Stigmatic Transcriptome Analysis of Self-Incompatible and Compatible Pollination in Corylus heterophylla Fisch. × Corylus avellana L

Sihao Hou; Tiantian Zhao; Zhen Yang; Lisong Liang; Wenxu Ma; Guixi Wang; Qinghua Ma

doi:10.3389/fpls.2022.800768

Stigmatic Transcriptome Analysis of Self-Incompatible and Compatible Pollination in Corylus heterophylla Fisch. × Corylus avellana L

Front Plant Sci. 2022 Mar 1:13:800768. doi: 10.3389/fpls.2022.800768. eCollection 2022.

Authors

Sihao Hou^{1

2

3

4}, Tiantian Zhao^{1

2

3

4}, Zhen Yang^{1

2

3

4}, Lisong Liang^{1

2

3

4}, Wenxu Ma^{1

2

3

4}, Guixi Wang^{1

2

3

4}, Qinghua Ma^{1

2

3

4}

Affiliations

¹ State Key Laboratory of Tree Genetics and Breeding, Beijing, China.
² Key Laboratory of Tree Breeding and Cultivation of the National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
³ Hazelnut Engineering and Technical Research Center of the State Forestry and Grassland Administration, Beijing, China.
⁴ National Forestry and Grassland Innovation Alliance on Hazelnut, Beijing, China.

Abstract

Self-incompatibility (SI) protects plants from inbreeding depression due to self-pollination and promotes the outcrossing process to maintain a high degree of heterozygosity during evolution. Corylus is an important woody oil and nut species that shows sporophytic SI (SSI). Yet the molecular mechanism of SI in Corylus remains largely unknown. Here we conducted self- ("Dawei" × "Dawei") and cross-pollination ("Dawei" × "Liaozhen No. 7") experiments and then performed an RNA-Seq analysis to investigate the mechanism of pollen-stigma interactions and identify those genes that may be responsible for SSI in Corylus. We uncovered 19,163 up- and 13,314 downregulated genes from the comparison of different pollination treatments. These differentially expressed genes (DEGs) were significantly enriched in plant-pathogen interaction, plant hormone signal transduction, and MAPK signaling pathway-plant. We found many notable genes potentially involved in pollen-stigma interactions and SSI mechanisms, including genes encoding receptor-like protein kinases (RLK), calcium-related genes, disease-resistance genes, and WRKY transcription factors. Four upregulated and five downregulated DEGs were consistently identified in those comparison groups involving self-incompatible pollination, suggesting they had important roles in pollen-pistil interactions. We further identified the S-locus region of the Corylus heterophylla genome based on molecular marker location. This predicted S-locus contains 38 genes, of which 8 share the same functional annotation as the S-locus genes of Corylus avellana: two PIX7 homologous genes (EVM0002129 and EVM0025536), three MIK2 homologous genes (EVM0002422, EVM0005666, and EVM0009820), one aldose 1-epimerase (EVM0002095), one 3-dehydroquinate synthase II (EVM0021283), and one At3g28850 homologous gene (EVM0016149). By characterizing the pistil process during the early postpollination phase via transcriptomic analysis, this study provides new knowledge and lays the foundation for subsequent analyses of pollen-pistil interactions.

Keywords: Corylus; cross-pollination; self-pollination; sporophytic self-incompatibility; transcriptome.