Effects of auxin (indole-3-butyric acid) on growth characteristics, lignification, and expression profiles of genes involved in lignin biosynthesis in carrot taproot

Ahmed Khadr; Guang-Long Wang; Ya-Hui Wang; Rong-Rong Zhang; Xin-Rui Wang; Zhi-Sheng Xu; Yong-Sheng Tian; Ai-Sheng Xiong

doi:10.7717/peerj.10492

Effects of auxin (indole-3-butyric acid) on growth characteristics, lignification, and expression profiles of genes involved in lignin biosynthesis in carrot taproot

PeerJ. 2020 Dec 8:8:e10492. doi: 10.7717/peerj.10492. eCollection 2020.

Authors

Ahmed Khadr^#^{1

2}, Guang-Long Wang^#³, Ya-Hui Wang¹, Rong-Rong Zhang¹, Xin-Rui Wang¹, Zhi-Sheng Xu¹, Yong-Sheng Tian¹, Ai-Sheng Xiong¹

Affiliations

¹ State Key Laboratory of Crop Genetics and Germplasm Enhancement, Ministry of Agriculture and Rural Affairs Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture, Nanjing Agricultural University, Nanjing, China.
² Department of Horticulture, Faculty of Agriculture, Damanhour University, Damanhour, Egypt.
³ School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, China.

^# Contributed equally.

Abstract

Carrot is an important root vegetable crop abundant in bioactive compounds including carotenoids, vitamins, and dietary fibers. Carrot intake and its products are gradually growing owing to its high antioxidant activity. Auxins are a class of plant hormones that control many processes of plant growth and development. Yet, the effects of exogenous application of auxin on lignin biosynthesis and gene expression profiles of lignin-related genes in carrot taproot are still unclear. In order to investigate the effect of exogenous indole-3-butyric acid (IBA) on lignin-related gene profiles, lignin accumulation, anatomical structures and morphological characteristics in carrot taproots, carrots were treated with different concentrations of IBA (0, 50, 100, and 150 µM). The results showed that IBA application significantly improved the growth parameters of carrot. The 100 or 150 µM IBA treatment increased the number and area of xylem vessels, whereas transcript levels of lignin-related genes were restricted, resulting in a decline in lignin content in carrot taproots. The results indicate that taproot development and lignin accumulation may be influenced by the auxin levels within carrot plants.

Keywords: Auxin; Daucus carota L.; Gene expression; Growth; Indole-3-butyric acid; Lignification.

Grants and funding

This work was supported by the National Natural Science Foundation of China (No. 31872098), the Natural Science Foundation of Jiangsu Province (No. BK20170460), and the Open Fund of the State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University (No. ZW201905). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.