Wheat truncated hemoglobin interacts with photosystem I PSK-I subunit and photosystem II subunit PsbS1

Recently, the truncated hemoglobin gene (trHb) was discovered in plant species, however, its role has not yet been determined. In this study, the gene expression of wheat trHb (TatrHb) was analyzed under various biotic and abiotic stresses. TatrHb transcript levels increased in NaCl-treated leaves and gibberellic acid (GA₃)-treated roots. In addition, sodium nitroprusside (SNP), a nitric oxide donor, induced an increase in TatrHb transcript levels in roots and leaves. A yeast two-hybrid assay (YIIH) was used to screen a hypoxia-treated wheat seedling library with the goal of determining the putative function of TatrHb. In this YIIH assay, photosynthesis-related genes that showed high homology to the Hordeum vulgare chloroplast photosystem I PSK-I subunit and Zea mays photosystem II subunit PsbS1 were detected and their interactions with TatrHb were confirmed. Subcellular localization of a TatrHb-green fluorescent protein (GFP) fusion protein and bimolecular fluorescence complementation (BiFC) assay suggested that TatrHb is involved in photosynthesis. The TatrHb-GFP fusion protein was localized in the plastids and the yellow fluorescent protein signal indicated that the TatrHb protein interacted with PSK-I and PsbS1 in the chloroplast.