Embryo rescue
Embryo rescueis one of the earliest and successful forms ofin-vitro culturetechniques that is used to assist in the development of plant embryos that might not survive to become viable plants.[1]Embryo rescue plays an important role in modernplant breeding,allowing the development of manyinterspecificand intergeneric food and ornamental plant crop hybrids. This technique nurtures the immature or weak embryo, thus allowing it the chance to survive. Plant embryos are multicellular structures that have the potential to develop into a new plant. The most widely used embryo rescue procedure is referred to as embryo culture, and involves excising plant embryos and placing them onto media culture.[2]Embryo rescue is most often used to create interspecific and intergeneric crosses that would normally produce seeds which are aborted. Interspecific incompatibility in plants can occur for many reasons, but most often embryo abortion occurs[3]In plant breeding, wide hybridization crosses can result in small shrunkenseedswhich indicate that fertilization has occurred, however the seed fails to develop. Many times, remote hybridizations will fail to undergo normal sexual reproduction, thus embryo rescue can assist in circumventing this problem.[4]
History
[edit]Embryo rescue was first documented in the 18th century when Charles Bonnet excisedPhaseolusandFagopyrumembryos and was successful in it, planted them in soil and the cross resulted in dwarf plants.[5]Soon after this, scientists began placing the embryos in various nutrient media. During the period of 1890 to 1904, systems for embryo rescue became systematic by applying nutrient solutions that contained salts and sugars and applyingaseptic technique.[6]The first successfulin vitroembryo culture was performed by Hanning in 1904, he however described problems with precocious embryos that resulted in small, weak, and often inviable plantlets.[7]
Applications
[edit]- Breeding of incompatible interspecific and intergeneric species
- Overcomingseed dormancy
- Determination of seed viability
- Recovery of maternal haploids that develop as a result ofchromosomeelimination following interspecific hybridization
- Used in studies on the physiology ofseed germinationand development
Techniques
[edit]Depending on the organ cultured, it may be referred to as eitherembryo,ovule,orovaryculture. Ovule culture or in vitro embryo culture is a modified technique of embryo rescue whereby embryos are cultured while still inside their ovules to prevent damaging them during the excision process.[8]Ovary or pod culture, on the other hand employs the use of an entire ovary into culture. It becomes necessary to excise the entire small embryo to prevent early embryo abortion. However, it is technically difficult to isolate the tiny intact embryos, so often ovaries with young embryos, or entire fertilized ovules will be used.[9]
Factors to consider
[edit]Embryosare manually excised and placed immediately onto aculture mediumthat provides the proper nutrients to support survival and growth (Miyajima 2006). While the disinfestation and explant excision processes differ for these three techniques, many of the factors that contribute to the successful recovery of viable plants are similar. The main factors that influence success are; thetime of culture,the composition of the medium,andtemperature and light.Timing mainly refers to the maturation stage of the embryo before excision. The optimal time especially for the rescue of embryos involving incompatible crosses would be just prior to embryo abortion. Nevertheless, due to difficulties involved with the rearing of young embryos compared to those that have reached the autotrophic phase of development, embryos are normally allowed to develop in vivo as long as possible. While in general, two main types of basal media are the most commonly used for embryo rescue studies, i.e.Murashige and Skoog medium(MS)[10][failed verification]andGamborg’s B-5[11][failed verification]media (Bridgen, 1994), the composition of the medium will vary in terms of the concentrations of media supplements required. This will generally depend on the stage of development of the embryo. For instance, young embryos would require a complex medium with high sucrose concentrations, while more mature embryos can usually develop on a simple medium with low levels of sucrose. The temperature and light requirement is generally species specific and thus its usually regulated to be the within the same temperature requirement as that of its parent with embryos of cool-season crops requiring lower temperatures than those of warm-season crops.
See also
[edit]- Plant embryogenesis
- Callus (cell biology)
- Plant tissue culture
- Plant hormone
- Hyperhydricity
- Somatic embryogenesis
References
[edit]- ^Sage, T.L.; Strumas, F.; Cole, W.W.; Barret,S (2010). "Embryo rescue and plant regeneration following interspecific crosses in the genusHylocereus(Cactaceae) ".Euphytica.174:73–82.doi:10.1007/s10681-010-0135-x.S2CID7837522.
- ^Miyajuma, D. (2006). "Ovules that failed to form seeds in zinnia (Zinnia violacecCav) ".Sci Hortic.107(2): 176–182.doi:10.1016/j.scienta.2005.06.014.
- ^Reed, Sandra (2005). Robert N. Trigiano; Dennis J. Gray (eds.).Plant Development and Biotechnology(PDF).CRC Press. pp. 235–239.ISBN0-8493-1614-6.Archived fromthe original(PDF)on 2012-03-12.Retrieved2011-04-18.
- ^Bridgen, Mark P. (1994)."A Review of Plant Embryo Culture".HortScience.29(11): 1243–1246.doi:10.21273/hortsci.29.11.1243.
- ^Sharma, D.R.; Daur, R.; Kumar K. (1996). "Embryo rescue in plants-a review".Euphytica.89(3): 325–337.doi:10.1007/BF00022289.S2CID206766831.
- ^Amanate-Bordeos, A.D.; Nelson, R.J.; Oliva, N.P.; Dalmacio, R.D.; Leung, H.; Sitch, L.A. (1992). "Transfer of blast and bacterial blight resistance from the tetrapliod wild riceOryza minutato the cultivated rice,O. sativa".Theor. Appl. Genet.84(3–4): 345–354.doi:10.1007/bf00229493.PMID24203194.S2CID6451011.
- ^Mehetre, S. S; Aher, A. R. (2004). "Embryo rescue: A tool to overcome incompatible interspecific hybridization inGossypiumLinn. --A review ".Indian Journal of Biotechnology.3:29–36.
- ^Cisneros, Aroldo; Tel-Zur (2010). "Embryo rescue and plant regeneration following interspecific crosses in the genusHylocereus(Cactaceae) ".Euphytica.174:73–82.doi:10.1007/s10681-010-0135-x.S2CID7837522.
- ^Ikeda, N.; Niimi, Y. Han D. (2003). "Production of seedling from ovules excised at the zygote stage inLiliumspp ".Plant Cell Tissue Organ Cult.73(2): 159–166.doi:10.1023/A:1022818413617.S2CID7305410.
- ^Murashige, T; Skoog, F. (1962). "A revised medium for rapid growth and bioassays with tobacco tissue cultures".Physiol. Plant.15(3): 473–497.doi:10.1111/j.1399-3054.1962.tb08052.x.S2CID84645704.
- ^Gamborg, O.L; Miller, R.A.; Ojima, K. (1968). "Nutrient requirements of suspension cultures of soybean root cells".Exp. Cell Res.50(1): 151–158 [157].doi:10.1016/0014-4827(68)90403-5.PMID5650857.