Artificial microRNAs reveal cell-specific differences in small RNA activity in pollen.

Pollen formation, while critical for the success of plant reproduction, also represents an important paradigm for differential cellular development within small groups of cells. In Arabidopsis thaliana pollen, the male meiotic product first divides asymmetrically to form a vegetative and a generative (germ) cell, the latter then dividing to generate two sperm cells. Here we have used artificial microRNAs to study small RNA processing in the different pollen cell types. Our data suggest that translational repression by small RNAs is enhanced in the sperm. This work also provides insights into germline RNA movement and the cell-autonomous action of microRNAs.