First Report of the Cyst Nematode (Heterodera elachista) on Rice in Hunan Province, China

Abstract

During a survey for the cyst nematodes (Heterodera elachista) from May to June of 2011, cyst nematodes were detected in hilly rice fields in five counties (Changsha, Pingjiang, Hengdong, Shaoyang, and Xiangxiang) of Hunan Province, China. Cyst nematodes obtained from soil samples and harvested rice root samples at these five locations had uniform morphological and molecular characteristics. Cysts (n = 20) had the following characteristics: spherical to lemon shaped, vulval cone ambifenestrate, vulval bridge narrow, medium sized underbridge, with a few dark brown bullae, body length (not including the neck) ranging from 354 to 586 μm (mean = 438.9 μm, st. dev. = 63.7); body width ranged from 283 to 495 μm (354.5, 60.1); fenestrate length of 30 to 50 μm (37.4, 5.0) and width of 25 to 47.5 μm (35.1, 7.1); underbridge length from 70 to 95 μm (83.4, 8.2); and vulval slit length from 30.3 to 55.5 μm (40.3, 9.1). J2 (n = 20) had the following characteristics: body length ranging from 404 to 525 μm (mean of 461.6 μm, st. dev. = 34.5); stylet length from 20 to 25 μm (22.5, 1.1) with rounded knob; tail length of 60 to 87.5 μm (67.3, 6.9); and hyaline terminal tail ranged from 30 to 50 μm (37.5, 6.4); lateral field with three lines. The mean and range of J2 were longer than those reported for H. elachista by Nobbs et al. (1) and Tanha et al. (4), but other morphological character values were within the range of those reported (4). DNA from a single cyst was extracted, the rDNA-internal transcribed spacer (ITS) and D2/D3 fragments of the 28S RNA were amplified with universal primers TW81 and AB28, D2A and D3B, respectively. Five ITS sequences (JN202913, JN202914, JN202915, JN202916, and JN202917) and five D2/D3 sequences (JN202918, JN202919, JN202920, JN202921, and JN202922) from nematode samples collected in Changsha, Hengdong, Shaoyang, Pingjiang, and Xiangxiang, respectively, were submitted to GenBank. These ITS sequences were remarkably similar to each other and exhibited 98.6 to 99.3% similarity with that of H. elachista isolate from Iran (AF498391), and 98.8 to 99.4% similarity with that of H. elachista isolates from Ningxia Province, China (HM560778 and HM560779). The D2/D3 sequences exhibited 99.7 to 100% similarity with that of H. elachista isolates from Ningxia Province, China (HM560842 and HM560843). These characteristics indicated that the five populations were H. elachista belonging to the ‘cyperi’ group (1,2). In glasshouse evaluations of the pathogenicity of these isolates, 500 second-stage juveniles were inoculated onto five 20-day-old seedlings of rice (Weiyou No.227) in 4.5-cm diameter 30-cm high tubes with six replicates. After 8 weeks, stunting and reduction of leaf length were observed and cysts were extracted from dried soil of each tube using sieves. Brown cysts (92 to 204) and white females (14 to 40) were obtained from inoculated rice from each tube. H. elachista can decrease yield by 7 to 19% and has the most severe impact during the later stages of plant growth (3). H. elachista has been previously identified from rice fields in Japan and Iran (3). To our knowledge, this is the first report of H. elachista on rice in Hunan Province, China. References: (1) J. M. Nobbs et al. Fundam. Appl. Nematol. 15:551, 1992. (2) S. A. Subbotin et al. Mol. Phylogenet. Evol. 21:1, 2001. (3) S. A. Subbotin et al. Systematics of Cyst Nematodes (Nematoda: Heteroderinae). Volume 8 Part B. Brill, Leiden, the Netherlands, 2010. (4) M. Z. Tanha et al. Nematology 5:99, 2003.

Heterodera elachista the Japanese cyst nematode parasitizing corn in Northern Italy: integrative diagnosis and bionomics

“…Morphology and morphometrics of cysts, second-stage juveniles and male (Table 1) fit closely with those of the original description of the Japanese cyst nematode, H. elachista, from upland rice in Japan (Ohshima, 1974), as well with subsequent reports in upland rice in Iran (Tanha Maafi et al, 2004), and in hilly rice fields in China (Ding et al, 2012), except for minor intraspecific variations ( Kazachenko, 1986, andHeterodera raskii Basnet &Jayaprakash, 1984, from which morphologically differs by several diagnostic features (Nobbs et al, 1992;Subbotin et al, 2010). Heterodera elachista infecting corn in Northern Italy is morphologically close to other cyst-nematodes attacking rice (H. oryzae and H. sacchari) but differs in some morphological characters including, considerably smaller cysts, lack of finger-like projections on the underbridge, and a shorter J2 body length (Nobbs et al, 1992;Subbotin et al, 2010).…”

“…Consequently, species identification based on sequencing of rDNA regions (D2-D3 and ITS1) was congruent with morphological and morphometrical data of this species in other studies (Tanha Maafi et al, 2003;Ding et al, 2012), and resulted useful for species identification. Additionally to these molecular markers, we have showed that differences in partial COI and hsp90 genes could separate this species form other closely related.…”

“…The results of the host-suitability test indicate that both rice and corn are good hosts for this nematode, and enlarge the host-range of this cyst nematode which had only been reported previously in rice in Japan, Iran and China (Ohshima, 1974;Tanha Maafi et al, 2004;Ding et al, 2012).…”

No-tillage cultivation reduces rice cyst nematode (Heterodera elachista) in continuous upland rice (Oryza sativa) culture and after conversion to soybean (Glycine max) in Kanto, Japan

“…The rice cyst nematode, Heterodera elachista, infests areas of upland rice (Oryza sativa) production in Japan (Ohshima, 1974), and causes severe yield losses in both upland and irrigated rice (Bridge et al, 2005). It has recently become a pest elsewhere in Asia (Ding et al, 2011) and in Europe (De Luca et al, 2013). Its host plants include rice, Japanese millet (Echinochloa esculenta), corn (Zea mays), wheat (Triticum aestivum), and oat (Avena sativa), but the major host is rice (Okada, 1960).…”

Heterodera guangdongensis n. sp. (Nematoda: Heteroderinae) from bamboo in Guangdong Province, China—a new cyst nematode in the Cyperi group

“…An RFLP-ITS-rRNA profile of this new species is also provided. (Ding et al 2012, Zhuo et al, 2014, H. koreana from Jiangxi (Wang et al 2012), H. hainanensis from Hainan (Zhuo et al 2013) and H. fengi from Guangdong (Wang et al 2013). Besides these nematodes, two other cystforming nematodes, H. oryzicola and Cactodera cacti (Filipjev & Schuurmans Stekhoven, 1941) Krall & Krall, 1978, have been reported in China's subtropical zones in the early years (Li et al 1985, Pan et al 1997.…”