Polygalacturonase (PG) plays a crucial role in plant growth and development, and in stress responses, by participating in the degradation of pectin and altering cell wall structure. Although studies on PG genes have been conducted in various plants, there is a lack of research on the identification and functional characterization of the PG gene family in cassava (Manihot esculenta Crantz). This study identified a total of 89 members of the MePG family in the cassava genome, encoding proteins with 183 to 808 amino acids, molecular weights ranging from 19.75 to 87.07 kDa, and theoretical pI values between 4.64 and 9.71. Most of the family members are predicted to be localized in the cell membrane. Chromosome mapping analysis revealed that MePG family members were unevenly distributed across 17 chromosomes. Based on evolutionary relationships, MePGs were classified into seven subgroups (A to G), with similar gene structures within subgroups and evidence of tandem duplication. Comparative analysis indicated that the PG family genes in cassava were more closely related to rubber than to Arabidopsis. The promoter regions of MePG genes were enriched with elements responsive to light, hormones, and stress. MePG genes exhibit tissue specificity and were associated with cassava growth and development. During postharvest deterioration of cassava, MePGs displayed similar expression patterns, particularly MePG20, MePG21, MePG25, MePG64 and MePG72, which showed an initial increase followed by a decrease in expression, suggesting that the genes may initially respond to stress, upregulate to break down pectin, and then downregulate as cell wall hydrolysis is completed. This implies a significant role for PG in stress responses. Collectively, the findings suggest that MePG gene family members may have evolved through segmental duplication and intron loss and may perform different functions by sensing various types of signals, leading to diverse expression patterns. This would study provide a foundation for further exploration of the role of MePGs in the postharvest deterioration mechanism of cassava roots.

Isoamylase (Isoamylase, ISA) catalyzes the hydrolysis of α-1,6 linkages, thereby affecting the branching structure of starch and promoting crystallization and granule formation. The study utilized yeast two-hybrid screening to identify proteins interacting with MeISA2 to explore new proteins that may interact with MeISA2 to influence cassava starch accumulation. A bait protein vector pGBKT7-MeISA2 was constructed, and it was demonstrated that MeISA2 did not possess autoactivation activity and was non-toxic to yeast cells. Through yeast two-hybrid screening of a cDNA library, a total of 7 candidate interacting proteins were obtained. Point-to-point yeast two-hybrid re-validation experiments confirmed the interaction between MeISA2 and MePsbO1. MePsbO1 belongs to the Photosystem II oxygen-evolving enhancer protein (PsbO) family, which facilitates the efficient operation of the photosynthetic electron transfer process. Bioinformatics analysis revealed that MePsbO1 had the closest phylogenetic relationship with HbPsbO1 from Hevea brasiliensis, a member of the Euphorbiaceae family, with a similarity of 90.12%, while its similarity to Arabidopsis thaliana AtPsbO1 was only 77.71%. It is predicted that MePsbO1 is localized in the chloroplast, and the MePsbO1 gene is predominantly expressed in leaves. Plant ISA is involved in the synthesis of transient leaf starch, thus it is hypothesized that MePsbO1 and MeISA2 may interact to jointly regulate the rate of photosynthesis and the accumulation of transient leaf starch. The results study would provide new insights into the mechanism by which the MeISA2 gene participates in the accumulation and distribution of photosynthetic products in cassava source organs.

LEC2 is an important member of the LAV subfamily in the plant B3 superfamily and plays a significant regulatory role in embryo development and meristem maintenance. To explore the function of the PvoLEC2 in the cell regeneration of Plukenetia volubilis, the genomic sequence of PvoLEC2 (gPvoLEC2) was cloned through phylogenetic analysis and molecular biology techniques. The function of gPvoLEC2 in promoting plant regeneration was verified in Nicotiana benthamiana, and the function of gPvoLEC2 was studied in P. volubilis hairy roots. Phylogenetic and gene structure analysis indicated that the LEC2-ABI3 subfamily of Euphorbiaceae plants such as P. volubilis, and Arabidopsis thaliana, Oryza sativa, Populus spp. were relatively conserved. Expression analysis showed that PvoLEC2 was only weakly expressed in the late stage of P. volubilis seed development (50-65 DAP), and the motifs and key amino acid sites of the B3 domain were conserved. Overexpression of gPvoLEC2 led to dwarfing of transgenic N. benthamiana plants, difficulty in the growth of the main stem, and abnormal leaf development. At the same time, the regeneration ability of gPvoLEC2 transgenic N. benthamiana organs in vitro was significantly higher than that of the wild type, but lower than that of the positive control-ZmWUS2 & STM transgenic N. benthamiana. Overexpression of gPvoLEC2 in P. volubilis hairy roots led to their shortening and thickening. The results indicate that the genomic sequence of PvoLEC2 is a functional sequence that promotes plant regeneration, but it also causes abnormal development.

