HO1 — Brassica napus

Summary

BnHO1 (DARMORV10_C07P25660.1) on chromosome C07 of oilseed rape encodes a heme oxygenase (decyclizing) enzyme, a member of the Haem_Oase family that binds heme and metal ions. The enzyme is localised to the chloroplast thylakoid membrane and envelope, and is associated with heme oxidation and phytochromobilin anabolism, a key step in phytochrome chromophore production. BnHO1 is associated with photomorphogenesis, chloroplast development, and red/far-red light phototransduction, as well as responses to nitrate, UV-C, and symbiotic bacteria. The gene has been linked to stem diameter, root length, auxin content, and tolerance to salinity, cadmium, boron, and oxidative stress. It is also linked to chlorophyll and carotenoid anabolism, sulfate assimilation, and chloroplast-nucleus signalling. Studies of related genes in other species link the family to phytochromobilin biosynthesis, iron homeostasis, and seedling photomorphogenesis.