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. 2011 Oct 21;6(10):e26696. doi: 10.1371/journal.pone.0026696

Figure 2. Meiotic defects in brca2a brca2b mutant plants and in wild-type Brca2-inactivated plants.

Figure 2

(A) Wild-type and brca2 double mutant plants exhibt no growth defect except for sterility. Chloralhydrate discolored siliques are full of seeds in wild-type plants in comparison with the discolored siliques of the brca2 double mutant plants. (B) Observation of meiocytes by DAPI staining in Brca2-deficient plants, transformed or not with the full length cDNA of AtBRCA2a, and in brca2a brca2b homozygous double mutant plants. (A–E) Different stages of meiosis in the wild-type plants. Meiosis is normal. (A) Prophase I stage, (B) diakinesis, the five bivalents are attached by a chiasma, (C) metaphase I with five aligned bivalents, (D) anaphase I, bivalents segregate into two sets of five univalents, (E) anaphase II, with four groups that contain five chromosomes each after sister chromatid separation. (F–J) Different stages of meiosis in wild-type plants transformed with the pDMC1::RNAi/BRCA2 construct. (F) Prophase I, (G) no normal diakinesis phase (H) metaphase I with condensed and entangled chromosomes, (I) anaphase I, with entangled and stretched chromosomes. (J) Anaphase II, with bridges extending between chromosomes. (K–O) Different stages of meiosis in brca2 double mutant plants. (K) Prophase I, (L) anaphase I, entangled and stretched chromosomes. (M) Metaphase II with entangled chromosomes. (N) anaphase II, fragmentated chromosomes. (O) telophase II with chromosome missegregation. (P–T) Different stages of meiosis in brca2 double mutant plants, transformed with the pDMC1::cDNA AtBRCA2a. Meiosis is restored to normal. (P) Prophase I stage, (Q) diakinesis, (R) metaphase I, (S) anaphase I, (T) anaphase II. Bar 10 µm.