The utility of transcription factors for manipulation of floral traits

Cross-pollination is an effective method of breeding flowering plants to produce novel variation. However, this strategy is often protracted or demands repeated crossing for several generations to obtain desired traits. Recently, gene-modification technologies have been utilized in plant breeding for manipulation of floral traits. Many homeotic genes that regulate flower development have been shown to encode transcription factors. In this review we describe the utility of transcription factors and a novel gene-silencing technology, the CRES-T system, to effectively manipulate floral traits. When AGAMOUS (AG) and APETALA3 (AP3) were subjected to this system in Arabidopsis, ag-like and ap3-like phenotypes, respectively, were induced with high efficiency as a dominant trait. Plant transcription factors are conserved between different species to some extent and consequently the chimeric repressor derived from Arabidopsis can be applied to other species without any modification. By applying this system, new floral color and shape phenotypes were obtained in Torenia fournieri and Ipomoea nil. Since the CRES-T system is able to overcome the problem of gene redundancy, polyploid plants may be also manipulated with this system. In addition, with the CRES-T system modification of the flower morphology of plants for which limited genome sequence information is available can be expected.