Expression of the Rice Homeobox Gene, OSH1, Causes Morphological Changes in Transgenic Kiwifruit.

Abstract

The rice gene, OSH1, contains a homeobox whose product is thought to have DNA binding activity. When OSH1 cDNA was introduced into kiwifruit plants under the control of three different promoters, only the transgenic kiwifruit plants containing the OSH1 cDNA under the control of the 35S promoter from cauliflower mosaic virus exhibited morphological changes. The morphology of these 35S-OSH1 transformed plants was divisible into three categories : normal-, mild-, and severe-phenotype. Severe-phenotype transgenic kiwifruits were very dwarfed with tiny leaves having dissected margins and lacked apical dominance. RNA blot analysis revealed that severe-phenotype plants had the highest level of OSH1 expression in all transgenic and wild-type kiwifruit plants. We conclude that OSH1 can act as a morphological regulator in transgenic kiwifruit, causing dwarfism and loss of apical dominance. If adapted these features may lead to labor-saving in kiwifruit vineyard management.