LAP3, a novel plant protein required for pollen development, is essential for proper exine formation

We isolated lap3-1 and lap3-2 mutants in a screen for pollen that displays abnormal stigma binding. Unlike wild-type pollen, lap3-1 and lap3-2 pollen exine is thinner, weaker, and is missing some connections between their roof-like tectum structures. We describe the mapping and identification of LAP3 as a novel gene that contains a repetitive motif found in b-propeller enzymes. Insertion mutations in LAP3 lead to male sterility. To investigate possible roles for LAP3 in pollen development, we assayed the metabolite profile of anther tissues containing devel- oping pollen grains and found that the lap3-2 defect leads to a broad range of metabolic changes. The largest changes were seen in levels of a straight-chain hydrocarbon non- acosane and in naringenin chalcone, an obligate compound in the flavonoid biosynthesis pathway.