore the molecular mechanism of detoxification of prochloraz by Lasiodiplodia theobromae from mango and to screen related functional genes. In this study, RNA-seq technology was used to analyze the transcriptome sequencing and functional annotation of prochloraz-treated and untreated strains of L. theobromae. Prochloraz had significant inhibitory activity against the sensitive strain with an EC₅₀ value of 0.12 mg/L. The EC₅₀ value of the two resistant strains was 7.67 and 32.67 times higher than that of the sensitive strain, respectively. GO functional enrichment and KEGG signaling pathway enrichment analyses were performed for differentially expressed genes (DEGs) between prochloraz-sensitive strains (DF04) and -resistant strains (HL02 and M108). Compared with the untreated (CK) with prochloraz, there were 5342, 1148, and 2568 DEGs in DF04, HL02, and M108, respectively, after 10 mg/L prochloraz treatment. Among them, a total of 566 DEGs were overlapped among the three strains. Compared with the sensitive strains, the resistant strains had 2078 and 3096 DEGs up-regulated and 1527 and 1793 down-regulated expression, respectively. GO enrichment showed that the highest number of genes were involved in cellular process and metabolic process between resistant and sensitive strains after prochloraz treatment, accounting for 18% and 16%, 17% and 15% in HL02 and M108, respectively. KEGG enrichment showed that DEGs were significantly enriched in metabolic pathways between resistant and sensitive strains after prochloraz treatment, with 64.98% and 63.39% in HL02 and M108, respectively. The analysis for DEGs related to detoxification metabolism identified 27, 17 and 59 cytochrome P450 (Cytochrome P450), glutathione transferase (GST) and ABC transporter protein (ABC transporter) genes, respectively. Eight genes were randomly screened for quantitative real-time PCR validation, and the results confirmed that the trends in the relative expression of these genes were consistent with the transcriptome data. Based on the significantly up-regulated expression of DEGS in the resistant strains, the final screening of 7 P450s genes, 8 GSTs genes and 11 ABC transporter protein genes may be related to the metabolic resistance mechanism of L. theobromae to prochloraz. The results would provide new insights into the mechanism of fungicide resistance and lay the foundation for in-depth analysis of the molecular mechanism of metabolic resistance to prochloraz.

Tonoplast intrinsic proteins (TIPs), which comprise a subfamily of aquaporin (AQP) mediating the water balance within plant cells, could be divided into five phylogenetic groups on the basis of sequence similarity, i.e., TIP1–TIP5. Based on the full-length transcriptome previously described in tigernut (Cyperus esculentus), a tuber-abundant TIP gene named CeTIP4;1 was cloned and characterized in this study. Sequence analyses revealed that CeTIP4;1 contained two conservative introns with a complete coding sequence of 753 base pairs (bp), putatively encoding 250 amino acids with the theoretical molecular weight of 25.57 kDa, the isoelectric point (pI) value of 6.02, and the grand average of hydropathicity (GRAVY) value of 0.884, implying its acidic and hydrophobic features. The deduced peptide possessed one conservative major intrinsic protein (MIP) domain and exhibited similar structural features with the structure resolved AtTIP2;1. Classification of CeTIP4;1 into the TIP4 group was supported by the phylogenetic analysis, which showed that CeTIP4;1 clusters with AtTIP4;1, OsTIP4;1, OsTIP4;2 and OsTIP4;3 with sequence similarities of 69.62%–82.94%. After gene cloning, a plant expression vector for subcellular localization, i.e., pNC-Cam1304-CeTIP4;1, was successfully constructed. When transiently overexpressed in tobacco (Nicotiana benthamiana) leaves, confocal laser scanning microscopy imaging showed that CeTIP4;1 was unexpectedly localized to the cell membrane. Further expression analysis indicated that CeTIP4;1 exhibited an apparent tissue-specific expression patter, predominately expressed in tuber, root, rhizome, and shoot apex. Moreover, among the four typical stages of developmental tuber examined in this study, i.e., initiation, medium swelling, late swelling, and maturation, CeTIP4;1 exhibited a bell-like expression pattern, peaking in medium swelling tubers and lowest in maturation tubers. These results lay a solid foundation for further uncovering the mechanism of water balance in tigernut tubers.

