BIG LEAF is a regulator of organ size and adventitious root formation in poplar

Document Type

Article

Publication Date

7-1-2017

Abstract

© 2017 Yordanov et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Here we report the discovery through activation tagging and subsequent characterization of the BIG LEAF (BL) gene from poplar. In poplar, BL regulates leaf size via positively affecting cell proliferation. Up and downregulation of the gene led to increased and decreased leaf size, respectively, and these phenotypes corresponded to increased and decreased cell numbers. BL function encompasses the early stages of leaf development as native BL expression was specific to the shoot apical meristem and leaf primordia and was absent from the later stages of leaf development and other organs. Consistently, BL downregulation reduced leaf size at the earliest stages of leaf development. Ectopic expression in mature leaves resulted in continued growth most probably via sustained cell proliferation and thus the increased leaf size. In contrast to the positive effect on leaf growth, ectopic BL expression in stems interfered with and significantly reduced stem thickening, suggesting that BL is a highly specific activator of growth. In addition, stem cuttings from BL overexpressing plants developed roots, whereas the wild type was difficult to root, demonstrating that BL is a positive regulator of adventitious rooting. Large transcriptomic changes in plants that over-expressed BL indicated that BL may have a broad integrative role, encompassing many genes linked to organ growth. We conclude that BL plays a fundamental role in control of leaf size and thus may be a useful tool for modifying plant biomass productivity and adventitious rooting.

Publication Title

PLoS ONE

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