A Pyrimidin-Like Plant Activator Stimulates Plant Disease Resistance and Promotes the Synthesis of Primary Metabolites.

Plant activators are chemicals that induce plant defense responses to various pathogens. Here, we reported a new potential plant activator, 6-(methoxymethyl)-2-[5-(trifluoromethyl)-2-pyridyl] pyrimidin-4-ol, named PPA2 (pyrimidin-type plant activator 2). Unlike the traditional commercial plant activator benzothiadiazole S-methyl ester (BTH), PPA2 was fully soluble in water, and it did not inhibit plant growth or root system development in rice (Oryza sativa). PPA2 pretreatment significantly increased plant resistance against bacterial infection in both Arabidopsis and rice, in conjunction with increases in the level of jasmonoyl-isoleucine and 12-oxo-phytodienoic acid. In addition, metabolite profiling indicated that BTH significantly reduced the abundance of various primary metabolites in rice seedlings, including most amino acids, sugars, and organic acids; by contrast, PPA2 promoted their synthesis. Our results thus indicate that PPA2 enhances plant defenses against bacterial infection through the jasmonic acid pathway, and that as a water-soluble compound that can promote the synthesis of primary metabolites it has broad potential applications in agriculture.

Large-scale rewiring of innate immunity circuitry and microRNA regulation during initial rice blast infection.

Rice blast is a recurrent fungal disease, and resistance to fungal infection is a complex trait. Therefore, a comprehensive examination of rice transcriptome and its variation during fungal infection is necessary to understand the complex gene regulatory networks. In this study, adopting Next-Generation Sequencing we profiled the transcriptomes and microRNAomes of rice varieties, one susceptible and the other resistant to M. oryzae, at multiple time points during the fungal infection. Our results revealed a substantial variation in the plant transcriptome and microRNAome as well as change to rice innate immunity during fungal infection. A number of putative R gene candidates were identified from a perturbed rice transcriptome analysis. The expression of genes and non-coding RNA molecules changed in both fungal resistant and susceptible plants during M. oryzae invasion discovered distinct pathways triggered in the susceptible and resistant plants. In addition, a number of fungus genes in the susceptible and resistant plants were constantly expressed at different time points, suggesting that they were likely to be the potential AVR genes. Our results revealed large-scale rewiring of innate immunity circuitry and microRNA regulation during initial rice blast infection, which would help to develop more robust blast-resistant rice plants.

Effect of WNT5A on epithelial-mesenchymal transition and its correlation with tumor invasion and metastasis in nasopharyngeal carcinoma.

OBJECTIVE: To investigate the correlation between nasopharyngeal carcinoma cell WNT5A and epithelial-mesenchymal transition (emt)/metastasis, and investigate its possible mechanisms. METHODS: RT-PCR and gene transfection were used to detect the expression of nasopharyngeal carcinoma cell strains WNT5A and EMT related factor 5-8F. Transient transfection of NPC cell line 5-8F was determined by liposome of plasmid with WNT5A gene. The differential expressions of WNT5A and EMT-related factors in cells before and after transfection were detected by RT-PCR. Cell scratch assay and Transwell assay were used to detect the motility abilities of cells before and after 5-8F transfection. RESULTS: The expressions of WNT5A and EMT related factors matrix metalloproteinase-2 of the WNT5A transferred group in the nasopharyngeal carcinoma cell line 5-8F were higher than the blank control group and the empty vector transferred group, and the transfer ability of the WNT5A transferred group was higher than that in the blank control group and the empty vector transferred group, while the expressions of EMT related factors E-cadherin were lower than that in the blank control group and the empty vector transferred group, and the transfer ability of the WNT5A transferred group was higher than that in the blank control group and the empty vector transferred group. CONCLUSIONS: In nasopharyngeal carcinoma cells, WNT5A can regulate the epithelial-mesenchymal transition and affect the ability of tumor invasion and metastasis of nasopharyngeal carcinoma.

Dissecting quantitative resistance against blast disease using heterogeneous inbred family lines in rice.

SHZ-2 is an indica rice cultivar that exhibits broad-spectrum resistance to rice blast; it is widely used as a resistance donor in breeding programs. To dissect the QTL responsible for broad-spectrum blast resistance, we crossed SHZ-2 to TXZ-13, a blast susceptible indica variety, to produce 244 BC(4)F(3) lines. These lines were evaluated for blast resistance in greenhouse and field conditions. Chromosomal introgressions from SHZ-2 into the TXZ-13 genome were identified using a single feature polymorphism microarray, SSR markers and gene-specific primers. Segregation analysis of the BC(4)F(3) population indicated that three regions on chromosomes 2, 6, and 9, designated as qBR2.1, qBR6.1, and qBR9.1, respectively, was associated with blast resistance and contributed 16.2, 14.9, and 22.3%, respectively, to the phenotypic variance of diseased leaf area (DLA). We further narrowed the three QTL regions using pairs of sister lines extracted from heterogeneous inbred families (HIF). Pairwise comparison of these lines enabled the determination of the relative contributions of individual QTL. The qBR9.1 conferred strong resistance, whereas qBR2.1 or qBR6.1 individually did not reduce disease under field conditions. However, when qBR2.1 and qBR6.1 were combined, they reduced disease by 19.5%, suggesting that small effect QTLs contribute to reduction of epidemics. The qBR6.1 and qBR9.1 regions contain nucleotide-binding sites and leucine rich repeats (NBS-LRR) sequences, whereas the qBR2.1 did not. In the qBR6.1 region, the patterns of expression of adjacent NBS-LRR genes were consistent in backcross generations and correlated with blast resistance, supporting the hypothesis that multiple resistance genes within a QTL region can contribute to non-race-specific quantitative resistance.