TITLE:
Effects of 17β-Estradiol on Growth, Primary Metabolism, Phenylpropanoid-Flavonoid Pathways and Pathogen Resistance in Arabidopsis thaliana
AUTHORS:
Pallavi Upadhyay, Camelia Maier
KEYWORDS:
Plant Ecology, Plant Physiology, Plant Host-Pathogen Interactions
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.13,
September
8,
2016
ABSTRACT: Mammalian sex hormones are spread in the environment
from natural and anthropogenic sources. In the present study, the effect of
estradiol on Arabidopsis thaliana growth primary metabolism, phenylpropanoid and flavonoid pathways and pathogen
resistance were investigated. Treatments of Arabidopsis plants with 10 and 100 nM 17β-estradiol
resulted in enhanced root growth and shoot biomass. In addition, treated plants
had an increased rate of photosynthesis with a concomitant increase in carbohydrate
and protein accumulation. Plants exposed to higher concentrations of 17β-estradiol (10 μM) had significantly
lower root growth, biomass, photosynthesis rate, primary metabolite and
phenylpropanoid and flavonoid contents indicating a toxic effect of estradiol.
Treatments with increasing estradiol concentrations (10 nM, 100 nM and 10 μM)
resulted in the downregulation of phenylpropanoid-flavonoid pathway genes (PAL1, PAL4, CHI and ANS) and subsequent decreased
accumulation of phenolics, flavonoids and anthocyanins. Estradiol-treated
plants were inoculated with Pseudomonas
syringae pv. Tomato DC3000 and basal resistance was determined. Estradiol
treatments rendered plants susceptible to the pathogen, thus compromising the
plant defense mechanisms. These results indicate that at low concentrations,
estradiol functions as a biostimulant of growth, yield and primary metabolism
of Arabidopsis. However, estradiol
functions as a potential transcriptional regulator of the phenylpropanoid
pathway genes in Arabidopsis, having
a negative effect on the phenylpropanoid and flavonoid biosynthetic pathways.