title: Suppression of NGB and NAB/ERabp1 in tomato modifies root responses to potato cyst nematode infestation.
abstract: Plant-parasitic nematodes cause significant damage to major crops throughout the world. The small number of genes conferring natural plant resistance and the limitations of chemical control require the development of new protective strategies. RNA interference or the inducible over-expression of nematicidal genes provides an environment-friendly approach to this problem. Candidate genes include NGB, which encodes a small GTP-binding protein, and NAB/ERabp1, which encodes an auxin-binding protein, which were identified as being up-regulated in tomato roots in a transcriptome screen of potato cyst nematode (Globodera rostochiensis) feeding sites. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization confirmed the localized up-regulation of these genes in syncytia and surrounding cells following nematode infection. Gene-silencing constructs were introduced into tomato, resulting in a 20%-98% decrease in transcription levels. Nematode infection tests conducted on transgenic plants showed 57%-82% reduction in the number of G. rostochiensis females in vitro and 30%-46% reduction in pot trials. Transmission electron microscopy revealed a deterioration of cytoplasm, and degraded mitochondria and plastids, in syncytia induced in plants with reduced NAB/ERabp1 expression. Cytoplasm in syncytia induced in plants with low NGB expression was strongly electron translucent and contained very few ribosomes; however, mitochondria and plastids remained intact. Functional impairments in syncytial cytoplasm of silenced plants may result from NGB's role in ribosome biogenesis; this was confirmed by localization of yellow fluorescent protein (YFP)-labelled NGB protein in nucleoli and co-repression of NGB in plants with reduced NAB/ERabp1 expression. These results demonstrate that NGB and NAB/ERabp1 play important roles in the development of nematode-induced syncytia.
authors.affiliation: Department of Plant Genetics, Breeding and Biotechnology, Warsaw University of Life Sciences (SGGW), Nowoursynowska 159, 02-787, Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Dąbrowska-Bronk
authors.forename: Magdalena
authors.initials: M
authors.lastname: Czarny
authors.forename: Anita
authors.initials: A
authors.lastname: Wiśniewska
authors.forename: Sylwia
authors.initials: S
authors.lastname: Fudali
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Baranowski
authors.forename: Mirosław
authors.initials: M
authors.lastname: Sobczak
authors.forename: Magdalena
authors.initials: M
authors.lastname: Święcicka
authors.forename: Mateusz
authors.initials: M
authors.lastname: Matuszkiewicz
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Brzyżek
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Wroblewski
authors.forename: Renata
authors.initials: R
authors.lastname: Dobosz
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bartoszewski
authors.forename: Marcin
authors.initials: M
authors.lastname: Filipecki
mesh_terms: D000818:Animals; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics*; D009348:Nematoda / Q000472:pathogenicity*; D018517:Plant Roots / Q000469:parasitology*; D012333:RNA, Messenger / Q000235:genetics; D011198:Solanum tuberosum / Q000469:parasitology*
chemical_list: D012333:RNA, Messenger
keywords: GTP-binding protein; Globodera; auxin-binding protein; gene silencing; tomato