Figure 4.

Increased heat-resistant and aborted seed phenotypes in AtHSBP-knockout lines were restored by complementation of AtHSBP transgene. A, Reverse transcription-PCR analysis of AtHSBP transcript levels in 6-d-old seedlings of the wild type (WT), Athsbp-1, and three independent complementary transgenic lines (AtHSBP-C1, -C2, and -C3; in the T3 generation) that harbored AtHSBP and bar genes in an Athsbp-1 background. AtACT2 (ACT2) is shown as a loading control. B, Basta resistance and seedling survival in acquired thermotolerance tests were calculated from 50 seedlings of each experiment, and 18.5 ± 1.5 wild-type seedlings survived after HS treatment. Data represent means ± sd (n = 3). *, Significant at P < 0.05 (Student's t test, as compared with the wild-type value). C, The complementary lines restored the wild-type seed set phenotype. The arrowheads indicate the aborted seeds. Bar = 1 mm. [See online article for color version of this figure.]