Modulating Rice Stress Tolerance by Transcription Factors

Abstract

Plants are non-mobile organisms and have to adapt to environmental stresses mostly by modulating their growth and development in addition to physiological and biochemical changes. Transcription factors (TFs) regulate genome expression in response to environmental and physiological signals, and some of them switch on plant adaptive developmental and physiological pathways. One TF is encoded by a single gene but regulates the expression of several other genes leading to the activation of complex adaptive mechanisms and hence represents major molecular targets to genetically improve the tolerance of crop plants against different stresses. In this review an updated account of the discovery of TFs involved in biotic and abiotic stress tolerance in the model monocotyledonous plant, rice (Oryza sativa L.) is presented. We illustrate how the elucidation of the function of these TFs can be used to set up genetic engineering strategies and to rationalize molecular breeding using molecular assisted selection towards enhancement of rice tolerance to various stresses. Attempts have also been made to provide information on the molecular mechanisms involved in stress resistance or tolerance processes. We discuss how the comparison of the action of TFs isolated from the dicotyledonous model plant Arabidopsis thaliana in rice and vice versa can contribute to determine whether common or divergent mechanisms underlie stress tolerance in the two plant species. Lastly, we discuss the necessity to discover TFs controlling specifically the root adaptive development which constitutes a major way for the plant to escape to several stresses such as water deficit or mineral nutrient deficiency.

Functional characterization of four APETALA2-family genes (RAP2.6, RAP2.6L, DREB19 and DREB26) in Arabidopsis

“…Since the completion of the Arabidopsis genome project and subsequent ongoing efforts in genomic research, many genes have been functionally characterized for stress tolerance. TFs represent most important molecular targets in genetic engineering of crop plants for stress tolerance (Nakashima and Yamaguchi-Shinozaki 2006;Khong et al 2008). This is due to the fact that a single TF can regulate the expression of numerous genes including its own gene and activates the adaptation process of organism to changed environment (Khong et al 2008).…”

“…TFs represent most important molecular targets in genetic engineering of crop plants for stress tolerance (Nakashima and Yamaguchi-Shinozaki 2006;Khong et al 2008). This is due to the fact that a single TF can regulate the expression of numerous genes including its own gene and activates the adaptation process of organism to changed environment (Khong et al 2008). Some examples of application of TF in stress tolerance include, AtMYB44 and GhDREB which conferred enhanced abiotic stress tolerance in Arabidopsis and wheat when overexpressed (Jung et al 2008;Gao et al 2009).…”

“…Areas under drought and salinity are increasing worldwide (Burke et al 2006) and, therefore, it is important to develop crops that can perform better when subjected to such environmental stresses. To date, many genes have been evaluated for stress tolerance and it has been shown that transcription factors (TFs) are highly effective in engineering stress tolerant plants (Sakuma et al 2006a, b;Bhatnagar-Mathur et al 2007;Khong et al 2008). TFs are DNA-binding proteins and more than 1500 TF genes are present in Arabidopsis thaliana which constitute over 5% of its genome (Riechmann et al 2000).…”

Association Mapping of Yield and Yield-related Traits Under Reproductive Stage Drought Stress in Rice (Oryza sativa L.)

“…Several TFs such as ARF, MYB, ZIP, NAC, NAM and MADS-box genes were involved in changes in root architecture and they help in tolerating drought stress (Okushima et al 2007; Xie et al 2000; Zhang and Forde, 1998). OsNAC1 has been reported to increase the number of lateral roots under drought stress, while OsNAC10 resulted in thicker roots (Khong et al 2008; Jeong, 2010). Since grain yield under drought is the most economic component under drought, floral meristic tissue activities, floral organ development, control of flowering time and pollen function play an important role in spikelet development and filling of spikelets to produce grains under drought stress (Hepworth et al 2006; Imaizumi et al 2003; Sonneveld et al 2005).…”

Naturally Existing Levels of Osmyb4 Gene Expression in Rice Cultivars Correlate with their Reaction to Fungal and Bacterial Pathogens

“…TF is encoded by a single gene but regulates the expression of several other genes leading to the activation of complex adaptive mechanisms and hence represents major molecular targets to genetically improve the tolerance of crop plants against different stresses (Khong et al. ). This review has illustrated how the elucidation of the function of these TFs can be used to set up genetic engineering strategies and to rationalize molecular breeding using molecular‐assisted selection towards enhancement of rice tolerance to various stresses.…”