The invention relates to the field of
plant gene engineering. The invention discloses two cotton
fiber elongation stage preferential expression promoters and their application. In the invention, the two cotton
fiber elongation stage preferential expression promoters of an island cotton
gene GbEXPA1 and an island cotton
gene GbEXPATR are cloned and identified, wherein
nucleotide sequences of the two cotton
fiber elongation stage preferential expression promoters are respectively shown in a sequence table 1 and a sequence table 2. In cotton, the two cotton
fiber elongation stage preferential expression promoters are fiber specific / preferential expression promoters. A
plant expression vector obtained by fusion construction of
DNA sequences of a GUS gene and the two cotton
fiber elongation stage preferential expression promoters of PGbEXPA1 and PGbEXPATR is transformed into cotton through an
agrobacterium tumefaciens-mediated genetic transformation method and the transgenic cotton is subjected to
dyeing identification. A result of the
dyeing identification shows that the GUS gene is preferentially expressed in cotton fibers. Expression
modes of the two cotton
fiber elongation stage preferential expression promoters are almost same. Through a series of processes of fusion of
cut promoter sequences and the GUS gene, a transgenic cotton
verification result shows that a sequence of -461bp to -1bp is a core sequence of the
promoter of PGbEXPA1. The invention also discloses a
recombinant expression vector containing the
promoter of PGbEXPA1. The
recombinant expression vector can be utilized for cultivation of a transgenic
plant, wherein the island cotton gene GbEXPA1 is specifically expressed in a root of the transgenic plant.