Development of transgenic crops based on photo‐biotechnology

Abstract

The phenotypes associated with plant photomorphogenesis such as the suppressed shade avoidance response and de-etiolation offer the potential for significant enhancement of crop yields. Of many light signal transducers and transcription factors involved in the photomorphogenic responses of plants, this review focuses on the transgenic overexpression of the photoreceptor genes at the uppermost stream of the signalling events, particularly phytochromes, crytochromes and phototropins as the transgenes for the genetic engineering of crops with improved harvest yields. In promoting the harvest yields of crops, the photoreceptors mediate the light regulation of photosynthetically important genes, and the improved yields often come with the tolerance to abiotic stresses such as drought, salinity and heavy metal ions. As a genetic engineering approach, the term photo-biotechnology has been coined to convey the idea that the greater the photosynthetic efficiency that crop plants can be engineered to possess, the stronger the resistance to biotic and abiotic stresses. Development of GM crops based on photoreceptor transgenes (mainly phytochromes, crytochromes and phototropins) is reviewed with the proposal of photo-biotechnology that the photoreceptors mediate the light regulation of photosynthetically important genes, and the improved yields often come with the added benefits of crops' tolerance to environmental stresses.

Transcriptional control of photosynthetic capacity: conservation and divergence from Arabidopsis to rice

“…By contrast, overexpression of the C-terminal domain of CRY1 promotes chloroplast development in dark-grown rice seedlings (Zhang et al, 2006). In addition, genetic engineering of photoreceptors in crop plants modifies the light regulation of several photosynthesis genes, resulting in improved production of photosynthates, as well as improved tolerance to abiotic stresses, such as drought, salinity and heavy metal ions (reviewed by Ganesan et al, 2017). Engineering of the photosynthesis gene regulatory network through altered light perception appears to have the potential to improve photosynthesis and, ultimately, yield.…”

Regulation of monocot and dicot plant development with constitutively active alleles of phytochrome B

“…Indeed, cross‐class heterologously expressed phyAs were significantly less labile than endogenous phyAs of host plants, indicating that heterologous Pfr‐phyAs were more resistant to the host protein degradation machinery (Boylan & Quail, 1989, 1991; Cherry et al, 1991; Garg et al, 2006; Kong et al, 2004; Stockhaus et al, 1992). This unique characteristic of phyA overexpression has been exploited for engineering crops with better agronomic traits (Ganesan et al, 2017; Gururani, Ganesan, & Song, 2015). It remains interesting to compare the functional interface of heterologous phyAs with the nuclear trafficking machinery in the same‐class and cross‐class transgenic lines.…”

“…Three major PHY lineages are present in flowering plant genomes, PHYA , PHYB, and PHYC , with gene expansion and/or loss having occurred in some eudicot species (Alba, Kelmenson, Cordonnier‐Pratt, & Pratt, 2000; Clack, Mathews, & Sharrock, 1994; Karve et al, 2012; Mathews, 2010; Sheehan, Farmer, & Brutnell, 2004; Takano et al, 2005). Transgenic phytochrome‐based crop improvement efforts have predominantly exploited PHYA overexpression because, unlike phyB, phyA remains active in FR‐enriched shade light (Ganesan, Lee, Kim, & Song, 2017). SARs that include rapid internode elongation, enhanced apical dominance, reduced photosynthesis efficiency, premature flowering and increased susceptibility to pathogen infection, reduce crop yields as plant density is increased (Carriedo, Maloof, & Brady, 2016).…”

Field studies reveal functions of chemical mediators in plant interactions

“…Such a perspective might also be beneficial when tackling urgent practical problems, such as sustainability in modern agro-ecosystems, which, we would argue, have too long been approached based on the reductionist understanding of the potted plant. In agricultural fields, where plants are grown at high density (a more common natural scenario), manipulation of the shade avoidance syndrome (SAS) can be a powerful tool for forcing ground cover and bushy crops to invest in yield and foliage rather than overtopping, 134 but a plastic response can increase yield in apically dominant crops like sunflowers by promoting efficient access to light in dense stands. 81 In the realm of crop protection, the use of repellent and attractive stimuli in the so-called ''push-pull'' strategy depends on understanding dynamics in populations and communities, and knowledge of the relevant traits in wild plants might facilitate the employment of this strategy in a way that is more robust to pest adaptation.…”