6-7 , a partial suppressor of max2-1, affects ribosomal protein gene RPS10B. (a,b) Effect of 6-7 on shoot architecture and branching in the wild-type MAX2 and in the max2-1 mutant background. (a) Plants aged 6 weeks. Scale bar: 5 cm. (b) Number of cauline nodes, cauline branches and rosette branches (≥0.5 cm) at maturity (Average ± SEM, n = 10). (c,d) The first leaves of 6-7 mutant seedlings (d) are slightly more pointed than those of wild-type (c) seedlings. (e) 6-7 carries a mutation in RPS10B, one of three Arabidopsis genes encoding ribosomal protein S10e. Gene mapping to a 126 kb interval on chromosome 5. Population size: about 1600 mutant individuals. Mutant rescue by JAtY TAC clone 49 K04, but not by 55I14, defined six candidate genes. Only one of these, RPS10B, carried a nonsense mutation in its coding region. (f) RT-PCR analysis showing reduced RPS10B transcript levels in 6-7. The primers used for RT-PCR are given in Table 5.