Genetic transformation of major cereal crops

Abstract

Of the more than 50,000 edible plant species in the world, at least 10,000 species are cereal grains. Three major cereal crops, rice (Oryza sativa), maize (Zea mays), and wheat (Triticum sp.), provide two-thirds of the world's food energy intake. Although crop yields have improved tremendously thanks to technological advances in the past 50 years, population increases and climate changes continue to threaten the sustainability of current crop productions. Whereas conventional and marker-assisted breeding programs continue to play a major role in crop improvement, genetic engineering has drawn an intense worldwide interest from the scientific community. In the past decade, genetic transformation technologies have revolutionized agricultural practices and millions of hectares of biotech crops have been cultured. Because of its unique ability to insert well-characterized gene sequences into the plant genome, genetic engineering can also provide effective tools to address fundamental biological questions. This technology is expected to continue to be an indispensable approach for both basic and applied research. Here, we overview briefly the development of the genetic transformation in the top seven cereals, namely maize, rice, wheat, barley (Hordeum vulgare), sorghum (Sorghum sp.), oat (Avena sativa), and millets. The advantages and disadvantages of the two major transformation methods, Agrobacterium tumefaciens-mediated and biolistic methods, are also discussed.

Combining ability and heterotic orientation of mid-altitude sub-humid tropical maize inbred lines for grain yield and related traits

“…Maize (Zea mays L.), together with wheat (Triticum aesivum L.) and rice (Oryza sativa L.) is one of the three most important cereal crops that feed two -third of the world population (Ji et al, 2013). In Sub -Saharan Africa (SSA), maize is a major staple cereal food crop with the significance comparable to rice in South East Asia and wheat in the Middle East.…”

In vitro transformation of pearl millet (Pennisetum glaucum (L). R. BR.): Selection of chlorsulfuron-resistant plants and long term expression of the gus gene under the control of the emu promoter

“…The biolistic method offers an effective alternative for the genetic transformation of cereal crops. Several successes, in transient expression of GUS and NPTII genes, have been indeed reported using this transformation method on Triticum eastivum (Jones, 2005;Tassy et al, 2014), Hordeum vulgare (Ji et al, 2013), Saccharum officinarum (Singh et al, 2013), Panicum virgatum (King et al, 2014) and Zea mays (Que et al, 2014;Qamar et al, 2015).…”

“…A variety of techniques such as polyethylene glycol (PEG) method, electroporation method, mild ultrasonication and biolistic have been proposed for genetic transformation of cereals. Some results have been obtained using the direct introduction of DNA into competent protoplasts by polyethylene glycol (PEG) induced uptake Bajaj, 2012;Ji et al, 2013), electroporation (Vasil, 2012;Jordan et al, 2013), followed by the growth of calli and in some cases, the regeneration of transformed plants (Shimamoto et al, 1989;Bajaj and Mohanty, 2005;Bahieldin et al, 2005;Danilova, 2007).…”

<b>Increased transient genetic transformation <i>in immature</i> embryos of Brazilian BR 451 maize co-cultivated with <i>Agrobacterium tumefaciens

“…While several maize genotypes have been effectively transformed (Ji, Xu, & Wang, 2013, Ombori et al, 2014Souza et al, 2017), Hi-II hybrid maize has been widely used for genetic transformation (Zhao et al, 2001;Frame et al, 2002;Frame, Main, Schick, & Wang, 2011;Lee & Zhang, 2016;Nahampun, Lopez-Arredondo, Xu, HerreraEstrella, & Wang, 2016) and is considered the model for maize plant transformation. However, the poor agronomic traits of the Hi-II hybrid (Ishida, Hiei, & Komari, 2007;Que et al, 2014) motivate the search for other maize genotypes that respond well to transformation.…”