AUTHOR=Kiranmai Kurnool , Lokanadha Rao Gunupuru , Pandurangaiah Merum , Nareshkumar Ambekar , Amaranatha Reddy Vennapusa , Lokesh Uppala , Venkatesh Boya , Anthony Johnson A. M. , Sudhakar Chinta 

TITLE=A Novel WRKY Transcription Factor, MuWRKY3 (Macrotyloma uniflorum Lam. Verdc.) Enhances Drought Stress Tolerance in Transgenic Groundnut (Arachis hypogaea L.) Plants

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00346

DOI=10.3389/fpls.2018.00346

ISSN=1664-462X

ABSTRACT=<p>Drought stress has adverse effects on growth, water relations, photosynthesis and yield of groundnut. WRKY transcription factors (TFs) are the plant-specific TFs which regulate several down-stream stress-responsive genes and play an essential role in plant biotic and abiotic stress responses. We found that <italic>WRKY3</italic> gene is highly up-regulated under drought stress conditions and therefore isolated a new <italic>WRKY3TF</italic> gene from a drought-adapted horsegram (<italic>Macrotyloma uniflorum</italic> Lam. Verdc.). Conserved domain studies revealed that protein encoded by this gene contains highly conserved regions of two WRKY domains and two C2H2 zinc-finger motifs. The fusion protein localization studies of transient <italic>MuWRKY</italic>3-YFP revealed its nuclear localization. Overexpression of <italic>MuWRKY3</italic> TF gene in groundnut (<italic>Arachis hypogaea</italic> L.) showed increased tolerance to drought stress compared to wild-type (WT) plants. <italic>MuWRKY3</italic> groundnut transgenics displayed lesser and delayed wilting symptoms than WT plants after 10-days of drought stress imposition. The transgenic groundnut plants expressing <italic>MuWRKY3</italic> showed less accumulation of malondialdehyde, hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), and superoxide anion (O<sub>2</sub><sup>∙-</sup>), accompanied by more free proline, total soluble sugar content, and activities of antioxidant enzymes than WT plants under drought stress. Moreover, a series of stress-related <italic>LEA, HSP, MIPS, APX, SOD</italic>, and <italic>CAT</italic> genes found up-regulated in the transgenic groundnut plants. The study demonstrates that nuclear-localized <italic>MuWRKY3</italic> TF regulates the expression of stress-responsive genes and the activity of ROS scavenging enzymes which results in improved drought tolerance in groundnut. We conclude that <italic>MuWRKY3</italic> may serve as a new putative candidate gene for the improvement of stress resistance in plants.</p>