Identification and characterization of double-stranded RNA associated with cytoplasmic male sterility in Vicia faba

Abstract

The cytoplasmic male sterility (CMS) trait of at least one line of Viea faba plants is always associated with the presence of high molecular weight double-stranded RNA in the leaf tissue extracts. Subcellular fractions of leaf tissue from CMS and fertile maintainer plants were initially analyzed in an attempt to locate, identify, and characterize the genetic material involved with the sterility trait. This CMS-associated high molecular weight RNA was found only in the cytosol of the "447" male sterile line ofV. faba plants and could not be isolated from the recurrent parent (maintainer), from lines that had been fertility-restored, or from lines that had reverted from the sterile condition. We have been able to move the CMS-associated RNA from donor to fertile host plants through a dodder bridge. These hosts not only contain the RNA but now exhibit a male sterile phenotype, as detected by visual examination of the flower, the pollen, morphological characteristics, and pollen staining ability.Male sterility is most useful for the production of commercial amounts of hybrid seed if the factors responsible for the trait are maternally inherited. Sources of such a cytoplasmic male sterility (CMS) have been found in many different species of plants (1). In the maize and sorghum cytoplasmic male sterile lines, it has been demonstrated that the genetic information responsible for the CMS trait resides in the mitochondria (2-4) apparently as episomal DNA (5). Research on these monocotyledonous plants has led to a transposon-like model for the mitochondrial CMS DNA (6). However, there has been very little research on the causes of CMS in the dicotyledonous plants. There have been suggestions that viruses or virus-like particles (VLPs) are responsible for the sterility in the broad bean plants (Vidafaba L.) and petunias (7-9).An electron microscopic study of "447" male sterile, maintainer, restored, and reverted V.faba lines has shown the presence of cytoplasmic spherical bodies (=70 nm in diameter) in only the male sterile plants (8). In a short report we have indicated that there are particles in the CMS plants that contain a family of double-stranded RNA (dsRNA) molecules (10); we now further characterize these nucleic acids and identify one of them as consistently being associated with the sterility trait.The dsRNA particle appears to have characteristics similar to a virus, leading us to help substantiate a mechanism of sterility which is quite different from that involving the episomal DNA in maize mitochondria. These results and the eventual transfer of the dsRNA agent and the CMS biological trait provide compelling biochemical evidence that cytoplasmic male sterility in the broad bean plant is caused by the presence of at least one dsRNA species. MATERIALS AND METHODSPlant Material. Seeds of V.faba L. were provided by D. A. Bond (Plant Breeding Institute, Cambridge, England) and P. Berthelem (Institut National de la Recherche Agronomique Station for Plant Improvement, LeRheu, France) or were purchased from...

Double-stranded RNA in Banana Plants with Bunchy Top Disease

“…The presence of dsRNA in infected but not healthy plants as well as the fact that the concentration of extractable dsRNA in infected plants is related specifically to the time of infection and incubation temperature indicates that a virus is responsible for the disease. There have been some reports of dsRNAs being isolated from healthy plants either as small heterogeneous molecules (Ikegami & Fraenkel-Conrat, 1979) or as large homogeneous molecules consistently associated with one particular cultivar (Grill & Garger, 1981;Dodds et al, 1984); however, in our work a single cultivar of banana was used throughout and homogeneous high molecular weight dsRNAs were never found in healthy plants. Gildow et al (1983) strains MAV, PAV and SEV.…”

Studies on virus infection of diseased Quercus robur (L) from forest stands in northern Germany

“…Büttner and Nienhaus (1989a, b) reported on virus contamination of soils and water in forested areas. The authors demonstrated that about 30% of the soil-root sam- (Grill and Garger, 1981;Wakarchuk and Hamilton, 1985). However, dsRNA species obtained from oak tissue were much smaller than nonviral dsRNA which were observed by these authors.…”

The Elusive Plant Mitochondrion as a Genetic System

“…Laver et al, 1991;Johns et al, 1992), multiple intragenic recombin,ltion events generating chimeric gene arrangements (e.g. Younig and Hanson, 1987;Levings, 1993), oftm producing polyc~istronic messages and, in one case, unumal viruslike particles (Grill and Garger, 1981). This diversity of mutations initially made it difficult to identify those features linking each system to a similar aberrant phenotype.…”