Plant disease resistance

About: Plant disease resistance is a research topic. Over the lifetime, 12952 publications have been published within this topic receiving 381820 citations. The topic is also known as: plant innate immunity.

The tomato gene Sw5 is a member of the coiled coil, nucleotide binding, leucine-rich repeat class of plant resistance genes and confers resistance to TSWV in tobacco

Abstract: Tomato spotted wilt virus is an important threat to tomato production worldwide. A single dominant resistance gene locus, Sw5, originating from Lycopersicon peruvianum, has been identified and introgressed in cultivated tomato plants. Here we present the genomic organization of a 35 250 bp fragment of a BAC clone overlapping the Sw5 locus. Two highly homologous (95%) resistance gene candidates were identified within 40 kb of the CT220 marker. The genes, tentatively named Sw5-a and Sw5-b, encode proteins of 1245 and 1246 amino acids, respectively, and are members of the coiled-coil, nucleotide-binding-ARC, leucine-rich repeat group of resistance gene candidates. Promoter and terminator regions of the genes are also highly homologous. Both genes significantly resemble the tomato nematode and aphid resistance gene Mi and, to a lesser extent, Pseudomonas syringae resistance gene Prf. Transformation of Nicotiana tabacum cv. SR1 plants revealed that the Sw5-b gene, but not the Sw5-a gene, is necessary and sufficient for conferring resistance against tomato spotted wilt virus.

Mapping loci controlling Brassica napus resistance to Leptosphaeria maculans under different screening conditions.

Abstract: Leptosphaeria maculans, the causal agent of blackleg of crucifers, is a major threat to rapeseed (Brassica napus) production throughout the world. Genes controlling blackleg resistance in B. napus were mapped using an F 1 -derived doubled haploid (DH) population of 105 lines and 138 restriction fragment length polymorphism (RFLP) markers. The host-pathogen interaction phenotype was assessed qualitatively and by several quantitative measurements using different environments and plant developmental stages. A single major locus controlling blackleg resistance (LEM1) was mapped to linkage group 6 based on qualitative scores of the interaction phenotype on inoculated cotyledons. This resistance locus was also identified by interval mapping using quantitative measurements of the interaction phenotype on cotyledon- and stem-inoculated plants. Four other genomic regions were significantly associated with quantitative measurements of resistance on cotyledon and stem, among them a marker locus interval in linkage group 17 that included a pathogenesis related gene (PR2). Two genomic regions associated with resistance in field-evaluated plants were different from those identified in cotyledon- and stem-evaluated plants. The use of different environments and plant developmental stages for mapping disease resistance loci is discussed

cDNA sequences for pea disease resistance response genes.

Abstract: The expression of the Group I disease resistance response genes (19149, pi176, and pi206) of Pisum sativum cv. Alaska is strongly associated with resistant interactions of the pea with the fungus Fusarium solani, the bacterium Pseudomonas syringae pv. pisi, and the fungal elicitor chitosan [19, 9, 6]. cDNAs for these genes were recloned into the Bluescript KSml3+ vector and sequenced by the Exo/Mung Bean nuclease method [3] and the method of Maxam and Gilbert [16]. Optimal alignment of the pi49 and pi176 cDNAs by the NUCALN program of Wilbur and Lipman [5] results in 696 out of 731 positions matching, plus six gaps, for an overall identity of 95o70, suggesting that these genes may be part of a multigene family. The cDNA for pi206 appears to be 5'-truncated. Although the mRNA for pi206 as measured by Northern analysis is approximately 950 nucleotides [19], the entire cDNA (excluding the poly(A) tail) is only 594 bp long. The predicted molecular weights of pi49 and pi176 are 16728 and 16901 Da, respectively, while the pi206 gene product would have to be at least 19360 Da. The 158 amino acid pi49 sequence differs by only 5 amino acid substitutions and one insertion/deletion from the 159 amino acid pi176 sequence. The FASTN and FASTP programs of Lipman and Pearson [14] were used to search for the Group I cDNA or protein sequences in the GenBank [2] Release 55.0 and PIR [10] databases, with no significant matches found. The D4HOM program [8] was used to compare the Group I sequences with other genes associated with disease resistance whose DNA or protein sequences are known, including bean chitinase [4], bean phenylalanine ammonia lyase [7], chalcone synthase from parsley [18], the pathogenesis-related protein p14 from tomato [15], pathogenesis-related protein PR-1 family from tobacco [17], and the hydroxyproline-rich glycoprotein from tomato [20]. No significant similarities were noted.