Transgenic rice: a valuable monocot system for crop improvement and gene research

Abstract

Since the first fertile transgenic rice was obtained during the late 1980s, studies on rice transformation have undergone rapid strides. Several physical methods of gene delivery, including Agrobacterium , have been employed to produce transgenic rice. Up to now, about 50 rice cultivars have been transformed that include many japonica and also a few indica cultivars. Consequent to the availability of an efficient transformation system in rice, the expression of monocot genes is better understood because expression of several genes and regulatory elements from rice and other related cereals such as wheat has been studied in rice. Genes of agronomic importance for herbicide, insect, virus, and fungal resistance have been introduced in rice, and some of the transgenics have already completed a few years of field trials. In this context, rice is being looked on as a model monocot plant to study gene expression and to introduce agronomically useful genes. While this progress is expected to supplement conventional breeding program of rice improvement in the near future, some impediments in the successful implementation of transgene technology, such as gene silencing, the presence of undesirable selection/marker genes, high cost, and constitutive vs. targeted/optimal expression of genes, are addressed.