IMPROVED CELL AND TISSUE CULTURE SYSTEMS FOR MAIZE.

PRELIMINARY LABORATORY WORK HAS IDENTIFIED TWO FACTORS WHICH EFFECT THE EASE OF INITIATION OF EMBRYOGENIC CULTURES OF MAIZE AND THE EASE OF MAINTENANCE OF SUCH CULTURES. THESE TWO FACTORS ARE DESCRIBED IN THE PROPOSAL. S-AZACYTIDINE APPEARS TO EXTEND THE WINDOW DURING WHICH TISSUE IS COMPETENT TO FORM EMBRYOGENIC CALLUS. THIS FACT MAY BE EXPLOITED TO INITITATE EMBRYOGENE CULTURES FROM OTHER TISSUES BESIDES IMMATURE SEXUAL EMBRYOS. BY CHANGING THE CARBON SOURCE IN THE TISSUE CULTURE MEDIUM FROM SUCROSE TO SORBITOL IT IS POSSIBLE TO GROW EMBRYOGENIC TYPE CALLUS ALMOST WITHOUT THE GROWTH OF NONEMBRYOGENIC CALLUS. N.P.T. PROPOSES TO INVESTIGATE THESE TWO PHENOMENA FURTHER AND TO DEVELOP IMPROVED SYSTEMS FOR MAIZE CULTURE AROUND THESE OBSERVATIONS. PHASE II OF THE RESEARCH WILL FOCUS ON APPLYING THE OBSERVATIONS TO PLANT REGENERATION FROM PROTOPLASTS IN CEREALS. THIS IS A CRITICAL LIMITATION TO THE USE OF GENE TRANSFER AND PROTOPLAST FUSION TECHNOLOGIES IN CEREAL SPECIES.