In a groundbreaking study published in Nature by Guillotin et al., 2023, researchers have drawn fascinating new insights into the evolutionary histories and traits of various grass species domesticated to create different crops. Using advanced transcriptomic analysis, the study compares the genetic blueprints of root cells in three grass species: Zea mays (maize), Sorghum bicolor (sorghum), and Setaria viridis (green foxtail).
Specialized cell types primarily drive the key characteristics that differentiate these species. The researchers used single-cell and single-nucleus RNA sequencing techniques to decipher the unique cell identity. These methods have been found to provide complementary data about cell identity in both dicots (plants with two embryonic leaves) and monocots (plants with a single embryonic leaf), which further justifies their combined analysis.
The study mapped cell types across the three species to identify consistent, orthologous marker genes. These marker genes, similar in different species that evolved from a common ancestral gene, are essential in understanding the fundamental cell biology underpinning these plants’ evolution and domestication.
The research team found that the transcriptomes, the complete set of RNA sequences in a cell, of specific cell types diverged more rapidly than others. This divergence is partly attributed to the recruitment of gene modules from other cell types, indicating an intricate level of cellular cross-talk during the evolutionary process.
Interestingly, the study also reveals that a recent whole-genome duplication in these species provides a rich source of new, highly localized gene expression domains. Moreover, these domains favor rapidly evolving cell types, which suggests that whole-genome duplication plays a crucial role in speeding up the evolution of certain plant species.
The cell-by-cell comparative analysis provides a detailed understanding of how fine-scale cellular profiling can extract conserved modules from a pan transcriptome, a term used to describe the full range of mRNA molecules produced by the genome. This granular perspective gives researchers a fresh lens through which to view the evolution of cells mediating essential crop functions.
The findings of Guillotin et al. have broad implications for our understanding of plant biology and the optimization of crop species. The research contributes to a growing body of evidence highlighting the importance of cellular diversity in the evolution of crops. It could shape future agricultural practices to enhance crop yield and resilience.
Photo by Lucas van Oort on Unsplash
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