Plant Growth Environment Effects on Rapeseed Microspore Development and Culture

Abstract

The influence of donor plant growth conditions on microspore embryogenesis in rapeseed (Brassica napus) was metric measurements of the microspores isolated from 2.5-to 5.0-millimeter buds showed that the microspores isolated from low-temperature-grown plants had significantly lower log 90-degree light scatter to forward angle light scatter and log 90-degree light scatter to time of flight ratios than those isolated from high-temperature-grown plants, suggesting that the former are more translucent than the latter. Thus, the effect of donor plant growth temperature on microspore embryogenesis may be mediated by a change in the physiology of the microspore cell, which results in the reduction of its cytoplasmic granularity and/ or exine density.Haploid plants can be produced by culturing anthers or isolated microspores of rapeseed (Brassica napus) (3, 9, 12, 13). Microspore to haploid embryo conversion frequencies as high as 10 to 50% have been reported (9, 16), but for most genotypes <1% of the microspores that are cultured will develop into embryos.Previous research with several plant species has shown that the conditions under which the donor plants were grown affect the frequency of androgenesis in culture. Seasonal variations in anther response were reported for a number of species including Solanum tuberosum (4), Hordeum vulgare (2), and Triticum aestivum (17). For B. napus, controlled studies of the effects of growth temperature, light intensity, and light duration on anther culture response showed that embryo production could be significantly increased by growing the donor plants at a low (1 5C) temperature (3,11,12) and high light (12,20). There is no detailed report of the 'Supported by the Ontario Ministry of Agriculture and Food.

Effect of genotype and medium culture content on microspore-derived embryo formation in Chinese cabbage (Brassica rapa ssp. chinensis) cv. Lastochka

“…The most important element of the DH technology allowing an increase in the yield of regenerated plants is the increased induction of microspore embryogenesis. Some parameters of DH technology (growing donor plants at low tempe ratures, heat treatment of microspores during the first days of cultivation (Lo and Pauls, 1992;Cegielska Taras et al, 2002), and the use of media with a high sucrose content (Baillie et al, 1992;Ilic Grubor et al, 1998;Ferrie et al, 1999;Lionneton et al, 2001) are universal for the Brassica genus. According to pub lished data, the efficiency of embryogenesis depends on factors such as the plant genotype, the develop mental stage of microspores, the type of pretreatment of buds and microspores, the composition of culture media, and culture conditions (Ferrie et al, 1995).…”

Cauliflower and Broccoli

“…Low temperatures probably vary endogenous levels of anther hormones and metabolites and could modify the frequency of symmetric cell division and control the characteristics of microspore (Lo and Pauls, 1992;Custers et al, 1994). High culture temperature is a key factor for the transition from gametophytic to sporophytic development of microspores by promotion of the vegetative nucleus in binucleate pollen (Custers et al, 1994).…”

Haploids in the Improvement of Crucifers

“…Microspores are generally embryogenic at the uninucleate stage (Kott et al 1990;Telmer et al 1992;Kott 1998), but those at an early binucleate stage are still able to change their developmental program from pollen maturation to the embryogenic pathway (Pechan and Keller 1988;Huang et al 1990). In this case a different cytological development is observed (Kott et al 1988;Zaki and Dickinson 1990;Lo and Pauls 1992;Telmer et al 1993), for example, an abundance of starch grains has been described (Telmer et al 1993). However, morphological differences between embryogenic and non-embryogenic microspores have also been observed (Zaki and Dickinson 1991;Nitta et al 1997).…”

“…Moreover, the development of these embryos was also better as cotyledons developed separately, in contrast to microspore-derived embryos from the other temperature variants where cotyledons were fused. The donor plant also influences microspore embryogenesis: In rapeseed (B. napus) this influence has been studied by Lo and Pauls (1992). They demonstrated that significantly higher embryo yields were obtained in microspore cultures initiated from donor plants grown at 15/12°C instead of 23/18°C in a light/dark cycle of 16/8 h.…”

“…In this context parameters such as developmental stage of the donor plants and buds (Pechan and Keller 1988;Baillie et al 1992), microspore density (Huang et al 1990;Barro and Martin 1999;Ferrie et al 1999), sucrose or polyethylene glycol as an osmoticum (Baillie et al 1992;IlicGrubor et al 1998;Ferrie et al 1999;Lionneton et al 2001) and temperature optimization during the culture period (Lo and Pauls 1992;Cegielska-Taras et al 2002) have been the object of various studies (cf. Table 1).…”