Submitted to: Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/13/2007
Publication Date: 8/1/2007
Citation: Tanha, M., Sturhan, D., Handoo, Z.A., Mor, M., Moens, M., Subbotin, S. 2007. Morphological and molecular studies on heterodera sacchari, h. goldeni, and h. leuceilyma (nematoda: heteroderidae). Nematology. 9(4):483-497. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that cause global crop losses exceeding $100 billion annually. Cyst nematodes are one of the most economically destructive groups of plant-parasitic nematodes. A major problem with determining the damage caused by specific cyst nematodes is that methods for their identification are inadequate. This report describes the discovery of new methods for identifying three economically important cyst nematode species by a collaboration of researchers from Belgium, Germany, Iran, Israel, Russia, and the United States (California Department of Food and Agriculture and ARS at Beltsville). These methods involved anatomical features obtained with light microscopes and high-powered electron microscopes, as well as DNA sequences. The newly discovered anatomical and molecular features are significant because they provide the details necessary for scientists to correctly identify these species wherever they may occur in the world. Therefore, this research will be used by research scientists, action agencies, and extension agencies engaged in nematode research and control.
Technical Abstract: Heterodera sacchari, H. leuceilyma and H. goldeni are closely related members of the H. sacchari species complex, which is mainly characterized and distinguished from all other described Heterodera species by the presence of finger-like projections of the strongly developed underbridge in the vulval cone of the cysts. Males are rare in all three species; they are described here for H. goldeni for the first time. Reproduction appears to be parthenogenetic. There are only minor morphological distinctions among the three species, particularly after our present studies have emended their original descriptions from various populations. Heterodera sacchari and H. goldeni showed differences in the ITS-rRNA gene sequences. Heterodera sacchari was described and reliably identified from many tropical African countries, H. leuceilyma is known only from Florida, USA, and H. goldeni has been identified in Egypt, Israel and Iran. All three species have grasses and other Poaceae as hosts; H. sacchari commonly attacks rice and sugarcane, and H. goldeni is shown to multiply on sugarcane ratoon seedlings successfully. Morphological data emending the descriptions of H. sacchari, H. goldeni and H. leuceilyma from various populations are presented and discussed along with their host distribution. Molecular characterization of H. sacchari and H. goldeni is provided. An analysis of phylogenetic relationships among species of the sacchari group using ITS-rRNA gene sequences is also presented.