ALBERT

Description: Background: The pepper fruit is the second most consumed vegetable worldwide. However, low temperature affects the vegetative development and reproduction of the pepper, resulting in economic losses. To identify cold-related genes regulated by abscisic acid (ABA) in pepper seedlings, cDNA representational difference analysis was previously performed using a suppression subtractive hybridization method. One of the genes cloned from the subtraction was homologous to Solanum tuberosum MBF1 (StMBF1) encoding the coactivator multiprotein bridging factor 1. Here, we have characterized this StMBF1 homolog (named CaMBF1) from Capsicum annuum and investigated its role in abiotic stress tolerance. Results: Tissue expression profile analysis using quantitative RT-PCR showed that CaMBF1 was expressed in all tested tissues, and high-level expression was detected in the flowers and seeds. The expression of CaMBF1 in pepper seedlings was dramatically suppressed by exogenously supplied salicylic acid, high salt, osmotic and heavy metal stresses. Constitutive overexpression of CaMBF1 in Arabidopsis aggravated the visible symptoms of leaf damage and the electrolyte leakage of cell damage caused by cold stress in seedlings. Furthermore, the expression of RD29A, ERD15, KIN1, and RD22 in the transgenic plants was lower than that in the wild-type plants. On the other hand, seed germination, cotyledon greening and lateral root formation were more severely influenced by salt stress in transgenic lines compared with wild-type plants, indicating that CaMBF1-overexpressing Arabidopsis plants were hypersensitive to salt stress. Conclusions: Overexpression of CaMBF1 in Arabidopsis displayed reduced tolerance to cold and high salt stress during seed germination and post-germination stages. CaMBF1 transgenic Arabidopsis may reduce stress tolerance by downregulating stress-responsive genes to aggravate the leaf damage caused by cold stress. CaMBF1 may be useful for genetic engineering of novel pepper cultivars in the future.

Description: Background: Polymorphisms of the CC chemokine receptor 6 (CCR6) and RNASET2 tag SNP have been shown to be associated with the susceptibility to several immune-related diseases. This study was conducted to identify the association of CCR6 and RNASET2 tag SNP with autoimmune thyroid diseases (AITDs) in the Chinese Han population. Methods: We enrolled 1061 patients with AITDs, including 701 patients with Graves’ disease (GD) and 360 patients with Hashimoto’s thyroiditis (HT), and 938 healthy individuals for a case–control genetic association study. Three CCR6 single nucleotides polymorphisms (SNPs) (rs3093023/rs3093024/rs6902119) and one tagging SNP (rs9355610) within RNASET2 gene were selected for genotyping by multiplex polymerase chain reaction (PCR) and ligase detection reaction (LDR). Results: The frequency of rs9355610 genotypes in the patients with GD differed significantly from that in the controls (p = 0.017). The frequency of the minor G allele of rs9355610 was significantly higher in the GD patients than in the healthy controls (p = 0.005, OR = 1.225, 95%CI:1.063-1.412). However, we could not find significant differences in the genotype or allele frequencies of HT patients compared with healthy controls. After gender stratification, the frequency of the minor G allele in both male and female GD patients was significantly higher than that in the healthy controls (p = 0.036, OR = 1.308, 95%CI:1.017-1.684 ; p = 0.048, OR = 1.19, 95%CI:1.001-1.413; respectively);. Furthermore, the frequency of haplotype AT in GD patients was significantly lower than that in their control groups (p = 0.003) and showed a protective effect against GD (OR = 0.806, 95%CI: 0.699-0.929). The frequency of haplotype GT in GD patients was significantly higher than that in their control groups (p = 0.048), indicating that GT was the risk haplotype to GD (OR = 1.267, 95%CI: 1.001-1.603). There were no significant differences in the allele or genotype frequencies of three SNPs of CCR6 (rs3093023/rs3093024/ rs6902119) gene between GD patients, HT patients and controls. Conclusions: Our results suggest that the rs9355610 tag SNP of RNASET2 gene is positively associated with susceptibility to GD in the Chinese Han population. No association was found for the tested CCR6 SNPs.

Description: Background Nine gene clusters dedicated to nonribosomal synthesis of secondary metabolites with possible antimicrobial action, including polymyxin and fusaricidin, were detected within the whole genome sequence of the plant growth-promoting rhizobacterium (PGPR) Paenibacillus polymyxa M-1. To survey the antimicrobial compounds expressed by M-1 we analyzed the active principle suppressing phytopathogenic Erwinia spp. Results P. polymyxa M-1 suppressed the growth of phytopathogenic Erwinia amylovora Ea 273, and E. carotovora, the causative agents of fire blight and soft rot, respectively. By MALDI-TOF mass spectrometry and reversed-phase high-performance liquid chromatography (RP-HPLC), two antibacterial compounds bearing molecular masses of 1190.9 Da and 1176.9 Da were detected as being the two components of polymyxin P, polymyxin P1 and P2, respectively. The active principle acting against the two Erwinia strains was isolated from TLC plates and identified by postsource decay (PSD)-MALDI-TOF mass spectrometry as polymyxin P1 and polymyxin P2. These findings were corroborated by domain structure analysis of the polymyxin (pmx) gene cluster detected in the M-1 chromosome which revealed that corresponding to the chemical structure of polymyxin P, the gene cluster is encoding D-Phe in position 6 and L-Thr in position 7. Conclusions Identical morphological changes in the cell wall of the bacterial phytopathogens treated with either crude polymyxin P or culture supernatant of M-1 corroborated that polymyxin P is the main component of the biocontrol effect exerted by strain M-1 against phytopathogenic Erwinia spp.