More than 40% of global calorie intake comes from three major crops – wheat, rice and corn. However, there are many underutilized crops, so-called “orphan crops,” that could improve the diversity and resilience of food supplies and boost food security in drought-prone areas. An international team led by researchers from the International Livestock Research Institute (ILRI) in Kenya has now fully sequenced the genome of Lablab purpureus, or the lablab bean, which will help scientists and cultivators better leverage the resilient traits of this orphan crop.
The lablab bean is a legume crop that is indigenous to Africa and cultivated in tropical regions throughout Africa and Asia but, like other orphan crops, has received little attention from researchers and breeders. Lablab plants are extremely drought-resilient, can improve soil fertility through nitrogen fixation and also contain bioactive compounds with potential pharmaceutical uses. The researchers used nanopore sequencing to sequence the genomes of both wild and domesticated lablab plants and utilized high-throughput chromosome conformation capture (Hi-C) to further analyze the species’ 11 chromosomes. Using the sequencing data, the team identified the plant’s protein-coding genes, performed gene family analysis comparing the species to other legumes and further analyzed genes related to fatty acid metabolism, arabinose metabolism and trypsin inhibition, which can have implications for traits such as seed oil content, plant defenses, drought tolerance and nutritional value.
The researchers noted that the lablab has a smaller genome and fewer species-specific orthogroups than other sequenced legumes. Their analysis showed that genes involved in fatty acid metabolism and arabinose metabolism were enriched in lablab-specific orthogroups; the latter is related to cell wall modification, which could contribute to the plant’s drought-resilience. Additionally, the team characterized the arrangement of trypsin inhibitor genes into five gene clusters, information which could aid in targeted breeding of the crop. Trypsin inhibition improves the plant’s resistance to pathogens and insects, but also reduces the availability of nutrients and digestibility of the legumes. Through genome-assisted breeding or gene-editing techniques, trypsin inhibition could be tailored to maximize nutritional value while maintaining defensive properties. This study was published in Nature Communications.
“The first green revolution was achieved with major crops like wheat and rice. Orphan crops like lablab could pave the way for the next green revolution,” noted lead author Oluwaseyi Shorinola, a scientist at ILRI and the John Innes Centre.
The genomic data and analysis provided through the study paves the way for wider cultivation and further improvement of lablab crops, which can boost food security and food system diversity in drought-prone areas. The researchers also noted that the portability and relatively low-cost of nanopore sequencing improves opportunities to study crop genetics in low-resource regions where food insecurity is more common.