Effects of ambient CO{sub 2} concentration on growth and nitrogen use in tobacco (Nicotiana tabacum) plants transformed with an antisense gene to the small subunit of ribulose-1,5-biphosphate carboxylase/oxygenase
- Australian National Univ., Canberra (Australia)
Growth of the R{sub 1} progeny of a tobacco plant (Nicotiana tabacum) transformed with an antisense gene to the small subunit of ribulose-1,5-carboxylase/oxygenase (Rubisco) was analyzed under 330 and 930 {mu}bar of CO{sub 2r} at an irradiance of 1000 {mu}mol quanta m{sup {minus}2} s{sup {minus}1}. Rubisco activity was reduced to 30 to 50% and 13 to 18% of that in the wild type when one and two copies of the antisense gene, respectively, were present in the genome, whereas null plants and wild-type plants had similar phenotypes. At 330 {mu}bar of CO{sub 2} all antisense plants were smaller than the wild type. There was no indication that Rubisco is present in excess in the wild type with respect to growth under high light. Raising ambient CO{sub 2} pressure to 930 {mu}bar caused plants with one copy of the DNA transferred from plasmid to plant genome to achieve the same size as the wild type at 330 {mu}bar, but plants with two copies remained smaller. The authors suggest other intrinsic rate-limiting processes independent of carbohydrate supply were involved. Under plentiful nitrogen supply, reduction in the amount of nitrogen invested in Rubisco was more than compensated for by an increase in leaf nitrate. Nitrogen content of organic matter, excluding Rubisco, was unaffected by the antisense gene. In contrast, it was systematically lower at elevated p{sub a} than at normal p{sub a}. Combined with the positive effects of p{sub a} on growth, this resulted in the single-dose antisense plants growing as fast at 930 {mu}bar of CO{sub 2} as the wild-type plants at 330 {mu}bar of CO{sub 2} but at a lower organic nitrogen cost.
- OSTI ID:
- 146528
- Journal Information:
- Plant Physiology (Bethesda), Vol. 103, Issue 4; Other Information: PBD: Dec 1993
- Country of Publication:
- United States
- Language:
- English
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