Overexpression ofZmDWF4improves major agronomic traits and enhances yield in maize

摘要

Brassinosteroids (BRs) are a class of plant-specific steroid hormones and play an essential role in plant growth and development. TheDWARF4(DWF4) gene encodes a C-22 hydroxylase, which is a rate-limiting enzyme in BR biosynthesis pathway. Here, theDWF4(ZmDWF4) in maize (Zea maysL.), the ortholog ofArabidopsis DWF4(CYP90B1), was transformed into elite inbred Q319 and driven maize ubiquitin promoter. In transgenic lines, the level of the endogenous BR precursor canosterone (CS) was significantly enhanced.ZmDWF4overexpression greatly improved grain yield per ear from 28.3 to 33.5% in transgenic lines compared with that in non-transgenic Q319 plants. Moreover,ZmDWF4overexpression significantly enhanced heterosis of combinations by increasing both seed number and seed weight up to 20.4% in transgenic hybrids. Further analysis revealed thatZmDWF4overexpression significantly improved several agronomic traits and leaf photosynthetic ability in transgenic lines. Finally, RNA-seq analysis suggested that overexpressingZmDWF4improved cell growth, cell division, and nutrient assimilation in transgenic kernels. Altogether, our results demonstrate that manipulating BR level by overexpressingZmDWF4effectively improves maize agronomic traits, and thus, provides a useful biotechnological strategy for the genetic improvement and further commercially favorable maize breeding.