Identification Of Tobacco Root Knot Nematode Species From Yunnan Province

Tobacco around the world is very important economic crop, and is main financial revenue source in many states and local governments. Yunnan province is one of the most important tobacco production areas in China, tobacco leaf yield and quality were put high value on by governments. However, over the past 20 years the damage caused by root-knot nematode disease has become increasingly serious due to the constant introduction, promotion and replacement of the tobacco varieties, etc. Therefore, the further understanding species and distribution of root-knot nematodes in tobacco growing areas of Yunnan province is of great significance for resistant tobacco breeding to root-knot nematode and for control of tobacco root-knot nematode disease.In this paper, a systematic study on tobacco root-knot nematode species and distribution was conducted in tobacco planting region in Yunnan province.25 root-knot nematode populations were collected from diseased tobacco roots and rhizophere soils in a total of three cities (Lincang, Yuxi and Qujing), one district (Wenshan) 12 counties and 20 towns. The root-knot nematode species were identified according to the morphological and molecular characteristics of the nematode populations, and morphological comparision of the same root-knot nematodes was carried out. The following main results were obtained:1. Three root-knot nematodes, i.e., Meloidogyne arenaria, M. javanica and M. incognita were identified in 25 nematode populations. Among them, M. arenaria was the dominant species.2. Distribution status of 25 root-knot nematode populations was analyzed. It was showed that the tobacco root-knot nematodes were mainly distributed in the central, west, and southwest in Yunnan province, especially more common in the western areas. In the northeast, east and southeast the tobacco root-knot nematode disease also occurred. Species test results indicated that M. arenaria and M. javanica was mainly distributed in the southwestern parts of Lincang and Yuxi cities in central area, test rates of these two species were 54% and 25%, respectively. M. incognita only occurred in the northeastern Zhaotong and test rate was 4.3%.3. Comparative analysis of morphological features of the two main root-knot nematodes (M. arenaria and M. javanica) was conducted. The results revealed that morphological variation among second stage juveniles and female perineal patterns of two root-knot nematodes was present.