Visualization of leaf and bracteal nectaries of cotton using digital microscopy to improve scoring accuracy and data preservation

Authors: Mendu, Lavanya; Scheffler, Jodi

Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2025
Publication Date: 2/6/2026
Citation: Mendu, L., Scheffler, J.A. 2026. Visualization of leaf and bracteal nectaries of cotton using digital microscopy to improve scoring accuracy and data preservation. Journal of Visualized Experiments. 228:1-11. https://doi.org/10.3791/69832.
DOI: https://doi.org/10.3791/69832

Interpretive Summary: Plants have specialized glands called nectaries that contain nectar. Nectaries are present in many plant species and occur in the flower and/or other plant parts such as leaves. In cotton, the presence or absence of nectaries is controlled by two genes (Ne1 and Ne2) but environmental conditions can affect how large the nectaries are and how easy they are to see. Because they can be difficult to see with the naked eye, there needs to be an accurate method to score if the trait is present or not and preserve the score. In cotton, visual scoring is prone to error as this trait is often not visible to the naked eye. Scoring using digital images is a more accurate method that can preserve information and help accurately score the nectary trait. This scoring with digital images of nectaries is also being used in studies to identify DNA markers that breeders can use for marker assisted selection (MAS) of the nectary trait. This scoring technique can be extended to other plant species in addition to studying other traits such as glands, plant hairs or plant color. Cotton with no nectaries is less attractive to insects and helps decrease insect damage without having to spray as many pesticides on the cotton crop. Using less pesticide saves the farmers money and causes less death of beneficial insects like honeybees.

Technical Abstract: The nectary trait exhibits diverse changes in morphology, structure, and function across plant species. Visual scoring is error prone as some phenotypes of this trait are not visible to the naked eye. Additionally, this trait expression is influenced by the environment stressing the need for proper scoring methods. Phenotypic scoring through digital images results in a more accurate method of scoring that can preserve information and help accurately to score the nectary trait. The digital imaging method described here can also be easily adapted to score other traits such as glands, hairs and color. These scoring methods are also adaptable to other plant species. In this article, we explain step by step processes on how to collect samples from the field or green house, then dissect, and observe them with a digital microscope. We also preserve the images for future analysis. For this method, we will use, as our example, scoring leaf and flower samples of cotton plants for the presence or absence of nectaries.