Juan Vicente Muñoz-Sanz, Elena Zuriaga, María L. Badenes, and Carlos Romero (2017). A disulfide bond A-like oxidoreductase is a strong candidate gene for self-incompatibility in apricot (Prunus armeniaca) pollen. Journal of Experimental Botany.
Fruit Tree Breeding Department. Instituto Valenciano de Investigaciones Agrarias (IVIA). CV-315, Km. 10,7. 46113 Moncada (Valencia), Spain
Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas. C/Ingeniero Fausto Elio s/n, 46022 Valencia, Spain
* Genomics work done at the David H. Murdock Research Institute
S-RNase based gametophytic self-incompatibility (SI) is a widespread prezygotic reproductive barrier in flowering
plants. In the Solanaceae, Plantaginaceae and Rosaceae gametophytic SI is controlled by the pistil-specific S-RNases
and the pollen S-locus F-box proteins but non-S-specific factors, namely modifiers, are also required. In apricot,
Prunus armeniaca (Rosaceae), we previously mapped two pollen-part mutations that confer self-compatibility in cultivars Canino and Katy at the distal end of chromosome 3 (M-locus) unlinked to the S-locus. Here, we used highresolution mapping to identify the M-locus with an ~134 kb segment containing ParM-1–16 genes. Gene expression analysis identified four genes preferentially expressed in anthers as modifier gene candidates, ParM-6, -7, -9 and -14. Variant calling of WGS Illumina data from Canino, Katy, and 10 self-incompatible cultivars detected a 358 bp miniature inverted-repeat transposable element (MITE) insertion in ParM-7 shared only by self-compatible apricots, supporting ParM-7 as strong candidate gene required for SI. ParM-7 encodes a disulfide bond A-like oxidoreductase protein, which we named ParMDO. The MITE insertion truncates the ParMDO ORF and produces a loss of SI function, suggesting that pollen rejection in Prunus is dependent on redox regulation. Based on phylogentic analyses we also suggest that ParMDO may have originated from a tandem duplication followed by subfunctionalization and pollenspecific expression.