Fig. 5.

aac2^A199D causes mitochondrial cristae degradation and extends antipodal lifespan when expressed in the central cell of wild-type plants. (A) Localization of pMEA::aac2^A199D_GFP in the central cell of the female gametophyte. (B and C) Central cell mitochondria in wild type (B) and pMEA::aac2^A199D_GFP (C). White arrows indicate cristae. (D and E) Frequencies of unfused polar nuclei (D) and persistent antipodal cells (E) in wild-type (black bar) and two independent pMEA::aac2^A199D_GFP transgenic lines (green bars); n = 361 for wild type, n = 452 for line 1 (pMEA::aac2^A199D_GFP/-; light green), n = 212 for line 2 (pMEA::aac2^A199D_GFP/ pMEA::aac2^A199D_GFP; dark green). Gametophytes were analyzed 2 d after emasculation. (F and G) Whole-mount clearing of a wild-type (F) and pMEA::aac2^A199D_GFP (G) gametophyte 2 d after emasculation. Arrows indicate the fused secondary nucleus and the unfused polar nuclei, respectively. Arrowheads indicate antipodals. (H) Localization of pHSFa2::aac2^A199D_GFP in antipodals (arrowhead) of the female gametophyte (overlay of GFP fluorescence with differential interference contrast image). (I and J) Frequencies of unfused polar nuclei (I) and persistent antipodal cells (J) in wild-type (black bar) and two independent pHSFa2::aac2^A199D_GFP/pHSFa2::aac2^A199D_GFP transgenic lines (gray bars); n = 241 for wild type, n = 239 for line 1 (light gray), n = 173 for line 2 (dark gray). (K) Model for SYCO function. SYCO-dependent mitochondria integrity is necessary for nuclei fusion in the central cell and negatively regulates antipodal lifespan in a noncell autonomous manner. Error bars, mean ± SEM. (Scale bar, 500 nm in B and C.)