Grouping in Rhizoctonia Solani by Hyphal Anastomosis Reaction

Abstract

Grouping of strains of Rhizoctonia solani Kuhn (teleomorph: Thanatephorus cucumeris [(Frank) Donk] based on hyphal anastomosis reactions has been described as the principle most helpful to plant pathologists in studies of R. solani during a 15 year period beginning in 1965 (Anderson, 1982). Similarly, Vilgalys and Cubeta (1994) state that “Since its inception, the anastomosis group concept has represented the single most important advance toward understanding genetic diversity in Rhizoctonia,”. Indeed, the anastomosis group concept has been and is a powerful tool to use as we seek to unravel the complex nature of this very important plant pathogenic fungus. Grouping based on hyphal anastomosis of Rhizoctonias other than R. solani, including the binucleates (Ogoshi et al., 1983) and those with Waitea teleomorphs (Oniki et al., 1985), is also successfully practiced although hyphal anastomosis reactions in Aquathanatephorus pendulus (Tu and Kimbrough, 1978) have not been studied. This chapter will focus only on hyphal anastomosis reactions in R. solani.