Improving in vivo maize doubled haploid production efficiency through early detection of false positives

In vivo doubled haploid (DH) technology provides a means of creating new maize inbred lines relatively quickly; however, productivity is limited by false-positive (FP) plants for haploidy and for dihaploidy, which consume resources of space and labour until detected. This work examines the potential for using stomata guard cell length measurement as a means for early detection of FP plants. We found that the true haploid and DH plants could be differentiated from FP and untreated diploid controls as early as Leaf 2 stage by stomata guard cell length measurement. Furthermore, DH plants were distinguishable from haploid and other diploid plants by the Leaf 7 growth stage. Results suggest that, when used together with screening through the anthocyanin colour marker system and flower fertility, stomata guard cell measurement is an easy, non-destructive, early screening method that may lead to a greater efficiency in DH production systems and optimization of resource allocation for space and labour.