dlf1 promotes floral transition by directly activating ZmMADS4 and ZmMADS67 in the maize shoot apex

Abstract

The floral transition of the maize (Zea mays ssp. mays) shoot apical meristem determines leaf number and flowering time, which are key traits influencing local adaptation and yield potential. dlf1 (delayed flowering1) encodes a basic leucine zipper protein that interacts with the florigen ZCN8 to mediate floral induction in the shoot apex. However, the mechanism of how dlf1 promotes floral transition remains largely unknown. We demonstrate that dlf1 underlies qLB7-1, a quantitative trait locus controlling leaf number and flowering time that was identified in a BC 2 S 3 population derived from a cross between maize and its wild ancestor, teosinte (Zea mays ssp. parviglumis). Transcriptome sequencing and chromatin immunoprecipitation sequencing demonstrated that DLF1 binds the core promoter of two AP1/FUL subfamily MADS-box genes, ZmMADS4 and ZmMADS67, to activate their expression. Knocking out ZmMADS4 and ZmMADS67 both increased leaf number and delayed flowering, indicating that they promote the floral transition. Nucleotide diversity analysis revealed that dlf1 and ZmMADS67 were targeted by selection, suggesting that they may have played important roles in maize flowering time adaptation. We show that dlf1 promotes maize floral transition by directly activating ZmMADS4 and ZmMADS67 in the shoot apex, providing novel insights into the mechanism of maize floral transition.

Linkage mapping combined with GWAS revealed the genetic structural relationship and candidate genes of maize flowering time-related traits

“…The floral transition is an important developmental trait for plant adaptation and reproduction and has been considered a critical selection criterion in crop breeding [1]. Over the past few decades, the major components and genetic pathways controlling maize flowering time have been preliminarily determined [2], and some important flowering time genes have been screened [3][4][5], but there are some challenges to study the flowering time of maize [6], and new regulatory sites still need to be uncovered.…”

Characterization of Frond and Flower Development and Identification of FT and FD Genes From Duckweed Lemna aequinoctialis Nd

“…The FAC activate downstream genes including the MADS-box transcription factors APETALA1 (AP1)/FRUITFUL (FUL) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) that strongly promote the transition of the shoot apex from the vegetative stage to the reproductive stage for floral organ formation. This regulatory process required for flowering is conserved across diverse plant species including tomato, poplar, and maize (Park et al, 2014;Tylewicz et al, 2015;Sun et al, 2020). In duckweeds, however, the expression and function of these flowering genes are not well characterized.…”

SDG102, a H3K36-Methyltransferase-Encoding Gene, Plays Pleiotropic Roles in Growth and Development of Maize (Zea mays L.)

“…The FT-like ZCN8 and its close paralog ZCN7 are key genes in controlling the flowering time in maize. Their proteins are produced in leaves and move to the shoot apex to promote MADS4 and MADS67 by interacting with DLF1, ultimately regulating the flowering time [9][10][11]15]. To obtain insights into the molecular mechanism underlying the downregulation of flowering genes in SDG102deficient plants, ChIP assays were conducted to investigate the histone methylation levels in the ZCN8/CZN7 chromatin.…”

“…ZCN8 from leaves interacts with DELAYED FLOWERING1 (DLF1), a maize ortholog of Arabidopsis FD, in the shoot apex to form a complex [10,13]. This complex activates the expression of AP1-like MADS-box meristem identity genes such as ZmMADS4 (or ZMM4), ZmMADS15 (or ZMM15), and ZmMADS67 (or ZMM28), marking the start of maize reproductive development [14,15]. ZmMADS1, a maize functional ortholog of the key flowering integrator SOC1 in A. thaliana, is a positive flowering regulator that directly promotes ZCN8 expression [16,17].…”