title: Exogenous gibberellin altered morphology, anatomic and transcriptional regulatory networks of hormones in carrot root and shoot.
abstract: BACKGROUND
  Gibberellins stimulate cell elongation and expansion during plant growth and development. Carrot is a root plant with great value and undergoes obvious alteration in organ size over the period of plant growth. However, the roles of gibberellins in carrot remain unclear.
  
  
  RESULTS
  To investigate the effects of gibberelliins on the growth of carrot, we treated carrot plants with gibberellic acid 3 (GA3) or paclobutrazol (a gibberellin inhibitor). The results found that GA3 dramatically reduced the root growth but stimulated the shoot growth of carrot. It also significantly promoted xylem development in the tuberous root of carrot. In addition, transcript levels of genes related to gibberellins, auxin, cytokinins, abscisic acid and brassinolides were altered in response to increased or reduced gibberellins.
  
  
  CONCLUSIONS
  The inhibited tuberous root growth but enhanced shoot growth in plants treated with GA3 can be principally attributed to the changes in the xylem development of carrot roots. Negative feedback regulation mechanism of gibberellin biosynthesis also occurred in response to altered gibberellin accumulation. Gibberellins may interact with other hormones to regulate carrot plant growth through crosstalk mechanisms. This study provided novel insights into the functions of gibberellins in the growth and development of carrot.
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China. 2013204025@njau.edu.cn.
authors.forename: Guang-Long
authors.initials: GL
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China. 2014104080@njau.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Que
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China. xuzhisheng@njau.edu.cn.
authors.forename: Zhi-Sheng
authors.initials: ZS
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China. wangf@njau.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China. xiongaisheng@njau.edu.cn.
authors.forename: Ai-Sheng
authors.initials: AS
authors.lastname: Xiong
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D018552:Daucus carota / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D005875:Gibberellins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D000040:Abscisic Acid; C007842:gibberellic acid