Abstract
Spike architecture largely affects grain number embraced, which is a key factor influencing wheat grain yield. Here, we systematically explore the genetic regulation network governing wheat spike development by integration of multi-omic data with population genetics. Transcriptome and epigenome profile of shoot apex at eight developmental stages were generated. Gain-of-chromatin accessibility and changes of H3K27me3 coordinately associate with the progressive transcriptome alteration for flowering. A core transcriptional regulation network (TRN) that likely drives various meristematic cell identities transition to form spike was constructed. Integration of the TRN and genome-wide association analysis (GWAS), 260 transcription factors (TFs) were identified, including 52 characterized factors in crops, but mostly unstudied. Multi-layer regulatory module among TaSPL6, TaMADS34 and TaMADS14 suggested by TRN was further validated experimentally. About 85 novel TFs contain high impact mutant lines in KN9204 TILLING library. Of them, 44 TFs with homozygous mutation, including NAC, bHLH, MYB, and WRKY, show altered spike architecture. In particular, TaMYB4-A positively regulates fertile spikelet number likely via regulating hormones homeostasis or signaling, while acting downstream of- and repressed by WFZP. The elite allele of TaMYB4-A, with higher expression and more fertile spikelet, was selected during breeding process in China. Collectively, we present invaluable resource of high-confidence regulators and novel strategy for understanding the genetic regulation of wheat spike development systematically.
Competing Interest Statement
The authors have declared no competing interest.
