Bacterial leaf pustule (BLP), caused by Xanthornonas axonopodis pv. glycines (Xag), is a worldwide disease of soybean, particularly in warm and humid regions. To date, little is known about the underlying molecular mechanisms of BLP resistance. The only single recessive resistance gene rxp has not been functionally identified yet, even though the genotypes carrying the gene have been widely used for BLP resistance breeding. Using a linkage mapping in a recombinant inbred line (RIL) population against the Xag strain Chinese C5, we identified that quantitative trait locus (QTL) qrxp–17–2 accounted for 74.33% of the total phenotypic variations. We also identified two minor QTLs, qrxp–05–1 and qrxp–17–1, that accounted for 7.26% and 22.26% of the total phenotypic variations, respectively, for the first time. Using a genome-wide association study (GWAS) in 476 cultivars of a soybean breeding germplasm population, we identified a total of 38 quantitative trait nucleotides (QTNs) on chromosomes (Chr) 5, 7, 8, 9,15, 17, 19, and 20 under artificial infection with C5, and 34 QTNs on Chr 4, 5, 6, 9, 13, 16, 17, 18, and 20 under natural morbidity condition. Taken together, three QTLs and 11 stable QTNs were detected in both linkage mapping and GWAS analysis, and located in three genomic regions with the major genomic region containing qrxp_17_2. Real-time RT-PCR analysis of the relative expression levels of five potential candidate genes in the resistant soybean cultivar W82 following Xag treatment showed that of Glyma.17G086300, which is located in qrxp–17–2, significantly increased in W82 at 24 and 72 h post-inoculation (hpi) when compared to that in the susceptible cultivar Jack. These results indicate that Glyma.17G086300 is a potential candidate gene for rxp and the QTLs and QTNs identified in this study will be useful for marker development for the breeding of Xag-resistant soybean cultivars.

Background: Anoectochilus roxburghii (Wall.) Lindl. is an endangered medicinal herb, and salt stress has been reported to promote the accumulation of bioactive secondary metabolites. Central carbon metabolism plays a key role in carbon allocation in plants; however, the integrated molecular and metabolic responses of A. roxburghii to salt stress remain largely unclear. Method: In this study, an integrated transcriptomic and metabolomic approach was employed to investigate the reprogramming of central carbon metabolism in A. roxburghii under 50, 100, and 200 mM NaCl treatments. Results: Metabolomic analysis revealed a significant accumulation of soluble sugars, which suggests enhanced osmotic adjustment and alteration in energy metabolism. Transcriptomic profiling identified 7019 upregulated and 5192 downregulated DEGs, with pathways related to the TCA cycle, galactose metabolism, and fructose/mannose metabolism predominantly upregulated, while oxidative phosphorylation was suppressed. Integrative transcriptome–metabolome profiling further identified key genes associated with oxaloacetate and fructose-6-phosphate, suggesting a coordinated regulation between central carbon metabolism and polysaccharide biosynthesis. Conclusions: Collectively, these findings demonstrate that salt stress induces coordinated metabolic and transcriptional reprogramming in A. roxburghii, driving carbon flux reallocation from growth-related processes toward osmoprotective metabolism. This provides a mechanistic basis for the enhancement of bioactive compounds under moderate stress and offers insights for improving both salt tolerance and medicinal quality in saline environments.