GASA (gibberellic acid-stimulated Arabidopsis) is a small molecule polypeptide widely presented in plants, playing an important role in plant growth and development processes. It has potential value especially in the regulation of mulberry bud dormancy. However, currently, the understanding of the functions of MaGASA genes in mulberry during the bud dormancy process is limited. The study aimed to identify the members of the mulberry GASA gene family and analyze the roles in bud dormancy. Bioinformatics methods were used to identify the members and analyze the physicochemical properties and other characteristics. Meanwhile, real-time fluorescence quantitative PCR and transcriptome data were utilized to analyze the expression patterns. The results showed that there were 12 MaGASA family members (MaGASA1-MaGASA12) in mulberry, which were distributed on eight chromosomes. There were differences in acidity and alkalinity among the members, and the average hydrophilicity coefficients were positive or negative, but all contained the GASA conserved domain. The phylogenetic tree showed that they had a close genetic relationship with peach. Collinearity analysis revealed that there were three collinear relationships in the MaGASA gene family. The promoter regions of MaGASAs contained cis-acting elements that respond to light, low temperature, and various hormones. The MaGASA family members showed tissue-variety specific expression. Among them, the expression level of MaGASA12 in mulberry buds was significantly higher than that in other parts. Transcriptome analysis indicated that the expression level of MaGASA12 decreased significantly during the dormancy breaking process, while the expression level of MaGASA10 increased sharply during the dormancy breaking process. The expression levels of MaGASA10 and MaGASA12 at different dormancy stages were detected by real-time fluorescence quantitative PCR technology, and the results further verified the conclusions of the transcriptome analysis, indicating that they may be related to the winter bud dormancy process of Morus. The research results would provide a theoretical reference for the in-depth study of the biological functions of MaGASA in mulberry and genetic breeding.

Stylosanthes guianensis, Pueraria phaseoloides, and Tephrosia candida were selected to investigate the impact mechanisms of green manures on soil physicochemical properties and nitrogen content in rubber tree leaves, through the analysis of natural abundance of ¹⁵N (δ¹⁵N) and partial least squares path analysis (PLS-PM) to elucidate the effects of different leguminous green manures on soil improvement and nitrogen uptake in young rubber plantations. Results showed that P. phaseoloides and S.guianensis treatments significantly increased soil alkaline nitrogen by 30.54% and 31.25%, respectively, while reducing available potassium by 8.40% and 6.87%, compared to natural grass cover. P. phaseoloides treatment had the strongest effect on increasing soil organic matter and available phosphorus content, with increases of 12.60% and 30.94%, respectively. S. guianensis treatment had the strongest effect on increasing the total nitrogen content in rubber trees leaves (an increase of 25.86%). Correlation analysis and PLS-PM indicated a significant positive correlation between leguminous green manures and soil alkaline nitrogen and total nitrogen content, with a significant positive effect. In conclusion, under the conditions of this study, leguminous green manures promoted the absorption and accumulation of nitrogen in rubber tree leaves by increasing soil alkaline nitrogen content. The rational selection or mixed planting of leguminous green manures can improve the nutrient absorption efficiency of rubber trees and contribute to the sustainable production of rubber plantations.

