Abstract
Mepiquat chloride (MC) is the most important plant growth retardant that is widely used in cotton (Gossypium hirsutum L.) production to suppress excessive vegetative growth and improve plant architecture. MicroRNAs (miRNAs) are important gene expression regulators that control plant growth and development. However, miRNA-mediated post-transcriptional regulation in MC-induced growth inhibition remains unclear. In this study, the dynamic expression profiles of miRNAs responsive to MC in cotton internodes were investigated. A total of 508 known miRNAs belonging to 197 families and five novel miRNAs were identified. Among them, 104 miRNAs were differentially expressed at 48, 72, or 96 h post MC treatment compared with the control (0 h); majority of them were highly conserved miRNAs. The number of differentially expressed miRNAs increased with time after treatment. The expression of 14 known miRNAs was continuously suppressed, whereas 12 known miRNAs and one novel miRNA were continuously induced by MC. The expression patterns of the nine differentially expressed miRNAs were verified using qRT-PCR. The targets of the known and novel miRNAs were predicted. Four conserved and six novel targets were validated using the RLM-5′ RACE assay. This study revealed that miRNAs play crucial regulatory roles in the MC-induced inhibition of internode elongation. It can improve our understanding of post-transcriptional gene regulation in MC-mediated growth inhibition and could potentially facilitate the breeding of dwarf cotton.
Highlights
Cotton (Gossypium hirsutum L.) is a worldwide cultivated economic crop that provides natural fiber materials and edible oil
We found that the transcriptional levels of genes related to GA biosynthesis and signaling and cell expansion were inhibited by Mepiquat chloride (MC) after 48 h of treatment owing to the timedependent translocation and accumulation of MC from the leaf to the internode (Wang L. et al, 2020)
We found that MC significantly altered the expression of a large number of genes related to cell cycle, cell wall structure, hormone metabolism, signal transduction, and secondary metabolism, and TFs (Wang L. et al, 2020). miRNA is a kind of important post-transcriptional regulator of gene expression
Summary
Cotton (Gossypium hirsutum L.) is a worldwide cultivated economic crop that provides natural fiber materials and edible oil. One of the major challenges in cotton production is the control of excessive vegetative growth during the entire developmental stage owing to its indeterminate growth habit. Serious production problems, such as auto-shading, fruit abscission, delayed maturity, and reduced. MC-Responsive miRNAs in Cotton Internode yield, often occur under excessive vegetative growth (Zhao and Oosterhuis, 2000). Mepiquat chloride (MC) is the most commonly used growth regulator in cotton production; it shortens internodes, decreases plant height, and reduces leaf area (Reddy et al, 1990; Rademacher, 2000; Siebert and Stewart, 2006; Curaba et al, 2013; Ren et al, 2013). The compact plant architecture and open canopy by MC application are important for maximizing cotton yield (Gwathmey and Clement, 2010; Ren et al, 2013)
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