Researchers from Würzburg in Germany have found out that Cereal crops are usually more tolerant to drought than other plants with the discovery tipped to go a long way into reinforcing efforts aimed at breeding crops that are resistant to drought. Cereals such as wheat, barley, and rice are important in feeding the global population.
According to the study, farmers produce 80 percent of all plant-based foods from grass crops. The ability of grass crops to adjust fast to dry conditions and sustain little amounts of water compared to other plants has been credited to their adaptability in harsh environments. However, in the face of an ever-expanding world population, the need to have technology that can enable other food crops to be tolerant to water scarcity has been emphasized.
This according to the researchers could be significant in the face of changing climatic conditions that more than likely entail more periods of hot and dry weather. Plant researchers led by Professor Rainer Hedrich from Würzburg University in Bavaria Germany looked into such possibilities by studying barley brewing to find out the reason why grasses are more stress tolerant hence “better crops” in dry environments than cereal crops.
Drought tolerance in plants
From their survey, the scientists found out that the difference between the two crops can be attributed to the availability of the SLAC1 protein of the guard cells. They discovered that only two amino acids which are protein building blocks are behind the grass plant’s drought tolerance nature. From this discovery, one of the scientists Rainer Hedrich sought to observe whether such a small difference could be harnessed to make tomatoes, potatoes or even rapeseed more tolerant to stress as well.
The researchers began by microscopically scrutinizing small pores called stomata on leafs responsible for facilitating the inhaling of carbon dioxide to enable photosynthesis to take place. Though they also serve as water outlets, pores in land plants have, with evolution adapted to actively opening and closing of their pores using special guard cells to prevent losing too much water through evaporation. As such, membrane proteins, for instance, SLAC1 play a significant role in the regulatory process by being the channels that guide ions into and out of the cells. Through a basic understanding of molecular activity during ion transportation through the plasma membrane of the guard cells, Hedrich believed that this is the key to improving drought tolerance ability as well as yields in crop plants.
The researchers also discovered that grasses stomata have a special feature in that two pairs of cells border the pores as opposed to other plants that only have a single cell pair. From this, the researchers were able to demonstrate that subsidiary cells can absorb and store both chloride and potassium from the guard cells when the stomata closes. When the pores open, they then pass the ions back to the guard cells. According to one of the researchers Dietmar Geiger, this ion shuttle service between the subsidiary and the guard cells enables the grass plant to regulate the stomata efficiently and quickly.
Measuring drought resistance
The second mechanism that enables grasses to be more tolerant in dry conditions was that when water is scarce, plants produce the stress hormone ABA or the abscisic acid. The guard cells then activate the SLAC1 ion channels hence initiating the closing of pores to protect the plant from withering immediately.
The researchers also found out that nitrate must be present in the brewing of barley which enables the plant to measure the shape of the photosynthesis process. According to the researchers, barley crop relies on two measuring systems in that it uses nitrate to assess the performance of the photosynthesis process and the ABA to register water availability. By combining the two, the researchers discovered that barley is well poised than other plants to negotiate between the extremes of dying from hunger or thirst when faced with water scarcity.
To get answers as to which mechanism is responsible for the differences in pores regulation at the molecular level, the researchers analyzed SLAC1 channels in a number of herbaceous plants and compared them to grasses. The procedure enabled the scientists to identify nitrate sensors in grasses.
In their next step, they hope to find out whether herbaceous agricultural crops do benefit from having a nitrate sensor. If this step can increase the crops stress levels, then Hedrich notes that they can consider breeding improved tomatoes, potatoes and rapeseed varieties.
Abiotic stress tolerance in cereals
The main advantage found in cereals that is not in other plants is their strong genetic makeup in abiotic stress tolerance. When cereal crops are exposed to environmental stresses, common responses are elicited by the plants to deal with these abiotic stresses. Cereal germplasm collections and landraces of the common cereals provide extensive natural variation that can be exploited in crop improvement programs. Moreover, physiology, breeding, and genetics of cereal crops provides a unique resource for genomics research which will aid in improving food security.