Promotes anthocyanin accumulation through interaction with PHYA, especially in response to far-red light, high light and sucrose treatment, probably by triggering A3G2XYLT/UF3GT expression (PubMed:21395597, PubMed:27143545). Required for gametophytes development as well as male-female gamete recognition during fertilization, possibly by regulating mitochondrial gene expression (PubMed:21123745). Represses PHYA-mediated PIF3 phosphorylation (PubMed:27143545). Interacts with phytochrome A (PHYA), both in Pr and Pfr forms (PubMed:21395597, PubMed:27143545). Binds to PIF3, a repressor of photomorphogenesis in response to phytochrome-mediated light signaling; this interaction may trigger the repression of PHYA-mediated PIF3 phosphorylation (PubMed:27143545). Interacts with SIGE/SIG5 in mitochondrion (PubMed:21123745). Interacts with RPS9M (via C terminus) (PubMed:29312411). Mostly expressed in flowers, cotyledons, leaves and siliques, and, to a lower extent, in roots and stems (PubMed:21123745, PubMed:21395597). Also detected at low levels in seedlings grown in continuous dark or light conditions (PubMed:21395597). Expressed in male and female gametophytes (PubMed:21123745). Levels in leaves diminishes after transition from the vegetative to the reproductive phase. Accumulates strongly in developmental tissues (PubMed:21395597). Highly expressed in the male (e.g. pollen grains and pollen tubes) and female (e.g. synergids, egg cell and central cell) gametophytes before and during, but not after fertilization. In fertilized ovules, levels decrease rapidely to become undetectable at the stage before the first division of the endosperm (PubMed:21123745). Phosphorylated by PHYA. Embryonic lethality in homozygous mutant. In heterozygous plants, impaired male-female gamete recognition when pollen of ank6 mutant is placed on ank6 female gamete. Defects in female gametophyte development at the one-nucleate stage (PubMed:21123745). Abnormal hypocotyls length. Reduced accumulation of anthocyanin in seedlings grown under far-red light, in response to high light and after sucrose treatment, associated with lower levels of the UDP-flavonoid-3'-glucosyl-transferase (A3G2XYLT/UF3GT), a major enzyme in the anthocyanin biosynthesis processes (PubMed:21395597).