Plants

Drought stress is the major environmental constraint in crop production. As climate change increases drought frequency, enhancing drought tolerance has become a major goal in barley breeding. Hordeum vulgare ssp. spontaneum, the wild and closest relative of cultivated barley, is a valuable genetic resource for breeding and developing drought-tolerant cultivars. This study aimed to compare physiological and transcriptomic responses of a drought-tolerant wild genotype (H. vulgare ssp. spontaneum) and a drought-sensitive cultivated barley genotype (‘Mona’ cultivar) under control and drought stress conditions. The wild genotype exhibited less physiological and growth impairment than the ‘Mona’ cultivar under drought stress. Transcriptome profiling identified 2564 differentially expressed genes (DEGs) in the drought-tolerant wild genotype and 2163 DEGs in the drought-sensitive cultivar. Notably, in the tolerant genotype, most DEGs were up-regulated, whereas in the sensitive cultivar, down-regulation was more frequently induced by drought. GO enrichment analysis revealed that the DEGs were predominantly associated with key stress-related biological processes, including cellular component organization, signaling pathways, ion transport, regulatory protein activity, reactive oxygen species (ROS) scavenging, hormone biosynthesis, and osmotic homeostasis. Comparative analysis showed that the drought-tolerant genotype harbored more functionally effective drought-responsive genes and had higher transcript abundance than the sensitive genotype. Overall, the tolerant genotype consistently exhibited superior physiological and functional performance under drought stress. These findings deepened our understanding of the evolutionary basis of drought tolerance in wild barley, while the shared functional mechanisms between the two subspecies identified physiological and transcriptional traits that could be exploited to improve barley under water-limited environments.

The integrated effects of biochar and humate on soil nutrient status, shoot nutrient accumulation, and grain composition and quality remain underexplored. This field study evaluated four treatments—control, rice husk biochar (RHB; 15 t/ha), potassium humate (KH; 6.3 kg/ha), and RHB + KH—on soil properties, shoot nutrient accumulation, grain nutrient composition, yield, and grain quality in a premium Thai rice production system. Compared with the control, RHB significantly increased soil pH and shoot accumulation of nitrogen (N; +93%), phosphorus (P; +321%), and potassium (K; +75%) and resulted in a greater grain P concentration and milled grain yield (+56%). RHB also increased volumetric expansion (+42%), with a significant RHB main effect detected in the factorial analysis. KH significantly increased soil total N (+11%) and ammonium (+19%), shoot N (+79%) and P (+363%) accumulation, and grain N concentration relative to the control, while also increasing milled grain yield (+144%) and grain protein content. KH also produced numerical increases in volumetric expansion (+21%) and grain elongation (+4%), although these responses were not significant in the factorial analysis. The RHB + KH treatment significantly increased soil total N (+18%), shoot N (+70%) and P (+423%) accumulation, and the grain K concentration relative to the control and produced treatment-specific changes in the amino acid profile. The amendment treatments generally decreased residual soil nitrate and available P concentrations, although the factorial response of nitrate included a significant RHB effect and RHB × KH interaction but no significant KH main effect. Grain carbohydrate content decreased under the amendment treatments, whereas TPC showed a treatment-specific response characterized by a significant KH effect and RHB × KH interaction. Principal component analysis revealed associations among soil properties, shoot nutrient accumulation, grain nutrient composition, yield, and grain quality attributes. These findings demonstrate distinct effects of RHB and KH, individually and in combination, on soil properties, shoot nutrient accumulation, and grain composition and quality. Overall, the amendments showed potential for modifying soil nutrient dynamics and shoot nutrient accumulation while altering selected grain nutritional and market-relevant quality attributes, although responses varied among individual parameters.

Cenchrus pauciflorus is a major invasive plant in the sandy lands of northern China, with the Horqin Sandy Land being a hotspot of its invasion, where soil phosphorus availability may influence its spread through arbuscular mycorrhizal fungi (AMF). To elucidate the effects of soil phosphorus on AMF communities and their role in the invasion of C. pauciflorus, we conducted a field survey at two sites with contrasting phosphorus backgrounds: Chajintai Ranch (high phosphorus) and Bahuta Sumu (low phosphorus). Rhizosphere soil and root samples of C. pauciflorus and the co-occurring native grass Setaria viridis were collected for high-throughput sequencing of 18S SSU rRNA gene to analyze AMF community composition and diversity. Two AMF species, Funneliformis mosseae and Diversispora epigaea, were selected for a pot experiment with C. pauciflorus. Five phosphorus treatments were established under high- and low-phosphorus conditions using different phosphorus forms. The effects of the two AMF species on the growth and reproduction of C. pauciflorus under different phosphorus treatments were analyzed. The results showed that Glomeraceae and Glomus were the predominant family and genus, respectively. Under Bahuta Sumu, Diversispora was relatively enriched in the roots of C. pauciflorus compared with S. viridis roots. However, other nutrient factors also varied between the two field sites, the independent effect of phosphorus on AMF community composition and diversity could not be fully disentangled. The pot experiment revealed that AMF inoculation did not significantly promote the growth of C. pauciflorus under high-phosphorus treatment. In contrast, when phosphorus was low and supplied in insoluble forms, both AMF species significantly promoted the growth and reproduction of C. pauciflorus. D. epigaea exhibited a stronger growth-promoting effect than F. mosseae, with significantly higher colonization rates in most treatments. In summary, C. pauciflorus is associated with the enrichment of specific AMF taxa in low-phosphorus habitats, which may in turn promote its growth by enhancing the acquisition of insoluble phosphorus. This may represent an important belowground symbiotic mechanism underlying its successful invasion in nutrient-poor sandy habitats.