Artificial Control of the Prunus Self-incompatibility System Using Antisense Oligonucleotides Against Pollen Genes

Prunus (Rosaceae) includes many commercially important fruit crop species that exhibit self-incompatibility (SI), including sweet cherry (P. avium L.), Japanese apricot (P. mume Sieb. et Zucc.), Japanese plum (P. salicina Lindl.), apricot (P. armeniaca L.), and almond (P. dulcis [Mill.] D. A. Webb.). These species exhibit S-ribonuclease-based gametophytic SI, which prevents self-pollen tube growth in the pistil. The successful production of self-fertilized progeny accomplished by artificially overcoming the SI barrier has not been reported in Prunus, but self-compatible (SC) Prunus mutants with mutated pollen S determinant S haplotype–specific F-box (SFB) or pollen modifier M-locus encoded glutathione S-transferase-like (MGST) genes have been identified and used as SC cultivars and breeding stocks. In this study, we suppressed translation of SFB or MGST mRNA in self-pollen using antisense oligonucleotides to overcome the SI barrier in P. avium, P. mume, and P. salicina. Over the three years of the study, we obtained self-fertilized progeny of SI Japanese plum ‘Sordum’ only when SFB or MGST was knocked down. We also found that the average length of the self-pollinated pollen tube in the pistil of ‘Sordum’ was increased following treatment with an antisense oligonucleotide against SFB. This is the first report regarding the successful production of selfed progeny of Prunus obtained by disrupting SI. Our findings also provide evidence that the loss of function of SFB or MGST in Prunus pollen leads to SC.