Abstract：The replacement of histone (H2A) with its variants in nucleosome regulates gene expression in plant. Although it is revealed that AtH2A involves in regulation of growth and development in Arabidopsis thaliana, study on function of H2A family members in plant is rare. In this study, A StH2A-1 cDNA was isolated from potato (Solanum tuberosum). A Nicotiana benthamiana transgenic line h2a-1, expressing antisense StH2A-1 cDNA displayed 31% lower leaf H2A contents than wild type (WT), leading to an apical dominance-deficient and late-flowering phenotype. BLAST outcome in Nicotiana benthamiana genome database showed that 4 NbH2As, sharing higher than 97% similarity with StH2A-1 uniquely contain a poly (Aln) motif with various length in the N-terminal of the amino acid sequences. Outcome of the reverse transcription polymerase chain reaction (RT-PCR) showed that accumulation of NbH2A mRNA, encoding NbH2A with N-terminal poly(Aln) was lower in the h2a-1 line than it in WT. The other NbH2As displayed a clearly higher mRNA accumulation in the h2a-1 line than it in WT. This suggested that NbH2As with and without N-terminal poly (Aln) may be complemented one another to function in gene expression regulation. RT-PCR also exhibited that mRNA accumulations of floral genes, including ELF4(EARLY FLOWERING 4), CO(CONSTANS) and FT(FLOWERING LOCUS T) in the h2a-1 line were down-regulated, suggesting that NbH2As with N-terminal poly(Aln) may involve in transcription of those genes. As a conclusion, StH2A-1 is associated with formation of apical dominance and regular flowering and positively regulates plant growth and development. The result may contribute to further understanding on function of H2A in plant growth and development.
