HaHB11 transformed maize has improved yield under waterlogging and defoliation in control and field conditions

HaHB11 is a sunflower transcription factor previously described as conferring improved yield to maize hybrids and lines. Here we report that transgenic HaHB11 maize lines exhibited a better performance funder waterlogging, both in greenhouse and field trials carried out during three growth cycles. One of these trials was particularly affected by a strong storm during flowering, causing severe defoliation. Controlled defoliation assays indicated that the transgenic genotypes were able to set more grains than controls. Hybrids were generated by crossing B73 HaHB11 lines with the contrasting Mo17 lines and tested in the field. These hybrids exhibited the same beneficial traits as the parental lines when compared with their respective controls. Waterlogging tolerance coursed via the root architecture improvement, including more xylem vessels, reduced tissue damage, less superoxide accumulation, and altered carbohydrate metabolism compared to controls. Multivariate analyses corroborated the robustness of the differential traits observed. Furthermore, canopy spectral reflectance data, computing 29 vegetation indices associated with biomass, chlorophyll, and abiotic stress, helped to identify genotypes as well as their growing conditions. Altogether the results reported here indicate that this sunflower gene constitutes a suitable tool to improve maize plants for environments prone to waterlogging and/or wind defoliation. One sentence summaryPhenotyping and big data analyses indicate that the transcription factor HaHB11 confers waterlogging and defoliation tolerance, and increased yield to maize lines and hybrids in all tested conditions.