Increasing the sucrose content of sugarcane, a major sugar crop, is a key breeding objective.  However, the complex genetic background of sugarcane affects development of sugarcane hybrids.  In this study, we sequenced 292 sugarcane germplasm accessions and identified 2,542,965 single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels).  We performed a genome-wide association study (GWAS) for two important sugarcane traits: sucrose content and stem diameter.  Both traits followed a normal distribution and showed typical characteristics of quantitative traits.  Population structure analysis revealed four subpopulations with an average genetic distance of 0.236.  GWAS of the sucrose content detected 27 SNPs.  After annotating genes at or near significant loci, 17 candidate genes were screened.  For stem diameter, GWAS revealed 19 SNPs, from which 9 candidate genes were identified.  These results improve our understanding of genetic mechanisms affecting sucrose content in sugarcane, and identify important genetic resources to accelerate breeding of new sugarcane varieties with high sucrose content.

Multiple cropping is a widely adopted land management strategy to improve agricultural productivity.  However, the environmental costs and agricultural sustainability of various rice cropping system remains unclear, particularly in tropical regions.  Here, we evaluated the productivity, economic benefits, and environmental sustainability of contrasting rotations including pepper-rice-rice, cowpea-rice-rice, and bitter gourd-rice-rice as triple cropping, and pepper-single rice , cowpea-single rice, bitter gourd-single rice, and fallow-rice-rice as double cropping.  The economic benefits of bitter gourd-single rice, and cowpea-single rice was higher than bitter gourd-rice-rice, and cowpea-rice-rice by 34.2%and 4.6%, respectively.  The environmental footprint indexes of the bitter gourd-rice-rice based on unit farmland area and economic benefit was 17.1-40.7% lower than bitter gourd-single rice. Similarly, the environmental footprint index of per area and per economic of cowpea-single rice decreased compared to cowpea-rice-rice by 25.6 and 21.3%, respectively.  These results indicate that reducing cropping intensity leads to lower environmental costs and higher economic benefits.  In addition, nitrogen and phosphorus footprints were found to be the dominant contributors to the overall environmental costs.  Meanwhile, optimizing fertilization and strategically arranging crop growth period are the key factors in improving the sustainability and productivity of the rotation systems.  In conclusion, bitter gourd-single rice and cowpea-single rice rotations are recommended as optimal cropping systems in tropical regions to reduce environmental impacts while maintaining high yields and economic benefits.

 Mechanized seed production with a large restorer-to-sterile parental row ratio is a developmental trend; however, the effects of different parental row ratios on spikelet pollination effectiveness and seed-setting rates remain unclear. In this study, a single-factor randomized block experiment was conducted in Sichuan, China, to evaluate the influence of parental row ratio designs on spikelet pollination effectiveness and seed-setting rate in sterile lines under unmanned aerial vehicle-assisted pollination conditions. In 2021 and 2022, R2 treatment significantly reduced the number of pollen grains and pollen grain number per spikelet position in the middle (M) and far (F) rows of the plot. However, this treatment yielded a significantly higher pollination rate of exposed stigma florets at each spikelet position in the near (N) and middle rows when compared to the results of the R1 and R3 treatments, resulting in a greater seed-setting rate. The number of pollen grains per stigma (1–3) did not significantly differ among the R1, R2, and R3 patterns in 2022. Over 50% of successfully pollinated florets had pollen loaded on a single stigma. In the C1 combination, the seed-setting rate of R2 increased by 43.07% (vs. R1) and 34.23% (vs. R3), with yield increases of 42.35% (vs. R1) and 18.53% (vs. R3). In the C2 combination, R2 seed-setting rate increased by 13.75% (vs. R1) and 34.62% (vs. R3), with final yield increases by 14.87% (vs. R1) and 29.80% (vs. R3). The R2 pattern reduced pollen loss by optimizing the matching degree between pollination wind field and parental strip width, providing a stable pollen supply for the sterile lines (N, M). This supply enhanced stigma pollen capture, thereby significantly increasing floret pollination rates, seed-setting rates, and yield. This study provides a theoretical basis and practical guidance for pollination strategies and optimization of parental row ratios in mechanized seed production.

Overapplication of nitrogen (N) is an important limiting factor in sustainable agricultural development. Breeding N-efficient genotypes is an effective approach to reduce crop N input, increase N-efficiency, and improve crop productive. However, the molecular mechanisms underlying low-N adaptations in peanut (Arachis hypogaea L.) roots are unknown. Herein, we compared root adaptation mechanisms to low-N stress between the N-efficient genotype JH15 (JH) and the N-inefficient genotype HY20 (HY), focusing on N metabolism and antioxidant capacity. Under N deficiency, JH exhibited a more developed root architecture, higher antioxidant activity, and higher N-metabolic enzyme levels under N deficiency. The expression of both high- and low-affinity nitrate transporter proteins (NRT2.5, NRT1.6), and the chloride channel protein CLC was upregulated in JH, with higher expression of genes encoding glutamine synthetase and asparagine synthase. However, only the low-affinity N transporters (NPF5.2, NPF7.3) were upregulated in HY. Flavonoid and isoflavonoid biosynthesis were the main metabolic pathways underlying the differences between the two genotypes under low-N treatment. The results of weighted gene co-expression network analysis and correlation network analysis revealed that differential expression of the key genes encoding caffeoyl-CoA O-methyltransferase, chalcone synthase, 2'-hydroxyisoflavone reductase, and shikimate hydroxycinnamoyl-CoA transferase affected key metabolites levels (epicatechin, kaempferol, calycosin, and biochanin A). We also found that WRKY40 and MYB30, MYB4, and bHLH35 may regulate flavonoids accumulation as positive and negative regulators, respectively. In summary, enhanced N uptake and assimilation and flavonoid accumulation in JH enhanced N metabolism and antioxidant capacity, improving N-efficiency.

The gut microbiota plays a critical role in regulating host fat deposition, yet the underlying mechanisms remain poorly understood. To investigate this question, this study employed germ-free (GF) and fecal microbiota transplantation (FMT) piglet models to systematically elucidate how microbiota-derived metabolites modulate fat deposition via N⁶-methyladenosine (m⁶A) RNA methylation. Although the FMT group showed no significant change in body weight compared with the GF group, it exhibited markedly increased subcutaneous and intramuscular fat deposition, as evidenced by larger adipocyte size (P<0.001), elevated serum and longissimus dorsi muscle triglyceride levels (P<0.05), and upregulated expression of adipogenic genes (P<0.05). Non-targeted metabolomics revealed elevated levels of bile acids, including hyodeoxycholic acid (HDCA), 12-ketodeoxycholic acid (12KDCA), and 3b-hydroxy-5-cholenoic acid (3b-h5-CA), as well as tryptophan metabolites indoxyl sulfate (IS) and L-kynurenine (L-Kyn) in the FMT group, and these metabolites were significantly correlated with lipid metabolism parameters. Mechanistic studies showed that these metabolites reduced m⁶A modification levels in mouse stromal vascular fraction (SVF) cells and fibro-adipogenic progenitor (FAPs) cells by upregulating fat mass and obesity-associated protein (FTO) and downregulating methyltransferase-like 3 (METTL3) (P<0.05), consistent with the in vivo observations in piglets. Furthermore, Bacteroides, Lactobacillus, Parabacteroides, and Akkermansia were identified as key genera involved in bile acid and tryptophan metabolism. Together, these findings reveal a gut microbiota–metabolite–m⁶A regulatory axis in fat deposition in pigs, providing new insights into host–microbiota interactions and offering potential strategies for improving metabolic health and meat quality in livestock.