Improved waterlogging tolerance of barley (Hordeum vulgare) by pretreatment with ethephon

Abstract

Root growth into hypoxic or anoxic waterlogged soil relies on internal aeration in plants. The plant hormone ethylene helps adapt to waterlogging by inducing the formation of aerenchyma, which provides a low-resistance pathway for the transport of oxygen from the shoot to the root apex. Waterlogging-susceptible crops including barley start to form aerenchyma after suffering waterlogging stress. But waterlogging can be fatal if aerenchyma formation is not fast enough. Here, we investigated whether pre-treating barley with ethephon, an ethylene-releasing agrochemical, could improve its tolerance to mimicked waterlogging conditions (using stagnant deoxygenated agar nutrient solution). In barley growing in aerated nutrient solution, ethephon treatment enhanced aerenchyma formation at the root tips and induced the development of shorter and shallower roots. Pre-treating barley leaves also delayed waterlogging-caused whiting and increased the percentages of viable root-tips under waterlogging conditions. However, the pretreatment did not noticeably increase fresh weight or shoot length. Further studies are needed to optimize ethephon treatment conditions to improve barley production under waterlogged conditions.

Opportunities for Improving Waterlogging Tolerance in Cereal Crops—Physiological Traits and Genetic Mechanisms

“…Maize roots were found to respond to environmental stress by increasing ACC synthase activity and ethylene biosynthesis [ 82 ]. Pre-treatment with ethephon, an ethylene-releasing agrochemical improved aerenchyma formation at root tips and delayed waterlogging-caused wilting in barley [ 83 ].…”

Genome-Wide Analysis of Gene Expression Provides New Insights into Waterlogging Responses in Barley (Hordeum vulgare L.)

“…In barley, like in other waterlogging-susceptible crops, aerenchyma is formed after waterlogging stress. The faster it is formed the higher the chances of survival are [23]. To overcome ROS injury, plants utilize ROS scavengers, such as glutathione S-transferase (GST), peroxidase (POD), and superoxide dismutase (SOD) [24,25].…”

Root system characteristics under different water regimes in three cereal species

“…Roots were collected using a pin-board, following the method of Kano-Nakata et al (2012). Prior to the taking of digitized photographs of the whole root system, root samples were sandwiched at the soil surface, has a higher waterlogging tolerance than the deeper root systems of wheat (Oyanagi et al 2004, Haque et al 2012) and barley (Shiono et al 2019). Thus, plants change RSA in response to soil water conditions and understanding root characteristics is necessary for improving plant adaptations to water stress.…”

“…2). Plants distributed its roots to the deep soil layer under drought and had more roots in shallow soil in WL soils, possibly as an adaptive mechanism to facilitate water and nutrient uptake under drought (Tsuji et al 2005;Uga et al 2013;Fang et al 2017) and also oxygen supply with excess water (Oyanagi et al 2004, Haque et al 2012, Shiono et al 2019. Such vertical distributions of root traits may be associated with root anatomical changes along root axis (Kadam et al 2015).…”