Australia is the largest producer, with 47.1% of the global production, while Europe is second according to FAOSTAT . In Europe L. angustifolius L. and L. luteus L. are the predominant cultivated species in the north and countries with more than 10,000 ha of lupins are Poland, the Russian Federation, Germany, Belarus, and Ukraine. In the south, where L. albus L. is predominant, Italy , France , and Spain are the main lupin-producing countries . Modern breeding efforts to improve white lupin agronomic characteristics are very recent . Thus, there is still significant variability even among commercial germplasm for the most essential breeding targets, namely, the seed’s nutritional value and the toxic, bitter secondary metabolites QAs . The total alkaloid content in white lupin varies from 0.02 to 12.73% of the seed’s dry weight. Cultivars possessing the pauper gene contain 0.02–0.05% alkaloids of the seed dry weight . The recently published white lupin pangenome study demonstrated that pauper locus has a key role in the species domestication and breeding .
Other important agronomic characters of white lupin, which attracted the breeders’ attention, are vernalization insensitivity , anthracnose resistance , yield stability , and abiotic-stress acclimation . White lupin’s global commercial potential has incited the breeding interest to focus not only in yield boost, but also in expanding its cultivation to agroclimatic regions, other than the Mediterranean basin, as extreme climate-change-related phenomena push the cultivation of some crops northwards . On top of that, restricted precipitation levels during spring and frequent dry spells, throughout the Mediterranean basin, as a consequence of climate change , have a detrimental impact on pollen fertility , pollinator-flower interactions , pod filling, and seed development, resulting in premature harvesting and yield losses.Anthracnose is a global fungal disease, responsible for devastating epidemics, characterized by signifificant yield losses . Temperatures over 10 ◦C and humid weather promote conidia germination, with 25 ◦C being optimal for fungal growth; whereas dry summer conditions are favorable for the preservation of inoculum on unharvested plant tissues .
Colletotrichum lupini, is mostly identified as the responsible pathogen for lupin anthracnose. Nonetheless, it has been reported in several other crops such as olive . The pathogen emerges as an alarming polyphagous phytopathogenic strain for the Mediterranean agriculture. White lupin breeding has been directed to the creation of elite anthracnose resistant cultivars, employing map construction, genomic screening, phenotyping tools, fifield experimentation, and generation of molecular markers, to detect anthracnose resistant accessions . Thus far, Ethiopian landraces have been extensively studied, revealing a highly diverse germplasm and embodying unique loci that confer resistance to anthracnose . Successful breeding significantly depends on the extent of the available genetic resourcesPhenotypic and molecular markers have already been used in few studies, to estimate the genetic diversity between wild and breeding white lupin germplasm, and to enable incorporation of potentially valuable alleles from distantly related wild accessions tothe genetic pool of elite cultivars .
Additionally, molecular markers are continuously developed, for the effective selection of germplasm with desired traits . Furthermore, genomic resources are now available in white lupin and their use will greatly advance our understanding of the species diversity. In such an effort, very recently genome sequences of 39 accessions were used to establish a white lupin pangenome that can be used as resource to identify genes linked to important agronomic traits and analyze genetic variability. Although such progress will inevitably lead to development of more sophisticated tools to explore genetic variation in white lupin genetic resources, up to now SSR markers have been proved integral tools to investigate species diversity. The Balkan Peninsula represents a yet untapped germplasm diversity center for white lupin, concealing potentially valuable loci in landraces and natural populations that could promote adaptability to climate-change-relevant extreme conditions . In this study we applied available SSR molecular markers linked to agronomically important traits and morphological seed characteristics to explore the genetic diversity of white lupin Greek landraces and compare it with that observed in commercial varieties and breeding lines.
Results of the study may facilitate marker assisted breeding in white lupin and enable identification and introgression of valuable alleles into new elite cultivars. All seed morphological characters’ measurements were statistically analyzed and a summary of the statistics is shown in Table 1. The Multivariate Analysis of Variance indicated that all 45 accessions are distinguished from one another, when regarding their seed morphology, with statistical significance . A Pearson’s correlation matrix revealed strong correlation between seed area with TSW, perimeter and width and between mean Gray Value with maximum and median Gray Value , suggesting, that a single character measurement is sufficient to represent highly correlated characters.