鑑定台灣地區水稻根瘤線蟲( Meloidogyne sp.) 的種類

Abstract

Rice (Oryza sativa) is an important staple food crop for the majority of human population in the world and particularly in Asia. More than 90% of the world rice is grown and consumed in Asia. Among various pests and diseases which constitute important constraints in the successful crop production, plant parasitic nematodes play an important role and account for yield losses to the extent of 90%. This study conducted a survey on the rice growing areas in Taiwan, a total of 8 root-knot nematode isolates were collected, one isolate was collected from Taoyuan District Agricultural Research and Extension Station (TRS), 2 isolates (YM-Tk14 and YM-Tn11) from District Yangmei, from Dayuan, Zhongli and Xinwu each collected one isolates and Lunbei had 2 (LBC and LBF). The single egg mass lines were established from these isolates and maintained on rice cv. Tainan11. The isolates were characterized using female perineal patterns, second-stage larvae body length, DNA sequence analyses and isozyme profiles in order to ascertain their identity. The perineal patterns from these isolates were dorsal ventral elongated with prominent ridges, oval to almost circular in shape and moderate in the height of arc. The patterns of the 8 isolates were similar to M. graminicola with some minor variations and overlap with M. oryzae and M. trifoliophila. The morphology of second-stage larvae was typical for the genus. It was distinguished by the second-stage larvae 225.97-285.11 μm long. It differs from closest relative M. oryzae and M. trifoliophila by shorter second-stage larvae. The mitochondrial DNA region (mtDNA) of the cytochrome oxidase subunit II (COII) of eight isolates all resulted a 531 bp product and each isolates have 3-5 clones sequenced. When blast the sequences with NCBI (Accession GU187309 and JN241927), they were 98-100% identical to M. graminicola. The 28S D2/D3 expansion segments within the ribosomal DNA (rDNA) of eight isolates all resulted a 764 bp product and each isolates had 3-5 clones sequenced, they were 99-100% identical to M. graminicola (Accession HQ420904) from NCBI. All 8 isolates had uniform phenotypes which was the VS1 esterase type, N1 GOT type and H1 SOD type, these phenotypes were typical for M. graminicola. Multienzyme phenotypes often offered biochemical profiles more valuable for definitive characterization of Meloidogyne species than single enzymes. This is the first study of identifying rice root-knot nematodes in Taiwan using multiple approaches. The results will contribute more information of Meloidogyne genus to the current database, and helped us to confirm the RKN nematode species associated with rice in Taiwan.