The silencing of TdIPK1 genes enhances micronutrient concentration in durum wheat grain

Phytic acid (PA) is the main storage form of phosphorus in kernel and is considered an anti-nutritional compound because of its ability to bind to essential minerals such as iron (Fe), zinc (Zn), potassium (K), calcium (Ca) and magnesium (Mg), thus limiting their availability, especially for populations whose diet is largely based on staple crops.

This study reports a promising nutrient biofortification approach of durum wheat. The approach was based on the silencing of the gene encoding the inositol pentakisphosphate 2- kinase 1 (IPK1), involved in the last step of the PA biosynthetic pathway, through a Targeting Induced Local Lesions IN Genomes (TILLING) approach. Single knockout mutants for the IPK1 homeoalleles were identified and crossed to pyramid the two mutations. Although an elevated number of plants (F₂ and F₃ progenies) were analysed, no genotypes lacking both the homeoalleles were recovered, suggesting that the expression of IPK1 is crucial for seed formation in the spike and/or for plant germination and development.

The characterization of the single null genotypes highlighted that the partial TdIPK1-B1^- mutants showed a lower accumulation of PA in the kernel along with a higher content of essential microelements (Fe, Mn, Zn) compared to the control wild-type. The pattern of mineral accumulation was different for the TdIPK1-A1^- mutants which only presented a greater accumulation of K.