A disulfide bond A-like oxidoreductase is a strong candidate gene for self-incompatibility in apricot (Prunus armeniaca) pollen

[EN] 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 high-resolution mapping to identify the M-locus with an similar to 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.This work was supported by two grants from the Ministerio de Economia y Competitividad del Gobierno de Espana (AGL19018-2010 and AGL2015-64625-C2-2-R). The authors want to thank Inmaculada Lopez for her technical contribution and Gary Clark for his assistance with the manuscript. Chris Dardick, Tetyana Zhebentyayeva, and Albert Abbott kindly provided Goldrich and SEO genomic sequences. We also thank Mario Fares, and especially, Bruce McClure for their insights and comments on the manuscript.Muñoz-Sanz, JV.; Zuriaga García, E.; Badenes, ML.; Romero Salvador, C. (2017). A disulfide bond A-like oxidoreductase is a strong candidate gene for self-incompatibility in apricot (Prunus armeniaca) pollen. Journal of Experimental Botany. 68(18):5069-5078. doi:10.1093/jxb/erx336S50695078681