Figure 3.

Flower phenotypes of M. truncatula sgl1 mutants. Two mature flowers developed on a single spike in wild type (R108). The bilateral symmetry along the dorsal-ventral axis was shown. B, Defective flowers developed on a single spike in sgl1-1 mutant. C, A close-up view of a single flower of the sgl1-1 mutant. D to I, Flower development in wild type (R108). D, Three FMs were initiated from I₂. E, In S3, the abaxial (Sab) and two lateral (Sl) sepal primordia were initiated. F, In S4, two adaxial sepal primordia (Sad) were initiated. The carpel primordium (C) and the abaxial (CPab) and two lateral (CPl) common primordia formed. G, In S5, four common primordia differentiated into petal and stamen primordia along the abaxial to adaxial axis. Subsequently, the adaxial common primordia produced one inner antepetal (Stp) and two outer antesepal (Sts) stamens and the standard primordium (Vexillum or Vx). H, At subsequent stages, all floral organ primordia formed. A, Alae petals; K, keel petals. I, Stamen primordia differentiated anthers at S8 (asterisk). Sg, Stigma. J to O, Flower development in sgl1 mutants. J, Multiple FM developed from a single I₂ inflorescence meristem in sgl1-1 mutant. K, A close-up view of an I₂ with multiple FM. L and M, An S5 FM in sgl1-1 mutant initiated three to six common primordia (CP) between sepal (S) and carpel (C) primordia. The carpel primordium was occasionally missing from the center of the FMs (asterisks in K and M). M, Secondary FM were initiated from the second whorl of FMs in sgl1-1 mutant. N, An S7 FM in sgl1-1 mutant with its carpel primordium (C) started to fold. Secondary FM started to differentiate. O, Secondary floral-like meristems developed between the carpel and sepal primordia and gave rise to proliferating structures with elongated sepals (S). Scale bars as indicated. [See online article for color version of this figure.]