A fundamental study on the new technique for production of Al-tolerant plants.

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The objectives of the present study are to clarify the mechanisms of Al-toxicity and Al tolerance and to offer fundamental information for the production of Al-tolerant plants. Results are summarized as follows.1. Mechanisms of Al toxicity and Al tolerance(1)Characteristics of Al uptake and translocation differ among plant species, and do not correlate with the differential Al tolerance among plant species.Al is highly deposited in the tip and the outer portions of roots, and in the cell wall. (2)Al considerably diffuses into root cells by metabolic inhibitors or in anaerobic conditions. Metabolically maintained Al excluding power of root plasmalemma is main strategy for Al tolerance.(3)pH ascending power of roots or the tolerances of the low nutrients in plants are not the cause of Al tolerance. (4)Phytotoxicity of Al ion species is in the order of hydroxy-Al polymer ions > monomeric Al ions > AlSCr^+_.2. Relationship between Al tolerance and the surface negativity of plasmalemma of root protoplasts.(1)Plasmalemma of root cells in the section is stained highly with basic dyes,i.e., methylene blue, in Al-sensitive plant species (measuring with multi-purpose graphic analyzer). (2)Methylene blue stainability of root protoplasts is low and zeta potential of them is high in Al-tolerant plant species. (3)Al and various basic dyes aggregate protoplasts and destroy the plasmalemma. (4)Root is composed of protoplasts of a range of Al tolerances. Root of Al-toleraht plant is composed of a large number of Al-tolerant protoplasts.3. Separation and culturing of Al-tolerant protoplasts(1)New technique for the separation of Al-tolerant protoplasts from original protplast population may be able to be developed by utilizing the plasmalemma negativity of Al-tolerant protoplasts. Conditions for culturing of tomato protoplasts are certified.