Structure-based characterization and compound identification of the wild-type THF class-II riboswitch.

Riboswitches are conserved regulatory RNA elements participating in various metabolic pathways. Recently, a novel RNA motif known as the folE RNA motif was discovered upstream of folE genes. It specifically senses tetrahydrofolate (THF) and is therefore termed THF-II riboswitch. To unravel the ligand recognition mechanism of this newly discovered riboswitch and decipher the underlying principles governing its tertiary folding, we determined both the free-form and bound-form THF-II riboswitch in the wild-type sequences. Combining structural information and isothermal titration calorimetry (ITC) binding assays on structure-based mutants, we successfully elucidated the significant long-range interactions governing the function of THF-II riboswitch and identified additional compounds, including alternative natural metabolites and potential lead compounds for drug discovery, that interact with THF-II riboswitch. Our structural research on the ligand recognition mechanism of the THF-II riboswitch not only paves the way for identification of compounds targeting riboswitches, but also facilitates the exploration of THF analogs in diverse biological contexts or for therapeutic applications.

Evaluation of Stripe Rust Resistance and Chip Detection Resistance Genes in 286 Xinjiang Wheat Cultivars and Breeding Lines.

Wheat stripe rust is a destructive disease worldwide, caused by Puccinia striiformis f. sp. tritici (Pst). Resistance breeding is the most effective method of controlling stripe rust. Xinjiang is a relatively independent epidemic region of wheat stripe rust in China. In recent years, wheat stripe rust in this area has shown an upward trend. Therefore, the purpose of this study was to evaluate the resistance level of wheat cultivars (lines) to the prevalent Pst races and determine the genetic background of stripe rust resistance genes in Xinjiang. Six predominant Pst races in China were used to study resistance of 286 wheat cultivars (lines) at both seedling under controlled conditions and adult-plant stages under field conditions. In the seedling tests, 175 (61.19%) entries were resistant to races CYR23, 125 (43.71%) to CYR29, 153 (53.50%) to CYR31, 88 (30.77%) to CYR32, 174 (60.84%) to CYR33, and 98 (34.27%) to CYR34. Among the resistant entries, 23 (8.04%) were resistant to all six races. In the field test, 135 (47.20%) entries were resistant to the tested mixed races. Through comparing the responses in the seedling and adult-plant stages, 109 (38.11%) entries were found to have adult-plant resistance (APR), and 14 (4.90%) entries have all-stage resistance (ASR). The 286 wheat entries were also tested using a wheat breeder chip containing 12 Yr resistance loci. Among these entries, 44 (15.38%) were found to have single gene, 221 (77.27%) have two or more genes, and 21 (7.34%) have none of the 12 genes, including 144 (50.35%) with Yr30 and 5 (1.75%) with YrSP. Entries with two or more genes have stronger resistance to Pst. Overall, the majority of entries have all-stage and/or adult-plant resistance, but their genes for resistance in addition to the 12 tested Yr genes need to be determined. It is also necessary to introduce more effective resistance genes in the breeding programs to improve stripe rust resistance in wheat cultivars in Xinjiang.

Molecular genotyping analysis suggested high clonality and simple marker loci in Puccinia striiformis f. sp. tritici population in Uzbekistan, Central Asian region.

Puccinia striiformis f. sp. tritici (Pst) is a destructive pathogen that causes wheat stripe rust worldwide. Understanding the population structure and dynamic of pathogen spread is critical to fight against this disease. Limited information is available for the population genetic structure of Pst in Uzbekistan, Central Asia. In this study, we carried out surveillance from 9 different regions (Andijan, Fergana, Jizzakh, Kashkadarya, Namangan, Samarkand, Sirdaryo, Surkhandarya and Tashkent) of Uzbekistan to fill this gap. A total of 255 isolates were collected, which were genotyped using 17 polymorphic simple sequence repeats (SSR) markers. The DAPC analysis results showed no population subdivision in these sample-collected regions except Surkhandarya. Multilocus genotype (MLG) analysis, FST, and Nei's genetic distance results indicated a clonal population (rBarD ≤ 0.12) and merely three MLGs accounting for 70% of the overall population. MLG-34 was predominant in all Uzbekistan regions, followed by MLG-36 and MLG-42. Low genotypic diversity was observed in Andijan, Fergana, Jizzakh, Kashkadarya, Namangan, Sirdaryo, and Tashkent (0.56 to 0.76), compared with Samarkand (0.82) and Surkhandarya (0.97). No virulence against Yr5, Yr15, YrSp, and Yr26 was found, while resistant was overcome against Yr1, Yr2, Yr6, Yr9, Yr17, and Yr44 genes (Virulence frequency =≥75%). Comparative study results of Uzbekistan with previous Himalayan population were showed divergence from China and Pakistan populations. Further studies need to be conducted in a worldwide context to understand migration patterns; for that purpose, collaborative work is essential due to the Pst long-distance migration capability.

Identification of Aly1 and Aly2 as Modulators of Cytoplasmic pH in Saccharomyces cerevisiae.

The regulation of intracellular pH in yeast (Saccharomyces cerevisiae) cells is critical for cell function and viability. In yeast, protons (H+) can be excreted from the cell by plasma membrane ATPase PMA1 and pumped into vacuoles by vacuolar H+-ATPase. Because PMA1 is critical to the survival of yeast cells, it is unknown whether other compensatory components are involved in pH homeostasis in the absence of PMA1. To elucidate how intracellular pH is regulated independently of PMA1, we employed a screening approach by exposing the yeast haploid deletion mutant library (ver 4.0) to the selective plant plasma membrane H+-ATPase inhibitor PS-1, which we previously reported. After repeated screenings and verification, we identified two proteins, Aly1 and Aly2, that play a role in the regulation of intracellular pH when PMA1 is deficient. Our research uncovers a new perspective on the regulation of intracellular pH related to PMA1 and also preliminarily reveals a role for Aly1 and Aly2 in the regulation of intracellular pH.

Bacillus cereus NJ01 induces SA- and ABA-mediated immunity against bacterial pathogens through the EDS1-WRKY18 module.

Emerging evidence suggests a beneficial role of rhizobacteria in ameliorating plant disease resistance in an environment-friendly way. In this study, we characterize a rhizobacterium, Bacillus cereus NJ01, that enhances bacterial pathogen resistance in rice and Arabidopsis. Transcriptome analyses show that root inoculation of NJ01 induces the expression of salicylic acid (SA)- and abscisic acid (ABA)-related genes in Arabidopsis leaves. Genetic evidence showed that EDS1, PAD4, and WRKY18 are required for B. cereus NJ01-induced bacterial resistance. An EDS1-PAD4 complex interacts with WRKY18 and enhances its DNA binding activity. WRKY18 directly binds to the W box in the promoter region of the SA biosynthesis gene ICS1 and ABA biosynthesis genes NCED3 and NCED5 and contributes to the NJ01-induced bacterial resistance. Taken together, our findings indicate a role of the EDS1/PAD4-WRKY18 complex in rhizobacteria-induced disease resistance.