Yunnan Institute of Tropical Crops

Intercropping is widely promoted to sustain soil function, yet evidence for its application in rubber-based agroforestry, particularly with the shade-tolerant herb Amomum villosum, is limited. We evaluated whether A. villosum intercropping improves soil properties and reorganizes microbiomes across the vertical profile of mature rubber plantations. Soil samples were taken at 0–10, 10–20, and 20–30 cm depths in both intercropped and monoculture stands. Physical and chemical properties were quantified, and bacterial (16S rRNA V3–V4) and fungal (ITS2) communities were analyzed using high-throughput amplicon sequencing with depth-resolved data on diversity, composition, and functional inference (FAPROTAX, FUNGuild). Intercropping consistently improved soil structure and fertility, with the strongest effects at 0–10 cm. Total porosity (12%), organic matter (38.9%), alkali-hydrolyzable nitrogen (75.4%), and available phosphorus (131%) were markedly higher than in monoculture. Benefits extended to mid-depth with a 65.2% increase in alkali-hydrolyzable nitrogen. Microbial richness (bacteria and fungi) increased, and communities separated clearly by treatment and depth. Intercropped soils showed higher relative abundances of copiotrophic and particle-attached phyla (e.g., Proteobacteria, Planctomycetota), while Acidobacteriota and several Chloroflexi declined. Nitrospirota increased with depth. Fungal trophic structure shifted away from pathotrophs at 20–30 cm and toward symbiotrophs, particularly arbuscular mycorrhizal lineages, at subsurface layers. Functional predictions indicated greater potential for nitrogen transformations (e.g., nitrogen fixation, nitrification), greater C₁/hydrocarbon utilization, and a reduced bacterial plant-pathogen signal under intercropping. Collectively, A. villosum intercropping reorganizes the soil environment and microbiome in mutually reinforcing ways—improving physical structure, enlarging near-term nitrogen supply, and favoring beneficial fungal guilds. These depth-resolved effects help explain the agronomic appeal of rubber–A. villosum systems and support their wider deployment in rubber plantations.

The pollen morphological characteristics of 16 pummelos and 4 other citrus germplasms from Vietnam, Thailand, and China were observed using scanning electron microscopy (SEM). Observations included equatorial view, polar view, and exine ornamentation. The results showed that the pollen of all tested materials was monads, prolate, or subprolate. The average polar axis length of the pollen ranged from 29.121 to 37.043 µm, and that of the equatorial axis ranged from 19.861 to 25.911 µm. A t-test revealed that the polar axis of pollen from Chinese pummelo germplasms was significantly longer than that of varieties from Southeast Asia, indicating certain geographical differentiation. The apertures were all colporate type, predominantly with four to five colpi (75% of grains); only four colpi were observed in the remainder (25%). The pollen exine ornamentation of pummelo germplasms was perforated, whereas that of other citrus types was reticulate. Pummelos exhibited a smaller pori diameter (0.264–0.673 µm) and wider distance between pori (0.581–1.118 µm), while other citrus species had larger lumina (1.253–1.684 µm) and narrower muri (0.443–0.664 µm). Principal component analysis (PCA) and cluster analysis were performed based on pollen traits, and two principal component factors were extracted. The pummelo germplasms were divided into two subgroups: sweet pummelo and red pummelo, which demonstrated a correlation among their pollen morphology, flesh color, and flesh flavor. The phenotypic diversity of pollen among different pummelo germplasms may provide a valuable auxiliary reference for the identification and systematic classification of pummelos.

Coffee (Coffea spp.), a globally important crop, faces challenges in germplasm conservation due to habitat loss, climate change, and limited genetic diversity validation. This study aimed to evaluate the genetic representativeness of a coffee germplasm collection (CCGC, n=185) spanning major global varieties and wild relatives using re-striction-site associated DNA sequencing (RAD-seq). We performed genome-wide SNP profiling (37,729 loci), population structure analysis (STRUCTURE, PCA), and selection sweep detection (π) to assess genetic diversity, differentiation, and functional gene coverage. Results demonstrated that CCGC captured 98% of known disease-resistance loci (e.g., SH3, RppM) and exhibited high genetic diversity (π=0.1456, He=0.3014). Population structure analysis (K=3) identified three genetically distinct subgroups, among which Group 2 exhibited the highest diversity (He=0.3014, comparable to global coffee genetic resources) and encompassed all known Hemileia vastatrix resistance loci. The SNP density (7.5× higher than 5K SNP arrays) enabled precise identification of 47 selective sweep regions linked to domestication and adaptation. These findings validate CCGC as a genomically representative resource for coffee breeding and conservation. This work advances coffee genetic research by bridging resource preservation with molecular breeding strategies to address climate resilience and sustainable production.

