Comparison between maize inbred lines: genetic distances in the expert's eye

To be registered on the national list for protection purposes, a new variet y has to be distinct from all existing varieties, uniform and stable. In Fr ance, distinction relies on morphological traits, but the final decision is made by an expert committee. In the future, molecular markers could also b e used, either for the management of reference collections or for the asses sment of essential derivation. Our aims were to investigate the relationshi ps between morphological or molecular distances and the opinion of experts in maize. Experts were asked to give a visual estimation of the relatedness between inbred lines. The results validate the French approach of distinct ion where a morphological distance index is first computed, and then used a s a sieve to carefully observe only the closest varieties. Experts are also shown to be able to reconstruct the relatedness between two inbred lines f rom their phenotype. In that sense, they perform much better than classical morphological distance indices. ((C) Inra/Elsevier, Paris.)