By analyzing leaves and roots across eight time points under each stress condition, researchers identified thousands of differentially expressed genes and key signaling pathways—including cutin/wax biosynthesis, ABA signaling, and phosphatidylinositol signaling—that regulate stress adaptation.
Global crop yields are declining due to rising temperatures, water scarcity, and salinized soils. Wheat, rice, and maize suffer yield losses ranging from 50% to 80% under these stressors. With the global population expected to exceed 9.7 billion by 2050, food production must rise by 70% to meet demand. While traditional breeding has improved resilience to some extent, its slow pace is no longer sufficient. Genetic engineering guided by insights into stress-responsive genes can accelerate the development of tolerant varieties. Pearl millet (Pennisetum glaucum), a hardy C4 cereal grown in arid regions of Africa and Asia, thrives under extreme heat and poor soils. It holds untapped potential as a genetic resource for stress resilience—but its molecular stress responses have remained largely unexplored.
A study (DOI: 10.48130/tp-0025-0017) published in Tropical Plants on 04 July 2025 by Linkai Huang's team, Sichuan Agricultural University, pinpoints critical gene networks that not only explain millet's robust survival but also offer molecular targets for engineering more resilient crops.
To investigate the molecular responses of pearl millet to abiotic stresses, researchers conducted transcriptomic profiling of leaves and roots under high-temperature, drought, and salt conditions across multiple time points. The analysis revealed that root tissues consistently exhibited stronger and more sustained transcriptional responses than leaves. Under heat stress, 14,021 differentially expressed genes (DEGs) were identified in roots compared to 11,541 in leaves, with greater activation of transcription factors (TFs) such as HSFs, WRKYs, NACs, and ERFs in roots. Functional enrichment showed that roots uniquely activated pathways like cutin, suberin, and wax biosynthesis and MAPK signaling, indicating tissue-specific stress adaptations. In response to drought stress, genes involved in abscisic acid (ABA) biosynthesis—including ZEP, NCED, ABA2, and AAO—were upregulated in roots, suggesting active ABA signaling for stomatal regulation and drought mitigation. Both roots and leaves showed significant enrichment in ABC transporter and plant hormone signal transduction pathways. Salt stress induced the highest number of DEGs in roots (14,168), where TFs such as ARFs were prominently expressed. Notably, 19 DEGs related to phosphoinositide synthesis, including INO1, PIK3, and PIP5K, were induced in roots, pointing to activation of the phosphatidylinositol signaling system and endocytosis as key salt-stress responses. A Venn analysis identified 9,024 DEGs responsive to all three stresses, with shared enrichment in pathways such as MAPK signaling, photosynthesis, and phenylpropanoid biosynthesis. However, these shared pathways exhibited stress-specific roles—for instance, ABC transporters regulated stomatal closure under heat, ABA transport under drought, and ion transport under salt stress. This integrative study reveals a complex, tissue-dependent transcriptional network in pearl millet that mobilizes both conserved and distinct molecular pathways to counter abiotic stress, offering valuable insights for breeding resilient crop varieties.
This high-resolution transcriptional landscape provides critical insights into the genetic architecture of abiotic stress responses in a non-model crop. It identifies a suite of candidate genes that could be leveraged for genetic engineering or precision breeding to develop stress-resilient cultivars—not only in pearl millet but also in related cereals like maize and sorghum. The functional diversity of conserved pathways—such as ABC transporters and MAPK signaling—under different stress contexts offers a nuanced understanding of adaptive flexibility. By translating these findings into crop improvement strategies, researchers can help mitigate yield losses, enhance food security, and ensure sustainable agricultural production in increasingly hostile climates.
