Cell-specific clock-controlled gene expression program regulates rhythmic fiber cell growth in cotton.

Area of Science:

• Plant Biology
• Molecular Genetics
• Cell Biology

Background:

• Cotton fibers are a vital natural cellulose source for textiles.
• The molecular mechanisms governing cotton fiber cell growth remain largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanisms of cotton fiber cell development.
• To identify key regulators of fiber growth and explore potential trait improvement strategies.

Main Methods:

• Developed an optimized protoplasting method.
• Integrated single-cell RNA sequencing (scRNA-seq) and single-cell ATAC sequencing (scATAC-seq) on wild type and fuzzless/lintless (fl) cotton ovules.
• Performed time-course diurnal transcriptomic analysis.

Main Results:

• Identified five distinct cell populations, including fiber cells, and mapped fiber lineage development.
• Demonstrated that primary fiber cell growth follows a circadian rhythmic pattern.
• Discovered the peptide GhRALF1 regulates fiber growth via auxin signaling and proton pump activity.
• Identified two cis-regulatory elements (TCP and TCP-like motifs) bound by GhTCP14s, modulating mitochondrial metabolism and protein translation in fiber cells.

Conclusions:

• Uncovered a fiber-specific, circadian clock-controlled gene expression program regulating cotton fiber growth.
• Proposed a novel strategy for improving cotton fiber traits by engineering the fiber cell circadian clock.