Ecological Associations of Spiroplasma Citri with Insects, Plants, and other Plant Mycoplasmas in the Western United States

Abstract

The discovery of the helical, plant pathogenic mollicute, Spiroplasma citri, has its roots in the recognition of a disease condition of cultivated citrus first observed in California in 1915 and referred to as “stubborn” according to Fawcett et al. (1944). A similar condition, called locally “little leaf”, was recognized from citrus in Palestine as early as 1928 (Reichert and Perlberger, 1931). Demonstrated to be graft-transmissible several decades ago, the nature of the causative agent of the condition called stubborn in several countries and little leaf in the eastern Mediterranean eluded discovery for several decades. Then, after Doi et al., (1967) found mycoplasma-like bodies in phloem elements of yellows diseased plats, and Ishiie et al.,(1967) reported remission of symptoms of mulberry dwarfs disease after treatment with tetracycline, Igwegbe and Calavan (1970) reported similar findings with citrus plants graftinoculated with stubborn. Amost immediately, investigators in France (Saglio et al., 1971) and California (Fudl-Allah et al., 1972) reported in vitro cultivation of a mycoplasma-like organism from stubborn-diseased citrus.