Human β-casein gene expression in transgenic tomato plants

A plant expression vector containing cDNA fragments encoding human β-casein (Hbca) and a bacterial luciferase reporter gene under control of the bi-directional mannopine synthase (mas) P1 and P2 dual promoters was introduced into tomato cotyledon cells using Agrobacterium tumefaciens mediated transformation methods. The presence of Hbca cDNA was detected in the genome of transgenic tomato plants by PCR amplification of a fragment of Hbca cDNA. Human β casein protein was quantified in tomato leaf and fruit tissues by chemiluminescent ELISA methods. Based on luminescence measurements, approximately 0.01 - 0.05% of the total soluble plant protein was found to be human β casein. This is the first report demonstrating synthesis of a calcium binding human milk protein in edible plant tissues in which cooking is not required prior to consumption. Expression of the Hbca gene in tomatoes provides a palatable hypoallergenic food source for delivery of a digestible calcium phosphate containing protein for supplementation of infant and adult nutrition.