Meloidogyne graminicola has emerged as one of the most destructive plant-parasitic nematodes affecting rice (Oryza sativa) production worldwide.  Resistance to M. graminicola in rice could be the most effective option for its management.  However, sources of germplasm with resistance to M. graminicola in rice remain limited.  Here, we describe the root attraction, gall formation and genetic analysis of the resistance to M. graminicola in the rice variety Huidao 5.  A nematode attraction assay showed that second-stage juveniles (J2s) of M. graminicola were attracted at the root tip of Huaidao 5 within 8 h without a significant reduction in attraction compared to the susceptible rice variety Nanjing 9108.  Microscopic observation of the infection revealed that the J2s invaded root tissues 12 h after inoculation, but their subsequent movement to the root tip was hindered in Huaidao 5, resulting in decreased nematode number compared to Nanjing 9108.  Additionally, we used the soil and hydroponic culture systems to simulate upland and flooding conditions in the paddy fields respectively, and found that gall number was significantly reduced, and nematode development was clearly suppressed in Huaidao 5.  To investigate the genetic basis of this resistance, cross breeding was performed between the Huaidao 5 and Nanjing 9108 varieties.  There was no reduction in the resistance of the F₁ offspring to M. graminicola in the greenhouse or field trials, suggesting that a dominant gene could control resistance in Huaidao 5.  In summary, this study provides a detailed characterization of a novel source of resistance to M. graminicola in rice, which is of great potential for use in crop breeding.

The effect of Aphelenchoides besseyi on 27 cultivars of rice (23 japonica and 4 indica) was assessed in the field for two seasons during 2010 and 2011. The vigorous pathogenic nematodes culturing on Botrytis cinerea were used for this experiment. Inoculation was carried out at the tilling stage; the growth parameters and nematode population were recorded at the end of growth of rice plants. The results showed that the cultivars differed in their response to infection. Most of cultivars were lack of the characteristic symptom of white tip, which was seen less frequently than the other two symptoms, namely small grains and erect panicles; moreover, the expression of symptoms was probably hereditary. The infection lowered the values of all the measured biological parameters, namely length of the stem and of the panicle, the number of filled grains per panicle, and 100-grain weight, in all the cultivars. The final nematode population indicated that the threshold of economic damage had also been exceeded in 10 cultivars, and none of them was immune. Three japonica cultivars proved most vulnerable whereas Tetep, an indica type, showed a level of resistance potentially useful in controlling A. besseyi.