A model for meiotic recombination and phenotypes of wild type and the <i>rfc1-2</i> mutant.

<p>(A) DNA double-strand breaks are resected to yield 3′ ssDNA overhangs. One of the single strands invades a homologous duplex to form a SEI intermediate. NCOs by the SDSA pathway accounts the majority of DSBs. The ZMM-dependent pathway requires the formation of dHJ and results in ∼80% of COs (Type I), whereas the MUS81-Mms4 dependent pathway produces ∼20% COs (Type II). The formation of both COs and NCOs requires DNA synthesis, but with distinct amounts. (B–N) Phenotypes of wild type and <i>rfc1-2.</i> Wild type (B) and <i>rfc1-2</i> (C) plants showed similar vegetative growth, but the mutant had shorter seedpods (arrow). A mutant flower (E) had normal organs similar to those in wild type (D). Wild type seedpods (F) and shorter <i>rfc1-2</i> mutant seedpods (G). Dissected young wild type (H) and mutant seedpods (I), with very few seeds. The boxed regions were enlarged from H and I. A wild type anther with viable pollen grains stained in red (J); a mutant anther (K) with few viable pollen grains (arrow) and a larger number of nonviable pollen grains stained in dark green. A wild type tetrad with four microspores (L). <i>rfc1-2</i> mutant polyads with additional small microspores (arrow) (M and N). Bar = 20 mm (B and C), 500 µm (D and E), 1 mm (F–I), 50 µm (J and K), and 10 µm (L–N).