Abstract
Erigeron breviscapus (Vant.) Hand.-Mazz. is a famous traditional Chinese medicine that has positive effects on the treatment of cardiovascular and cerebrovascular diseases. With the increase of market demand (RMB 500 million per year) and the sharp decrease of wild resources, it is an urgent task to cultivate high-quality and high-yield varieties of E. breviscapus. However, it is difficult to obtain homozygous lines in breeding due to the self-incompatibility (SI) of E. breviscapus. Here, we first proved that E. breviscapus has sporophyte SI (SSI) characteristics. Characterization of the ARC1 gene in E. breviscapus showed that EbARC1 is a constitutive expression gene located in the nucleus. Overexpression of EbARC1 in Arabidopsis thaliana L. (Col-0) could cause transformation of transgenic lines from self-compatibility (SC) into SI. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated that EbARC1 and EbExo70A1 interact with each other in the nucleus, and the EbARC1-ubox domain and EbExo70A1-N are the key interaction regions, suggesting that EbARC1 may ubiquitinate EbExo70A to regulate SI response. This study of the SSI mechanism in E. breviscapus has laid the foundation for further understanding SSI in Asteraceae and breeding E. breviscapus varieties.
Highlights
Sexual reproduction of flowering plants is a complex biological process that involves recognition between pollen and stigma
Previous studies have shown that both self-compatibility (SC) and SI are present in Asteraceae [22]
We observed that stamen height in transgenic lines was lower than stigma compared with wild-type plants (Figure 4E). These results show that EbARC1 mediates the SI response in A. thaliana
Summary
Sexual reproduction of flowering plants is a complex biological process that involves recognition between pollen and stigma. In order to ensure biodiversity, several effective mechanisms in plants have evolved to avoid inbreeding and promote heterosexuality, such as herkogamy, dichogamy, and self-incompatibility (SI) [1,2,3,4,5]. SI is a process in which the specific recognition of stigma and pollen rejects self-pollen fertilization [6]. According to the genetic control pattern, SI has been widely accepted as either sporophyte SI (SSI) or gametophyte SI (GSI) [7]. The SSI mechanism in other plants is still poorly understood, except in Brassica
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