In order to clarify the situation of macrofungal resources in Haikou, the analysis on species diversity of macrofungi in Haikou was carried out based on the samples collected by the authors in 2022 and deposited in Fungarium of the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (FCATAS). A total of 110 species of macrofungi, belonging to 69 genera, 32 families, 10 orders, and 2 phyla, were identified based on morphological and molecular evindence. Two new species, 10 new Chinese records, and 33 new records in Hainan were found. Five dominances with more than 5% in total species were Polyporaceae, Hypoxylaceae, Agaricaceae, Xylariaceae, Omphalotaceae and Pleurotaceae, including 55 species, accounting for 50.00% of the total species. The assessment of the utilization value of the macrofungi showed that there were 8 edible species, 14 medicinal species, and 3 poisonous species in Haikou, indicating the resources have good application prospects. According to the records of “Redilist of China’s Biodiversity-Macrofungi”, 44 species of macrofungi in Haikou were assessed. Among them, Macrocybe gigantea was near to be threatened (NT), 27 species were least concerned (LC), and 16 species were data deficient (DD). The present study would provide important scientific basis for the protection, utilization and management of macrofungal resources in this area.

To evaluate the functional germplasm resources of Cymbopogon citratus, the differences in betaine, alkaloid and flavone contents were analyzed. 45 C. citratus from Hainan, Fujian, Guizhou and Yunnan were evaluated by analyzing the content of betaine, alkaloids and flavonoids. The water extract of C. citratus mainly contained flavonoids (24.30%), alkaloids (13.53%) and betaine monomers (10.52%). The betaine content of HK-2 was the highest, reaching 5.65 mg/g. The alkaloid content of HK-1-1 was the highest, reaching 8.66 mg/g. The flavonoid content of YX-1 was the highest, reaching 43.15 mg/g. There were significant differences in the content of betaine, alkaloid and flavonoid in different storage locations, regions and altitudes of the resources. The mouse model of constipation induced by loperamide demonstrated that betaine had the effect of moistening the intestines and promoting bowel movements. Finally, based on the established functional resource evaluation method for C. citratus, first-class C. citratus resources YX-1, WN-2, GM-1, ZZ-1, RL-1 and YJ-4 were selected. The results of this study are helpful for the screening, evaluation and breeding utilization of functional resources of C. citratus, and could also provide scientific basis for the study of functional mechanisms and the development and utilization of functional products.

Fruit abscission in off-season longan is very serious during fruit development in Hainan, China, and severely affectse the formation of production. However, the research on the regulation of longan fruit abscission mainly is focused on fruit thinning, and there are very few studies on fruit preservation. The mechanism of abscission is mainly focused on hydrolase genes and reactive oxygen species, there is no report of fruit respiration on carbohydrate metabolism affecting fruit abscission. Previous studies showed that the decrease in carbohydrate level in fruit was closely related to fruit abscission. In order to further understand the relationship of carbohydrate metabolism and abscission, fruit clusters of off-season Chuliang longan were detached from tree body, the peduncles were immediately inserted into pure water and defoliation treatmented after detachment, which caused starvation stress and induced fruit abscission. Therefore, detachment of the fruit clusters from the tree served as starvation stress treatment. Change in the fruit abscission rate in the starvation stressed fruit clusters, respiratory oxygen consumption rate and fruit removal force in the three developmental stages under detachment were examined, and the effects of different light intensity on fruit respiration in the three stages were analyzed. It was found that longan fruit at different developmental stages differed in sensitivity to starvation stress, which rapidly initiated the fruit abscission response in all the three stages, but there were large differences in speed of fruit shedding. Young fruits responded to starvation stress for two days later than those in the middle and the late fruit development stage would lead to more intense fruit abscission response in the middle and the late stages. Respiratory oxygen consumption rate was the lowest in the young fruit stage. With the increase of light intensity, the respiration of young fruits did not cause a decrease in oxygen, but rather a release of oxygen. The decrease in the fruit removal force was also slower than that in the middle and late stages of fruit development. Therefore, it is concluded that fruit respiration was closely related to fruit abscission under starvation stress. Stronger fruit respiration intensity would result in faster fruit abscission under starvation stress and faster fruit removal force decreases. Young green fruits may carry out photosynthesis, which partially compensates for the respiratory consumption of carbohydrates in fruit, resulting in slower fruit abscission under starvation treatment. In the longan young fruit stage, the main reasons of slow fruit abscission under starvation stress are low respiratory oxygen consumption rate and certain photosynthetic capacity. Therefore, it is conclude that the young longan fruit is a partially autotrophic organ.