The influence of root exudates on neighboring plants is one of the important factors determining the coexistence status of plants and their neighbors. This study aimed to explore the effects of the root exudates of Stylosanthes guianensis and cultivation substrates on the growth and physiological characteristics of Hevea brasiliensis seedlings. We cultivated H. brasiliensis seedlings with distilled water, sterilized vermiculite, and soil as cultivation substrates, and compared the differences in biomass accumulation and distribution, aboveground and underground morphological characteristics and physiological characteristics of H. brasiliensis when they respectively were irrigated with nutrient solutions containing the root exudates of S. guianensis and containing their own root exudates. The results showed that in soil culture and distilled water culture, the aboveground biomass, underground biomass, total biomass, primary lateral root number, chlorophyll content, carotenoid content, soluble carbohydrate content and root vitality of H. brasiliensis seedlings under the treatment of S. guianensis root exudates were significantly higher than those under the treatment of their own root exudate (P<0.05), except for the difference of root-shoot ratio, plant height and root length. Moreover, except for root vitality, the increase extent of the indexes was distilled water culture > soil culture. The malondialdehyde (MDA) content of S. guianensis root exudate treatment was significantly lower than that of H. brasiliensis root exudate treatment (P<0.05). When cultured with sterilized vermiculite, there were no significant differences in biomass index, morphological index and MDA content of H. brasiliensis seedlings treated with root exudates of two kinds of plants, but chlorophyll content, carotenoid content, soluble sugar content, and root vitality were significantly increased under root exudates of S. guianensis treatment (P<0.05). The comprehensive evaluation of membership function of H. brasiliensis seedlings cultivated in the substrates under the treatment of root exudates of S. guianensis was higher than that of their own root exudates, and the comprehensive evaluation of cultivation substrates under the treatment of the same root exudates was vermiculite culture > distilled water culture > soil culture. It indicates that the root exudates of S. guianensis can significantly improve the physiological function of H. brasiliensis seedlings and promote their growth, but the response of H. brasiliensiss to root exudates is significantly affected by the cultivation substrate.

After intercropping pepper with areca nut, pepper plants recovered their growth. This might be related to the mutual interaction between the rhizospheres of the two plants, especially the promoting effect of areca nut root exudates on pepper plants. However, the specific components that play a role remain unclear, which makes it difficult to provide a basis for in-depth research. In this study, the root exudates of pepper and areca nut seedlings were extracted by hydroponics. The full components of the root exudates were identified by LC-MS/MS metabolomics, and the specific differential components unique to areca nut root exudates were screened out. After classification, these were used as the exogenous substances and added to further clarify the effects of different components on pepper seed germination and seedling growth. A total of 426 metabolites were detected in the root exudates of pepper, and 438 metabolites were identified in those of areca nut. There were 509 differential metabolites between areca nut and pepper, among which 329 were significantly different, and 138 were more abundant in areca nut and 191 in pepper. The contents of flavonoids and organic acids were higher in areca nut root exudates than those in pepper, while the contents of sugars, phenolic acids, coumarins, benzoic acids and amino acids were higher in pepper than in areca nut. After classification of the differential metabolites with high content in areca nut root exudates into organic acids, amino acids, phenolic acids, sugars and flavonoids, two with higher fold differences were selected as specific components for addition. The results showed that the addition of flavonoids had the highest germination rate and germination potential of pepper seeds, and the height of seedlings, dry weight of aboveground and underground parts were the highest. The addition of organic acids and phenolic acids was second, while the effects of sugars and amino acids were not obvious. In conclusion, there are many specific differential components in areca nut root exudates, but the promoting effects of different components on the growth of pepper seedlings in soil culture after intercropping are different. Among them, the flavonoids group has a large number and high content, and has obvious promoting effects on pepper seed germination and seedling growth, which is the main component of areca nut root exudates that alleviates the disorder of pepper intercropping. The results of this study provides a basis and theoretical evidence for revealing the mechanism of rhizosphere interaction between the two plants and analyzing the alleviation of pepper intercropping disorder by intercropping with areca nut.

The browning of the fruit pericarp is one of the most significant quality deterioration characteristics of litchi during storage, transportation, and circulation after harvest, which seriously affects its commercial value. In this study, three stress treatments were applied to litchi, mild dehydration treatment (DT), heat shock treatment (HT), and cold shock treatment (CT). We analyzed the changes in appearance quality, browning index, physiological indices, and the activities of polyphenol oxidase (PPO), peroxidase (POD), and superoxide dismutase (SOD) after treatment to explore a new approach to delay pericarp browning by inducing resistance in litchi. The results indicated that after the three stress treatments, the browning of the litchi pericarp was exacerbated, accompanied by a decrease in pericarp brightness, water content, and increased membrane permeability at room temperature. The browning in the DT group was the most rapid, reaching a browning index of 4.99 on the 6th day. In contrast, HT and CT significantly delayed the browning of the litchi pericarp. The completely browned pericarp in the DT group was dry, yellow, and brittle, with the lowest water content (27.76%), which was significantly lower than that in the HT and CT groups (45.20% and 42.99%, respectively). The order of respiration rates was CT>HT>DT, and the relative electrical conductivity was DT>HT>CT. The activity of PPO and POD in the HT and CT groups was inhibited during the early part of storage, while the activity of SOD significantly increased at the later stage. Transmission electron microscopy results showed that the cell structure of the brown peel was destroyed and the contents were largely degraded in the DT and CT groups, whereas the brown pericarp cells in the HT group remained structurally intact and contained a large amount of coalesced sediments. Correlation analysis results showed that the browning index of the litchi pericarp under the three stress treatments was positively correlated with relative conductivity and negatively correlated with L^* (brightness), water content in the pericarp, and anthocyanin content (P<0.05). In conclusion, mild dehydration treatment led to rapid browning of litchi, while heat shock and cold shock stress treatments maintained higher water content in the pericarp and respiratory intensity of the litchi fruit. The treatments inhibited the increase of relative electrical conductivity and the activities of PPO and POD enzymes and increased the activity of SOD in the later storage period by stimulating the litchi’s self-resistance, thereby inhibiting the browning of litchi fruits and delaying the decline in fruit quality.

