Microspore-derived embryos

Taylor, D.C., N. Weber, D.L. Barton, E.W. Underhill, L.R. Hogge, R.J. Weselake, and M.K. Pomeroy. 1991. Triacylglycerol bioassembly in microspore-derived embryos of Brassica napus L. cv Reston. Plant Physiol. 97 65-79. 

Supena, E.D.J. Winarto, B. Riksen, T. Dubas, E. van Lammeren, A. Offringa, R. Boutilier, K. Custers, J. (2008). Regeneration of zygotic-like microspore-derived embryos suggests an important role for the suspensor in early embryo patterning, foumal of Experimental Botany, Vol.59, No.4, (March 2008), pp. 803-814, ISSN 1460-2431... 

Yeung, E.C. Rahman, M.H. Thorpe, T.A. (1996). Comparative development of zygotic and microspore-derived embryos in Brasska napus L. cv. Topas. I. Histodifferentiation. International Journal of Plant Sciences, Vol.157, No.l, Ganuary 1996), pp. 27-39, ISSN 1537 5315... 

Kott, L.S. Beversdorf, W.D. (1990). Enhanced plant regeneration from microspore-derived embryos of Brassica mpus by chilling, partial desiccation and age selection. Plant Cell, Tissue and Organ Culture, 23 187-192... 

A gene that has been identified to be differentially expressed between late-stage microspore derived embryos and mature pollen is one that encodes a cysteine-labeled metallothionine... 

For in vitro studies microspore-derived embryos (MDEs) were initiated from flower buds of 3.4 to 3.6 mm. The MDEs were grown at 15 or 25°C as previously described (Wilmer et al., 1996). ABA was added at 350 °Cday together with fresh medium, while control treatments received fresh medium with a trace of methanol, the solvent for ABA. 

Holbrook, L.A., van Rooijen, G.J.H., Wilen, R.W. and Moloney, M.M. (1991) Oil body proteins in microspore-derived embryos of Brassica napus. Plant Physiol. 97, 1051-1058. 

Sangwan, R.S., Gauthier, D.A., Turpin, D.H., Pomeroy, M.K. and Plaxton, W.C. (1992a) Pyruvate-kinase isoenzymes from zygotic and microspore-derived embryos of Brassica napus. Planta 187, 198-202. 

Taylor, D.C., Weber, N., Hogge, L.R., Underhill, E.W. and Pomeroy, M.K. (1992b) Formation of trierucoylglycerol (trierucin) from 1,2-dierucoylglycerol by a homogenate of microspore-derived embryos of Brassica napus L. J. Am. Oil Chem. Soc. 69, 355-358. 

Weselake, R.J., Pomeroy, M.K., Furukawa, T.L. and Oishi, R.L. (1993) Partial puriflcationi of diacylglycerol acyltransferase from microspore-derived embryos of oilseed rape, in Seed Oils for the Future, eds. S.L. MacKenzie and D.C. Taylor, American Oil Chemists Society, Champaign, IL, pp. 103-115. 

Both somatic and microspore-derived embryos of oil plants are valuable tools in applied lipid biochemistry. It is well known from the Uterature that cultured embryos of various oil plants accumulate triaeylglycerols during maturation and that they synthesize unusual fatty adds found in the seeds. The capacity of cultured embryos and embryogenic cells of oil plants as model systems is, therefore, reviewed with respect to their usefulness in studying the mechanisms of genetic control of biosynthesis and assembly of triacylglycerols in oil seeds. 

Table 8. Content and fatty acid composition of triacylglycerols in mature microspore-derived embryos of . napus cv. Reston and cv. Topas and in mature Reston and Topas seeds. Adapted from Taylor et al. [51]...

Microspore-derived embryos from both early (14 d in culture) and mid-late (21-29 d in culture) cotyledonary stages yielded highly active cell-free enzyme preparations for studies of triacylglycerol biosynthesis in vitro [108]. 

