Last week, it was announced that researchers from the John Innes Centre, UK and the University of Jordan have developed a variety of barley that is four times more drought-tolerant than other barley varieties. Why do we need drought-tolerant crops, and what is so significant about this barley?
All plants need water to grow. Consequently, agriculture is highly dependent on water and accounts for 70% of global water consumption. This is a massive amount of water. To put it another way, it takes around 2000-3000 litres of water to produce the food that one person typically eats in a single day! In many regions, not enough rain falls to provide sufficient water to crops and the fields have to be irrigated with water taken from rivers and underground sources.
This huge input of water into agriculture is not sustainable. Since 1970, the percentage of Earth’s surface affected by drought has doubled, and in future, the amount of fresh water available for use in agriculture is likely to continue to decrease. Water availability made it onto the shortlist for the Longitude Prize 2014, as one of the greatest issues of our time alongside food security, antibiotics, carbon-zero flight, paralysis and dementia. Kofi Annan (United Nations Secretary General 1997-2006) likened the impending water crisis to the need for increased food production that drove the Green Revolution of the 20th Century:
We need a Blue Revolution in agriculture that focuses on increasing productivity per unit of water – more crop per drop. (Kofi Annan 2008)
One way to help reduce the amount of water required to grow crops is to develop drought-tolerant varieties. The barley developed by John Innes Centre and University of Jordan scientists is a genetically-modified variety that has had an extra copy of an existing barley gene (HvSNAC1) inserted into it. HvSNAC1 promotes the closure of pores (stomata) on the surface of barley leaves to reduce water loss when water is scarce. Barley plants with an extra copy of the HvSNAC1 gene closed their stomata more readily under drought conditions, and the plants grew much better than normal barley under these conditions.
Stomata need to open to enable gaseous exchange in and out of the leaf. Therefore, you might expect a “trade off” between drought-tolerance and gaseous exchange, with the drought-tolerant barley plants performing less well in water-abundant conditions. However, because HvSNAC1 is only activated when water is scarce, the drought-tolerant barley grew just as well as normal barley when water was abundant.
The results are promising, but the researchers are the first to admit that it will be a while before drought-tolerant barley is grown commercially. The barley used in this work (Golden Promise) is popular amongst scientists as a research tool but is not widely grown for food production (except for whisky production in Scotland). The drought-tolerance trait would need to be transferred to varieties of barley that are more commonly used for food production. The research also opens the door for the development of other drought-tolerant crops because genes highly similar to HvSNAC1 are found in other crop species.
This post was inspired by a conversation I had with Dr Wendy Harwood (John Innes Centre), one of the scientists leading this research. I’m grateful for the facts she provided (and the Kofi Annan quote).
1) Abdallat et al (2013) Overexpression of the transcription factor HvSNAC1 improves drought tolerance in barley (Hordeum vulgare L.). Journal of Molecular Breeding.
2) John Innes Centre News. https://www.jic.ac.uk/news/2014/06/drought-tolerant-crops/ (retrieved 01/07/14)