Morphological and molecular characterization, including parasitic and pathogenic studies of a new spherical cyst nematode species, Globodera vulgaris n. sp. (Nematoda: Heteroderidae), associated with potatoes in China.

Abstract

In this study, a new spherical cyst nematode belonging to the genus Globodera, herein described as Globodera vulgaris n. sp., was extracted from the roots and rhizosphere soil of potato and circumjacent weeds belonging to different families in three provinces in southwest China. The new species was characterized by 8-24 ridges between the anus and fenestra and an average Granek's ratio of 2.8-3.8 in cysts, a head with 3-4 annules and dorsal knob anteriorly projected and ventral knobs round or anteriorly projected in second stage juveniles, and a head with 3-5 annules, spicule short and average length less than 30.0 μm, with a developed velum in males. Pathogenicity tests showed that G. vulgaris n. sp. infected potato but did not damage or affect the potato yield compared to control, and it parasitized tomato with a low reproduction rate (RF < 1) while did not parasitize tobacco (RF = 0). The new species was close to G. rostochiensis based on molecular diagnostic marker sequences and constructed phylogenetic analysis, that is internal transcribed spacers of ribosomal DNA (ITS), large-subunit rDNA (LSU) and small-subunit rDNA (SSU). However, the new species exhibited differences from G. rostochiensis in terms of morphological characteristics, a wide host preference, lack of damage to hosts, and egg hatching rate induced by hatching factors.