Targeting carbon for crop yield and drought resilience

Abstract

Current methods of crop improvement are not keeping pace with projected increases in population growth. Breeding, focused around key traits of stem height and disease resistance, delivered the step‐change yield improvements of the green revolution of the 1960s. However, subsequently, yield increases through conventional breeding have been below the projected requirement of 2.4% per year required by 2050. Genetic modification (GM) mainly for herbicide tolerance and insect resistance has been transformational, akin to a second green revolution, although GM has yet to make major inroads into intrinsic yield processes themselves. Drought imposes the major restriction on crop yields globally but, as yet, has not benefited substantially from genetic improvement and still presents a major challenge to agriculture. Much still has to be learnt about the complex process of how drought limits yield and what should be targeted. Mechanisms of drought adaptation from the natural environment cannot be taken into crops without significant modification for the agricultural environment because mechanisms of drought tolerance are often in contrast with mechanisms of high productivity required in agriculture. However, through convergence of fundamental and translational science, it would appear that a mechanism of sucrose allocation in crops can be modified for both productivity and resilience to drought and other stresses. Recent publications show how this mechanism can be targeted by GM, natural variation and a new chemical approach. Here, with an emphasis on drought, we highlight how understanding fundamental science about how crops grow, develop and what limits their growth and yield can be combined with targeted genetic selection and pioneering chemical intervention technology for transformational yield improvements. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Water scarcity impacts on global food production

“…DroughtGard (DG), is an example of an hybrid trait that was developed to maximize crop yield potential under drought conditions. The DG hybrid gene, cspB (cold shock protein) helps in the production of proteins essential for plant growth and stabilizing RNA even when water is scarce (Griffiths and Paul, 2017). DG has shown to increase crop yield by 1.5-2% each year and as shown in the figure below ( Fig.…”

Dynamic changes in the starch-sugar interconversion within plant source and sink tissues promote a better abiotic stress response

“…High T6P relative to SnRK activates storage pathways such as starch biosynthesis, especially in the sink (Bledsoe et al, 2017;Griffiths et al, 2016a;Lawlor and Paul, 2014;Martinez-Barajas et al, 2011) and likely in a tissue-specific manner (Wurzinger et al, 2018). Conversely, reduced T6P signals 'starvation', activating SnRK1 for the mobilization of starch and other reserves to generate sucrose for transport to the cells that need it (Bledsoe et al, 2017;Griffiths and Paul, 2017;Yu et al, 2015). SnRK1 subunits can bind to starch granules and are associated with maltose, and could conceivably act as cytosolic sensors of released glucose (Avila-Castaneda et al, 2014).…”

“…More data is needed to strengthen the connectivity among these physiological and biochemical events (Griffiths and Paul, 2017;Griffiths et al, 2016a;Henry et al, 2015;Paul et al, 2017;Yu et al, 2015). Still, when all of the data are considered, it seems compelling that T6P/SnRK1 activity is a key regulator of assimilate distribution between sink and source to enhance survival under abiotic stress, and that starch metabolism, i.e.…”

Imperative role of trehalose metabolism and trehalose‐6‐phosphate signaling on salt stress responses in plants

“…Plant hexokinase (HXK) is involved in sugar sensing and signaling and is proposed to be a dual‐function enzyme with both catalytic and regulatory functions. T6P has a role in controlling sugar signaling through its interaction with hexokinase (Griffiths & Paul, 2017). No target of T6P has been found in plants, where hexokinases are insensitive to T6P (Eastmond & Graham, 2003).…”