Priscilla Olayide, Erik Alexandersson, Oren Tzfadia, Marit Lenman, Andreas Gisel, Livia Stavolone

Plant Physiol Biochem.; 2023 Jun; 199:107713. doi: 10.1016/j.plaphy.2023.107713.

Abstract

Cassava (Manihot esculenta Crantz) is a predominant food security crop in several developing countries. Its storage roots, rich in carbohydrate, are deficient in essential micronutrients, including provitamin A carotenoids. Increasing carotenoid content in cassava storage roots is important to reduce the incidence of vitamin A deficiency, a public health problem in sub-Saharan Africa. However, cassava improvement advances slowly, mainly due to limited information on the molecular factors influencing β-carotene accumulation in cassava. To address this problem, we performed comparative transcriptomic and untargeted metabolic analyses of roots and leaves of eleven African cassava landraces ranging from white to deep yellow colour, to uncover regulators of carotenoid biosynthesis and accumulation with conserved function in yellow cassava roots. Sequence analysis confirmed the presence of a mutation, known to influence β-carotene content, in PSY transcripts of deep yellow but not of pale yellow genotypes. We identified genes and metabolites with expression and accumulation levels significantly associated with β-carotene content. Particularly an increased activity of the abscisic acid catabolism pathway together with a reduced amount of L-carnitine, may be related to the carotenoid pathway flux, higher in yellow than in white storage roots. In fact, NCED_3.1 was specifically expressed at a lower level in all yellow genotypes suggesting that it could be a potential target for increasing carotenoid accumulation in cassava. These results expand the knowledge on metabolite compositions and molecular mechanisms influencing carotenoid biosynthesis and accumulation in cassava and provide novel information for biotechnological applications and genetic improvement of cassava with high nutritional values.

See https://pubmed.ncbi.nlm.nih.gov/37126903/ or https://www.sciencedirect.com/science/article/pii/S0981942823002243?via%3Dihub

Fig. 3. Expression of carotenoid pathway genes in leaves and roots. (A) Principal components Biplot analysis of the significantly expressed genes in leaves (left panel) and roots (right panel). The separation between genotypes is visualized with PC1 vs PC2 (B) Heatmap of the significantly expressed genes in leaves and roots. Columns (genotypes) are ordered from left to right by increasing β -carotene content in roots. Rows (genes) are ordered from top to bottom according to the pathway sequence.