Overexpression of hemoglobin gene in barley increase drought tolerance through ethylene pathway inhibition
Drought is one of the major constraint of crops worldwide. Breeding for drought resistance is a complex task for which a sound knowledge of plant responses to drought at all level, from crop physiology to molecular changes is needed. Nitric oxide (NO) is a key messenger in plant stress responses but its exact role during drought remains unclear. Thus, we investigated the role of NO during drought by employing transgenic barley plants (UHb) overexpressing the barley non-symbiotic hemoglobin gene HvHb1 (Hb) that oxidizes NO to NO3-. Overexpression of the hemoglobin gene in UHb plants was confirmed both under well-watered and drought conditions and this was related to lower level of NO released, measured in vivo, in intact plants. Interestingly, both UHb genotypes assessed were significantly more tolerant to drought stress than wild types (WT) when monitored over 18 days’ time courses that reduced relative water content progressively up to 20%. Overexpression of Hb gene was associated with reduction in the expression of several genes of ethylene pathway, i.e. 1-aminocyclopropane-1-carboxylate [ACC] synthase (ACS), which catalyzes the first committed step in ethylene biosynthesis and 1-aminocyclopropane-1- carboxylate oxidase (ACO) that oxidizes ACC to ethylene. Downregulation of ethylene related genes observed in UHb genotypes was associated to reduction of ethylene, measured in vivo in intact plants, and with the improvement of drought related parameters in UHb plants. In addition, the higher level of ethylene observed in WT plants was associated with early senescence and reduction of chlorophyll content of the leaves under drought. Thus, we conclude that ethylene pathway inhibition mediated by NO regulation contribute to drought tolerance in barley.
| Main Authors: | , , , , , , , |
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| Format: | comunicación de congreso biblioteca |
| Language: | English |
| Published: |
2017
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| Online Access: | http://hdl.handle.net/10261/167692 |
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