Method of elevating photosynthesis speed of plant by improving pyruvate phosphate dikinase

Abstract

The present invention relates to the transformation of C4 plants. It also relates to the high-level expression of foreign genes in C4 plants. More specifically, the present invention relates to the creation of C4 plants retaining an excellent photosynthetic capacity at low temperature by achieving high-level expression of an enzyme constituting the C4 photosynthetic pathway. In the present invention, C4 plants are transformed using an expression cassette that comprises a promoter, a C4 plant genomic gene, under control of said promoter, encoding an enzyme constituting a photosynthetic pathway, and a terminator. The C4 plant genomic gene encoding an enzyme constituting a photosynthetic pathway is preferably a C4 plant genome-derived PPDK gene or a modified form thereof. The present invention is particularly useful in improving the production of C4 plants having PPDK (especially, in improving the production of maize under low temperature conditions).

1 . An expression cassette that comprises a promoter, a C4 plant genomic gene under control of said promoter, and a terminator, wherein the C4 plant genomic gene consists of any DNA selected from:
 (a) a DNA molecule consisting of a partial nucleotide sequence of SEQ ID NO: 16 which corresponds to the C-terminal ⅙ region of PPDK;   (b) a DNA molecule consisting of a nucleotide sequence derived from a partial nucleotide sequence of SEQ ID NO: 16 which corresponds to the C-terminal ⅙ region of PPDK by deletion, substitution, addition or insertion of one or more nucleotides, and encoding a protein possessing an activity in increasing the expression level of PPDK in a C4 plant;   (c) a DNA molecule being hybridizable under stringent conditions to the DNA molecule complementary to the DNA molecule consisting of a partial nucleotide sequence of SEQ ID NO: 16 which corresponds to the C-terminal ⅙ region of PPDK, and encoding a protein possessing an activity in increasing the expression level of PPDK in a C4 plant; and   (d) a DNA molecule consisting of a nucleotide sequence being at least 50% homologous to a partial nucleotide sequence of SEQ ID NO: 16 which corresponds to the C-terminal ⅙ region of PPDK, and encoding a protein possessing an activity in increasing the expression level of PPDK in a C4 plant.   
     
     
         2 . The expression cassette according to  claim 1 , for enhancing photosynthesis rate in a C4 plant under low temperature conditions. 
     
     
         3 . The expression cassette according to  claim 1 , wherein the PPDK activity is a cold-tolerant PPDK activity. 
     
     
         4 . A recombinant vector containing the expression cassette according to  claims 1 ,  2  or  3 .