Physiological mechanisms underlying OsNAC5-dependent tolerance of rice plants to abiotic stress

Abstract

To understand the functions of transcription factor OsNAC5 in response to abiotic stress, we generated transgenic rice plants with knockdown OsNAC5 by RNA-interfered (RNAi) and overexpressing OsNAC5, and investigated the effects of cold, drought and salt stress on wild-type (WT), RNAi and overexpression rice lines. Our results demonstrated that RNAi lines became less tolerant to these stresses than WT plants, while overexpression of OsNAC5 in Arabidopsis and rice enhanced tolerance to these stresses. The mechanisms underlying the changes in tolerance of the transgenic rice plants to abiotic stresses were explored by measuring free proline (Pro) and soluble sugar contents in WT and transgenic plants. Accumulation of Pro and soluble sugars was positively correlated with OsNAC5 expression levels. The less accumulation of Pro in RNAi lines may be accounted for by inhibition of Pro synthesis and transport at transcriptional levels. In addition, knockdown and overexpression of OsNAC5 enhanced and reduced accumulation of malondialdehyde and H(2)O(2), suggesting that knockdown of OsNAC5 renders RNAi plants more susceptible to oxidative damage. The RNAi lines displayed higher Na(+)/K(+) ratio due to greater accumulation of Na(+) ions than WT under salt stress conditions, and expression of genes encoding tonoplast Na(+)/H(+) antiporter was lower in RNAi lines than in WT under both control and salt-stressed conditions. Seed germination of RNAi and overexpression plants was more and less inhibited by salt and mannitol than that of WT, respectively. Seed germination of overexpression and RNAi plants was more and less sensitive than that of WT to ABA. These findings highlight the important role of OsNAC5 played in the tolerance of rice plants to abiotic stress by regulating downstream targets associated with accumulation of compatible solutes, Na(+) ions, H(2)O(2) and malondialdehyde.

Tackling Drought Stress: RECEPTOR-LIKE KINASES Present New Approaches

“…An increase in stress tolerance is often aimed for by rather general approaches, namely, ectopic overexpression or knockdown of a particular key component of stress signaling pathways (Nelson et al, 2007;Xiao et al, 2007;Castiglioni et al, 2008;Jung et al, 2008;Li et al, 2011;Song et al, 2011;Yan et al, 2011). Ectopic expression of components involved in abiotic stress responses has led to improved stress tolerance, but also reduced plant growth (Flowers, 2004;Bartels and Sunkar, 2005;Umezawa et al, 2006).…”

Overexpression of BrTSR53 Gene Improves Tolerance of Rice Plant to Salt Stress

“…NAC proteins are involved in the regulation of a number of plant growth processes, such as embryo growth, lateral root formation and growth, flower growth, leaf senescence, and secondary wall thickenings (Hu et al 2008, Zheng et al 2009and Song et al 2011. Over-expressing NAC transcription factor gene can enhance the tolerance of rice to salt stress compared to the wild-type in rice (Hu et al 2008).…”

Role of Reactive Oxygen Species and Contribution of New Players in Defense Mechanism under Drought Stress in Rice

“…Overexpression of OsSRO1c leads to enhanced drought and oxidative stress tolerance (You et al, 2013). Similarly, overexpression of OsNAC5 (Song et al, 2011) andONAC095 transcription factor improves drought and oxidative stress tolerance in rice . In plants, drought stress induces ROS generation, which in turn triggers the expression of several ROS scavenging gene families.…”