Plant Science 158 2000 1 – 18
Review
Rice transformation for crop improvement and functional genomics
Akhilesh K. Tyagi, Amitabh Mohanty
Centre for Plant Molecular Biology and Department of Plant Molecular Biology, Uni6ersity of Delhi South Campus, Benito Juarez Road, New Delhi
110021
, India Received 20 March 2000; received in revised form 15 June 2000; accepted 16 June 2000
Abstract
Although several japonica and some indica varieties of rice have already been transformed, there is significant scope for improvement in the technology for transformation of economically important indica varieties. Successful transformation of rice
employing Agrobacterium and recent advances in direct gene transfer by biolistics, evidenced by transfer of multiple genes, have removed some of the serious impediments in the area of gene engineering. The transfer of genes for nutritionally important
biosynthetic pathway has provided many opportunities for performing metabolic engineering. Other useful genes for resistance against pests, diseases and abiotic stresses have also been transferred to rice. But the limited knowledge about important target
genes requires rapid progress in the field of functional genomics. Transgenic rice system can be applied to isolate new genes, promoters, and enhancers and their functions could be unravelled. The combination of novel regulatory systems for targeted
expression and useful new genes should pave the way for improvement of rice and other cereals. © 2000 Elsevier Science Ireland Ltd. All rights reserved.
Keywords
:
Crop improvement; Functional genomics; Genetic transformation; Oryza sati6a www.elsevier.comlocateplantsci
1. Introduction
Rice is the staple food for more than one third of world’s population. It is estimated that to feed
the growing world population total food production will have to increase by 60 in the next 25 years [1].
Although the world food supply has more than doubled since the onset of the green revolution, the
task of providing food for an additional 2.5 billion people would have to be accomplished without a
significant increase in the area under cultivation. In fact, the problem is compounded by the loss of land
to urban development, degradation of productive land, and the decreasing yield of several conven-
tional varieties which contributed immensely to- wards the green revolution. Besides, every year all
over the world, crops worth several million dollars are lost due to damage caused by various biotic and
abiotic stresses [2]. Although over the years plant breeders have contributed significantly to increased
food production, the time has come to synchronize plant breeding with biotechnology leading to preci-
sion breeding for rice improvement [3] by providing breeding lines with desired traits such as resistance
against pests and pathogens, tolerance to salinity and drought as well as improved nutritional quality
[4].
The rapid strides that rice biotechnology has made [5 – 8] after the recovery of the first transgenic
rice plantlets in 1988 [9 – 11] is amazing. In addition, due to its small genome size and the availability of
a lot of data in the form of expressed sequence tags ESTs and structural genomics, rice provides
Corresponding author. Tel.: + 91-11-467-3216; fax: + 91-11-688- 5270.
E-mail address
:
aktpmbhotmail.com A.K. Tyagi. 0168-945200 - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved.
PII: S 0 1 6 8 - 9 4 5 2 0 0 0 0 3 2 5 - 3
a valuable crop system for the introduction of useful genes and to accommodate new approaches to
address various fundamental problems in plant biology, such as elucidation of various principles of
gene regulation and functional genomics in mono- cots [12 – 14]. In this article, work on genetic trans-
formation of rice, with special emphasis on transfer of economically important traits, has been reviewed
along with the potential of transgenic rice for functional genomics. Previously, related aspects
have been discussed by Ayers and Park [5], Christou [6], Goff [15] and Tyagi et al. [8].
2. Development of rice transformation system
