The Genetic Architecture of Maize Flowering Time

TLDR

Flowering time is a complex trait that governs maize adaptation to local environments. The study used 5,000 recombinant inbred lines from a maize NAM population to dissect flowering time variation. No large‑effect QTLs were found; instead, many small‑effect QTLs shared across families with founder‑specific allelic effects were identified, and a simple additive model accurately predicts flowering time, contrasting with rice and Arabidopsis.

Abstract

Flowering time is a complex trait that controls adaptation of plants to their local environment in the outcrossing species Zea mays (maize). We dissected variation for flowering time with a set of 5000 recombinant inbred lines (maize Nested Association Mapping population, NAM). Nearly a million plants were assayed in eight environments but showed no evidence for any single large-effect quantitative trait loci (QTLs). Instead, we identified evidence for numerous small-effect QTLs shared among families; however, allelic effects differ across founder lines. We identified no individual QTLs at which allelic effects are determined by geographic origin or large effects for epistasis or environmental interactions. Thus, a simple additive model accurately predicts flowering time for maize, in contrast to the genetic architecture observed in the selfing plant species rice and Arabidopsis.