ScORK17, a transmembrane receptor-like kinase predominantly expressed in ovules is involved in seed development

The mRNA expression of the Solanum chacoense Ovule Receptor Kinase 17 (ScORK17), a receptor kinase of the LRR-VI subfamily, is highly specific to the female reproductive tissues. No LRR-VI subfamily members in any plant species have yet been attributed a function. A phylogenetic tree inferred using the kinase domain of LRR-VI subfamily members separated the family into two clades: one containing an average of 8.2 LRR per protein and a second clade containing an average of 2.7. In situ hybridization analyses showed that the ScORK17 signal was mainly detected in the single ovule integument and in the endothelium. Transient expression analysis also revealed that ScORK17 was N-glycosylated in planta. Overexpression of ScORK17 in S. chacoense did not produce plants with an altered phenotype. However, when heterologous transformation was performed with a full-length ScORK17 clone in A. thaliana, the resulting transgenic plants showed reduced seed set, mainly due to aberrant embryo sac development, thus supporting a developmental role for ScORK17 in ovule and seed development.