Selection at ultra-low density identifies plants escaping virus infection and leads towards high-performing lentil (Lens culinaris L.) varieties

摘要

Cultivated lentil (Lens culinaris L.) landraces offer a challenge to exploiting their genetic variability and deriving new pure-line varieties. For insect-transmitted viruses, low densities favour increased virus spread. The objective of the present work was to evaluate a selection procedure applied within a landrace under ultra-low plant density and low-input conditions toward the isolation of high-performing genotypes that escape virus infection. Field trials were conducted through four growing seasons (2006-2011) in the Democritus University of Thrace research farm in Orestiada, Greece. Selection of individual plants for high grain yield was applied for three generations, while virus presence was tested by enzyme-linked immunosorbent assay in the seeds used or the plants selected in each selection cycle. Early high plant-to-plant phenotypic variability, reflected by high coefficient of variation (CV) values, was partly attributed to virus infection. However, sister lines were consistently higher yielding and of lower CV than the mother population (MP). Second generation lines yielded up to 136 and 23% more than the source landrace at the ultra-low density and dense stand, respectively. Pea seed-borne mosaic virus was detected in the seeds of the MP, whereas bean yellow mosaic virus and bean leafroll virus were mainly involved in the subsequent selection rounds. In general, the highest-yielding plants were free of the viruses detected during experimentation. It was concluded that selection at ultra-low density of the highest-yielding plants from the sister lines with the lowest CV constitute an effective way to improve the health status of the seeds produced and result in high yielding and potentially virus-tolerant pure-line varieties.