Sheath blight (ShB) caused by Rhizoctonia solani Kühn is one of the most serious diseases in rice and is highly susceptible to climate and environmental influences, high humidity climate conditions combined with higher temperatures often lead to more severe occurrences of ShB. The heterotrophic R. solani and rice might compete for sugar at the border of interaction; however, the underlying mechanism remains unclear. In this study, we demonstrated that the expression level of Sugar will eventually be exported transporters (SWEETs) induction was higher in ShB susceptible varieties than in ShB resistant varieties by R. solani inoculation. Inoculation of R. solani revealed that most sweet mutants were less susceptible to ShB than the wild-type. Also, sugar transporters (STPs) gene expression was sensitive to R. solani infection. STPs were localized at the plasma membrane and transported hexose in yeast. Knockdown of STP4 increased the susceptibility of rice to ShB. Interestingly, sequence analysis identified two monosaccharide transporter genes (hereafter named RsMST). RsMSTs transported 2-deoxyglucose, a toxic glucose analog in yeast, suggesting their role as glucose transporter. Spray-induced gene silencing of RsMST1 or RsMST2 dramatically suppressed their expression level and reduced virulence of R. solani. These data suggested that R. solani might induce SWEETs to efflux sugar from the cytosol to apoplast, and STP and RsMSTs compete for sugar at the apoplast for host defense and pathogen virulence. This study provided important insights for ShB-resistant breeding in rice.
Rain-fed potato (Solanum tuberosum) fields in drylands significantly contribute to nitrous oxide (N2O) emissions, making them an important focus of agricultural greenhouse gas research. Film mulching and ridging are key agricultural methods in potato cultivation. Investigating the impact of these methods on N2O emissions, nitrifying/denitrifying functional genes, and microbial communities can provide a theoretical basis for soil emission reduction and more sustainable dryland agriculture. We examine the effects of flat tillage with mulching, ridge tillage with mulching, flat tillage without mulching, and ridge tillage without mulching, on potato fields under natural rainfall conditions in Wuchuan County, China. N2O emission fluxes were monitored using a static (dark) chamber and gas chromatography. Real-time quantitative PCR (q-PCR) was used to quantify abundances of nitrifying and denitrifying bacteria related to N2O emissions at various potato-growth stages. Illumina high-throughput sequencing was used to investigate microbial community structure by targeting 16S rRNA genes; related soil elements (soil temperatures and moisture) are analyzed. Mulching and ridging indirectly influence N2O emissions, nitrifying/denitrifying functional gene copy numbers, and microbial community structure by altering soil temperature and moisture. Cumulative N2O emissions and emission intensity were both consistently higher in ridge tillage with mulching during the potato-growing period. Ammonia-oxidizing archaea are the main microorganisms that control N2O emissions, with nitrification-coupled denitrification also being an important mechanism contributing to high N2O emissions during soil dry–wet cycles. Increased soil temperature and moisture elevated N2O emissions and functional gene copy numbers. The combination of mulching and ridging effectively uses the characteristics of both practices, making Nitrospira the dominant genus, and significantly increases N2O emissions.