# Genetic Variation of a Lentil (_Lens culinaris_) Landrace during Three Generations of Breeding
## 1 Introduction  
Lentil is one of the most important cultivated pulses worldwide, being high in protein, a good source of vitamins A and B, fiber, potassium, and iron, ideal for vegetarians, and an inexpensive food for low-income people [1]. Even though lentil has been cultivated for almost 10,000 years, systematic breeding research has been carried out only recently [2]. Due to the shortage of improved varieties, farmers prefer to cultivate landraces because they adapt readily to local environments [3]. Lentil cultivation suffers frequent production failures due to biotic and abiotic constraints. A wide range of pathogens can infect lentils, with fungal diseases being the most important [4]. Although focus has been concentrated on biotic stresses because of the obvious and serious reduction in yield and quality, abiotic stresses are also a major factor that cause a great loss in lentil production. Climate and soil variation and their interaction in different regions, affect lentils' productivity by influencing foliar and soil-borne diseases, pests, and associated rhizobia [5]. Characterization of available germplasm is significant for breeders aiming to breed improved high yielding varieties with excellent quality and value [6]. Breeding strategies could exploit the existing variation within landraces to broaden the genetic base of commercial crops [7]. Landraces are the primary material used by breeders due to their contribution as a gene pool from which breeders can derive elite varieties [1]. Lentil is a self-pollinated species due to cleistogamy and dehiscence of anthers before opening of the flower. Thus, naturally evolving lentil landraces are highly heterogeneous populations, which consist of a mixture of several fairly homozygous genotypes genotypes [2]. Nevertheless, field studies indicate that the degree of outcrossing in lentilcan range from 0.06 to 5.12% between cultivars and can be, depending on environmental conditions and the genotype, as high as 22% within the same cultivar [8], which may further expand genetic diversity within a lentil landrace. Therefore, lentil landraces offer the option to apply single-plant selection as a short-time tool to breed high-yielding and stable pure-line varieties [3]. Plant breeding collects, induces, and rearranges genetic diversity by selecting superior genotypes conforming to specific criteria. A balance between the positive and negative effects of breeding on allelic richness determines the increase or loss of diversity [9]. Applying a breeding methodology, breeders should know how selection influences genetic diversity, how it affects the number of alleles in the breeding population, and what are the effects on the genetic background of the improved gene pool [10]. The honeycomb pedigree breeding program was carried out within a lentil landrace at an ultra-low density to prevent plant-to-plant interference for any input; absence of competition was assumed to facilitate the identification of genotypes of both high yield capacity and the ability to escape seed-borne and aphid-transmitted viruses [2]. Single-plant selection for three successive generations led to promising sister lines on grain yield and virus tolerance [2; 11; 12]. The breeding scheme implied that the selected single-plant progeny sister lines should have similar genetic identity, which could be followed in next generations. This property would enable a study of genetic relationships of the selected genotypes and answer to specific questions: (a) what is the extent of genetic diversity of the mother population; (b) what are the genetic relationships of selected plants in the first cycle; (c) how consistent is the selection procedure regarding the genetic makeup of each selection generation, and (d) what is the allelic composition of the improved selected plants compared to the original population. Addressing these questions is important for application of modern selection and breeding technology tools to shape landraces into useful cultivars preserving their agricultural significance [13].