Dan Lewis is best known for his work on plant breeding systems. Self-incompatibility is common in hermaphroditic plants as a mechanism that prevents inbreeding; it may be determined by genes expressed in the haploid gametes (gametophytic) or by those expressed in the diploid tissue that gives rise to gametes (sporophytic). At different times in his career, Lewis contributed to a better understanding of both these systems, but it was his work on the gametophytic system in the evening primrose,
Oenothera organensis
, that broke new ground and enabled him to predict a molecular recognition between different proteins produced in the pollen and style; these proteins were encoded by tightly linked genes at a complex self-incompatibility (
S
) locus. Modern molecular techniques have since confirmed these predictions and revealed the actual nature of the proteins and their interactions. The research began as part of a programme of breeding plants of horticultural and agricultural importance while working at the John Innes Institute, the foremost place to study genetics in the UK at that time. The Institution had William Bateson (FRS 1894) as its first director, followed by Sir Daniel Hall (FRS 1909), who in turn was succeeded in 1939 by Cyril Darlington (FRS 1941). To begin your career there in the 1930s was almost guaranteed to lead to scientific success.
Geography of plant breeding systems, agroclimatic similarity, and agricultural productivity: evidence from Nigeria