Vast agricultural areas are affected by flooding, causing up to 80% yield reduction and resulting in multibillion dollar losses. Up to now, the focus of plant breeders was predominantly on detrimental effects of anoxia, while other (potentially equally important) traits were essentially neglected; one of these is soil elemental toxicity. Excess water triggers a progressive decrease in soil redox potential, thus increasing the concentration of Mn²⁺ that can be toxic to plants if above a specific threshold. This work aimed to quantify the relative contribution of Mn²⁺ toxicity to waterlogging stress tolerance, using barley as a case study. Twenty barley (Hordeum vulgare) genotypes contrasting in waterlogging stress tolerance were studied for their ability to cope with toxic (1 mM) amounts of Mn²⁺ in the root rhizosphere. Under Mn²⁺ toxicity, chlorophyll content of most waterlogging-tolerant genotypes (TX9425, Yerong, CPI-71284-48 and CM72) remained above 60% of the control value, whereas sensitive genotypes (Franklin and Naso Nijo) had 35% less chlorophyll than 35% of controls. Manganese concentration in leaves was not related to visual Mn²⁺ toxicity symptoms, suggesting that various Mn²⁺ tolerance mechanisms might operate in different tolerant genotypes, i.e. avoidance versus tissue tolerance. The overall significant (r = 0.60) correlation between tolerance to Mn²⁺ toxicity and waterlogging in barley suggests that plant breeding for tolerance to waterlogging traits may be advanced by targeting mechanisms conferring tolerance to Mn²⁺ toxicity, at least in this species.

Item Type:	Refereed Article
Keywords:	breeding, chlorophyll, Hordeum vulgare, Mn2+ toxicity, sequestration, tissue tolerance, waterlogging tolerance.
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Crop and pasture production
Research Field:	Crop and pasture improvement (incl. selection and breeding)
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Grains and seeds
Objective Field:	Barley
UTAS Author:	Huang, X (Mr Xin Huang)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
UTAS Author:	Shabala, L (Associate Professor Lana Shabala)
UTAS Author:	Zhou, M (Professor Meixue Zhou)
ID Code:	92941
Year Published:	2015
Funding Support:	Australian Research Council (LP120200516)
Web of Science® Times Cited:	22
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2014-07-02
Last Modified:	2017-11-02
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