Identification Of Root-knot Nematodes From Protected Cultivation And Resistance Of Vegetable Cultivars

Root-knot nematodes (RKN) are widely distributed throughout the world and have a wide range of hosts. It is one of the most important phyto-nematodes. Zhejiang, situated in sub-tropical areas with abundant rainfall, is considered a suitable area for root-knot nematodes reproduction. Research on sample collection, morphology and molecular identification from different areas of Zhejiang province; Analyze the distribution as well as the occurrence of these nematodes in the facility cultivation; Test the resistance of main cultivated vegetables to Meloidogyne incognita, and especially the resistance characteristics of M. incognita to Gynura bicolor. The main results including:1. Based on the morphological characters (perineal pattern of females and morphometrics of second stage juveniles, etc.), ITS-PCR of rDNA. SCAR and multiplex PCR technology methods, all the40root-knot nematode populations collected from Hangzhou, Xiaoshan, Yongjia and Ruian were identified as Meloidogyne incognita. Distribution and occurrence of second stage juveniles in the facility cultivation were made by studying the juvenile dynamics in soil. It was found that nematode density was different in every soil layer, and highest in the layer of5-20cm and lowest in the layers of0-5cm and deeper20cm from upper soils; Nematode densities consistently changed by timing periods and two peaks were reached at June and September.2. Fifty-two vegetable cultivars resistant to M. incognita screening were conducted in the greenhouse. The results showed that the varieties of Chinese cabbage, turnip and pumpkin were all resistant; Varieties of cucumber, long melon, towel gourd, bitter melon, pepper and eggplant were highly susceptible; In the four bean varieties, both Qiujiang6and Ziqiujiang512were susceptible; Gaochan8cowpea were resistant; Of the12tomato cultivars, Zheza203, Zhefen702, Hangza1and Kaite1were highly susceptible, Zhefen202and Zheza205were susceptible, Jahong6, Chunzhan7, Chunzhan8, Xianchongjue1and Xianchongjue3were resistant.3. Resistant reaction of3resistant tomato cultivars, Chunzhan7, Xianke1and Chunzhan8, to4different Meloidogyne incognita populations were evaluated. It was found that virulence differentiation were present among different geographic root-knot nematode populations. Chunzhan7is high resistant to Yongjia and Hangzhou populations, resistant to Xiaoshan population and moderate resistant to Ruian. Chunzhan8and Xianke1tomatoes are highly resistant to Hangzhou, Xiaoshan and Yongjia populations. They are separately resistance and moderate resistance to Ruian population. This finding is very useful for studying the virulence differentiation of root-knot nematodes.4. Comparison inoculation tests of M. incognita to G. bicolor and tomato (cv. Zheza203). a high susceptible cultivar to M. incognita, showed that G. Bicolor was highly resistant. Infection and development of M. incognita in G. bicolor and tomato were systematic observed. Second stage juveniles of M. incognita was found inside the tomato roots after2dpi of inoculation. Third stage juveniles and females of RKN were observed after7and17dpi respectively. High densities of oocysts were exposed on tomato roots after27dpi and hatched second stage juveniles were detected after30dpi. In contrast, few second stage juveniles of M. incognita was found in G. bicolor roots after7dpi, and few third stage juveniles and necrotic cells were discovered in G. bicolor roots after30dpi and80dpi. No adult female of M. incognita were detected.. This means that M. incognita populations in this study can not reproduct in G. bicolor. It was concluded that Gynura bicolor is a useful resistant vegetable to root-knot nematodes.