Cytological, Genetic, and Molecular Analysis to Characterize Compatible and Incompatible Interactions Between Medicago truncatula and Colletotrichum trifolii

Abstract

In this study, a new pathosystem was established using the model plant Medicago truncatula and Colletotrichum trifolii, the causal agent of anthracnose on Medicago sativa. Screening of a few M. truncatula lines identified Jemalong and F83005.5 as resistant and susceptible to Colletotrichum trifolii race 1, respectively. Symptom analysis and cytological studies indicated that resistance of Jemalong was associated with a hypersensitive response of the plant. The two selected lines were crossed, and inoculations with C. trifolii were performed on the resulting F1 and F2 progenies. Examination of the disease phenotypes indicated that resistance was dominant and was probably due to a major resistance gene. Molecular components of the resistance were analyzed through macroarray experiments. Expression profiling of 126 expressed sequence tags corresponding to 92 genes, which were selected for their putative functions in plant defense or signal transduction, were compared in Jemalong and F83005.5 lines. A strong correlation was observed between the number of up-regulated genes and the resistance phenotype. Large differences appeared at 48 h postinoculation; more than 40% of the tested genes were up-regulated in the Jemalong line compared with only 10% in the susceptible line. Interestingly, some nodulin genes were also induced in the resistant line upon inoculation with C. trifolii.

Coffee resistance to the main diseases: leaf rust and coffee berry disease

“…(O´Connell and Bailey, 1986;Trevorrow et al, 1988;Bailey et al, 1990;Mould et al, 1991;Torregrosa et al, 2004). In the bean anthracnose pathosystem, this early HR does not occur in the compatible interactions, thereby indicating a high correlation between the HR and the racecultivar specificity (Esquerré-Tugayé et al, 1992).…”

“…The host cell wall modifications, namely the increase in the levels of hydroxyproline-rich glycoproteins (HRGPs), as well as the early accumulation of phenolic compounds in the infected host cells have also been associated with host resistance to Colletotrichum spp. (Esquerré-Tugayé et al, 1992;Skipp et al, 1995;Torregrosa et al, 2004). In the M. truncatula -C. trifolli incompatible interaction, one of the earlier phenolic compounds accumulated is the phytoalexin medicarpin, which is synthesized through the mobilization of several enzymes of the phenylpropanoid pathway.…”

Recent Advances in Legume-Microbe Interactions: Recognition, Defense Response, and Symbiosis from a Genomic Perspective

“…Expression profiling was carried out from 16 to 72 hai with the fungal pathogen Colletotrichum trifolii in leaves of a susceptible and resistant genotype (Torregrosa et al, 2004). At 16 hai, both genotypes responded to infection by upregulation of genes for PR proteins, lipoxygenases, cell wall proteins, and phenylpropanoid pathway enzymes.…”

“…Previously, these genes were described as nodule limited in expression (Scheres et al, 1990;Gamas et al, 1998). Upregulation of specific PR-10 genes was also observed in the resistant interaction of M. truncatula with C. trifolii (Torregrosa et al, 2004). Although PR-10-like proteins accumulated in M. truncatula roots after inoculation with the oomycete pathogen Aphanomyces eutiches, the proteins were associated with a susceptible reaction (Colditz et al, 2005).…”

Cryptic Virulence and Avirulence Alleles Revealed by Controlled Sexual Recombination in Pea Aphids

“…The susceptible host was DZA315.16, an Algerian ecotype. Jemalong A17 and DZA315.16 are highly polymorphic and have been used as parents to generate recombinant inbred lines (RILs) developed from an F 2 mapping population (Thoquet et al 2002;Torregrosa et al 2004). Mapping of QTL from this population identified two loci (RAP1 and RAP2) conferring pea aphid resistance and a third independent locus controlling a hypersensitive-like (HR-like) response that results in aphid-induced lesions (AIL) (Stewart et al 2009).…”