Beschreibung:
<jats:p> The hooded (hdd) floral mutant of Lathyrus odoratus L. (sweet pea) has a concave standard petal compared with the flat standard petal of the wild type. This trait was used by Bateson, Punnett, and Saunders in early studies of Mendelian inheritance (c.1905). Here we provide four lines of evidence that this phenotype results from a mutation in the CYCLOIDEA2 (CYC2) gene. (i) CYC2 is expressed in the standard petals of wild-type L. odoratus, whereas the same methods fail to detect expression in hdd plants. (ii) Genomic sequencing reveals that the CYC2 gene sequence of hdd plants is truncated at the TCP box and likely nonfunctional. (iii) In a population of 118 plants, the hdd phenotype cosegregated with the mutant allele of CYC2 without exception. (iv) CYC2 is known to act as a dorsal petal identity gene. Consistent with this, the standard petal in hdd flowers has the epidermal and pigment characteristics of wing petals, indicating that the hdd mutation results in a shift in dorsiventral petal-type identity. We conclude that the mutation in CYC2 is responsible for the hdd phenotype, and is therefore the L. odoratus equivalent of the lobed standard (lst1) mutant in Pisum. </jats:p>