Abstract:
The Green Revolution greatly improved world staple crop yields and saved millions of people from hunger, but it left the drylands behind. This situation is now made worse by climate change. To address this challenge, we must breed heat- and drought-resilient alternative crops. Here we propose a breeding system that can more than double yields in the dryland cash crop sesame, by harnessing hybrid vigor (or heterosis). Our early field experiments have revealed high potential for heterosis in sesame, with F1 hybrids often yielding 70% more than their parents, and up to 150% more.

Following this, we have attempted to establish "heterotic groups" of inbred lines, to facilitate breeding new parents within groups and to increase heterosis of F1 hybrids between different groups. 35 diverse, elite lines were systematically crossed, with 210 resulting F1 hybrids evaluated in the field. Cluster analysis of heterosis in the F1s identified three heterotic groups, allowing us to better predict combinations of parents to maximize hybrid performance. 

To accelerate heterosis breeding in sesame, high-quality reference genomes are being developed, for one representative of each of the three heterotic group. This will facilitate QTL mapping of genes that underlie heterosis in hybrids between these groups. Gene expression analysis of these three parents and their F1s is also underway. These studies will help identify the specific loci and mechanisms driving heterosis. It should also allow genomic prediction of heterosis and heterotic groups for untested hybrids and parents, accelerating breeding and yield gain for this promising dryland crop.

Bio:
Conner Johnson is a PhD student in the Plant Breeding and Genetics group at KAUST, under Professor Jesse Poland. He holds a bachelor's degree in Sustainable Agriculture and a master's in Plant Health Management from Ohio State University. His previous work focused on soil health, soil carbon sequestration, and the impacts of soil-dwelling nematode diseases on crops. His research vision is to breed alternative dryland crops to diversify crop rotations, increase soil carbon and soil health, and improve livelihoods for impoverished farmers and communities in the developing drylands of the world.