Studying seed development is important for understanding plant evolution and engineering food production. Previous discoveries have shown that maternal small interfering RNAs (siRNAs), which induce RNA-directed DNA methylation (RdDM) through NRPD1-mediated pathway, regulate seed development in Arabidopsis. However, it was ambiguous whether the maternal expression of these NRPD1-siRNAs is from the seed coat (maternal) or from the endosperm (uniparentally expressed alleles). Here, Kirkbride et al. used laser-capture microdissection (LCM) to separate small RNA in the endosperm and seed coat and investigate their biological effects. This study shows that the spatial-temporal expression of specific AGAMOUS-LIKE (AGL) transcription factors is regulated by maternal siRNAs, and the ON/OFF of these imprinted genes in the endosperm changes seed size. These discoveries provide a potential strategy to optimize seed production and crop yields.
(Summary written for Plantae, Plant Science Research Weekly)
Journal reference: Kirkbride et al, 2019, Proc. Natl. Acad. Sci. USA