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Article|01 Aug 2021|OPEN
Molecular characteristics of S-RNase alleles as the determinant of self-incompatibility in the style of Fragaria viridis
Jianke Du1,2, Chunfeng Ge1,3, Tingting Li1, Sanhong Wang1, Zhihong Gao1, Hidenori Sassa2 & Yushan Qiao1,
1Laboratory of Fruit Crop Biotechnology, College of Horticulture, Nanjing Agricultural University, Nanjing 210095 Jiangsu, China
2Laboratory of Genetics and Plant Breeding, Graduate School of Horticulture, Chiba University, Matsudo 271-8510 Chiba, Japan
3Present address: Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014 Jiangsu, China

Horticulture Research 8,
Article number: 185 (2021)
doi: 10.1038/hortres.2021.185
Views: 143

Received: 12 Jan 2021
Revised: 29 May 2021
Accepted: 01 Jun 2021
Published online: 01 Aug 2021

Abstract

Strawberry (Fragaria spp.) is a member of the Rosoideae subfamily in the family Rosaceae. The self-incompatibility (SI) of some diploid species is a key agronomic trait that acts as a basic pollination barrier; however, the genetic mechanism underlying SI control in strawberry remains unclear. Two candidate S-RNases (Sa- and Sb-RNase) identified in the transcriptome of the styles of the self-incompatible Fragaria viridis 42 were confirmed to be SI determinants at the S locus following genotype identification and intraspecific hybridization using selfing progenies. Whole-genome collinearity and RNase T2 family analysis revealed that only an S locus exists in Fragaria; however, none of the compatible species contained S-RNase. Although the results of interspecific hybridization experiments showed that F. viridis (SI) styles could accept pollen from F. mandshurica (self-compatible), the reciprocal cross was incompatible. Sa and Sb-RNase contain large introns, and their noncoding sequences (promotors and introns) can be transcribed into long noncoding RNAs (lncRNAs). Overall, the genus Fragaria exhibits S-RNase-based gametophytic SI, and S-RNase loss occurs at the S locus of compatible germplasms. In addition, a type of SI-independent unilateral incompatibility exists between compatible and incompatible Fragaria species. Furthermore, the large introns and neighboring lncRNAs in S-RNase in Fragaria could offer clues about S-RNase expression strategies.