Horticulturae, Vol. 11, Pages 969: Transcriptome Analysis Reveals That PpSLFL3 Is Associated with Cross-Incompatibility in the Peach Landrace ‘Liuyefeitao’

Horticulturae doi: 10.3390/horticulturae11080969

Authors:
Haijing Wang
Chunsheng Liu
Yating Liu
Yudie Zhang
Meilan Wu
Haiping Li
Man Zhang
Kun Xiao
Kai Su
Chenguang Zhang
Gang Li
Xiaoying Li
Libin Zhang
Junkai Wu

The peach landrace ‘Liuyefeitao’ exhibits the unique reproductive trait of self-compatibility combined with cross-incompatibility, contrasting with typical Prunus species in this way. In preliminary studies involving controlled pollination assays, we showed complete pollen tube arrest in cross-pollinated styles, whereas self-pollination enabled full tube elongation. S-genotyping identified a homozygous S2S2 genotype with intact S2-RNase but a truncated PpSFB2 due to a frameshift mutation. Transcriptome profiling of the styles revealed 7937 differentially expressed genes (DEGs) between self- and cross-pollination treatments, with significant enrichment in plant MAPK signaling, plant–pathogen interactions, and plant hormone signaling transduction pathways (|Fold Change| ≥ 2, FDR < 0.01). Notably, PpSLFL3 (a pollen F-box gene) showed down-regulation in cross-pollinated styles, as validated by means of qRT-PCR. Protein interaction assays revealed direct binding between PpSLFL3 and S2-RNase via Y2H and BiFC analysis, suggesting its role in mediating SCF complex-dependent degradation. We propose that insufficient PpSLFL3 expression during cross-pollination disrupts SCF ubiquitin ligase complex-mediated degradation of non-self S2-RNase, leading to the toxic degradation of RNA in pollen tubes by S2-RNase. This mechanism is mechanistically similar to unilateral reproductive barriers in Solanaceae but represents a novel regulatory module in Rosaceae. Our findings provide critical insights into the evolution of cross-incompatibility systems and molecular breeding strategies for Prunus species.

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