The changing patterns of soil chemical properties, enzyme activity, and microbial diversity in rubber plantations intercropped with three potato varieties (Jianchuanhong or JCH, Zishu or ZS, Daniujiao or DJN) were studied in this study. The results showed that rubber plantation intercropped with potatoes could significantly increase the soil organic matter, total nitrogen, total phosphorus, total potassium, alkaline dissolved nitrogen, effective phosphorus, soil β-glucosidase, N-acetyl β-D-glucosidase, acid phosphatase and aryl sulfatase activities, compared with rubber monoculture. There were significant differences among different potato varieties, with nutrient contents ranked as JCH>ZS>DJN, and enzyme activity ranked as DJN>JCH>ZS. Potatoes intercropped significantly increased the richness and diversity indexes of soil microorgnisms, and no significant differences among potato varieties. However, there was significant difference in the influence of different potato varieties on the abundance of specific microorgnisms in soil. The overall trend was that the abundance of specific bacterial such as Chloroflexi, Desulfobacterota were significantly decreased; the abundance of specific fungal such as Mortierellomycota, Chytridiomycota, and Kickxellomycota were significant increased. LEfSE analyses revealed that some beneficial microorganisms involved in material cycle or antagonistic to plant pathogens were enriched in the intercroppedg soil. DJN, ZS and JCH enriched 16, 26 and 31 marker microorganisms, respectively. Redundancy and correlation analysis showed that soil nutrient and enzyme activity were significantly correlated with the abundance of specific bacteria and fungi in the soil of rubber plantation. The increase of soil nutrients and enzyme activity decreased the abundance of specific bacterial and significantly increased the abundance of specific fungi. In conclusion, potato intercropped significantly increased soil nutrients, enzyme activity and soil microbial community diversity, but decreased the abundance of specific bacteria and increased the abundance of specific fungi. There were significant differences in the effects of different potato varieties on soil nutrients and enzyme activity, which may be related to the enrichment of different beneficial microorganisms. This study would provide a new idea and data support for the intercropping in rubber plantation.

In order to clarify the application effect of controlled-release urea combined with common urea on rubber trees, a 2-year field experiment was conducted to study the effects of different proportions of controlled-release urea combined with common urea on the yield, leaf and latex mineral nutrients and soil nitrogen content of rubber trees under the condition of nitrogen reduction, and to provide a reference base for reasonable nitrogen application in the cultivation of rubber trees. The results showed that the combined application of controlled-release urea and common urea increased the dry rubber yield and the nitrogen content of leaves. Compared with conventional fertilization, the dry rubber yield increased by 16.28%-39.13% (2021) and 7.94%-9.69% (2022), nitrogen content in leaves increased by 10.54%-19.17% (2021) and 10.24%-21.50% (2022), and the leaf nitrogen content of the combined application of controlled-release urea combined and common urea was above normal value. Combined application of controlled-release urea and common urea also increased the soil alkali-hydrolytic nitrogen content in the fertilization hole of rubber plantation by 11.27%-80.36% compared with conventional fertilization. When the ratio of controlled release urea and common urea was 50:50, the dry rubber yield (2022), leaf nitrogen content (2021—2022) and soil alkali-hydrolyzed nitrogen content (2021—2022) were significantly higher than those of conventional fertilization. Overall, under the conditions of this experiment, the combination of controlled-release urea and common urea at a ratio of 50∶50 could obtain a higher dry rubber yield, improve the nutritional status of leaves, maintain soil nitrogen level, and help to achieve green and efficient fertilizer management of rubber trees.

