Plant Science

Sneaky Smut

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Science  21 Feb 2014:
Vol. 343, Issue 6173, pp. 818
DOI: 10.1126/science.343.6173.818-a
CREDIT: JAMAIN/WIKIMEDIA COMMONS

When the fungus Ustilago maydis colonizes a maize plant, causing corn smut, its hyphae wind their way through to the vascular tissue, which is rich in resources that sustain fungal growth. The fungus also secretes an effector protein called Tin2, which causes the plant to produce anthocyanins, flavonoid pigments that lend a reddish color. Tanaka et al. now show that Tin2 contributes to the virulence of U. maydis and also induces the expression of genes that encode the plant's anthocyanin biosynthetic pathway. This results in more anthocyanin. Not so coincidentally, it also results in less lignin, the complex polymer that lends sturdiness to cell walls. This is because the biosynthetic pathways for anthocyanins and lignins share a common precursor. Plants with reduced lignin content were overly susceptible to fungal infection, which suggests that Tin2 promotes anthocyanin production at the expense of lignin production, reducing the plant's barriers to fungal growth.

eLife 3, e01355 (2014).

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