Molecular characteristics of S-RNase alleles as the determinant of self-incompatibility in the style of Fragaria viridis

Jianke Du; Chunfeng Ge; Tingting Li; Sanhong Wang; Zhihong Gao; Hidenori Sassa; Yushan Qiao

doi:10.1038/s41438-021-00623-x

Molecular characteristics of S-RNase alleles as the determinant of self-incompatibility in the style of Fragaria viridis

Hortic Res. 2021 Aug 1;8(1):185. doi: 10.1038/s41438-021-00623-x.

Authors

Jianke Du^{1

2}, Chunfeng Ge^{1

3}, Tingting Li¹, Sanhong Wang¹, Zhihong Gao¹, Hidenori Sassa², Yushan Qiao⁴

Affiliations

¹ Laboratory of Fruit Crop Biotechnology, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.
² Laboratory of Genetics and Plant Breeding, Graduate School of Horticulture, Chiba University, Matsudo, 271-8510, Chiba, Japan.
³ Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, Jiangsu, China.
⁴ Laboratory of Fruit Crop Biotechnology, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China. qiaoyushan@njau.edu.cn.

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 (S_a- and S_b-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. S_a and S_b-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.

Abstract

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