Abstract
BackgroundMepiquat chloride (MC), a plant growth regulator, enhances root growth by promoting lateral root formation in cotton. However, the underlying molecular mechanisms of this phenomenon is still unknown.MethodsIn this study, we used 10 cotton (Gossypium hirsutum Linn.) cultivars to perform a seed treatment with MC to investigate lateral root formation, and selected a MC sensitive cotton cultivar for dynamic monitor of root growth and transcriptome analysis during lateral root development upon MC seed treatment.ResultsThe results showed that MC treated seeds promotes the lateral root formation in a dosage-depended manner and the effective promotion region is within 5 cm from the base of primary root. MC treated seeds induce endogenous auxin level by altering gene expression of both gibberellin (GA) biosynthesis and signaling and abscisic acid (ABA) signaling. Meanwhile, MC treated seeds differentially express genes involved in indole acetic acid (IAA) synthesis and transport. Furthermore, MC-induced IAA regulates the expression of genes related to cell cycle and division for lateral root development.ConclusionsOur data suggest that MC orchestrates GA and ABA metabolism and signaling, which further regulates auxin biosynthesis, transport, and signaling to promote the cell division responsible for lateral root formation.
Highlights
Mepiquat chloride (MC), a plant growth regulator, enhances root growth by promoting lateral root formation in cotton
We demonstrate that MC orchestrates GA and abscisic acid (ABA) metabolism, which further regulates auxin biosynthesis, transport, and signaling to control the cell division responsible for lateral root development
MC promotes the development of lateral roots in cotton seedlings To study the effects of MC on the lateral root formation, we pretreated cotton seeds with MC and found that seeds treated with MC significantly increased the lateral root number of the tested cotton cultivars, with the exception of GX3 and L37 (Fig. 1a)
Summary
Mepiquat chloride (MC), a plant growth regulator, enhances root growth by promoting lateral root formation in cotton. Methods: In this study, we used 10 cotton (Gossypium hirsutum Linn.) cultivars to perform a seed treatment with MC to investigate lateral root formation, and selected a MC sensitive cotton cultivar for dynamic monitor of root growth and transcriptome analysis during lateral root development upon MC seed treatment. The root system plays a pivotal role for plant growth by providing above ground mechanical support and controlling water and nutrient acquisition. The development of lateral roots has a decisive influence on both crop growth and harvest yield [3, 4]. Lateral root initiation originates from asymmetric cell division of xylem pole-pericycle. Auxin transport affects the asymmetric cell division [5, 6, 16,17,18]. AUX1 facilitates shootderived indole acetic acid (IAA) loading to the vascular
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