Identification of NBS-Type Resistance Gene Homologs in Tobacco Genome

Abstract

Tobacco (Nicotiana tabacum) is an important cash crop and an ideal experimental system for studies on plant-pathogen interaction. The sequenced tobacco genome provides an opportunity for examining resistance gene homologs (RGHs) in the tobacco genome. Thirty nucleotide-binding site-type RGHs were annotated from genomic data, and another 281 putative RGHs were identified via PCR amplification from wild and cultivated tobacco. The newly identified RGHs are similar to other known RGHs, and some were categorized into new groups or branches that are different from known Nicotiana R genes or RGHs. Of the 281RGHs, 146 were identified from a single tobacco genome. We did not find any polymorphism at the RGHs in cultivated accessions, implying that strong domestication selection and/or demographic effects might have caused a sharp reduction in nucleotide diversity. Three positive selection sites were found in several RGH groups, while purifying selection is pervasive in the RGH family.Our results provide a primary RGH pool and several positively selected sites for the further functional validation of resistance genes in tobacco.

Characteristic of the Pepper CaRGA2 Gene in Defense Responses against Phytophthora capsici Leonian

“…RGAs are abundant in plant genomes, according to sequenced genomes and PCR amplification, through degenerate primers based on conserved motifs [14]. RGA studies have been performed in the family Solanaceae [15]. The relation of RGAs to plant R genes can be described as: (1) RGAs are actual R genes [16]; (2) RGAs are linked and co-segregate with resistance gene [17,18]; (3) RGAs are not functionally related to R genes.…”

Virus-Induced Gene Silencing of a Putative Glutathione S-Transferase Gene Compromised Ol-1-Mediated Resistance against Powdery Mildew in Tomato

“…Plants have evolved defense mechanisms to protect themselves against these pathogens (Bi et al 2011;Yang et al 2010). The R gene-mediated resistance response is an important defense mechanism in which many gene products forms the signal transduction pathway (Leng et al 2010;Zhang et al 2010;Zhao et al 2010). Some genes are essential for the resistance response and loss of function of these genes can result in the loss of resistance against pathogens (Aswati Nair et al 2010;Huang et al 2010;.…”

Evaluation of High-Resolution Melting for Gene Mapping in Rice

“…However, diseases, such as bacterial blight, have caused severe reductions in rice yield (Zhao et al 2010). To improve resistance and raise the yield, great efforts have been made to clone resistance genes in rice and other plants (Feng et al 2009;Zhao et al 2009;Leng et al 2010). Many resistance genes have been cloned and now contribute to improve disease resistance; one example is gene Xa21, which confers resistance to almost all Indian and Philippine races of Xanthomonas oryzae pv.…”