Using phenomics and genomics to unlock landrace and wild relative diversity for crop improvement

This chapter discusses some of the activities and achievements of the Plant Genetic Resources (PGR) Secure project, which aims to: (i) identify host plant resistance to the cabbage whitefly (Aleyrodes proletella) and cabbage aphid (Brevicoryne brassicae) via a germplasm screen where both are specialist phloem-feeding insects that feed only on members of the Brassicaceae family; (ii) elucidate the resistance mechanism; and (iii) provide tools to breeders that will facilitate resistance breeding. It is shown that the PGR Secure project has delivered valuable information on the extent of whitefly and aphid resistance in landrace accessions of Brassica oleracea var. capitata, as well as in wild relatives of B. oleracea. The whitefly resistance present in Brassica villosa, B. incana and B. montana is expressed both in 6- and 12-week-old plants, which indicates that this form of resistance is probably different from that already present in B. oleracea. These sources can be used in breeding resistant varieties. By combining novel phenomics, genomics and transcriptomics technologies, resistance breeding can be speeded up significantly. The developed and publicly available 90 k Affymetrix Axiom Brassica array can play an important role in this. The single nucleotide polymorphism markers linked to the resistance quantitative trait loci (QTLs) will facilitate an efficient introgression of the QTLs into high-yielding varieties