Morphological, transcriptomic, and metabolomic differences between two sugarcane sister lines with contrasting resistance to orange rust disease

Yupeng Zhou¹, Edvin Sebastian Mihail¹, Ziliang Luo¹, Sushma Sood², Md Sariful Islam² and Jianping Wang¹

¹Department of Agronomy, College of Agricultural and Life Sciences, University of Florida, USA; wangjp@ufl.edu

²Sugarcane Production Research Unit, USDA ARS SEA, 12990 US Hwy 441 N, Canal Point, FL 33438, USA

Sugarcane production in most of the Americas has suffered yield losses from sugarcane orange rust disease (SORD) caused by Puccinia kuehnii for a decade. Developing resistant cultivars is a key breeding goal, but the genetic mechanisms of resistance to SORD remain unclear. This study examined two sugarcane sister lines with contrasting resistance responses, differing in a major quantitative trait loci (QTL) region linked to resistance to SORD. The resistant line (540) had smaller stomata and lower stomatal density than the susceptible line (664). Transcriptomic analysis revealed increased cell surface modification activity in the resistant line, possibly activating surface receptors. Genes linked to anti-fungal molecule biosynthesis (hordatines, arabidopyrones, and alkaloids) were also upregulated, along with lncRNAs involved in transcriptional regulation. Joint transcriptomic-metabolomic analysis indicated that the resistant line had higher production of phenylpropanoid derivatives, especially ferulate-based compounds with antioxidant and antifungal properties. This provides fundamental information and resources of sugarcane molecular genetic mechanisms to SORD, which will facilitate the sugarcane breeding programs in developing disease-resistant cultivars.