Carotenoid cleavage dioxygenases (HD-CCD1A and B) contribute as strong negative regulators of β-carotene in Indian bread wheat (cv. HD2967).

Wheat (Triticum aestivum L.) is the most common cereal crop that is considered to be deficient in provitamin A carotenoids. Carotenoids are prone to degrade into apocarotenoids by the activity of carotenoid cleavage dioxygenases (CCDs). Hence, in this study, multiple CCDs were cloned from commercial Indian wheat cultivar HD2967 to understand their role in provitamin A carotenoids degradation. The homoeolog specific expression of HD-CCD1 and HD-CCD4 at different grain filling stages revealed the higher expression of transcripts arising from the A and B subgenomes of HD-CCD1. Furthermore, the grain development stages showed a strong negative correlation of HD-CCD1A (r = - 0.969) and B (r = - 0.970) homoeologs expression to that of β-carotene accumulation. It suggested that they could be potentially involved in deciding the turn-over of β-carotene in wheat grain. Three-dimensional (3D) structures for all six homoeologs of HD-CCD1 and HD-CCD4 were predicted using maize VP14 template to gain better insight into their molecular mechanism. Ramachandran plot assessment revealed that ~ 90% of residues are in the most favoured region. Docking studies with various carotenoid substrates revealed the higher affinity of HD-CCD1A and B for β-carotene and β-cryptoxanthin. Bacterial complementation analysis validated the functional role of all six homoeologs with HD-CCD1B showing the highest activity followed by HD-CCD1A for β-carotene degradation. Results of this study provide valuable insights into the characteristics of HD-CCDs in wheat and thereby justifying them (HD-CCD1A and B) as the candidate genes for employing genome editing tools for developing β-carotene enriched wheat grains. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02775-y. © King Abdulaziz City for Science and Technology 2021.