Comparative phylogenetic analysis of genome-wide Mlo gene family members from Glycine max and Arabidopsis thaliana

Abstract

Powdery mildew locus O (Mlo) gene family is one of the largest seven transmembrane protein-encoding gene families. The Mlo proteins act as negative regulators of powdery mildew resistance and a loss-of-function mutation in Mlo is known to confer broad-spectrum resistance to powdery mildew. In addition, the Mlo gene family members are known to participate in various developmental and biotic and abiotic stress response-related pathways. Therefore, a genome-wide similarity search using the characterized Mlo protein sequences of Arabidopsis thaliana was carried out to identify putative Mlo genes in soybean (Glycine max) genome. This search identified 39 Mlo domain containing protein-encoding genes that were distributed on 15 of the 20 G. max chromosomes. The putative promoter regions of these Mlo genes contained response elements for different external stimuli, including different hormones and abiotic stresses. Of the 39 GmMlo proteins, 35 were rich (8.7-13.1 %) in leucine, while five were serine-rich (9.2-11.9 %). Furthermore, all the GmMlo members were localized in the plasma membrane. Phylogenetic analysis of the GmMlo and the AtMlo proteins classified them into three main clusters, and the cluster I comprised two sub-clusters. Multiple sequence alignment visualized the location of seven transmembrane domains, and a conserved CaM-binding domain. Some of the GmMlo proteins (GmMlo10, 20, 22, 23, 32, 36, 37) contained less than seven transmembrane domains. The motif analysis yielded 27 motifs; out of these, motif 2, the only motif present in all the GmMlos, was highly conserved and three amino acid residues were essentially invariant. Five of the GmMlo members were much smaller in size; presumably they originated through deletion following a gene duplication event. The presence of a large number of GmMlo members in the G. max genome may be due to its paleopolyploid nature and the large genome size as compared to that of Arabidopsis. The findings of this study may further help in characterization and isolation of individual GmMlo members.

PCA22 acts as a suppressor of atrzf1 to mediate proline accumulation in response to abiotic stress in Arabidopsis

“…4C). The serine-rich domain is a common protein motif involved in defense responses, abiotic stress, growth regulation, wounding, and plant development (Sripinyowanich et al , 2013; Deshmukh et al , 2014). The serine-rich domain is also found in the products of the Porteresia coarctata serine - rich - protein ( PcSrp ) and Capsicum annuum RING - finger protein 1 ( CaRFP1 ) genes, whose functions are dependent on salinity and biotic stress conditions, respectively (Mahalakshmi et al , 2006; Hong et al , 2007).…”

Molecular cloning and characterization of a Mlo gene in rubber tree (Hevea brasiliensis)

“…Studies have shown that Mlo interacts with calmodulin in vitro and requires calmodulin, but not heterotrimeric G-proteins, to function (Kim et al, 2002b;Lorek et al, 2013). To date,15,17,9,12,and 39 Mlo paralogs have been reported in the genomes of Arabidopsis, grape, maize, rice and soybean, respectively (Consonni et al, 2006;Devoto et al, 2003;Feechan et al, 2008;Liu and Zhu, 2008;Deshmukh et al, 2014). Phylogenetic analysis using 17 members of grape Mlo gene family and members from rice, barley, tomato, maize, wheat, and Arabidopsis, resulted in the formation of six clades with clade VI containing AtMlo3, which in previous analyses was identified as a single divergent lineage (Feechan et al, 2008).…”

Expression Profiling of MLO Family Genes under Podosphaera xanthii Infection and Exogenous Application of Phytohormones in Cucumis melo L.

“…The medium size gene family MLO are variably distributed and 39, 15, 17, 12, 21, 13 and 38 MLO genes were noticed in soybean, Arabidopsis, grape, rice, apple, cucumber, and cotton, respectively [8,10,13,26,36,42,44]. MLO genes have been thoroughly studied both in many monocots and dicots.…”