Chlorophyll-binding protein AtSep2 overexpression causes leaf yellowing and enhances tolerance to high light stress in poplar

Abstract

Poplar is a tree species used in urban greening, and colored leaf poplar is in great demand because of its higher ornamental value and function. In this study, we generated a golden leaf 84 K poplar (Populus alba × Populus glandulosa) by overexpressing the AtSep2 (stress-enhanced protein) gene from Arabidopsis. AtSep2 belongs to the light-harvesting chlorophyll (Chl)-binding complex (LHC)-like family and contains a conserved Chl-binding motif. Subcellular localization analysis showed that AtSep2 was mainly localized in the chloroplasts of poplar leaves. AtSep2 overexpression caused the golden leaf phenotype in poplar by reducing total Chl content. Before and after high light stress, the relative reduction in total Chl content and maximum quantum yield of PSII photochemistry (Fv/Fm) in transgenic poplar leaves was lower than that in wild-type (WT) leaves. Transgenic poplar leaves accumulated less reactive oxygen species (ROS) and had a higher net photosynthetic rate (Pn) than WT leaves under high light stress. Overall, AtSep2 overexpression caused the golden leaf phenotype and enhanced the tolerance of poplar leaves to high light stress. The present study suggests that AtSep2 is ideal for the genetic improvement of the golden leaf phenotype in poplar and other ornamental plants.

Keywords

• stress-enhanced protein
• poplar
• golden leaf
• high light tolerance