Advancing cotton fiber research with variable-pressure scanning electron microscopy (VP-SEM)

Authors: Bai, Fang; Jansen, Michael

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2025
Publication Date: 5/1/2025
Citation: Bai, F., Jansen, M.A. 2025. Advancing cotton fiber research with variable-pressure scanning electron microscopy (VP-SEM). Frontiers in Plant Science. 16:1562682. 10.3389/fpls.2025.1562682.
DOI: https://doi.org/10.3389/fpls.2025.1562682

Interpretive Summary: Cotton is an essential crop for the global textile industry with its success closely tied to advancements in fiber yield and quality. Traditional imaging methods, like scanning electron microscopy (SEM), have been instrumental in studying cotton fibers, but face limitations due to labor-intensive preparation and the potential for specimen damage. This study introduces the variable-pressure scanning electron microscopy (VP-SEM) protocol that overcomes the challenges of traditional SEM methods and revolutionizes cotton fiber imaging by, minimizing time spent on sample preparation, reducing costs and artifacts, and preserving the integrity of samples. Due to its ability to observe critical stages of cotton fiber development in real time, the method lays the foundation for future research resulting in significant improvements in cotton yield and quality. The applicability of VP-SEM, as a simplified high-throughput method, extends beyond cotton offering agronomic and horticultural scientists a new tool for advancing agricultural science and crop improvement.

Technical Abstract: Cotton fibers, as highly extended, thickened epidermal seed structures, are a crucial renewable resource in textile production. Cotton plants produce two main types of fiber cells: wide, hemisphere-shaped fibers and narrow, and tapered fibers. Both types stabilize through secondary cell wall development, with the mature narrow fibers being particularly valued for spinning into fine, strong yarns, suitable for premium cotton fabrics. Traditional methods for studying fiber development and cell types, such as scanning electron microscopy (SEM), are often time-intensive and costly. SEM preparation steps, including fixation, dehydration, and sputter coating, can cause shrinkage and other image distortions, limiting the accuracy of observations. Variable-pressure scanning electron microscopy (VP-SEM) offers an alternative approach, operating under low pressure rather than a high-vacuum environment, which can be advantageous for imaging live samples with minimal sample preparation. In this study, we applied VP-SEM to observe fiber cell initiation and early elongation in the conventional upland cotton cultivar UGA 230 at 0 and 1-day post-anthesis. Two SEM detectors, the ultra-variable-pressure detector and backscattered electrons, were used to capture detailed images. Optimal imaging conditions were identified with a 15 keV accelerating voltage and a 50 Pa pressure setting, enabling clear visualization of early fiber development without the need for extensive preparation. This VP-SEM protocol not only facilitates high-resolution imaging of cotton fibers at early developmental stages but also reduces time and expense, minimizing sample damage. Additionally, this optimized approach can be adapted for other fresh biological samples, making it a versatile tool for real-time imaging across various studies in plant biology and beyond.