Genetic diversity and population structure of leafy kale andBrassica rupestrisRaf. in south Italy

Abstract

Local varieties of leafy kales (Brassica oleracea L.) are grown in home gardens in Calabria and Sicily for self-consumption, in the same area where the wild relative Brassica rupestris Raf. also grows. With the use of AFLP markers, comparisons were made of the genetic diversity and population structure of ten wild and 22 cultivated populations, as well as of a hybrid population and of four commercial cultivars of different B. oleracea crops. The level of genetic diversity was higher in leafy kales than in wild populations and this diversity was mainly distributed within populations. Wild populations remained distinct from cultivated material. Additionally, most wild populations were distinctively isolated from each other. On the other hand, it was not possible to molecularly distinguish even geographically distant leafy kale populations from each other or from different B. oleracea crops. It was possible to detect inter-crossing between leafy kales and B. rupestris. Findings from this study illustrate the existing level of genetic diversity in the B. oleracea gene pool. Individual populations (either wild or leafy kales) with higher levels of genetic diversity have been identified and suggestions are given for an informed conservation strategy. Domestication hypotheses are also discussed.

Evidence for two domestication lineages supporting a middle-eastern origin forBrassica oleraceacrops from diversified kale populations

“…Domestication of B. oleracea dates back to as early as around 400 BC, based on for example descriptions of kales by the Greek scholar Theophrastrus (370–285 BC). In older writings (800–600 BC) the kales were not yet mentioned [ 12 , 13 ]. Northwestern Europe and the Mediterranean/Middle east regions are hypothetical ancestral areas for domesticated B. oleracea , of which the latter obtains more weight from ancient literature [ 2 , 13 ].…”

Recent progress in the use of ‘omics technologies in brassicaceous vegetables

“…A doubled haploid population derived from crosses of two broccoli cultivars was genotyped by SSR and AFLP markers and QTL analysis identified loci for horticulturally important characteristics ( Walley et al, 2012 ). Plant genetic resources have been characterized using AFLP markers to assess the huge genetic diversity present in gene banks, including Dutch and Italian B. oleracea ( van Hintum et al, 2007 ; Maggioni et al, 2014 ) and Czech B. oleracea var. capitata accessions ( Faltusova et al, 2011 ).…”

Different Shades of Kale—Approaches to Analyze Kale Variety Interrelations

“…Despite the wide distribution and morphological diversity, to date, there has not been a strong focus on kale in the Brassica research area. Studies on Turkish kale populations [ 13 ], kale cultivars and landraces from Europe [ 14 , 15 ], wild and cultivated populations of leafy kale in Italy [ 16 ], collards in the USA [ 17 , 18 ], and a recent study on the vegetative domestication syndrome of kale [ 19 ] are sole exceptions. Extensive insights into interrelationships in kale are crucial, given the huge diversity of varieties, not only considering the cross-compatibility of kales with all other varieties of Brassica oleracea , but also concerning studies demonstrating that closely related cultivars are phytochemically more similar to each other [ 12 ].…”