Identification of an Embryonic Cell-Specific Region within the Pineapple SERK1 Promoter.

Luan Luan,Wang Wang,He He,Ding Ding,Xie Xie,Li Li,Liu Liu,Chen Chen,Lin Lin,Mao Mao,Xia Xia

doi:10.3390/genes10110883

Abstract

Plant tissue culture methods, such as somatic embryogenesis, are attractive alternatives to traditional breeding methods for plant propagation. However, they often suffer from limited efficiency. Somatic embryogenesis receptor kinase (SERK)1 is a marker gene of early somatic embryogenesis in several plants, including pineapple. It can be selectively induced and promotes a key step in somatic embryogenesis. We investigated the embryonic cell-specific transcriptional regulation of AcSERK1 by constructing a series of vectors carrying the GUS (Beta-glucuronidase) reporter gene under the control of different candidate cis-regulatory sequences. These vectors were transfected into both embryonic and non-embryonic callus, and three immature embryo stages and the embryonic-specific activity of the promoter fragments was analyzed. We found that the activity of the regulatory sequence of AcSERK1 lacking −983 nt ~−880 nt, which included the transcription initiation site, was significantly reduced in the embryonic callus of pineapple, accompanied by the loss of embryonic cell-specific promoter activity. Thus, this fragment is an essential functional segment with highly specific promoter activity for embryonic cells, and it is active only from the early stages of somatic embryo development to the globular embryo stage. This study lays the foundation for identifying mechanisms that enhance the efficiency of somatic embryogenesis in pineapple and other plants.

Highlights

The pineapple (Ananas comosus L.) is a perennial herb from the Bromeliaceae family and one of the world’s most important tropical fruit species
SERK1 is known to promote somatic embryogenesis (SE), and we previously identified promoter activity in the complete 50 upstream regulatory sequence (−2090~+258) of AcSERK1 that was specific to embryonic cells [30]
The callus was collected at each timepoint and used for Agrobacterium-mediated transient transformation with a recombinant expression vector containing the previously isolated AcSERK1 regulatory sequence upstream of the GUS reporter gene, and incubated for two days

Summary

Introduction

The pineapple (Ananas comosus L.) is a perennial herb from the Bromeliaceae family and one of the world’s most important tropical fruit species. Pineapple is largely vegetatively propagated because the species is self-sterile This has traditionally involved sucker propagation, which is a simple and low-cost process. It suffers from several significant limitations, including a low reproductive coefficient, prolonged production periods, and non-uniform growth and development [1]. To avoid these problems, pineapple breeding by tissue culture has been developed as an attractive alternative to traditional breeding methods. Pineapple breeding by tissue culture has been developed as an attractive alternative to traditional breeding methods This approach has several key advantages, including rapid and uniform growth and development of plants, a two-month reduction in production cycle, and viral disease reduction

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Conclusion