Enhanced Gene Expression Rather than Natural Polymorphism in Coding Sequence of the OsbZIP23 Determines Drought Tolerance and Yield Improvement in Rice Genotypes
Authors: Avishek Dey
Srimonta Gayen
Soumitra K Sen
Milan Kumar Samanta
Mrinal K Maiti
Journal: PLoS ONE (2016)
Discipline: Multidisciplinary
Keywords: Drought tolerance; OsbZIP23 gene; Allelic polymorphism; Abiotic stress adaptation; ABA signaling pathway
Affiliations: Adv. Lab. for Plant Genetic Engineering, Advanced Technology Development Center, Indian Institute of Technology Kharagpur, Kharagpur 721302, India., Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.

Abstract:  Drought is one of the major limiting factors for productivity of crops including rice (Oryza sativa L.). Understanding the role of allelic variations of key regulatory genes involved in stress-tolerance is essential for developing an effective strategy to combat drought. The bZIP transcription factors play a crucial role in abiotic-stress adaptation in plants via abscisic acid (ABA) signaling pathway. The present study aimed to search for allelic polymorphism in the OsbZIP23 gene across selected drought-tolerant and drought-sensitive rice genotypes, and to characterize the new allele through overexpression (OE) and gene-silencing (RNAi). Analyses of the coding DNA sequence (CDS) of the cloned OsbZIP23 gene revealed single nucleotide polymorphism at four places and a 15-nucleotide deletion at one place. The single-copy OsbZIP23 gene is expressed at relatively higher level in leaf tissues of drought-tolerant genotypes, and its abundance is more in reproductive stage. Cloning and sequence analyses of the OsbZIP23-promoter from drought-tolerant O. rufipogon and drought-sensitive IR20 cultivar showed variation in the number of stress-responsive cis-elements and a 35-nucleotide deletion at 5'-UTR in IR20. Analysis of the GFP reporter gene function revealed that the promoter activity of O. rufipogon is comparatively higher than that of IR20. The overexpression of any of the two polymorphic forms (1083 bp and 1068 bp CDS) of OsbZIP23 improved drought tolerance and yield-related traits significantly by retaining higher content of cellular water, soluble sugar and proline; and exhibited decrease in membrane lipid peroxidation in comparison to RNAi lines and non-transgenic plants. The OE lines showed higher expression of target genes-OsRab16B, OsRab21 and OsLEA3-1 and increased ABA sensitivity; indicating that OsbZIP23 is a positive transcriptional-regulator of the ABA-signaling pathway. Taken together, the present study concludes that the enhanced gene expression rather than natural polymorphism in coding sequence of OsbZIP23 is accountable for improved drought tolerance and yield performance in rice genotypes. 

Retracted: No

PubPeer comments:
null, 
null, 
null, 
null, 
 An email from Kaitlyn Keller, Publications Manager, PLOS ONE, indicates that this paper is set to be corrected: u00e2u0080u009cIn light of these concerns, and following an institutional investigation, we have decided to proceed with the retraction of pone.0111253 and pone.0094472. Additionally, we will be publishing a correction on the third article, pone.0150763.u00e2u0080u009d , 
null, 
null, 
null, 
 October 2017 correction: https: journals.plos.org plosone article?id=10.1371 journal.pone.0187172  During the preparation of this article for publication, an error was introduced into Fig 6A. The left-most column in this figure should be labeled NT and the following three columns should be labeled OER#5, OER#7 and OEN#9 in that order. The corrected figure is included here.  In response to concerns raised by readers, the authors would like to further clarify that they duplicated NT panels in Fig 9A, 9B, 9D and 9E. The panels were duplicated to represent the observed phenotype of NT plants, which was the same in all three replicate plates examined in this study and was used to compare separately with the OE and RNAi lines in the respective panels. Three of the dishes in Fig 9B reproduce dishes in Fig 9A, although they were rotated in error during the preparation of the figure. The authors apologize that this duplication was not clearly described in the figure legend. The authors have provided a corrected Fig 9 with identical NT rows in Fig 9A and 9B. Here is the photo from Comment #1 (not mine) showing Figure 9A and 9B, since the Imgur photo does not show correctly : ![file] And here is a comparison of the original Figures 9D and E: ![file] ,