Tissue specificity and expression level of gusA under rolD, mannopine synthase and translation elongation factor 1 subunit alpha promoters in transgenic Gladiolus plants

Transgenic plants of Gladiolus cv. Jenny Lee were developed that contain th e bargusA fusion gene under either the mannopine synthase 2 (mas2), transla tion elongation factor 1 subunit alpha (EF-1 alpha), rolD, or the cauliflow er mosaic virus 35S (CaMV 35S) promoters. The relative level of gusA expres sion in leaves of five to ten independently transformed, in-vitro-grown pla nts representing each promoter was similar for transgenic plants containing the rolD and CaMV 35S promoter and 2.0-fold and 3.3-fold higher than the l evel for the mas2 and EF-1 alpha promoters , respectively. The maximum leve l of gusA specific activity by leaves was 135-173 nmol 4-methylumbelliferon e (4-MU)/h per milligram protein for plants containing either CaMV 35S or r olD as compared to only 27-38 nmol 4-MU/h per milligram protein for plants with either mas2 or EF-1 alpha. Histochemical staining confirmed the relati vely high level of gusA expression throughout the length of the older, 6-cm -long leaves of plants that contained bargusA under rolD, whereas gusA expr ession was infrequently observed throughout the older leaves of plants cont aining either the mas2 or EF-1 alpha promoters. In contrast to the older le aves, staining showed that strong gusA expression was frequently observed t hroughout young leaves of plants with either the mas2, EF-1 alpha, or rolD promoters. Roots of plants with the rolD and EF-1 alpha promoters showed st rong gusA expression specifically in 93% and 68%, respectively, of the root tips. Roots of the plants with the mas2 promoter showed strong gusA expres sion throughout the entire length of the root.