The anther regeneration system is the earliest in vitro tissue culture regeneration plant system of Hevea brasiliensis established in China, and the regenerated plants were named self-rooted juvenile clone, which have the advantages of rapid growth, high resistance as seedlings and genetic homogeneity as grafted seedlings, and yield increase by more than 20% due to rejuvenation. However, the buds collection period is only about 60 d per year, which does not allow for a year-round supply of callus formed by dedifferentiation anther wall cells, resulting in unsustainable research relying on this material. In this study, Reyan73397 stamens were utilized to study the callus induction and somatic embryogenesis of anther callus at different developmental periods (0 d, 7 d, 14 d, 21 d, 28 d, 35 d and 42 d), which were stored at two low temperatures of 15 ℃ and 20 ℃ for 15 d. The results showed that temperature 15 ℃ and 20 ℃ had no significant effect on the stages of callus induction and somatic embryogenesis after preservation, except that the number of embryogenic callus was significantly lower than that of the control the developmental period had significant effect on callus induction and somatic embryogenesis after preservation, and showed the greatest effect on the stage of cotyledonary embryo formation, of which the anther callus at 21 d and 35 d responded strongly, the number of cotyledonary embryos of 21 d anther callus was significantly higher than that of the control, and the number of cotyledonary embryos of 35 d anther callus was significantly lower than that of the control after preservation; the preservation of anther callus with different developmental periods for 15 d at 15 ℃ and 20 ℃ could extend the supply time of anther callus for 15~60 d, and primary cotyledonary embryos for 27-95 d compared to the control; the optimal solution was to keep the anther callus with developmental periods at 21 d at 15 ℃ and 20 ℃ for 15days, which could prolong the supply of anther callus and primary cotyledonary embryo for 60 days and 60-95 days separately. Although the treatment reduced the number of callus by 46.61%, it promoted the formation of cotyledon embryo by 27.18% in number. In this study, the short-term preservation of H. brasiliensis anther callus was realized, which would greatly alleviate the difficulty of insufficient source of genetic transformation receptors due to the short flowering period, the study time could be carried out for the whole year from 60 days to 240 days, which could help to speed up the research on optimization of the genetic transformation system of anther callus in Hevea brasiliensis.

Powdery mildew (Erysiphe quercicola) can infect a variety of economically important crops, and seriously threatens the rubber industry. In order to explore the molecular mechanism of the pathogenesis, the genome of E. quercicola (HO-73 strain) was sequenced and 133 candidate secreted effector proteins (candiate secreted effector proteins, CSEPs), which have homologous proteins only in other powdery mildew, were identified. An effector protein, CSEP02974, which is conserved in powdery mildew, was identified. The function of the signal peptide in secreted protein was assayed using the yeast secretion system. CSEP02974 was a cytoplasmic effector protein verified by using the Agrobacterium-mediated transient expression system and localization analysis. Further, CSEP02974 expression in Arabidopsis thaliana inhibited chitin- or flg22-induced callose deposition and ROS accumulation. The result suggests that CSEP02974 is a virulence factor in suppressing plant immunity. CSEP02974 was silenced by spraying exogenous double-stranded RNA on E. quercicola. Pathogenicity analysis showed that this gene silencing led to inhibitions of extended growth and infection. In conclusion, this study identified a key E quercicola virulence factor, which would provide an important clue on the mechanism of interaction between rubber tree and E. quercicola.

Conopomorpha sinensis is a main pest for litchi and longan. Currently, chemical pesticide control is still the primary technique on C. sinensis, which brings negative effects on the environment and increases insect pesticide resistance. Therefore, one imminent task is to develop new control strategies. The insecticidal plant glyceride oil, a new developed agricultural spray oil with no pesticide resistance, has a similar insecticidal effect compared with mineral oil. The contact insecticidal effects on C. sinensis eggs, pupae, adults and oviposition deterrent effect on adults of plant spray oil were evaluated by the spray method, and the evaluation of the field control effect was also conducted. The eggs, pupae, and adults were all susceptible to the oil. With 4.55 g/L of plant spray oil, the mortality rate of adult worms reached 100%, the emergence rate of pupae was less than 20%, the hatching inhibition rate of 1-day-old eggs was over 40%, and the plant spray oil had a certain repelling impact on spawning. Furthermore, the rate of fruit decay in the litchi orchard was greatly decreased by the oil treatment at the concentration of 4.55 g/L. The oil mixed with pesticides could reduce pesticide usage by half, while the rate of fruit decay was reduced to 1%. The results suggested that plant spray oil could be utilized to control C. sinensis in orchards, lessen the application of chemical pesticides, greatly enhance the control effect of C. sinensis, and offer a research foundation for the long-term, healthy growth of the litchi industry.