INFLUENCE OF THE INDOLEACETIC ACID-LYSINE SYNTHETASE GENE (IAAL) OF PSEUDOMONAS-SYRINGAE SUBSP SAVASTANOI ON YIELD ATTRIBUTES OF POTATOES

The iaaL gene of Pseudomonas syringae subsp. savastanoi encodes an ind oleacetic acid-lysine synthetase which conjugates free indoleacetic ac id (IAA) with lysine. IAA-lys is biologically less active than free IA A. The iaaL coding region was expressed under the control of the cauli flower mosaic virus 35S promoter and transgenic potato plants were pro duced (SPENA et al. 1991). 35S iaaL potato plants are characterized by increased internodal length and epinastic bending of older leaves. In three greenhouse experiments with plants grown in pots of different s ize and in two growth chamber experiments tuber number increased in ia aL transgenic plants compared to untransformed and vector-transformed controls of the same genotype. The increase in tuber numbers observed under controlled conditions was reflected in tuber, yield which increa sed in the pot grown transgenics.