Soil salinization is an ecological environment issue globally and is one of the major abiotic stress factors that cause crop loss worldwide as well as hindering crop productivity. Halotolerant plant growth-promoting rhizobacteria (PGPR) having potential to promote crop growth and increase salt tolerance in crops can be employed to counter this issue in a more effective and eco-friendly way. The recent study aimed to assess the salinity tolerance and growth-promoting capacity of Bacillus tequilenis Bt-RS isolated from the rhizosphere soil of islands in the South China Sea, for assessment, the corresponding media were used for qualitative and quantitative analysis. A pot trail was also conducted to further evaluated its bacterial consortium to promote banana seedlings growth under salinity stress. The results showed that strain Bt-RS could grow well under the condition of 0-10% NaCl content with various types of salts. The strain Bt-RS also possessed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity along with indole acetic acid (IAA, up to 6.4 mg/L under the condition of 1%-5% NaCl). Base on the pot experiment, the banana seedlings that were inoculated with Bt-RS displayed a significant increase in height, leaf area, fresh weight of above ground and underground, as well as dry weight of above ground and underground (40.30%, 93.00%, 102.38%, 81.08%, 65.82% and 50.50%, respectively) compared to the control group under normal conditions; The 200 mmol/L NaCl-stress treatment significantly increased the growth of banana seedlings in height, leaf area, fresh and dry weight of both above ground and underground by 20.55%, 65.01%, 98.14%, 144.93%, 87.85% and 54.01% respectively, when compared with the control group. The plant height, leaf area and biomass of banana seedlings were significantly increased in both normal conditions and salt stress environment (P<0.05). There was no difference in plant height and leaf area between the experimental group under salt stress environment and the control group under normal conditions, indicating that applying Bt-RS can alleviated the adverse effects of NaCl stress and enhanced banana seedlings growth attributes. In conclusion, the strain B. tequilensis Bt-RS exhibits high salt tolerance and possess the ability to produce IAA and ACC deaminase, making it a valuable strain for improving banana seedling growth and salt tolerance, and also providing resources of strain for developing and utilizing in saline soil.

This research aimed to identify a pathogenic fungus of the brown spot disease in the leaves of Cycas and screen for its chemical control agents, which provides a theoretical basis for the protection of Cycas. The pathogenic fungus was isolated from the lesion spots in some Cycas leaves. The pathogenicity of the fungus was confirmed by isolating and purifying the infected leaf tissues and reintroduced to the healthy leaves of Cycas diannanensis following Koch’s postulates. Morphological identification of the pathogenic fungus was conducted. To further confirm the identification, a phylogenetic tree was constructed using eight gene sequences: SSU, LSU, GAPDH, tef1, rpb2, Alt, OPA10-2 and ITS. Effective chemical control agents were screened from seven chemical agents by inhibition assay in vitro. Phylogenetic analyses showed that this pathogen was Alternaria burnsii. Among the tested chemical agents, the most effective inhibition was fluoxastrobin, which displayed 73.48% inhibition rate at a concentration of 0.67 mg/L.

Natural rubber, a crucial industrial raw material worldwide, and a significant part of the income for Laotian farmers, is influenced by alternative planting policies and fluctuations in rubber prices. Aaccurate and rapid monitoring of local artificial rubber plantation is of crucial significance for promoting the sustainable development of the rubber industry. Most research has focused on the extraction of rubber plantation information in small areas, typically utilizing single or dual-temporal image classification, which fails to capture the long-term expansion characteristics of rubber forests. To investigate the long-term, large-scale expansion features of rubber plantation, this study selected a continuous thirty-year Landsat time series imagery from 1990 to 2020. The LandTrendr algorithm was employed to extract changes in rubber plantation across Laos over the three decades. International rubber futures prices and terrain data were also utilized for spatiotemporal change analysis. The selected feature combination, after optimization, can better extract rubber forest distribution. The overall accuracy of rubber forest distribution extraction in 2020 was 89.85%, with a Kappa coefficient of 0.82, revealing Laos’ rubber plantation area to be 321 000 hectares in 2020. The overall accuracy of rubber forest expansion change monitoring using the LandTrendr algorithm and secondary classification was 92.44%, with a Kappa coefficient of 0.82. The expansion of artificial rubber forests in Laos was closely related to the rubber futures market. Through terrain factor analysis, it is deduced that rubber forests are suitable for planting in low-altitude, gently sloping, and sunny areas. This study effectively monitors changes in rubber forests at the national level over an extended period, providing valuable data support for the development of the rubber industry and policy control.