Table 10. Comparison of in vivo and in vitro rates of triacylglycerol biosynthesis in developing zygotic and microspore-derived embryos of B. napus cv Reston. After Taylor et aL [108]...

Fig. 11a. Incorporation of C-erucoyl moieties (supplied as 40 rM C 22 l-CoA) into triacylglycerols by an homogenate of microspore-derived embryos of B. napus incubated in the presence ( ) and absence ( ) of G-3-P [108J. b) Incorporation of C-eracic add (19.2 pM) into triacylglycerols by an homogenate of developing seeds of Crambe abyssinica, incubated in the presence of 1 mM G-3-P ( ) [ 115] incorporation of C G-3-P (200 jiM) into triacylglycerols by a microsomal fraction from developing seeds of Unmanthes douglasU incubated in the presence of 100 pM 22 1-CoA ( ) [119]...

Table 12. Biosynthesis of lipid species containing C-labeled oleoyl, eicosenoyl, and erucoyl moieties by homogenates prepared from early cotyledonary stage (14 d in culture) microspore-derived embryos. Incubations were conducted under various elongation/incorporation conditions. Final concentrations of G-3-P, acyl-CoAs and malonyl-CoA were 200 pM, 18 pM and 1 mM, respectively. After Taylor et al. [118]...

Fig. 13. Incorporation of C-oleoyl-CoA and C-erucoyl-CoA, 40 pM each, into triacyl-glycerols by homogenates of microspore-derived embryos of B. napus cv Topas (tow erucic acid cultivar) incubated in the presence and absence of200 pM G-3-P. The data are presented as pmoles labeled acyl moieties incorporated per min and mg protein. D. C. Taylor (unpublished data)...

Microspore-derived embryos from a low erucic acid B. napus cultivar (Topas) were also screened for the ability to biosynthesize triacylglycerols in vitro. In the presence of G-3-P, homogenates prepared from mid-cotyledonary stage MD Topas embryos incorporated erucoyl- and oleoyl moieties into triacylglycerols at equal rates (Fig. 13). Thus, the breeding effort which produced low erucic acid cultivars of B. napus did not adversely affect the capacity of such embryos to incorporate very long-chain fatty acids into triacylglycerols. Rather, such cultivars are impaired in the ability to biosynthesize eicosenoic and erucic acids. 

In in vitro cultured microspore-derived embryos a maximum in erucic acid content at about 15°C could not be observed. Levels of 22 1 never exceeded 30% average content was about 20% at the temperatures tested. Reston, that showed a clear increase of 22 1 at 15°C in plants, even showed an opposite tendency in vitro (fig 3). Obviously some factor is missing in this system which controls the erucic/oleic acids ratio in complete seeds. Abscisic acid (ABA), which is known to be important in seed development and does have a stimulating effect on the level of 22 1 [3], might be the missing factor. Application of ABA (0.5-50 liM) leads to a twofold... 

Figure 3 Fatty acid composition of oil from seeds and microspore-derived embryos of Reston grown at 15, 20 and 25°C.

Figure 4 Effect of various ABA concentrations in the medium on the erucic acid level of oil from microspore-derived embryos of Reston. Embryos were treated with ABA during the third part of development and harvested at 1000 °Cday.

This effect of growth temperature observed in plants, was not found in microspore-derived embryos... 

Holbrook LA, Magus JR, Taylor DC. Abscisic acid induction of elongase activity, biosynthesis and accumulation of very long chain monounsaturated fatty acids and oil body proteins in microspore-derived embryos of Brassica napus L cv Reston. Plant Sci 1992 84 99-115. 

INTERACTION OF PHOTOREACTIVE SUBSTRATE ANALOGS WITH DIACYLGLYCEROL ACYLTRANSFERASE FROM MICROSPORE-DERIVED EMBRYOS OF OILSEED RAPE... 

Weselake RJ, Taylor DC, Pomeroy MK, Lawson SL, Underhill EW. Properties of diacylglycerol acyltransferase from microspore-derived embryos of Brassica napus. Phytochemistry 1991 30 3533-3538. 

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