“…In nature, mature grains of rice, maize, wheat and barley plants have evolved different colours such as yellow, purple, red, blue and black due to different pigmentations (Abdel-Aal et al, 2006;Paulaneyer et al, 2017), potentially as a result of environmental adaptation because common pigments such as anthocyanins and flavonoids are strong antioxidants and can help plants address various stress conditions (Jia et al, 2020;Kaur et al, 2022;Shomali et al, 2022). Unlike other colours, the black grain trait, prominently observed in wild rice (Zhu et al, 2011) and wild barley (Long et al, 2019;Shoeva et al, 2020), was attributed to the accumulation of plant melanins instead of anthocyanins in the lemma and/or pericarp (Fei et al, 2021;Shoeva et al, 2020;Varga et al, 2016). Noteworthy, the black hull trait in rice needs to be differentiated from the deep purple colouration trait (often mistaken as black), which is mainly due to anthocyanin accumulation and is controlled by candidate genes in the anthocyanin biosynthesis pathway (Mackon et al, 2021;Oikawa et al, 2015;Upadhyaya et al, 2021).…”