Freeze response indicators in sugarcane (Saccharum spp. hybrids)

A recent series of extreme weather events in Southern U.S. (2022 winter freeze followed by 2023 summer drought) calls for quantitative markers to expedite the release of climate resilient sugarcane varieties. A cluster analysis revealed potential markers for freeze damage including fluorescent amino acids. Of 8 cultivars investigated, tolerant variety HoCP 04-838 sustained 3-5 fold lower stalk fracture from the freeze; contained among the highest fiber; and maintained the lowest particulate juice decomposition byproducts (p<0.05). Based on those observations, fluorescence cellular markers were developed in fiber components of sugarcane to assess cold tolerance. Fluorescence microscopy visualized a cluster of markers in lignin cells around the vascular bundles of HoCP 04-838, within the far-red emission ranges attributable to lipids and other hydrophobic components. Cellular distributions of markers were made visible using fluorescent nanoparticles designed to enhance cellular uptake and imaging at wider wavelengths. Developed chemical phenotyping approaches offer advantages over post-freeze damage assessment currently used in the breeding program, as no genetic marker exists for cold tolerance of sugarcane.