Over-Expression of the Cell-Cycle Gene LaCDKB1;2 Promotes Cell Proliferation and the Formation of Normal Cotyledonary Embryos during Larix kaempferi Somatic Embryogenesis.

Yanhui Kang,Wanfeng Li,Liwang Qi,Lifeng Zhang

doi:10.3390/genes12091435

Yanhui Kang, Wanfeng Li + Show 2 more

Open Access

https://doi.org/10.3390/genes12091435

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Abstract

Somatic embryogenesis is an effective tool for the production of forest tree seedlings with desirable characteristics; however, the low initiation frequency and productivity of high-quality mature somatic embryos are still limiting factors for Larix kaempferi (Japanese larch). Here, we analyzed the expression pattern of L. kaempferi cyclin-dependent kinase B 1;2 (LaCDKB1;2) during somatic embryogenesis in L. kaempferi and its relationship with the cell proliferation rate. We also analyzed the effect of LaCDKB1;2 over-expression on somatic embryo quality. The results revealed a positive correlation between LaCDKB1;2 expression and the cell proliferation rate during the proliferation stage. After LaCDKB1;2 over-expression, the proliferation rate of cultures increased, and the number of somatic embryos in transgenic cultures was 2.69 times that in non-transformed cultures. Notably, the number of normal cotyledonary embryos in transgenic cultures was 3 times that in non-transformed cultures, indicating that LaCDKB1;2 not only increases the proliferation of cultures and the number of somatic embryos but also improves the quality of somatic embryos. These results provide insight into the regulatory mechanisms of somatic embryogenesis as well as new Larix breeding material.

Highlights

Somatic embryogenesis is an effective technique that is used for the large-scale multiplication of superior clones in conifers
Members from the Arabidopsis thaliana CDKB2 family play roles in both cell-cycle regulation and meristem organization, and disruption of CDKB2 function leads to severe meristematic defects [21]
The results showed that the fusion protein GFP was only detected in the transgenic cultures (Figure 7C,D)

Summary

Introduction

Somatic embryogenesis is an effective technique that is used for the large-scale multiplication of superior clones in conifers. Research on somatic embryogenesis in conifers has made remarkable progress, but there are still many problems, such as the low initiation frequency and productivity of somatic embryos [7,8,9] as well as the high frequency of abnormal embryos [10] These problems make it important to understand the mechanisms underlying somatic embryogenesis, and, as such, in recent years, these factors have been studied in L. kaempferi [10,11,12,13,14,15,16,17,18,19]. Cell division and cell-cycle progression are controlled by many regulators, among which cyclin-dependent kinases (CDKs) play important roles via phosphorylation.

Plant Materials and Culture Conditions

Bioinformatics Analysis

Western Blot

Morphological Analysis of Somatic Embryos

Findings

Conclusions