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Transcriptome analysis of resistant and susceptible alfalfa cultivars infected with root-knot nematode Meloidogyne incognita
O. A. Postnikova (1), M. Hult (2), J. Shao (1), A. Skantar (2), L. G. NEMCHINOV (1). (1) USDA ARS MPPL, Beltsville, MD, U.S.A.; (2) USDA ARS Nematology Lab, Beltsville, MD, U.S.A.

Root-knot nematodes (RKN, <i>Meloidogyne</i> spp<i>.</i>) are widely distributed and economically important sedentary endoparasites of agricultural crops and they may inflict significant damage to alfalfa fields. No studies have been published on global gene expression profiling in alfalfa infected with RKN or any other plant parasitic nematode. In this work, we performed root transcriptome analysis of resistant (cv. Moapa 69) and susceptible (cv. Lahontan) alfalfa cultivars infected with RKN <i>Meloidogyne incognita, </i>a major pest worldwide. A total of 1,701,622,580 pair-end reads were generated on an Illumina Hi-Seq 2000 platform from the roots of both cultivars and assembled into 45,595 and 47,590 transcripts in cvs Moapa 69 and Lahontan, respectively. Bioinformatic analysis revealed a number of common and unique genes that were differentially expressed in susceptible and resistant lines as a result of nematode infection. Although the susceptible cultivar showed a more pronounced defense response to the infection, feeding sites were successfully established in its roots. Basal gene expression levels under normal conditions differed between the two cultivars as well, which may confer advantage to one of the genotypes toward resistance to nematodes. Functional roles of the differentially expressed genes were predicted. Candidate genes that contribute to protection against <i>M. incognita</i> in alfalfa were proposed.

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