| The root lesion nematode belonging to the genus Pratylenchus is top three most important plant nematodes in the world.Pratylenchus widely distributed in China,causing the great damage to crops.Pratylenchus zeae,P.brachyurus and P.parazeae can parasitize sugarcane.It is believed that P.zeae and P.brachyurus are major parasitic nematodes on sugarcane,and P.parazeae was found to parasitize sugarcane in 2015 in China.In this paper,the reproduction of P.zeae,P.brachyurus and P.parazeae were tested through the tissue culture.The pathogenicities of P.zeae,P.brachyurus and P.parazeae to sugarcane were also tested by using potted trials.The results are as follows:(1)P.zeae,P.brachyurus and P.parazeae can complete their life cycles and reproduce on carrot calli,but the reproduction ability of Pratylenchus spp.in different temperature was different.In 20℃,all three nematodes have low fecundities;the reproduction ability of Pratylenchus spp in 25℃ was stronger than 20℃;the optimum temperature was 30 ℃ for reproduction of the three nematodes;in the same temperature,the reproduction ability of P.zeae was the highest,followed by P.brachyurus and P.parazeae.(2).P.zeae,P.brachyurus and P.parazeae infected sugarcane roots showed that the nematodes are migratory endoparasitic and move longitudinally in the root cortex,but do not invade stele.Cortical cells adjacent to infected ones showed dense granular cytoplasm,thickened walls and a hypertrophied nucleus and nucleolus.Pratylenchus spp can enter the sugarcane roots for feeding and reproduction and move freely within the tissue.Brown or black patches in roots,root reduction and plant dysplasia are the most obvious symptoms of root-lesion nematode disease on sugarcane.(3)P.zeae,P.brachyurus and P.parazeae are all pathogenic to the sugarcane Yuetang 00-236,but the pathogenic ability is different.The pathogenic ability of P.zeae is the strongest,following by P.brachyurus and P.parazeae.This paper tested the reproduction and pathogenicity of P.zeae,P.brachyurus and P.parazeae,demonstrating their pathogenicities to sugarcane.All these results have academic importance and practial significance in evaluating risk level of root-lesion nematode,screening resistant varieties and establishing pertinent control measures. |
