Table 1.
Survey of dieback disease of Carya cathayensis.
Fig 1.
Dieback and basal stem canker in Carya cathayensis.
A: Tree dieback symptoms; B: basal stem necrotic tissue; C: stem-bark extended necrotic zone.
Fig 2.
Phytophthora cinnamomi ST402 isolate morphological characteristics.
A: seven-day-old colony on PARP medium; B: sporangia; C: gametangia; D: oospore.
Fig 3.
Phylogenetic analysis of Phytophthora species generated using ITS and COI gene sequences.
Phylogenetic tree was rooted to Pythium aphanidermatum (CBS 28779) as an outgroup taxon.
Fig 4.
Pathogenicity of the Phytophthora cinnamomi ST402 isolate to Carya cathayensis seedlings.
A: P. cinnamomi ST402 isolate stem necrosis symptoms 7 days postinoculation; B: Box-plot diagram of P. cinnamomi ST402 isolate necrotic length in C. cathayensis stems (N = 20) 7 and 14 days postinoculation. Asterisks (*) and (**) indicate significant differences derived from two-sample comparisons at P = 0.05 and P = 0.01, respectively.
Fig 5.
Specificity (A) and sensitivity (B) of Pcinn100006 loop-mediated isothermal amplification (LAMP) to Phytophthora cinnamomi.
A. LAMP reactions conducted for P. cinnamomi specificity and results visualized using hydroxynaphthol blue (upper column) and 1% agarose gel (lower column). M: DNA marker (DL2000, TaKaRa); Pci: P. cinnamomi ST402; Pca: P. cathayensis CP29; Pin: P. infestans; Fox: Fusarium oxysporum; Pul: Pythium ultimum; Vda: Verticillium dahliae. B. LAMP reactions performed for determining P. cinnamomi sensitivity and results visualized using hydroxynaphthol blue (upper column) and 1% agarose gel (lower column). P. cinnamomi ST402 isolate genomic DNA used as templates (20, 2, 0.2, 0.02, 0.002, and 0.0002 ng per 25 μL reaction mixture). M: DNA marker (DL2000, TaKaRa); +: positive reaction; −: negative reaction.
Fig 6.
Detection of Phytophthora cinnamomi in Carya cathayensis orchard soil samples.
Rhododendron leaf or P. cinnamomic-specific LAMP was conducted using DNA samples extracted directly from soil specimens collected from 0 to 5 cm depth around C. cathayensis basal stems in a Linan County commercial orchard in July 2019 (A) and July 2020 (B). The hollow and solid squares indicate asymptomatic and necrotic symptoms in C. cathayensis plants, respectively. The hollow and solid triangles indicate negative and positive detection by performing baiting assays as per methods described in Materials and methods. Hollow and solid ovals indicate negative and positive detection results by LAMP, respectively.