Frontiers in Plant Science (Jan 2018)

Auxin-to-Gibberellin Ratio as a Signal for Light Intensity and Quality in Regulating Soybean Growth and Matter Partitioning

  • Feng Yang,
  • Feng Yang,
  • Feng Yang,
  • Yuanfang Fan,
  • Yuanfang Fan,
  • Yuanfang Fan,
  • Xiaoling Wu,
  • Xiaoling Wu,
  • Xiaoling Wu,
  • Yajiao Cheng,
  • Yajiao Cheng,
  • Yajiao Cheng,
  • Qinlin Liu,
  • Qinlin Liu,
  • Qinlin Liu,
  • Lingyang Feng,
  • Lingyang Feng,
  • Lingyang Feng,
  • Junxu Chen,
  • Junxu Chen,
  • Junxu Chen,
  • Zhonglin Wang,
  • Zhonglin Wang,
  • Zhonglin Wang,
  • Xiaochun Wang,
  • Xiaochun Wang,
  • Xiaochun Wang,
  • Taiwen Yong,
  • Taiwen Yong,
  • Taiwen Yong,
  • Weiguo Liu,
  • Weiguo Liu,
  • Weiguo Liu,
  • Jiang Liu,
  • Jiang Liu,
  • Jiang Liu,
  • Junbo Du,
  • Junbo Du,
  • Junbo Du,
  • Kai Shu,
  • Kai Shu,
  • Kai Shu,
  • Wenyu Yang,
  • Wenyu Yang,
  • Wenyu Yang

DOI
https://doi.org/10.3389/fpls.2018.00056
Journal volume & issue
Vol. 9

Abstract

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The intensity and quality (red to far-red (R/Fr) ratio) of light directly affect growth of plant under shading. Gibberellins (GAs) and auxin [indole-3-acetic acid (IAA)] play important roles in mediating the shading adaptive responses of plants. Thus, the intensity and quality of the uncoupling light from shading were assessed to identify the influence of each component on the morphology and matter distribution of the leaf, stem, and petiole. This assessment was based on the changes in endogenous Gibberellin 1 (GA1) and IAA levels. Soybean plants were grown in a growth chamber with four treatments [normal (N), N+Fr, low (L), and L+Fr light]. Results revealed that the reductions in photosynthetically active radiation (PAR) and R/Fr ratio equally increased height and stem mass fractions (SMFs) of the soybean seedling. The light intensity significantly influenced the dry mass per unit area and mass fraction of soybean leaves, whereas the light quality regulated the petiole elongation and mass fraction. Low R/Fr ratio (high Fr light) increased the soybean biomass by improving the photosynthetic assimilation rate and quantum yield of photosystem II. In addition, the IAA and GA1 levels in the leaf, stem, and petiole did not reflect the growth response trends of each tissue toward light intensity and quality; however, trends of the IAA-to-GA1 content ratios were similar to those of the growth and matter allocation of each soybean tissue under different light environments. Therefore, the response of growth and matter allocation of soybean to light intensity and quality may be regulated by the IAA-to-GA1 content ratio in the tissues of the soybean plant.

Keywords