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Characterization of rice homeobox genes, OsHOX22 and OsHOX24, and over-expression of OsHOX24 in transgenic Arabidopsis suggest their role in abiotic stress response

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Title Characterization of rice homeobox genes, OsHOX22 and OsHOX24, and over-expression of OsHOX24 in transgenic Arabidopsis suggest their role in abiotic stress response
 
Creator Bhattacharjee, Annapurna
Khurana, Jitendra P.
Jain, Mukesh
 
Subject rice
abiotic stress
homeobox transcription factors
gene expression
DNA binding
protein–protein interaction
 
Description Accepted date: 25 April 2016
Homeobox transcription factors are well known regulators of plant growth and development. In this study, we carried out functional analysis of two candidate stress-responsive HD-ZIP I class homeobox genes from rice, OsHOX22, and OsHOX24. These genes were highly up-regulated under various abiotic stress conditions at different stages of rice development, including seedling, mature and reproductive stages. The transcript levels of these genes were enhanced significantly in the presence of plant hormones, including abscisic acid (ABA), auxin, salicylic acid, and gibberellic acid. The recombinant full-length and truncated homeobox proteins were found to be localized in the nucleus. Electrophoretic mobility shift assay established the binding of these homeobox proteins with specific DNA sequences, AH1 (CAAT(A/T)ATTG) and AH2 (CAAT(C/G)ATTG). Transactivation assays in yeast revealed the transcriptional activation potential of full-length OsHOX22 and OsHOX24 proteins. Homo- and hetero-dimerization capabilities of these proteins have also been demonstrated. Further, we identified putative novel interacting proteins of OsHOX22 and OsHOX24 via yeast-two hybrid analysis. Over-expression of OsHOX24 imparted higher sensitivity to stress hormone, ABA, and abiotic stresses in the transgenic Arabidopsis plants as revealed by various physiological and phenotypic assays. Microarray analysis revealed differential expression of several stress-responsive genes in transgenic lines as compared to wild-type. Many of these genes were found to be involved in transcriptional regulation and various metabolic pathways. Altogether, our results suggest the possible role of OsHOX22/OsHOX24 homeobox proteins as negative regulators in abiotic stress responses.
AB acknowledges the award of research fellowship from the Council of Scientific and Industrial Research, New Delhi. MJ acknowledges the financial support of the Department of Science and Technology (F. No. SR/SO/PS/07/2011 from 2012 to 2015), Government of India, New Delhi, and core grant from NIPGR. JPK thanks Indian Council of Agricultural Research, New Delhi, for financial support (F. No. NFBSFARA/Phen-2015/2010-11). We are thankful to Dr. R. Garg for help with EMSA experiments.
 
Date 2016-05-26T11:10:03Z
2016-05-26T11:10:03Z
2016
 
Type Article
 
Identifier Front. Plant Sc., 7: 627
1664-462X
http://172.16.0.77:8080/jspui/handle/123456789/653
http://journal.frontiersin.org/article/10.3389/fpls.2016.00627/full
dx.doi.org/10.3389/fpls.2016.00627
 
Language en_US
 
Publisher Frontiers Media S.A.