Progress for the pea of prosperity.


This issue of The Plant Journal features the release of a high-quality reference genome for cowpea (Vigna unguiculata L. Walp), one of the most widely cultivated legumes in the world. Built using state-of-the-art technologies and an innovative assembly approach, this reference genome promises to be a valuable resource to both scientists and breeders. Cowpea originated in Africa, although the exact region where it was domesticated is still a contested topic (Lush and Evans, 1981). There are two main cultivated forms, unguiculata and sesquipedialis. The dominant subspecies V. unguiculata is widely cultivated in Africa, India, the Middle East, and the Americas, mainly for dry grain. It is particularly important in sub-Saharan Africa, where it serves as the main source of protein in the human diet. Millions of sub-Saharan Africans depend on cowpea production for food, animal feed, and cash income (FAO, 2004). Cultivated in Eastern and Southern Asia, V. sesquipedialis is known as asparagus bean or ‘yard-long’ bean. It features strikingly long pods (up to 1 meter) that are harvested at an immature stage, quite popular in Chinese and other Asian cuisines. One of the most ancient crops known to humankind, cowpea has a rich history that spans across continents. Perhaps for this reason, it has many common names in English: cowpea, black-eyed pea, southern pea, bachapin bean, crowder pea, china pea, and cowgram (FAO, 2004). In the southern U.S., legend has it that eating black-eyed peas on New Year’s Eve brings a prosperous new year. The crop arrived in the country in the early 1700s with the transatlantic slave trade and was planted in the Carolinas, the largest producers of rice in the U.S. at the time (Harris, 2010). Enslaved West Africans were brought there because of their knowledge of rice production, and along came their native crop, the cowpea. As in Africa, it was often planted at the borders of the fields to control weeds and enrich the soil, and cattle grazed on it (hence the name cowpea). Cowpea was also introduced to Northern Mexico in the late 1600s by the Italian Jesuit missionary Eusebio Francisco Kino (Castetter and Bell, 1942). It spread into what is now California, where landraces that resemble those of modern-day Iberian Peninsula can still be found. Other cultures also associate black-eyed peas (i.e., cowpeas) with luck. Sephardic Jews eat them during the Jewish New Year to bring fertility and good fortune. In a little known but fascinating bit of ancient history, black-eyed peas found their way to the Jewish New Year meal by accident: according to historian Gil Marks, a list of five foods mentioned in the Talmud to eat on New Year included fenugreek (rubia), but Sephardim may have confused that with lubia, the word for blackeyed peas (Marks, 2010). Cowpea is more than just a lucky pea: it also offers exceptional nutritional qualities and is remarkably resilient to harsh environments. Cowpea grains have high contents of protein, carbohydrates, essential amino acids and minerals, along with a relatively low content of fat (Iqbal et al., 2006; Jayathilake et al., 2018). In addition, the crop is highly resistant to high temperatures and drought stress (Ehlers and Hall, 1997), the most resilient among the major crop legumes. With this unique combination of qualities, cowpea is a key crop for food and nutritional security in the face of climate change. The availability of a high-quality genome sequence will support progress in cowpea research and breeding. The publication of the reference genome sequence (see Figure) is the product of a large collaborative effort led by Stefano Lonardi, Mar ıa Mu~ noz-Amatria ın, and Timothy Close. Lonardi is a Professor of Computer Science and Engineering at the University of California Riverside (UCR), and Mu~ noz-Amatria ın, who was a Project Scientist at UCR, is now an Assistant Professor at Colorado State University. Timothy Close is a Professor of Botany and Plant Sciences at UCR. Contributions from scientists in several institutions in the U.S. and other countries rounded out the team effort. Cowpea research at UCR began with now-retired Professor Anthony Hall in the mid-70s. Hall led the cowpea effort at UCR for over 25 years and established partnerships with African researchers that laid the foundation of collaborations that continue to this day. Funding from the Feed the Future Innovation Lab for Climate-Resilient Cowpea (USAID) and the Tropical Legumes project of the Generation Challenge Program (CGIAR) enabled the group at UCR to start developing genomic resources with colleagues in West Africa, including short-read sequences and a SNP genotyping assay (Mu~ noz-Amatria ın et al., 2017). The reference genome was funded mainly through the National Science Foundation BREAD program.