Identification of peptidome-based biomarkers of cassava mosaic disease resistance in different cassava varieties.

Cassava, a major economic crop in Thailand, yielded over 3 million USD in exports in 2023. However, its production has been declining since 2021 due to cassava mosaic disease (CMD) outbreaks, which affect cassava plantations. CMD infections have recently increased due to the scarcity of healthy stems and CMD-resistant varieties, the latter being key to controlling its spread. Developing novel methods is critical for accelerating the cultivation of high-yield, CMD-resistant varieties. In this study, signature peptide patterns were determined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography-tandem MS (LC-MS/MS) to screen for CMD-resistant varieties. Peptide mass fingerprint (PMF) analyses revealed distinct peptide barcodes across 11 varieties, clearly delineating CMD-resistant and CMD-tolerant phenotypes. LC-MS/MS and orthogonal partial least squares-discriminant analysis (OPLS-DA) further demonstrated clear distinctions between the peptide profiles of different phenotypes. Heatmap and PMF analyses consistently revealed unique peptide patterns across the varieties. Volcano plot analysis identified seven upregulated peptides-TATTVAGS, PAAGGGGG, PNELLSYSE, SSIEEGGS, GGGVGGPL, NNGGGFSV, and GPGPAPAA-in CMD-resistant plants. These peptides were associated with proteins containing CONSTANS-like zinc finger, C2H2-type, GST N-terminal, Tubby-like F-box, nuclear-localized AT-hook motif, auxin response factor, and C2 domains. Altogether, this study identified peptidome-based biomarkers for screening CMD-resistant varieties; however, further validation using larger samples is necessary.