Abstract
BackgroundAuxin may have a positive effect on plants under drought stress. White clover is widely cultivated and often prone to water shortages. In the present study, we investigated the effects of exogenous indole − 3-acetic acid (IAA) on growth and physiological changes of white clover under drought stress condition. The contents of endogenous IAA and other hormones including ABA, CTK, JA, GA, IAA, and SA were assayed. Moreover, expressions of auxin-responsive genes, drought-responsive genes and leaf senescence-associated genes were detected in response to exogenous IAA.ResultsCompared to control, drought stress alone significantly diminished stem dry weigh, relative water content (RWC) and total chlorophyll content (Chl). Exogenous IAA treatment significantly increased RWC and Chl, whereas L-AOPP treatment drastically decreased stem dry weight, RWC and Chl under drought stress condition. Additionally, exogenous IAA treatment significantly increased ABA content and JA content, up-regulated expression of auxin responsive genes (GH3.1, GH3.9, IAA8), drought stress responsive genes (bZIP11, DREB2, MYB14, MYB48, WRKY2, WRKY56, WRKY108715 and RD22), and down-regulated expressions of auxin-responding genes (GH3.3, GH3.6, IAA27) and leaf senescence genes (SAG101 and SAG102) in the presence of PEG. Contrarily, L-AOPP treatment significantly reduced contents of ABA, GA3 and JA, down-regulated expressions of GH3.1, GH3.9, IAA8, bZIP11, DREB2, MYB14, MYB48, WRKY2, WRKY56, WRKY108715, ERD and RD22, and up-regulated SAG101 and SAG102.ConclusionsExogenous IAA improved drought tolerance of white clover possibly due to endogenous plant hormone concentration changes and modulation of genes involving in drought stress response and leaf senescence. These results provided useful information to understand mechanisms of IAA improved drought tolerance in white clover.
Highlights
Auxin may have a positive effect on plants under drought stress
Our results showed that relative water content (RWC) and Total chlorophyll content (Chl) of white clover in control remained stable
Exogenous indole − 3acetic acid (IAA) activated responsive gene GH3.9 and resulted in the strong drought resistance in plants [59]. These results showed that exogenous IAA could enhance drought resistance in white clover, and GH3.1 and GH3.9 gene was involved in drought tolerance
Summary
Auxin may have a positive effect on plants under drought stress. White clover is widely cultivated and often prone to water shortages. We investigated the effects of exogenous indole − 3acetic acid (IAA) on growth and physiological changes of white clover under drought stress condition. Drought stress adversely impacts plant growth and has attracted researchers’ attention due to its effects on a variety of physiological and metabolic mechanisms in plants [2,3,4]. Plants accumulate low-molecular-weight osmolytes to recruit potassium and other nutrient ions, and increase root elongation to enhance water uptake. Phytohormones, such as auxins (IAA), abscisic acid (ABA), cytokinin (CTK), salicylic acid (SA), gibberellin (GA) and jasmonic acid (JA), could modulate the plant tolerance to drought stress. Accumulating evidences indicate the possible link between IAA and other hormones [13,14,15], indicating the cross-talks among phytohormones might play key roles during plant stress response
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call