Fructose-1,6-bisphosphatase (FBP) is a crucial regulatory enzyme in sucrose synthesis and photosynthetic carbon assimilation, functioning through two distinct isoforms: cytosolic FBP (cyFBP) and chloroplastic FBP (cpFBP). However, the identification and functional characterization of FBP genes in Saccharum remains limited. In this study, we conducted a systematic identification and comparative genomics analyses of FBPs in three Saccharum species. We further examined their expression patterns across leaf developmental zones, spatiotemporal profiles, and responses to diurnal rhythms and hormonal treatments. Our analysis identified 95 FBP genes, including 44 cyFBPs and 51 cpFBPs. Comparative analyses revealed significant divergence in physicochemical properties, gene structures, and motif compositions between the two isoforms. Expression profiling indicated that both cyFBPs and cpFBPs were predominantly expressed in leaves, particularly in maturing and mature zones. During diurnal cycles, their expression peaked around the night-day transition, with cpFBPs exhibiting earlier peaks than cyFBPs. FBP genes in Saccharum spontaneum displayed greater diurnal sensitivity than those in Saccharum officinarum. Hormonal treatments further revealed significant regulatory divergence in FBP genes, both between isoforms and across species. Notably, cyFBP_2 and cpFBP_2 members consistently exhibited higher expression levels across all datasets, suggesting their pivotal roles in sugarcane physiology. These findings not only identify potential target genes for enhancing sucrose accumulation, but also highlight the breeding value of S. spontaneum and S. officinarum in sugarcane breeding.

Grain width is one of the important factors determining grain yield and appearance quality. However, the genetic and molecular mechanisms controlling grain width remain be largely unexplored. In this study, we characterized a grain width mutant gw4 (grain width on chromosome 4), which showed reduced grain width but did not affect grain length. Sequence analysis revealed that a single base substitution (G to A) of LOC_Os04g01590 in gw4 resulted in the conversion of original encoded glycine to aspartate. The gene encodes an arginase that is localized on the mitochondrial and is highly expressed in panicles. RNA-seq and expression analysis showed that gw4 can control glume width by regulating the expression of cell cycle and cell expansion genes. Additionally, we also found that GS2 acts upstream of GW4 and regulates its expression by directly binding to GW4 promoter. In conclusion, we revealed that GW4 plays an important role in maintaining rice grain development. These results provide new insight into the genetic mechanism of arginase in the control of grain width and provide a potential target for molecular breeding of grain size.

Buchwaldoboletus xylophilus is an edible bolete species belonging to the family Boletaceae and the genus Buchwaldoboletus. It is found in tropical and subtropical regions, which are known for their rare wild resources. In this study, wild B. xylophilus was isolated and cultured, and its biological characteristics and artificial cultivation techniques were studied. The results show that the optimal carbon source, nitrogen source, and inorganic salt for the mycelium growth of B. xylophilus were maltose, ammonium tartrate, and magnesium sulfate, respectively. The most appropriate temperature was 28 °C, and the pH value was between 5 and 6. The most effective combination was determined via orthogonal experimentation, as follows: dextrose, ammonium nitrate, potassium dihydrogen phosphate, and 28 °C. The results of artificial cultivation in mushroom houses show that the mycelium of B. xylophilus was strong and grew well on the culture medium. The mycelial growth rate was 4.54 mm/d, and the fungus bags were filled about 50 days after inoculation. The primordia formed 9 to 14 days after covering with soil and the fruiting body matured in 6~8 days. The average yield of fresh mushrooms reached 131.07 ± 29.38 g/bag, and the average biological efficiency reached 28.48 ± 6.39%. In this study, artificial cultivation technology in respect of B. xylophilus in mushroom houses is reported for the first time. The fruiting bodies obtained through cultivation were identified using morphological and molecular biological methods. This technology offers benefits such as affordability, a brief cultivation cycle, substantial yields, and superior quality, making it ideal for industrial-scale and extensive cultivation.