Mutations in Argonaute5 illuminate epistatic interactions of the K1 and I loci ($)

Classic studies revealed an interesting genetic relationship between two loci that control pigmentation in soybeans seeds. Dominant alleles of the I locus suppress pigmentation through the production of small interfering RNAs that target chalcone synthase RNA (an enzyme involved in pigment production).  Other I alleles including iⁱ and i^k lead to partially pigmented seeds. The effect of the I alleles are epistatically suppressed by the k1 allele. Cho et al. show that the K1 locus encodes Argonaute5, a protein involved in siRNA-mediated silencing. The k1 allele has a small deletion in the AGO5 gene that restricts the ability of I-locus derived siRNAs to suppress pigment synthesis. As always, the identification of the molecular basis for a classically-defined genetic anomaly makes for an interesting paper to read with students.  Plant Cell ​10.​1105/​tpc.​17.​00162