SUMMARYTwo in p/anta-induced (ipi) genes, designated ipiB and ipiO, of the potato late blight fungus, Phytophthora infestans (Mont.) de Bary, were isolated from a genomic library by a differential hybridization procedure [Pieterse et al., Physiol. Mol. Plant Pathol. (1993a) in press]. Both genes are expressed at high levels in the early phases of the pathogenic interaction of P. infestans with its host plant potato, suggesting that their gene products have a function in the early stages of the infection process. Here, we describe the nucleotide (nt) sequence and genomic organization of ipiB and ipi0. The ipiB gene belongs to a small gene family consisting of at least three genes, designated ipiBl, ipiB2 and ipiB3, which are clustered in a head-to-tail arrangement. The three ipiB genes are highly homologous throughout the coding regions and 5' and 3' flanking regions. The P. infestans genome contains two very similar ipi0 genes, ipi01 and ipi02, which are closely linked and arranged in an inverted orientation. The ipiB genes encode three novel, highly similar Glyrich proteins of 301, 343 and 347 amino acids (aa), respectively. The Gly-rich domains of the IPI-B proteins are predominantly composed of two repeats with the core sequences,
In order to isolate in planta-induced genes encoding putative pathogenicity factors of the late blight fungus Phytophthora infestans, a genomic library was differentially screened. For the differential hybridization, labeled firststrand cDNA synthesized on mRNA isolated from P. infestans-infected potato leaves and on mRNA isolated from the fungus grown in vitro were used as probes. This screening resulted in the isolation of the P. infestans calmodulin gene. The gene, designated calA, contains an open reading frame of 447 base pairs without introns and is unique in the P. infestans genome. The predicted amino acid sequence is 89.9-94.6% identical to calmodulins from higher eukaryotes, whereas the identity to calmodulins of higher fungi is significantly less (60.8-85.1%). Expression studies revealed that the P. infestans calA gene is constitutively expressed in in vitro grown mycelium. However, during pathogenesis on potato the level of P. infestans calmodulin mRNA is increased approximately fivefold.Additional keywords: calcium-binding protein, differential screening, Oomycetes, pathogenicity, potato late blight.The fungal plant pathogen Phytophthora infestans (Mont.) de Bary (Oomycetes), the causal agent of potato late blight, is one of the most devastating diseases of potato (Solanum tuberosum (L.)). Infection of potato leaves and tubers by a virulent strain of this hemibiotrophic fungus initially causes a rapidly spreading lesion followed by necrosis, which results in complete destruction of the infected tissue.The specialization of P. infestans on solanaceous plants such as potato and tomato implies a mechanism for recognition that most likely requires the exchange of signals between host and pathogen. On the one hand, infection of the host by P. infestans induces specific expression of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.