A gene regulatory network for tiller development mediated by Tin8 in maize.

The complex gene regulatory network underlying maize tiller development remains largely unknown. Here we identified two major quantitative trait loci (QTLs) for tiller number, Tin8 on chromosome 8 and the previously known Tb1 on chromosome 1, in a population derived from a teosinte-maize cross. Map-based cloning and association mapping revealed that Tin8 corresponding to Zcn8 encoding a PEBP-related kinase, is down-regulated in transcription and thus results in decreased tiller number. Strong interaction between Tin8 and the key gen Tb1 was detected for tiller number. Further RNA-seq analysis showed that the expressions of 13 genes related to tiller development were controlled by Tin8. Our results support the existence of a complex gene regulatory network for the outgrowth of maize tiller bud, in which Zcn8 controls 13 tiller-related genes including four genes for hormonal responses. Especially, Zcn8 represses Gt1, D14 and Tru1, through the interaction of Tb1.