An important method for plant genetic modification is using peptide/pDNA complexes to transfer genes into plant cells. With conventional carrier peptides, the peptide sequence must contain a high amount of cationic amino acids to condense and introduce pDNA. As a result, the dissociation of pDNA from the complex is inefficient, often causing problems. Herein, we designed a new peptide carrier that mimics the basic leucine zipper (bZIP) domain of DNA-binding proteins, in which (LU)₄ is the leucine zipper motif and (KUA)₃ is the basic DNA-binding and cell-penetrating motif (U = α-aminoisobutyric acid). After (KUA)₃-(LU)₄ peptide was mixed with pDNA, DNA molecules were condensed to form nanoparticles of approximately 130 nm. Furthermore, when complexes of (KUA)₃-(LU)₄ peptide and pDNA were introduced into the leaves of Arabidopsis thaliana (A. thaliana), expression of the reporter protein was detected in the plant cells. Thus, (KUA)₃-(LU)₄ peptide that mimics the bZIP domain is a novel and efficient carrier for pDNA with high dissociation efficiency.