Occurrence of Meloidogyne fallax in North America, and Molecular Characterization of M. fallax and M. minor from U.S. Golf Course Greens

Abstract

Nischwitz, C, Skantar, A., Handoo, Z. A., Huit, M. N., Schmitt, M. E., and McClure, M. A. 2013. Occurrence of Meloidogyne fallax in North America, and molecular characterization of M. fallax and M. minor from U.S. golf course greens. Plant Dis. 97:1424-1430.Several species of root-knot nematodes {Meloidogyne spp.) are known to have significant presence on turfgrass in golf course greens, particularly in the western United States. Nematodes isolated from a golf course in King County, WA were identified as Meloidogyne minor based on analysis of the large ribosomal subunit (LSU 28S D2-D3 expansion segment), the internal transcribed spacers 1 and 2 (ITS rDNA), the intergenic spacer region 2 (IGS2), and the nuclear proteincoding gene Hsp90. Sequence-characterized amplified region (SCAR) primers that were originally designed to be specific for M. fallax were found to cross-react with M. minor. A population from Califomia was determined to be M. fallax based on juvenile tail morphology and analysis of the ribosomal markers and Hsp90, comprising tlie first report of this species in North America. Using trees based on Hsp90 genomic alignments, the phylogenetic relationships of these populations and known root-knot nematode species were congruent with previous trees based on ribosomal genes. Resolution of M. fallax and M. chitwoodi using Hsp90 was equivalent to species separation obtained with 28S or 18S rDNA alignments. The strengths and weaknesses of ribosomal and Hsp90 markers, and the use of SCAR polymerase chain reaction as diagnostic tools are discussed.

Multigene phylogeny of root-knot nematodes and molecular characterization of Meloidogyne nataliei Golden, Rose & Bird, 1981 (Nematoda: Tylenchida)

“…16 using same gene and but larger number of species confirmed the presence of these three major clades within Meloidogyne . Several other genes were also successfully used for reconstruction of Meloidogyne single gene phylogeny: the ITS rRNA 3,11,17–24 , the D2-D3 of 28S rRNA 3,11,15,18–25 ; the RNA polymerase II gene ( rpb1 ) 26,27 , the region between the COII and 16S rRNA genes of mtDNA 3,20,22–24,28 ; hsp90 29 , COI 3,15,16,24,30,31 and IGS rRNA 32 , COII 15 . However, it has been shown by Hugall et al .…”

Morphological variability in second-stage juveniles and males of Meloidogyne chitwoodi

“…Distinguishing M. chitwoodi and M. fallax is essential as they are both quarantine pests and cause serious problems in potato yet differ in their geographical distribution. Meloidogyne chitwoodi is widespread in the western USA, but M. fallax has so far only been detected in California (Nischwitz et al, 2013). Conversely, M. chitwoodi and M. fallax have a relatively similar distribution in Europe (Wesemael et al, 2011).…”

A molecular beacon real-time polymerase chain reaction assay for the identification of M. chitwoodi, M. fallax, and M. minor

“…Both M. chitwoodi and M. fallax can cause significant damage to potato tubers, and some data indicate that M. fallax is more aggressive on potato than M. chitwoodi (Van Meggelen et al, 1994;Van Der Beek et al, 1998;Suffert and Giltrap, 2012). Although M. fallax has not been reported on potato in the USA, it was detected during a survey of golf course greens in California (Nischwitz et al, 2013). Follow up surveys by APHIS in California did not detect M. fallax, so it is considered "not present" in the USA (Kantor et al, 2022), but there remains a threat of introduction.…”

“…There is also limited information about M. minor infectivity on potato cultivars commonly used in the USA, such as the Russets. Recently M. minor was reported on turf grass in the USA (McClure et al, 2012;Nischwitz et al, 2013). It is possible that this nematode could be accidentally transmitted from golf courses to arable land via contaminated sports shoes or equipment (Morris et al, 2011;Morris et al, 2013).…”

“…The drawback to the SCAR-PCR is that it is not as sensitive as PCR-RFLP, and it requires at least two juveniles of M. chitwoodi or one juvenile of M. fallax as template (Zijlstra, 2000). Moreover, the previously designed SCAR-PCR primers for M. fallax were shown to cross-react with M. minor allowing for falsepositives (Nischwitz et al, 2013). A multiplex real-time PCR (TaqMan) using primers designed for the ITS region was developed for the simultaneous detection of M. chitwoodi and M. fallax (Zijlstra and Van Hoof, 2006).…”