Citrus is one of the most important fruits in China, and its post-harvest occurrence of citrus green mold is a serious threat to the quality and safety of citrus, and also causes mycotoxin contamination in the fruit. A strain of Streptomyces sp. R₂A-15 with good antagonistic effect on the pathogen of citrus green mold was isolated from the root soil of red orange plants in the red orange orchard of Jiuzhoujiang, Lianjiang, Zhanjiang city, Guangdong province. The optimization of the fermentation conditions and stability analysis of the bacterial inhibition activity were studied to provide reference for the preparation and application of the biocontrol agent of citrus green mold. In this study, Penicillium digitatum was used as the target fungus, and the fermentation broth was used as the inhibitory activity according to the size of the diameter of the inhibition zone by paper diffusion method. The fermentation medium of strain R₂A-15 was optimized using one-way and cross-combination tests, and the fermentation conditions were optimized by response surface analysis to improve the inhibitory activity of the fermentation broth, and the stability of the fermentation broth was investigated under different acid-base, temperature and ultraviolet light conditions. The optimum carbon source for the fermentation medium of the strain was cornmeal and the optimum nitrogen source was acid-hydrolyzed casein in the one-way and cross-combination tests. Based on response surface analysis, it was concluded that cornmeal and fermentation time had a significant effect on the bacteriostatic activity of the fermentation broth. The optimal fermentation medium for maximum inhibitory activity of the fermentation broth, as determined by validation tests, was 12.09 g of cornmeal, 4.00 g of acid-hydrolyzed casein, 2.00 g of calcium carbonate, 2.00 g of magnesium sulfate, 2.00 g of dipotassium hydrogen phosphate, 1.00 g of sodium chloride, and 1 L of distilled water. The optimal fermentation conditions were: initial fermentation pH 7.0, fermentation time 37.50 h, fermentation temperature 34 ℃, inoculum volume 3%, and shake flask filling volume 100 mL/250 mL. The bacteriostatic activity of the fermentation broth of the strains increased by 39% after optimization. The overall bacteriostatic activity of the fermentation broth of the strain could be maintained at a relatively stable and high activity level after treatment with different temperatures and ultraviolet light conditions, but the bacteriostatic activity of the fermentation broth decreased under strong acid and alkali. The results indicate that Streptomyces sp. R₂A-15 has a good and stable inhibitory effect on the citrus green mold pathogen, and has a good prospect for practical application, which lays a foundation for the later scale fermentation as well as the development of bacterial agents.

Rhynchostylis is an epiphytic orchid belonging to the Orchidaceae family. It possesses high ornamental and economic value. In this study, based on the collection of 10 different germplasm resources from three common species of Rhynchostylis, 21 pairs of SSR polymorphic primers were selected using fluorescent-labeled capillary electrophoresis for allele variation detection. Among them, 13 primer pairs exhibited high polymorphism, resulting in a total of 47 amplified alleles. The average number of observed alleles (N_a) was 2.238, and the average number of effective alleles (N_e) was 1.860. The observed heterozygosity (H_o) of the 21 loci ranged from 0 to 0.778, with a mean of 0.421, while the expected heterozygosity (H_e) ranged from 0.148 to 0.574, with a mean of only 0.340. The Shannon index (I) ranged from 0.096 to 0.987, with a mean of 0.567. The clustering results and PCoA analyses of the 10 germplasm were consistent with the traditional botanical classification, and all the germplasm could be classified into three taxa by species. On this basis, four pairs of core primers were selected to construct a molecular ID for each germplasm. This study lays a foundation for the collection, conservation, identification, development and utilization of the germplasm resources of Rhynchostylis.

The sisal zebra disease, caused by fungal pathogen Phytophthora nicotianae Breda, is one of the main diseases in sisal, which seriously affects the development of sisal industry. The pathogenic mechanism is not clear up to now. In order to obtain new anti-zero disease sisal variety, Yuexi 114 and H.11648 were used as the parents to breed new offsprings. Rema No.1 is one of the backcross progenies of Yuexi 114 and H.11648. Morphological traits including leaf shape, leaf color, have/none marginal spine, apical spine type, leaf length, leaf width, thickness of leaf base, length of apical spine, and spine basal width, plant height, inflorescence shape and flower stalk height, number of pedical, flower, fruit and seed characters, number of leaf, fiber ratio were examined. Ploidy level, genome size and resistance to P. nicotianae Breda was determined by an analysis of wall removal and low permeability flame drying method, flow cytometry, and inoculating P. nicotianae Breda in field and lab respectively. Rema No.1 is characterized by the presence of gray green, fleshier and rigid, sword-leaf with wax powder on the leaf surface, 1.2-2.0 cm apical spine, none marginal spine. Leaf length, leaf width and leaf base is about 130 cm, 16 cm, and 3.5 cm, respectively. The leaves rise in a spiral arrangement around the stem. Rema No.1 is also characterized by plant height 1.8-2.5 m, flower stalk 3-7 m, paniculate inflorescence, with 20-32 pedicals, complete flower, yellow flower with 6 petals, oblong capsule, dark brown to almost black upon maturity, lunate black seeds, marginate. leaves 360-400, leaf fiber ratio 3.5%, fiber length 100 cm. The life span is 6-9 years. Rema No1 is tetraploid (2X=4n), chromosome number is between 104-118, the genome size of Rema No. 1 is 2C=11.69 pg. Rema No.1 is high resistant to Phytophthora nicotianae Breda, and would be the main cultures in high incidence area of zero leaf disease in sisal planting region.

