Fig. 6. erecta-105 erl1-2 erl2-1 triple mutations lead to dramatically reduced plant growth, aberrant flower development, and reduced cell numbers in petals and pedicels. (A) 12-day-old seedlings of wild type and erecta-105 erl1-2 erl2-1. Scale bars: 3 mm. (B) 24-day-old plants of erecta-105 and erecta-105 erl1-2 erl2-1. Scale bars: 1 cm. (C) Phenotypic variation of seven-week-old erecta-105 erl1-2 erl2-1 plants. Although the main inflorescence stem (arrowheads) always exhibits severe elongation defects, axillary branches occasionally show various degrees of phenotypic rescue. Scale bars: 5 mm. (D) Scanning electron micrographs of erecta-105 and erecta-105 erl1-2 erl2-1 flowers at stage 9. Note that one sepal was removed from the erecta-105 flower and several sepals were removed from erecta-105 erl1-2 erl2-1. Anther development and polar expansion of petals (arrowhead) are severely defective in the erecta-105 erl1-2 erl2-1 flower. Scale bars: 40 µm. (E) Flowers of erecta-105 and erecta-105 erl1-2 erl2-1 with mild phenotype. One sepal and two petals were removed from the erecta-105 flower to expose the inner organs. Note that none of the floral organs were removed from the erecta-105 erl1-2 erl2-1 flowers. The triple mutant flowers have reduced numbers of organs and develop characteristic needle-like petals. Scale bars: 0.5 mm. (F) Scanning electron micrographs of petal abaxial epidermis cells of erecta-105 and erecta-105 erl1-2 erl2-1. The images are taken at the same magnifications. Scale bars: 10 µm. (G) Longitudinal sections of mature pedicels from wild type, erecta-105, erecta-105 erl1-2, erecta-105 erl2-1 and erecta-105 erl1-2 erl2-1 plants. All combinations of mutants shown have defects in shape, size and number of cells in the cortex cell file (asterisks). Scale bars: 50 µm. (H) Longitudinal section of the mature flower of erecta-105 and erecta-105 erl1-2 erl2-1. The lack of proper ovule and anther (asterisk) differentiation is visible in erecta-105 erl1-2 erl2-1. The images are taken under the same magnifications. Scale bars: 0.2 mm. (I) Number of cells in the longitudinal cortex file of a mature pedicel of wild type, erecta-105, erecta-105 erl1-2, erecta-105 erl2-1 and erecta-105 erl1-2 erl2-1 plants. (J) Effect of erecta-105 and erecta-105 erl1-2 erl2-1 mutations on RNA levels of genes regulating meristem (STM, WUS) or organ (ANT, KNAT1, D-type cyclins) growth. Semi-quantative RT-PCR analysis was performed. An actin fragment was amplified simultaneously as a control. The number of PCR cycles were as follows: ANT, 28 cycles; STM, 28 cycles; WUS, 29 cycles; KNAT1, 32 cycles; CYCD2;1, 32 cycles; CYCD3;1, 29 cycles; actin, 24 cycles.