Transcriptional analysis through RNA sequencing of giant cells induced by Meloidogyne graminicola in rice roots

Abstract

One of the reasons for the progressive yield decline observed in aerobic rice production is the rapid build-up of populations of the rice root knot nematode Meloidogyne graminicola. These nematodes induce specialized feeding cells inside root tissue, called giant cells. By injecting effectors in and sipping metabolites out of these cells, they reprogramme normal cell development and deprive the plant of its nutrients. In this research we have studied the transcriptome of giant cells in rice, after isolation of these cells by laser-capture microdissection. The expression profiles revealed a general induction of primary metabolism inside the giant cells. Although the roots were shielded from light induction, we detected a remarkable induction of genes involved in chloroplast biogenesis and tetrapyrrole synthesis. The presence of chloroplast-like structures inside these dark-grown cells was confirmed by confocal microscopy. On the other hand, genes involved in secondary metabolism and more specifically, the majority of defence-related genes were strongly suppressed in the giant cells. In addition, significant induction of transcripts involved in epigenetic processes was detected inside these cells 7 days after infection.

Gene expression analysis inMusa acuminataduring compatible interactions withMeloidogyne incognita

“…In contrast, gene expression data for galls and giant cells formed as a result of RKN infection revealed suppression of plant immune responses and activation of primary metabolism. Similar suppression of plant defence pathways due to RKNs, involving PR proteins and flavonoid, phenylpropanoid and jasmonate biosynthesis pathways, was also observed by Ji et al (2013).…”

“…Recent transcriptome analysis of gall tissues induced by the biotrophic RKN M. graminicola has revealed suppression of ETI, SA and ET/JA defence pathways, together with activation of gibberellic acid and BR biosynthesis and signalling (Kyndt et al, 2012a;Ji et al, 2013;Nahar et al, 2013;Nguyên et al, 2014). The phytohormone ABA, although more typically associated with abiotic stress responses, together with auxins, BRs, cytokinins and gibberellins, which are known regulators of plant developmental, also all appear to play overlapping roles in plant immune responses to RKNs (Kyndt et al, 2014).…”

“…Most research to date on host gene expression in response to RKNs has focused on interactions in dicotyledonous host plants (e.g. Jammes et al, 2005;Alkharouf et al, 2006;Ithal et al, 2007a;Klink et al, 2007;Szakasits et al, 2009;Barcala et al, 2010;Bagnaresi et al, 2013;Guimaraes et al, 2015), with relatively few studies on monocotyledonous hosts (Kyndt et al, 2012a;Ji et al, 2013;Nguyên et al, 2014). Analysis of the transcriptome of compatible interactions between nematodes and monocotyledonous hosts has so far been limited to studies only on rice.…”

“…Analysis of the transcriptome of compatible interactions between nematodes and monocotyledonous hosts has so far been limited to studies only on rice. Kyndt and colleagues (2012a) compared gene expression following susceptible host challenge with the sedentary RKN Meloidogyne graminicola and the migratory root rot nematode Hirschmanniella oryzae, with Ji et al (2013) characterizing the transcriptome of giant cells induced by M. graminicola. In these studies, plant root necrosis following infection with the migratory nematode H. oryzae resulted in induction of plant immune responses that included the jasmonate biosynthesis pathway, the production of PR proteins and activation of WRKY TFs (Kyndt et al, 2012a).…”

Rice Root-Knot Nematode (Meloidogyne graminicola) an Emerging Problem

“…The former study provides RNA-seq data obtained from roots infected with root rot nematode H.oryzae in comparison with uninfected roots and root galls induced by M. graminicola, at three and seven days after inoculation compared with control root tips (Kyndt et al, 2012). Ji et al, (2013) focus on the gene expression inside laser capture microdisected giant cells at 7 and 14 DAI and compared this profile with vascular cells from uninfected roots. In rice, M. graminicola able to suppress transcription of key immune regulatory genes (Kyndt et al, 2012).…”