The Gene Families RPW8, HSP20 and FMO in Gossypium raimondii

Comparative Genomics and Bioinformatics

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Vieira Hoffmann, Lucia; Gonçalves de Abreu , Aluana; Oliveira Borba, Tereza Cristina; Guedes Siqueira Coelho , Alexandre; Neves de Mello , Raquel; Gonçalves Narciso , Marcelo; Paterson, Andrew; Vieira Hoffmann, Lucia; Gonçalves de Abreu , Aluana; Oliveira Borba, Tereza Cristina; Guedes Siqueira Coelho , Alexandre; Neves de Mello , Raquel; Gonçalves Narciso , Marcelo; Paterson, Andrew

Vieira Hoffmann, Lucia; Vieira Hoffmann, Lucia

Vieira Hoffmann, Lucia; Vieira Hoffmann, Lucia

Plants are resistant if they inhibit pathogen development, while tolerance refers to plant productivity despite the presence of a pathogen. Basal resistance is the low resistance level which may be present in susceptible plants. The genes related to those mechanisms may be presented in a considerable number even in plant pathogen interactions where the resistance have been shown to be triggered by a single gene. To investigate the presence of genes of Gossypium raimondii that are not R genes but may be related to resistance, basal resistance or tolerance to pathogens, one Arabidopsis gene of three selected gene families, RPW8 (recognition of powdery mildew), HSP20 (20KDa heat shock proteins) and FMO (flavin dependent monooxygenases), was used to conduct a local blastp system against all G. raimondii proteome library using a cut-off e-value of 10-10 . All the downloaded proteins were submitted to Pfam database (http://pfam.sanger.ac.uk/) to confirm the gene families. Multiple alignments with complete protein sequences were conducted in ClustalW and phylogenetic trees were constructed using the Neighbor-joining methods, pairwise deletion and p-distance on the MEGA 4.1 program. Five RPW8W homologs are found in G. raimondii, the same of Arabidopisis ecotype Ms-0. RPW8 is a family of disease resistance genes with a putative N-terminal transmembrane and a coiledcoil domain. In Arabdodsis, by triggering hypersensitive response, they confer resistance to all the four powdery mildew species. So it differs from most of the disease resistance genes which are specific to pathogen races. The G. raimondii genome showed a total of 24 HSP20 like proteins. One of the genes present in chromosome 04 grouped with one of the genes of chromosome 08 according to the MEGA analyses, indicating segments duplications. HSP20 supposedly have been evolved from the original property as chaperones to have different functions on response to environmental stresses, such as the caused by salt, alcohol, chilling oxidative injury or heavy metals. In tomato, the HSP20 RSl2 interacts with the resistance protein which confers resistance to Fusarium oxysporum, and hypersensitive resistance response was not normally activated in the presence of the resistance gene when this particularly chaperone was absent. F. oxysporum is also an important pathogen to cotton. The number of FMO like proteins G. raimondii is 26, while in Arabidopsis 29 proteins have been annotated as FMOs. The greater number of genes in Arabidopsis can be explained by the absence in G. raimondii of YUCCA family of FMO, which apparently is present exclusively in crucifers and is responsible for the biosynthesis of glucosinolates. One Arabidopsis FMO gene was shown to increase basal resistance to pathogens, through the accumulation of salicylic acid and possibly by inactivation of pathogen-derived virulence factors, analogy to the detoxification function of FMO proteins in animals. FMO like proteins are distributed among 12 chromosomes. Two pairs of closely related genes were found in chromosomes 09 and 10, indicating segments duplications, consistently with the synteny of the segments those chromosomes found in dot plot analysis and the hypothesis of a whole genome duplication.