Tigernut (Cyperus esculentus L.) is an herbaceous oil crop uniquely accumulating a high level of oil in the underground tubers. Water, which accounts for approximately 85% of immature tubers, is essential for tuber development and metabolism. Plasma membrane intrinsic proteins (PIPs) represent the main channel that mediates the efficient water transport across the cell membrane. This study presents the characterization of CePIP2;1, a PIP gene highly abundant in tigernut tubers. This gene with three introns was shown to encode 288 amino acids with the theoretical molecular weight of 30.34 kDa, the isoelectric point of 8.60, the grand average of hydropathicity of 0.529, and the instability index of 29.60, implying it’s stable, basic and hydrophobic characteristics. The protein was shown to possess one conservative MIP (major intrinsic protein) domain, and presence of the F-H-T-R ar/R selectivity filter and Q-S-A-F-W Froger’s positions implies a putatively efficient water transport activity. Phylogenetic analysis revealed that CePIP2;1 clusters with OsPIP2;1, OsPIP2;2, and OsPIP2;3 with the similarities of 91.72%, 90.31% and 84.98%, respectively, supporting its assignment into the PIP2 group of the PIP subfamily. Subcellular localization analysis showed that CePIP2;1 was localized to the cell membrane of Nicotiana benthamiana leaves. Although CePIP2;1 was characterized as a dominant isoform in tubers, expression analysis indicated that its transcripts were relatively more in leaves, leaf sheaths, rhizomes, and roots with the most in leaves, in contrast to a comparable level to that in shoot apexes. Among four typical stages (S₁–S₄) of tuber development examined in this study, CePIP2;1 was shown to exhibit a bell-shaped expression pattern, peaking at S₂. These results laid a solid foundation for further uncovering the mechanism of water balance in tigernut.

This paper reports a new record Orchidaceae genus—Vandopsis Pfitz, and two new record species—V. gigantea (Lindl.) Pfitz and Dendrolirium tomentosum (J. Koenig) in Guangdong province. The detailed morphological description, habitat distribution and color photos are provided. The findings expand the distribution range of those taxons and is of great significance to the flora study.

Banana Fusarium wilt is a fungal disease which is the most harmful and difficult to control in banana production in China. Due to the influence of banana Fusarium wilt, the banana planting area in China has been decreasing year by year in recent years, which has brought huge economic losses to the subtropical and tropical banana industries in China. The disease occurred because the vascular bundle of banana was invaded by Fusarium oxysporum f. sp. cubense (Foc), and its propagation speed was fast, which caused the yellowing of banana leaves and plant wilting. By comparing the genome and transcriptome sequences of Foc race 1 (Foc1, N2) and race 4 (Foc4, B2), a secreted protein FoSP1 located in the lineage-specific region with high expression was screened out. The results showed that the open reading frame of FoSP1 gene was 387 bp, encoding 129 amino acids, and its signal peptide cleavage site was located between the 20th and 21st amino acid residues, and the protein had no known domain and functional site, so it was inferred that FoSP1 was a new secreted protein. In order to study the biological function of the protein in Foc4 strain, the split-marker method was used to knock out the FoSP1 gene of B2 strain, and the phenotype analysis and pathogenicity determination of the correctly knocked-out mutant were carried out. The results showed that compared with wild-type B2 strain, there was no significant difference in the vegetative growth of FoSP1 gene knockout mutants, and they were insensitive to exogenous stresses such as NaCl, D-sorbitol and H₂O₂, but the conidial yield and germination rate of knockout mutants were significantly reduced, and their pathogenicity to Brazilian banana was significantly weakened. It is inferred that the secreted protein FoSP1 does not participate in the vegetative growth of B2 strain, but plays an important role in the process of sporulation and pathogenicity. This result lays a foundation for further study on the pathogenic mechanism of secreted proteins in the genome lineage-specific region of Foc4.

This study was conducted to compare the difference of heat tolerance of different Oncidium cultivars, and to establish a system for evaluating identification indexes of Oncidium heat tolerance. Seven indexes, including the leaf thickness, leaf water content and high temperature semi-lethal temperature (HLT₅₀), of 38 common O. hybridum cultivars were measured, and the yellow leaf rate and heat injury grade (HIG) of different cultivars were observed under high temperature stress. The evaluation indexes of heat tolerance of Oncidium were screened by analyzing the correlation among different indexes and combining with principal component analysis, to establish the evaluation system of heat resistance of Oncidium cultivars. The results showed that the leaf thickness, leaf water content, HLT₅₀, yellow leaf rate and HIG could well reflect the response of Oncidium to high temperature stress, which could be taken as the index for evaluating Oncidium heat tolerance. The 38 cultivars could be classified into three categories: heat-tolerant cultivars (12 cultivars), moderate heat-tolerant cultivars (3 cultivars) and non-heat-tolerant cultivars (23 cultivars) by cluster analysis based on heat-tolerant index. The results of this study could provide a reference for material selection of Oncidium in hot area, and also provide parental resource for the breeding of Oncidium with high heat tolerance.