After the initial screening, 36 mutant lines putatively resulting in faster than usual germination at 10°C were identified. However, after retesting these lines, only five were found to be demonstrably faster than the wild type. Despite using a suboptimal germination temperature (10°C), which is competent to alleviate Arabidopsis seed dormancy (Salaita et al., 2005) and capable of accentuating differences in commencement of radicle protrusion, the longer the seeds had been after-ripened (AR) prior to the analysis, the more restricted became the period in which a measurable difference in germination percentage was observed (compare Fig. 33.3 (6 months AR) and Salaita et al. (2005) (~1 month AR) ). Statistically significant differences in percentage germination were observed at fewer time points at the optimal (25°C) germination temperature (Salaita et al., 2005). However, while percentage germination has been depicted every 12 h in Fig. 33.3, data was collected every hour. The ability to examine the progression of radicle protrusion every hour facilitated the discrimination between bona fide ctg mutants and false positives, particularly at 25°C.
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