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.

Isolation of Arabidopsis genes that differentiate between resistance responses mediated by the RPS2 and RPM1 disease resistance genes.

Abstract: The Arabidopsis disease resistance gene RPS2 is involved in recognition of bacterial pathogens carrying the avirulence gene avrRpt2, and the RPM1 resistance gene is involved in recognition of pathogens carrying avrRpm1 or avrB. We identified and cloned two Arabidopsis genes, AIG1 and AIG2 (for avrRpt2-induced gene), that exhibit RPS2- and avrRpt2-dependent induction early after infection with Pseudomonas syringae pv maculicola strain ES4326 carrying avrRpt2. However, ES4326 carrying avrRpm1 or avrB did not induce early expression of AIG1 and AIG2. Conversely, ES4326 carrying avrRpm1 or avrB induced early expression of the previously isolated defense-related gene ELI3, whereas ES4326 carrying avrRpt2 did not. The induction patterns of the AIG genes and ELI3 demonstrate that different resistance gene-avr gene combinations can elicit distinct defense responses. Furthermore, by examining the expression of AIG1 and ELI3 in plants infiltrated with a mixed inoculum of ES4326 carrying avrRpt2 and ES4326 carrying avrRpm1, we found that there is interference between the RPS2- and RPM1-mediated resistance responses.

Molecular Marker Mapping of Leaf Rust Resistance Gene Lr46 and Its Association with Stripe Rust Resistance Gene Yr29 in Wheat

Abstract: Leaf and stripe rusts, caused by Puccinia triticina and P. striiformis, respectively, are globally important fungal diseases of wheat that cause significant annual yield losses. A gene that confers slow rusting resistance to leaf rust, designated as Lr46, has recently been located on wheat chromosome 1B. The objectives of our study were to establish the precise genomic location of gene Lr46 using molecular approaches and to determine if there was an association of this locus with adult plant resistance to stripe rust. A population of 146 F(5) and F(6) lines produced from the cross of susceptible 'Avocet S' with resistant 'Pavon 76' was developed and classified for leaf rust and stripe rust severity for three seasons. Using patterns of segregation for the two diseases, we estimated that at least two genes with additive effects conferred resistance to leaf rust and three to four genes conferred resistance to stripe rust. Bulked segregant analysis and linkage mapping using amplified fragment length polymorphisms with the 'Avocet' x 'Pavon 76' population, F(3) progeny lines of a single chromosome recombinant line population from the cross 'Lalbahadur' x 'Lalbahadur (Pavon 1B)', and the International Triticeae Mapping Initiative population established the genomic location of Lr46 at the distal end of the long arm of wheat chromosome 1B. A gene that is closely linked to Lr46 and confers moderate levels of adult plant resistance to stripe rust is identified and designated as Yr29.

Molecular cloning of a new receptor-like kinase gene encoded at the Lr10 disease resistance locus of wheat

Abstract: More than 100 resistance genes against wheat rust pathogens have been described in wheat and its relatives. Although many of them have been extensively used in wheat resistance breeding, none of these resistance loci has yet been analyzed at the molecular level. By screening a set of near-isogenic lines carrying different leaf rust resistance genes with a wheat probe encoding a serine/ threonine protein kinase, we detected a polymorphic DNA fragment in the line with the Lr10 resistance gene. This fragment mapped to the Lr10 disease resistance locus and encodes a receptor-like protein kinase which we called LRK10. LRK10 contains a new type of extracellular domain not found in known plant or animal receptor kinases. Several conserved amino acids in S-domain glycoproteins and receptor-like kinases were also found in LRK10, suggesting that LRK10 and S-domain proteins belong to the same superfamily of specific recognition molecules in plants. Lrk10 was expressed at low levels in young seedlings and belongs to a gene family. Analysis of wheat lines with and without the Lr10 gene demonstrated that Lrk10 and Lr10 belong to the same genetic locus. We conclude that gene isolation based on protein kinase homology can identify new receptor domains and provide candidates for disease resistance genes in the complex wheat genome.

Root exudates drive the soil-borne legacy of aboveground pathogen infection

Abstract: Plants are capable of building up beneficial rhizosphere communities as is evidenced by disease-suppressive soils. However, it is not known how and why soil bacterial communities are impacted by plant exposure to foliar pathogens and if such responses might improve plant performance in the presence of the pathogen. Here, we conditioned soil by growing multiple generations (five) of Arabidopsis thaliana inoculated aboveground with Pseudomonas syringae pv tomato (Pst) in the same soil. We then examined rhizosphere communities and plant performance in a subsequent generation (sixth) grown in pathogen-conditioned versus control-conditioned soil. Moreover, we assessed the role of altered root exudation profiles in shaping the root microbiome of infected plants. Plants grown in conditioned soil showed increased levels of jasmonic acid and improved disease resistance. Illumina Miseq 16S rRNA gene tag sequencing revealed that both rhizosphere and bulk soil bacterial communities were altered by Pst infection. Infected plants exhibited significantly higher exudation of amino acids, nucleotides, and long-chain organic acids (LCOAs) (C > 6) and lower exudation levels for sugars, alcohols, and short-chain organic acids (SCOAs) (C ≤ 6). Interestingly, addition of exogenous amino acids and LCOA also elicited a disease-suppressive response. Collectively, our data suggest that plants can recruit beneficial rhizosphere communities via modification of plant exudation patterns in response to exposure to aboveground pathogens to the benefit of subsequent plant generations.

RESISTANCE TO FUSARIUM OXYSPORUM 1, a dominant Arabidopsis disease-resistance gene, is not race specific.

Abstract: Arabidopsis thaliana ecotypes differ in their susceptibility to Fusarium wilt diseases. Ecotype Taynuilt-0 (Ty-0) is susceptible to Fusarium oxysporum forma specialis (f.) matthioli whereas Columbia-0 (Col-0) is resistant. Segregation analysis of a cross between Ty-0 and Col-0 revealed six dominant RESISTANCE TO FUSARIUM OXYSPORUM (RFO) loci that significantly contribute to f. matthioli resistance in Col-0 relative to Ty-0. We refer to the locus with the strongest effect as RFO1. Ty-0 plants in which only the Col-0 allele of RFO1 (RFO1Col-0) was introduced were resistant to f. matthioli. Surprisingly, RFO1Col-0 also conferred resistance to f. raphani, demonstrating that RFO1-mediated resistance is not race specific. Expression of resistance by RFO2, RFO4, or RFO6 was dependent on RFO1Col-0. Map-based cloning of RFO1Col-0 showed that RFO1 is identical to the previously named Arabidopsis gene WAKL22 (WALL-ASSOCIATED KINASE-LIKE KINASE 22), which encodes a receptor-like kinase that does not contain an extracellular leucine-rich repeat domain. Consistent with these results, a Col-0 rfo1 loss-of-function mutant was more susceptible to f. matthioli, f. conglutinans, and f. raphani. Thus, RFO1 encodes a novel type of dominant disease-resistance protein that confers resistance to a broad spectrum of Fusarium races.