Role of the Root Nodule in the Bacterial-Induced Chlorosis of Soybeans1
- Herbert W. Johnson and
- Francis E. Clark2
Plant grafting experiments with chlorosis-susceptible and chlorosis-resistant varieties of soybean, observations on a difficultly-nodulating experimental line, and isolations of bacteria from chlorotic plants were made in order to characterize more fully the bacterial-induced chlorosis of soybeans. The plant grafts showed that an interaction between susceptible rootstocks and specific rhizobia was responsible for the onset of chlorosis. Top growth of chlorosis-susceptible varieties showed no chlorosis when grown on resistant rootstocks; in the reverse graft, chlorotic top growth was obtained. Observations on the difficultly-nodulating line showed that chlorosis developed only after root nodules were formed. No invasion of the aboveground parts of chlorotic plants by root-nodule bacteria could be demonstrated. It was concluded that when certain strains of rhizobia invade and nodulate chlorosis-susceptible varieties of soybean, some growth-damaging or chlorophyll-inhibiting factor is formed in nodular tissue.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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