Highly interactive nature of flower‐specific enhancers and promoters, and its potential impact on tissue‐specific expression and engineering of multiple genes or agronomic traits. Issue 7 (4th June 2014)

• Record Type: Journal Article
• Authors: Wen, Zhifeng; Yang, Yazhou; Zhang, Jinjin; Wang, Xiping; Singer, Stacy; Liu, Zhongchi; Yang, Yingjun; Yan, Guohua; Liu, Zongrang
• Is Part Of: Plant biotechnology journal. Volume 12:Issue 7(2014:Sep.)
• Page Start: 951
• Page End: 962
• Publication Date: 2014-06-04
• Subjects: Plant biotechnology -- Periodicals; Plant genetic engineering -- Periodicals; 630.272
• DOI: 10.1111/pbi.12203
• Languages: English
• ISSNs: 1467-7644

Abstract

<abstract abstract-type="main" id="pbi12203-abs-0001"> <title>Summary</title> <p>Molecular stacking enables multiple traits to be effectively engineered in crops using a single vector. However, the co‐existence of distinct plant promoters in the same transgenic unit might, like their mammalian counterparts, interfere with one another. In this study, we devised a novel approach to investigate enhancer–promoter and promoter–promoter interactions in transgenic plants and demonstrated that three of four flower‐specific enhancer/promoters were capable of distantly activating a pollen‐ and stigma‐specific <italic>Pps</italic> promoter (fused to the cytotoxic <italic>DT‐A</italic> gene) in other tissues, as revealed by novel tissue ablation phenotypes in transgenic plants. The <italic>NtAGI1</italic> enhancer exclusively activated stamen‐ and carpel‐specific <italic>DT‐A</italic> expression, thus resulting in tissue ablation in an orientation‐independent manner; this activation was completely abolished by the insertion of an enhancer‐blocking insulator (<italic>EXOB</italic>) between the <italic>NtAGI1</italic> enhancer and <italic>Pps</italic> promoter. Similarly, <italic>AGL8</italic> and <italic>AP1Lb1</italic>, but not <italic>AP1La</italic>, promoters also activated distinct tissue‐specific <italic>DT‐A</italic> expression and ablation, with the former causing global growth retardation and the latter ablating apical inflorescences. While the tissue specificity of the enhancer/promoters generally defined their activation specificities, the strength of their activity in particular tissues or developmental stages appeared to determine whether activation actually occurred. Our findings provide the first evidence that plant‐derived enhancer/promoters can distantly interact/interfere with one another, which could pose potential problems for the tissue‐specific engineering of multiple traits using a single‐vector stacking approach. Therefore, our work highlights the importance of adopting enhancer‐blocking insulators in transformation vectors to minimize promoter–promoter interactions. The practical and fundamental significance of these findings will be discussed.</p> </abstract>