Phlobaphenes modify pericarp thickness in maize and accumulation of the fumonisin mycotoxins

Abstract

phlobaphenes are insoluble phenolic compounds which are accumulated in a limited number of tissues such as seed pericarp and cob glumes, conferring on them a typical red-brown pigmentation. These secondary metabolites, derived from 3-deoxy flavonoids, are thought to have an important role in plants' resistance against various pathogens, e.g. by reducing fungal infection, and also to have beneficial effects on human and animal health due to their high antioxidant power. The aim of this work was to determine the role of phlobaphenes in reducing mycotoxin contamination on maize kernels. We analysed the effect of the P1 (pericarp color 1) gene on phlobaphenes accumulation, pericarp thickness and fumonisins accumulation. Analysing fumonisins accumulation in different genetic backgrounds through three seasons, we found a clear decrease of these toxins through the three years (Wilcoxon test, Z = 2.2, p = 0.0277) in coloured lines compared with the isogenic non-coloured ones. The coloured lines, carrying P1 allele showed an increase of phlobaphenes (about 10-14 fold) with respect to colourless lines. Furthermore there was a correlation between phlobaphenes accumulation and pericarp thickness (R = 0.9318; p = 0.0067). Taken together, these results suggest that the P1 gene plays a central role in regulating phlobaphenes accumulation in maize kernels, and indirectly, also tackles mycotoxins accumulation. The development and cultivation of corn varieties rich in phlobaphenes could be a powerful tool to reduce the loss of both quality and yield due to mycotoxin contamination, increasing the safety and the quality of the maize product.

Ectopic Expression of a Maize Gene Is Induced by Composite Insertions Generated Through Alternative Transposition

“…Because phlobaphene pigment accumulation is correlated with kernel pericarp thickness and reduced mycotoxin contamination on maize kernels (Landoni et al 2020), the ectopic expression of p2 induced by CI alleles could be beneficial.…”

“…Furthermore, the target p1/p2 locus plays a central role in regulating phlobaphene biosynthesis in maize tissues ( Grotewold et al 1994 ). Because phlobaphene pigment accumulation is correlated with kernel pericarp thickness and reduced mycotoxin contamination on maize kernels ( Landoni et al 2020 ), the ectopic expression of p2 induced by CI alleles could be beneficial.…”

Ectopic expression of a maize gene is induced by Composite Insertions generated through Alternative Transposition

“…A recent study has demonstrated a direct correlation between phlobaphene accumulation and kernel pericarp thickness, as well as reductions in mycotoxin contamination on maize kernels. Therefore, the ectopic expression of p2 induced by CI alleles could be beneficial to the plants (Landoni et al, 2020).…”

Transposon-induced inversions activate gene expression in Maize pericarp

“…The phlobaphene pigments controlled by the maize p1 gene are non-essential, and many modern corn varieties lack significant kernel pericarp color. However, a recent study reported that high phlobaphene levels were associated with increased kernel pericarp thickness and reduced mycotoxin contamination when compared to isogenic colorless pericarp lines lacking an active p1 gene (Landoni et al 2020). Because the p1 and p2-encoded proteins are highly similar and regulate the same flavonoid biosynthetic pathway (Zhang P. et al 2000), similar effects are likely induced by the expression of p2 in the pericarp.…”