The potato cyst nematode, Globodera rostochiensis, is an important pest of potato. Like other pathogens, plant parasitic nematodes are presumed to employ effector proteins, secreted into the apoplast as well as the host cytoplasm, to alter plant cellular functions and successfully infect their hosts. We have generated a library of ORFs encoding putative G. rostochiensis putative apoplastic effectors in vectors for expression in planta. These clones were assessed for morphological and developmental effects on plants as well as their ability to induce or suppress plant defenses. Several CLAVATA3/ESR-like proteins induced developmental phenotypes, whereas predicted cell wall-modifying proteins induced necrosis and chlorosis, consistent with roles in cell fate alteration and tissue invasion, respectively. When directed to the apoplast with a signal peptide, two effectors, an ubiquitin extension protein (GrUBCEP12) and an expansin-like protein (GrEXPB2), suppressed defense responses including NB-LRR signaling induced in the cytoplasm. GrEXPB2 also elicited defense response in species- and sequence-specific manner. Our results are consistent with the scenario whereby potato cyst nematodes secrete effectors that modulate host cell fate and metabolism as well as modifying host cell walls. Furthermore, we show a novel role for an apoplastic expansin-like protein in suppressing intra-cellular defense responses.

Highlights  Detection and discrimination of plant stress origin using hyperspectral imaging.  Nematode infestation can be reliably differentiated from the water deficiency.  Abiotic drought resulted in the most obvious differences in the light spectrum.  Identification of nematode infestation possible with specific spectral regions.  Reliable prediction of nematode infestation even in early stages of infestation.

Variability in the genes for toxin A, toxin B and other pathogenicity locus regions is well known and is the basis for the distribution of Clostridium difficile strains into variant toxinotypes. Previous data have indicated that some C. difficile strains have a non-functional truncated form of the binary toxin (CDT) locus. This study analysed variability in the CDT locus and the presence of deleted tcdC genes in C. difficile strains. A total of 146 strains were screened, including known variant toxinotypes and non-variant A + B + (toxinotype 0) and A " B " C. difficile strains. In all of the strains studied, only two forms of the CDT locus were found: a full-length 4.3 kb fragment encoding the functional binary toxin or a truncated 2.3 kb fragment. Whilst the full-length CDT locus was found almost exclusively in variant toxinotypes, the truncated form was detected in 79 % of toxinotype 0 strains. Non-toxinogenic A " B " strains with a truncated version were not found and only rarely possessed the full-length CDT locus (A " B " CDT + strains). Four different forms of the tcdC gene were found; three represented deleted versions and typically were found in toxinotypes III-VII, XI, XIV-XVI and XXIV. INTRODUCTIONOver the last decade, Clostridium difficile has developed into one of the most important nosocomial pathogens. This Gram-positive, sporulating micro-organism is associated with post-antibiotic intestinal infections, and the prevalence rate and disease severity seem to be rising (McDonald et al., 2006). Additionally, a new highly virulent and multiresistant type (BI/NAP1/027) has emerged recently and is spreading in Canada, the USA, the UK, the Netherlands, Belgium and France (Loo et al., 2005;Pepin et al., 2004;McDonald et al., 2005;Smith, 2005; Joseph et al., 2005;Kuijper et al., 2006;Tachon et al., 2006). In addition to high fluoroquinolone resistance, this epidemic type has some features previously known but uncommon among C. difficile isolates: variant genes for toxins A (TcdA) and B (TcdB), production of the binary toxin (CDT) and deletions in the tcdC gene.Variability in the tcdA and tcdB genes has been well studied and the strains with changed genes have been grouped into toxinotypes (Rupnik et al., 1998). Major changes are defined as deletions and RFLPs in all six PCR fragments covering tcdA and tcdB, whilst minor changes are limited to only one of the PCR fragments (usually the A3 fragment) covering the toxin genes or other pathogenicity locus (PaLoc) regions. To date, 22 toxinotypes have been described and two additional types are reported in this paper. The best-studied and the most widespread are toxinotypes III (including ribotypes 027, 034, 075 and 080) and VIII (including ribotypes 017 and 047) .Binary toxin CDT is detected in some strains in addition to TcdA and TcdB, the primary virulence factors of C. difficile (Popoff et al., 1988;Rupnik et al., 2003a). Binary toxin CDT is composed of two unlinked components, the enzymic (CDTa) and binding (CDTb) components, and acts as an actin-specific AD...

