Expression profiles of a banana fruit linker histone H1 gene MaHIS1 and its interaction with a WRKY transcription factor.

UNLABELLED: Chromatin remodeling-related proteins, such as linker histone H1, involving in fruit ripening and stress responses are poorly understood. In the present study, a novel cDNA encoding linker histone H1 gene, designated as MaHIS1 was isolated and characterized from banana fruit. The full-length cDNA sequence was 1,253 bp with an open-reading frame (ORF) of 948 bp, encoding 315 amino acids with a molecular weight of 31.98 kDa and a theoretical isoelectric point of 10.67. Subcellular localization analysis showed that MaHIS1 was a nucleus-localized protein. Real-time PCR analysis indicated that expression of MaHIS1 gene is induced by external and internal ethylene during fruit postharvest ripening. Accumulation of MaHIS1 transcript was also obviously enhanced by exogenous hormones, including methyl jasmonate, abscisic acid, and hydrogen peroxide (H₂O₂), as well as stresses, such as chilling and pathogen Colletotrichum musae infection. Moreover, yeast two-hybrid and bimolecular fluorescence complementation assays showed that MaHIS1 could interact with a transcription factor (TF) MaWRKY1. Taken together, our results suggest that MaHIS1 may be related to ripening and stress responses of banana fruit, and be likely functionally coordinating with MaWRKY1 in these physiological processes. KEY MESSAGE: MaHIS1 may be related to ripening and stress responses of banana fruit, and it also could interact with WRKY TF, which expands the very limited information regarding the functions of linker histone H1 in fruits.