Venturing Beyond Beans and Peas: What Can We Learn from Chamaecrista?

Expanding legume research beyond the model members of the subfamily Papilionoideae (papilionoids) is necessary if we wish to capture more of the diversity of the enormous, economically important legume family. Chamaecrista fasciculata is emerging as a nonpapilionoid model, belonging to the paraphyletic subfamily Caesalpinioideae within the mimosoid clade. Mimosoids diverged from the common ancestor of soybean (Glycine max), Medicago truncatula, and Lotus japonicus nearly 60 million years ago-nearly contemporaneously with the origin of legumes. There is growing interest within the legume community in C. fasciculata as a complementary legume model for a number of reasons, including phylogenetic position, nodulation within a clade of limited nodulating species, nonpapilionoid floral morphology, herbaceous growth habit, and tractability in laboratory and field settings. Whole-transcriptome sequencing (WTS) of C. fasciculata shoots, roots, and nodules, along with gene expression and single nucleotide polymorphism (SNP) profiling, provides community resources to address fundamental questions about legume evolution. A range of ecotypes, development of functional genomics tools, and an integration of research and undergraduate education leverage these genomic resources.