A plant whose heat tolerance is improved and/or growth is promoted is produced by a step of obtaining a transformed plant cell by introducing a DNA selected from the group consisting of (a) a DNA encoding a protein comprising an amino acid sequence represented by SEQ ID NO: 2, (b) a DNA containing a coding region of a nucleotide sequence represented by SEQ ID NO: 1, (c) a DNA encoding a protein having an amino acid sequence in which one or more amino acids have been substituted, deleted, inserted and/or added in the amino acid sequence represented by SEQ ID NO: 2 and involved in a growth-promoting effect and heat tolerance, (d) a DNA encoding a protein hybridized to a DNA comprising the nucleotide sequence represented by SEQ ID NO: 1 under stringent conditions and involved in a growth-promoting effect and heat tolerance, and (e) a DNA encoding a protein with an amino acid sequence identity of 90% or more to the amino acid sequence represented by SEQ ID NO: 2 and involved in a growth-promoting effect, heat tolerance, dry tolerance and salt tolerance into a plant cell, and a step of regenerating a transgenic plant from the transformed plant cell.
