Transgenic plants that exhibit enhanced nitrogen assimilation

Abstract

Transgenic plants containing free amino acids, particularly at least one amino acid selected from among glutamic acid, asparagine, aspartic acid, serine, threonine, alanine and histidine accumulated in a large amount, in edible parts thereof, and a method of producing them are provided. In this method, glutamate dehydrogenase (GDH) gene is introduced into a plant together with a regulator sequence suitable for over expressing the sequence encoding GDH gene in plant cells.

Description

[0001] This application is a continuation-in-part of co-pending application Ser. No. 08 / 132,334 filed Oct. 6, 1993, which is hereby incorporated by reference in its entirety.1. INTRODUCTION[0003] The present invention relates generally to genetic-engineering plants to display enhanced nitrogen assimilatory and utilization capacities, grow larger, more efficiently or rapidly, and / or have enriched nitrogen contents in vegetative and / or reproductive plant parts and / or increased biomass. More particularly, this invention relates to producing transgenic plants engineered to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. The engineered plants may be productively cultivated under conditions of low nitrogen fertilizer input or in nitrogen poor soils. Alternatively, the engineered plants may be used to achieve faster growing or maturing crops, higher crop yields and / or more nutritious products under ideal cultivation conditions.2. BACKGROUND OF ...

AI Technical Summary

Benefits of technology

[0026] The invention has utility in improving important agronomic characteristics of crop plants. One of the improvements would be the ability of the engineered plants to be productively cultivated with lower nitrogen fertilizer inputs and on nitrogen-poor soil. Additional improvements include more vigorous (i.e., faster) growth as well as greater vegetative and / or reproductive yield under normal cultivation conditions (i.e., non-limiting nutrient conditions). To achieve these same improvements, traditional crop breeding methods would require screening large segregating populations. The present invention circumvent the need for such large scale screening by producing plants many of which, if not most, would have the desired characteristics.

Problems solved by technology

Nitrogen is often the rate-limiting element in plant growth and all field crops have a fundamental dependence on inorganic nitrogenous fertilizer.

There are, however, considerable difficulties associated with the screening of extensive populations in conventional breeding programs for traits which are difficult to assess under field conditions, and such selection strategies have been largely unsuccessful.

By contrast, numerous studies examining overexpression of glutamine synthetase (GS) have failed to report any positive effect of the overexpression on plant growth.

Moreover, it is unclear whether the faster growth produce mature plants with greater biomass or reproductive yield.

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