Differentially expressed stress-related genes in the compatible citrus-Citrus leprosis virus interaction

Abstract

Leprosis, caused by Citrus leprosis virus, cytoplasmic type (CiLV-C), is the main viral disease in the Brazilian citrus industry. This occurs because of the widespread source of inoculum and the year-round presence of the vector, the tenuipalpid mite Brevipalpus phoenicis, in citrus plants. In addition, while some Citrus species are resistant to CiLV-C, C. sinensis, the main cultivated species in the country, is extremely susceptible to the disease. The main objective of this work was to identify genes in C. sinensis cv. Pêra plants that were differentially expressed after the host was challenged with CiLV-C. In order to accomplish that, cDNA libraries were constructed from healthy and CiLV-inoculated sweet orange leaves. Two hundred and fifty-four genes were found to differ significantly in terms of expression, with 193 of them induced and 61 repressed after inoculation. Here we discuss the possible roles of a sub-set of these genes involved in metabolism, energy, signaling and cell rescue, defense and virulence, and indicate which kind of response may take place in the initial steps of the disease. Although the symptoms induced by CiLV-C in its compatible interaction with sweet orange resemble those of hypersensitive response (HR) in incompatible interactions, our data indicate that, apparently, the manifestation of leprosis symptoms should not be considered HR.

Genetic basis of qualitative and quantitative resistance to powdery mildew in wheat: from consensus regions to candidate genes

“…Most of the candidate genes encode NBS-LRR proteins, LRR-protein kinases, receptor-like protein kinases, WRKY or NAC transcription factors, pathogenesis-related proteins, cell transporters, or glutathione transferases (involved in the metabolism of reactive oxygen species), or proteins involved in lipid metabolism, amino-acid biosynthesis or cell wall modifications upon powdery mildew attack. As examples, on chromosome 1A there are genes that correspond to putative ketol-acid reductoisomerase, an enzyme induced by plant–pathogen interactions [39] near MQTL2 ( Xcdo1160 - 53.6 cM) and under the individual QTL QPm_Lan ( Xmwg632 - 80.3 cM; [40]). Three other genes of interest are a thioredoxin, 1,4-benzoquinone reductase, and a protein kinase (markers Swes578 - 51.6 cM, CA651264 - 55.9 cM - , and wPt-5011 - 59.1 cM, respectively); these are positioned under the individual QTL QPm.osu-1B [41].…”

The influence of citrus rootstocks on the relationship between the mite Brevipalpus phoenicis and citrus leprosis disease

“…It is known that plants respond to stresses, both abiotic and biotic, in a complex manner. However, there is a lack of studies that aim to elucidate the responses of plants to stressors, especially when a viral agent is involved . According to Bastianel et al , the symptoms of leprosis become visible only a few weeks after CiLV inoculation.…”

Quantitative trait loci analysis of citrus leprosis resistance in an interspecific backcross family of (Citrus reticulata Blanco × C. sinensis L. Osbeck) × C. sinensis L. Osb

“…The fact that CiLV-C causes only chlorotic and necrotic local lesions in susceptible hosts and never invades them systemically (Marques et al 2007), has raised questions regarding whether or not the symptoms could be a variation of the hypersensitive response (HR) observed in viral-incompatible interactions. However, Freitas-Astúa et al (2007) suggested that the two responses are very different at the molecular level and hence, the manifestation of leprosis symptoms should not be considered as a HR. Other genetics mechanisms seem to be involved in the response to citrus leprosis, a very complex pathosystem.…”