IDENTIFICATION OF THE MOLECULAR BIOLOGY AND GENETICS OF ALUMINUM TOLERANCE

ENVIRONMENTAL STRESSES ARE A MAJOR FOCUS IN THE DEVELOPMENT OF ECONOMICALLY IMPROVED CROP CULTIVARS BUT TO DATE LITTLE PROGRESS HAS BEEN MADE IN DEVELOPING PROCESSES WHICH CAN IMPROVE ON THE UNDERSTANDING OF STRESS TOLERANCE OR AID IN THE DEVELOPMENT OF STRESS TOLERANT CULTIVARS. THE PROPOSED RESEARCH DEVELOPS A COMPREHENSIVE APPROACH TO UNDERSTANDING STRESS TOLERANCE. ALUMINUM TOXICITY HAS BEEN CHOSEN AS A MODEL STRESS. THIS PROPOSAL UTILIZES THE GENUS CERATOPTERIS AS AN EXPERIMENTAL PLANT SYSTEM AS WELL AS ALUMINUM TOLERANT AND SENSITIVE CULTIVARS OF SORGHUM. NPI HAS A LARGE NUMBER X-IRRADIATED MUTANTS OF CERATOPTERIS WHICH ARE A1 TOLERANT. THE ADVANTAGE OF UTILIZING CERATOPTERIS IS THAT MUTATIONS HAVE BEEN INTRODUCED IN THE SINGLE CELL HAPLOID SPORE STAGE. AFTER GERMINATION, THE GAMETOPHYTES CAN BE SELFED TO PRODUCE COMPLETELY HOMOZYGOUS DIPLOID PLANTS. THE IDENTIFICATION OF THESE MUTATIONS SHOULD IDENTIFY THE GENES INVOLVED IN A1 TOLERANCE. IN CONJUNCTION WITH THIS APPROACH, NPI HAS PROPOSED TO IDENTIFY THE GENES INVOLVED IN A1 TOLERANCE BY SCREENING A CDNA LIBRARY FROM SORGHUM WITH POLYA+ RNA FROM A1 TOLERANT AND SENSITIVE CULTIVARS OF SORGHUM. THOSE SEQUENCES WHOSE TRANSCRIPTION IS AFFECTED (QUALITATIVELY OR QUANTITATIVELY) WILL BE IDENTIFIED AND STUDIED IN DEPTH. IT IS ANTICIPATED THAT BY EXAMINING BOTH NATURAL VARIATION AND INDUCED MUTATIONS THAT LEAD TO A1 TOLERANCE A NUMBER OF GENES INVOLVED IN THIS STRESS CAN BE IDENTIFIED.