In recent years, Setaria viridis (L.) P. Beauv. has increased its popularity as a model plant for genetic studies with C₄ monocotyledons. The BBCH-scale comprises a detailed phenotypic analysis, based on predefined growth stages, allowing for the construction of a comprehensive tool for morphological studies. We constructed a BBCH-scale for the ME034V wild-type accession and compared it with two independent mutants of the LONESOME HIGHWAY (LWH), which did not have noticeable morphological phenotypes. Our analysis showed that the main growth stages (0, 1, 2, and 7) showed homogeneity between the wild accession and the mutants. However, developmental changes between accessions were observable by comparing the secondaries of these main stages. There were significant differences between the wild accession and the mutants in relation to the main stages 4, 5, and 9. The total life cycle was reduced by 5 days in the svlhw-1 mutant. With a short life cycle like Setaria viridis, the observed changes can probably be attributed to genetic factors since the environmental conditions were strictly controlled. Thus, we showed that the BBCH-scale offers a powerful system to discriminate between Setaria viridis mutants that would otherwise be indistinguishable.

Climate change and the resulting abiotic stresses that emerge due to anthropogenic activities are the main causes of agricultural losses worldwide. Abiotic stresses such as water scarcity, extreme temperatures, high irradiance, saline soils, nutrient deprivation and heavy metal contamination compromise the development and productivity of crops on a global scale. In this scenario, understanding the response of C4 plants to different abiotic stresses is of utmost importance, as they constitute major pillars of the global economy. To further our understanding of the response of C4 monocots, Setaria viridis and Setaria italica have gradually emerged as powerful model species for elucidating the physiological, biochemical, and molecular mechanisms of plant adaptation to abiotic stresses. This review integrates recent findings on the morphophysiological, transcriptomic, and metabolic responses of S. viridis and S. italica to drought, elevated heat and light, saline soils, nutrient deficiencies and heavy metal contamination. Comparative analyses highlight conserved and divergent stress-response pathways between the domesticated S. italica and its wild progenitor S. viridis. Together, these findings reinforce Setaria as a versatile C4 model for unraveling mechanisms of abiotic stress tolerance and highlight its potential as a genetic resource for developing climate-resilient cereal and bioenergy crops.

Climate change and the resulting abiotic stresses that emerge due to anthropogenic activities are the main causes of agricultural losses worldwide. Abiotic stresses such as water scarcity, extreme temperatures, high irradiance, saline soils, nutrient deprivation and heavy metal contamination compromise the development and productivity of crops on a global scale. In this scenario, understanding the response of C₄ plants to different abiotic stresses is of utmost importance, as they constitute major pillars of the global economy. To further our understanding of the response of C₄ monocots, Setaria viridis and Setaria italica have gradually emerged as powerful model species for elucidating the physiological, biochemical, and molecular mechanisms of plant adaptation to abiotic stresses. This review integrates recent findings on the morphophysiological, transcriptomic, and metabolic responses of S. viridis and S. italica to drought, elevated heat and light, saline soils, nutrient deficiencies and heavy metal contamination. Comparative analyses highlight conserved and divergent stress-response pathways between the domesticated S. italica and its wild progenitor S. viridis. Together, these findings reinforce Setaria as a versatile C₄ model for unraveling mechanisms of abiotic stress tolerance and highlight its potential as a genetic resource for developing climate-resilient cereal and bioenergy crops.

Auxin is one of the major driving forces of plant development and requires careful regulation of transporter proteins to establish polar auxin transport. The PIN-FORMED ( PIN ) family plays a pivotal role in plant development by establishing auxin gradients that govern vascular patterning and organogenesis. However, the PIN family remains severely underexplored in Setaria viridis , a well-established model for C ₄ monocots. In this study, we identified and characterized 13 PIN genes in the S. viridis genome. Phylogenetic and collinearity analyses revealed duplication events in the SvPIN1, SvPIN5 and SvPIN10 subfamilies. Structural analysis uncovered unique features, including potential pseudogenization of SvPIN5a . Expression profiling across five developmental stages unveiled the potential developmental roles of SvPINs , with SvPIN1 and SvPIN10 paralogues predominantly expressed in shoots and panicles, SvPIN2 and SvPIN9 in roots, while SvPIN5b showed leaf-enriched expression, suggesting potential involvement in Kranz anatomy development. Hormonal treatments in callus cultures revealed auxin-mediated upregulation of SvPIN1b, SvPIN2, SvPIN5d, SvPIN8 and SvPIN10a . Our findings provide significant insights into the role of PIN genes in S. viridis and other C ₄ monocots, establishing a foundation for future functional studies and offering potential targets for crop improvement through auxin transport manipulation. Key Message: This study characterizes the PIN-FORMED auxin transporter family in the C ₄ model Setaria viridis , revealing gene duplication, tissue-specific expression, and hormonal regulation that may influence C ₄ traits.