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Transcriptome profile of Carrizo citrange roots in response to Phytophthora parasitica infection

Zunaira Afzal: University of Florida

<div><em>Phytophthora </em>diseases are the most important soil-borne diseases of citrus in almost all citrus groves of the world. <em>Phytophthora parasitica</em> is among the most widespread <em>Phytophthora</em> species, known to cause root rot, foot rot/gummosis and brown rot of fruits in citrus. Current understanding of citrus-<em>Phytophthora</em> interaction at the whole genome level is very limited. In this study, we have analyzed the transcriptome of a commonly used Carrizo citrange citrus rootstock in response to <em>P. parasitica</em> infection using the RNA-seq technology. In total, we have identified 8284 differentially expressed transcripts (DETs) among <em>P. parasitica</em>-inoculated and mock-treated roots. Of these, 4916 genes were differentially expressed at 24 hours post inoculation and 6718 genes were differentially expressed at 48 hours post inoculation, which corresponds to the biotrophic and necrotrophic phases of <em>P. parasitica</em> infection cycles, respectively. Gene ontology analysis of DETs suggested substantial transcriptional reprogramming of diverse cellular processes particularly the biotic stress response pathways in Carrizo citrange roots. Many <em>R</em> genes, <em>Pathogenesis Related (PR)</em> genes, autophagy-related genes and several other genes putatively involved in plant immunity and systemic acquired resistance (SAR) were upregulated in response to <em>P. parasitica</em> infection. Analysis reported here lays out a strong foundation for future studies aimed at improving resistance of citrus rootstocks to <em>P. parasitica</em> infection.</div>