03083nas a2200169 4500008004100000022001400041245009000055210006900145260001600214300001400230490000700244520255200251100001302803700001302816700001402829856007002843 2014 eng d a0191-291700aFirst Report of Phytophthora tentaculata Causing Stem and Root Rot on Celery in China0 aFirst Report of Phytophthora tentaculata Causing Stem and Root R cJan-03-2014 a421 - 4210 v983 a

Celery (Apium graveolens) is an important vegetable in China. In August 2012, about 20 to 70% declining plants with root and basal stem rot were observed in Bengbu, Anhui Province, China. Typical symptoms included large dark brown to black water-soaked lesions near the soil line of stems. As the disease progressed, lesions girdled the stem, and plants became brown, wilted, and eventually died. A Phytophthora-like organism was consistently isolated from symptomatic tissues on a selective medium, P5ARP. Resultant isolates were identified as Phytophthora tentaculata based on their morphological features and rDNA sequence. Sporangia, chlamydospores, hyphal swellings, and oospores were produced on V8 agar. Sporangia were ovoid to pyriform, 28.5 to 52.5 × 21.5 to 40.6 μm, average 35.3 × 29.8 μm, with one or occasionally two papillae. Chlamydospores were spherical, 21.3 to 30.2 μm in diameter, average 25.7 μm. The isolates were homothallic, and one or occasionally two paragynous antheridia were attached to the global oogonia (24 to 39 μm in diameter, average 29.5 μm). The internal transcribed spacer region of rDNA was amplified with primer pair ITS1/ITS4 for one isolate (1), and the sequence (GenBank Accession No. KF501392) showed >99% similarity with those P. tentaculata isolates deposited in GenBank (AJ854302.1). Pathogenicity was confirmed by inoculating Shijihuangqin, a local cultivar of celery, with isolate PT12081. The isolate was cultivated on V8 agar at 25°C for 5 to 7 days to produce sporangia. Five 2-month-old, disease-free celery were drench-inoculated with 10 ml of a suspension of 2 × 104 zoospores/ml, and five control plants per pot were treated with sterile water. There were four pots for each of the inoculated and non-inoculated treatments, and the experiment was repeated twice. All plants were maintained at 25°C for 10 days. Symptoms similar to those observed in the field developed 7 days after inoculation. Ten days later, five plants wilted and two or three died in each pot inoculated with PT12081, but the control plants remained symptomless. P. tentaculata was consistently re-isolated from the symptomatic plants. P. tentaculata has been reported to infect Chrysanthemum spp., Delphinium ajacis, Verbena spp., and Origanum vulgare (2,3). To our knowledge, this is the first report of Phytophthora blight caused by P. tentaculata on celery in China.

1 aWang, T.1 aZhao, W.1 aQi, R.-D. uhttp://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-06-13-0592-PDN