The canola microspore-derived embryo as a model system to study developmental processes in plants

Abstract

The ability of micrmpores to undergo embryo development after a successful induction treatment provides a unique experimental system to study a variety of developmental processes in plants. Recent published results focus on the cellular and molecular aspects of the early induction process. In this review, besides summarizing the current findings, the advantages of using the MDE system to study other aspects of embryo development are emphasized. The continual improvement of culturing procedures, media components, and molecular methods guarantees exciting new findings in the near future. Keywords: Brassica, embryo development, microspore-derived embryosThe reports by Maheshwari in 1964 and1966 demonstrated that microspores of a flowering plant, Datura, are capable of developing into haploid plants. This discovery clearly illustrates the added developmental potential of microspores as they can switch from gametophytic to sporophytic development under appropriate conditions. As a result, this observation has enabled further development of haploid plant technology. Since the original reports by Guha and Maheshwari, successes have been reported for different species (see Jain et al., 1996-t997). A majority of studies have been focused on tobacco, Brassica species, and different varieties of barley, rice and wheat. This is primarily due to their economic importance or their ease of manipulation. Although a large amount of information is available in the literature, emphasis is usually placed on the pre-culturing conditions, the stress treatments, the media components and the early cellular, biochemical and molecular events related to the induction process. The purpose of this review is to summarize recent findings and to draw attention to the usefulness of the rnicrospore-derived embryo (MDE) system in the study of other processes related to embryo development and maturation. Since not every aspect of MDE development will be discussed, readers are urged to consult reviews by Ferrie et al.

Microspore-derived Embryo Formation and Morphological Changes during the Isolated Microspore Culture of Radish (Raphanus sativus L.)

“…7A). Similar observations of the microspore to embryo have been also reported for B. napus (Yeung, 2002;Yeung et al, 1996). However, anatomical observations of MDE formation process have not been reported for R. sativus L. In general, MDE formation showed differences in response according to the genotype of the donor plant (Babbar et al, 2004;Smykal, 2002).…”

Improvements in the production of doubled haploids in durum wheat (Triticum turgidum L.) through isolated microspore culture

“…Nowadays, a lot of basic research on microspore embryogenesis is being done with Brassica napus L. (Yeung 2002;Belmonte et al 2006;Supena et al 2008) but also with ArabidopsisBrassica (Boutilier et al 2002) with Picea glauca (Stasolla and Yeung 2003) and with soft wheat and barley (Hosp et al 2007). They are studying the metabolic and morphological reasons for the development of well formed embryos.…”

Buthionine sulfoximine (BSO)-mediated improvement in cultured embryo quality in vitro entails changes in ascorbate metabolism, meristem development and embryo maturation

“…Androgenesis has been obtained in a variety of systems through the development of optimized protocols and is routinely used as an integrated tool in many breeding programs. Over the past years the canola Brassica napus MDE system has received increasing attention as a model to study embryogenesis in plants for a variety of reasons (Yeung 2002;Boutilier et al 2005). First, a large numbers of synchronized embryos can be rapidly and eYciently produced.…”

“…Finally, the genetic similarities between Brassica and Arabidopsis can be exploited to apply the genomic information available in the latter for improving and understanding the mechanisms regulating Brassica embryogenesis. Due to these advantages, it is not surprising that the B. napus MDE culture system has been extensively utilized to investigate anatomical, physiological, and molecular events occurring during embryo development in vitro (reviewed in Yeung 2002;Boutilier et al 2005). Recent transcriptome and proteome analyses have focused on the molecular events delineating the induction of microspore embryogenesis, that is the initial transition from gametophytic to embryonic cell state (Joosen et al 2007;Malik et al 2007).…”