The tropical group of root-knot nematodes (RKN) including Meloidogyne ethiopica and M. luci is a highly polyphagus and damaging group of agricultural pests. M. ethiopica has been detected in several European countries (Slovenia, Italy, Greece) and also in Turkey. However, a description of a new sister species M. luci calls for reclassification of all European and Turkish M. ethiopica populations reported up to date as M. luci. Accurate identification can be accomplished through analysis of the esterase isozyme pattern, which is the most distinguishing character between the two otherwise very similar species. Both species display a three banded esterase pattern where the upper band is slightly shifted between the two species. In addition, molecular characterization of M. ethiopica and M. luci populations revealed that the ITS, SSU, and LSU of the rDNA regions are not appropriate markers for studying relationships among the tropical group of RKNs. However, the COII/lRNA region on mtDNA proved to be very useful for analyzing the phylogenetic relationship of these very closely related species/populations. Mitochondrial sequences with low levels of heteroplasmy allowed clustering of all M. luci populations in a monophyletic clade with a clear separation of this recently described species from M. ethiopica. At the same time, a very close relationship between M. ethiopica and M. luci was confirmed again.

Root-knot nematodes from the genus Meloidogyne are polyphagous plant endoparasites and agricultural pests of global importance. Here, we report the high-quality genome sequence of Meloidogyne luci population SI-Smartno V13. The resulting genome assembly of M. luci SI-Smartno V13 consists of 327 contigs, with an N50 contig length of 1,711,905 bp and a total assembly length of 209.16 Mb.

Root-knot nematodes are considered the most important group of plant-parasitic nematodes due to their wide range of plant hosts and subsequent role in yield losses in agricultural production systems. Chemical nematicides are the primary control method, but ecotoxicity issues with some compounds has led to their phasing-out and consequential development of new control strategies, including biological control. We evaluated the nematicidal activity of Bacillus firmus I-1582 in pot and microplot experiments against Meloidogyne luci. I-1582 reduced nematode counts by 51% and 53% compared to the untreated control in pot and microplot experiments, respectively. I-1582 presence in the rhizosphere had concurrent nematicidal and plant growth-promoting effects, measured using plant morphology, relative chlorophyll content, elemental composition and hyperspectral imaging. Hyperspectral imaging in the 400–2500 nm spectral range and supervised classification using partial least squares support vector machines successfully differentiated B. firmus-treated and untreated plants, with 97.4% and 96.3% accuracy in pot and microplot experiments, respectively. Visible and shortwave infrared spectral regions associated with chlorophyll, N–H and C–N stretches in proteins were most relevant for treatment discrimination. This study shows the ability of hyperspectral imaging to rapidly assess the success of biological measures for pest control.

Root-knot nematodes (RKN) of the tropical group reproducing as a rule with mitotic parthenogenesis are highly polyphagous and damaging pests causing great loses in crop production. Morphometrical and molecular characters of three closely related tropical RKN species have been analysed in order to identify species-specific diagnostic parameters and examine the relationship between species. Morphometrical characters of M. ethiopica, M. luci and M. inornata isolates were similar and overlapped when compared between species and isolates of the same species indicating a very close relationship between the three species. Additionally, structure of map-1 genes was analysed, which provided the evidence of identical structure of map-1 family genes in M. ethiopica, M. inornata and M. luci. The unique structure of map-1 genes when compared to the other tropical RKN species further supports close relationship of the three species and therefore we have classified them together as M. ethiopica group. In addition, our results showed that the emergence of a virulent M. luci population does not correlate with the loss of map-1 genes as it was previously indicated for M. incognita (Castagnone-Sereno et al. 2009). Further, we have developed novel molecular methods to aid in identification of these nematodes: a PCR based method with primers specific for the M. ethiopica group comprising M. ethiopica M. luci and M. inornata; and a PCR based method with primers specific for the tropical RKN group species. Our results show that species of Meloidogyne ethiopica group share high similarity at morphological and genetic level. Isolates maintained in the following culture collections:

Graphical abstract