Coffee is an important economic crop in Yunnan, China. To investigate the effects of bee pollination on coffee production, this study examined the species of pollinating bees and the foraging behavior of dominant bee species during the coffee flowering period in Lisou, Ximeng, Yunnan. Additionally, the study evaluated and compared the fruit traits of coffee under bee pollination and control groups. The results showed that the bee species visiting coffee flowers included Apis dorsata, Apis cerana cerana, Apis florea and bumblebees (Bombus spp.), with A. dorsata and A. cerana cerana being the dominant species. A. dorsata visited coffee flowers throughout the day (from 9: 00 to 17: 00), while A. cerana cerana primarily foraged in the morning. However, the visiting duration per flower of A. cerana cerana was extremely significantly longer than that of A. dorsata (P<0.01). Introducing A. cerana cerana colonies increased the number of flower-visiting bees. Compared with the control group, the bee pollination group showed significantly higher fruit set rates, single fruit weight, seed weight, and seed number. Moreover, the fruit skins became thinner, and other traits improved, with a higher proportion of fruits reaching high maturity at harvest. The findings suggest that bee pollination can significantly improve coffee fruit traits, promote fruit maturation, and effectively enhance coffee quality. The results would provide a theoretical basis for improving coffee cultivation and productivity.

External application of regulator can reduce the damage of plants under low temperature stress, and 2,4-epibrassinolide (EBR) is a regulator that can enhance the cold resistance of plants. The study was aimed to investigate the influences of exogenous 2,4-epibrassinolide on the physiological characteristics of Dendrobium hybrida seedlings under low-temperature stress. In this study, the seedlings of Dendrobium hybrida ‘Sweel Maple’ were treated with various concentrations of EBR solutions (0, 0.1, 0.5, 1.0, 1.5, 2.0 mg/L) through foliar spraying, and then treated under 5 ℃ low-temperature in artificial climate chamber. The yellowing leaf rate, defoliation rate and the malondialdehyde (MDA), soluble sugar, soluble protein, proline and chlorophyll content of treated samples were measured. The results indicated that EBR could significantly reduce the rates of yellow leaves and defoliation in D. hybrida seedlings under temperature stress, with the optimal treatment concentration being 2.0 mg/L. Compared with the control, the rate of 50% yellow leaves, 100% yellow leaves, and defoliation decreased by 27.41%, 16.55% and 20.64%, respectively. Additionally, 2.0 mg/L EBR effectively mitigated the decline in chlorophyll content in seedlings’ leaves under low-temperature stress and decreased the relative electrical conductivity and MDA content. Specifically, the relative electrical conductivity decreased by 14.33% and the MDA content by 29.03%, compared to the control. Furthermore, 2.0 mg/L EBR enhanced the content of osmotic adjustment substances in the seedlings’ leaves under low-temperature stress. On the eighth day of stress, the soluble protein and soluble sugar contents reached 1.68 mg/mL and 46.49 mg/mL, respectively, while proline content peaked at 142.28 μg/mL on the second day after returning to normal temperature, which was significantly higher than that in the control. In summary, EBR effectively alleviated the damage caused by low-temperature stress to D. hybrida seedlings. Various indicators demonstrated that 2.0 mg/L EBR exhibited the most prominent effect in enhancing the seedlings’ cold resistance, making it the optimal treatment concentration.