Lignin Biosynthesis Driven by <i>CAD</i> Genes Underpins Drought Tolerance in Sugarcane: Genomic Insights for Crop Improvement
2025
Yue Wang | Weitong Zhao | Peiting Li | Junjie Zhao | Zhiwei Yang | Chaohua Huang | Guoqiang Huang | Liangnian Xu | Jiayong Liu | Yong Zhao | Yuebin Zhang | Zuhu Deng | Xinwang Zhao
Sugarcane (<i>Saccharum</i> spp.), a vital economic crop, suffers significant yield losses from drought. This study elucidates the genetic regulation of lignin biosynthesis—a key drought-resistance mechanism—by analyzing three contrasting accessions: drought-sensitive <i>Saccharum officinarum</i> (Badila), drought-resistant hybrid (XTT22), and drought-tolerant wild <i>Saccharum spontaneum</i> (SES-208) under progressive drought (7–21 days). Physiological analyses revealed pronounced lignin accumulation in XTT22 roots/leaves, driven by elevated coniferyl/sinapyl alcohol substrates, while Badila showed minimal deposition. Genomic characterization of cinnamyl/sinapyl alcohol dehydrogenase (<i>CAD/SAD</i>) families across six sugarcane genomes identified 322 genes phylogenetically clustered into three clades. Class I members (<i>CAD1</i>, <i>CAD5</i>, etc.) were critical for lignin biosynthesis, with tandem/segmental duplications driving family expansion and promoters enriched in stress-responsive <i>cis</i>-elements (ABA, MeJA, light). Transcriptomics and qRT-PCR confirmed strong correlations between Class I <i>CAD</i> expression, lignin content, and drought tolerance. These findings establish <i>CAD</i> Class I genes as novel molecular targets for enhancing drought resilience in sugarcane breeding programs.
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