A regulatory network controlling developmental boundaries and meristem fates contributed to maize domestication

Abstract

During domestication, early farmers selected different vegetative and reproductive traits, but identifying the causative loci has been hampered by their epistasis and functional redundancy. Using chromatin immunoprecipitation sequencing combined with genome-wide association analysis, we uncovered a developmental regulator that controls both types of trait while acting upstream of multiple domestication loci. tasselsheath4 (tsh4) is a new maize domestication gene that establishes developmental boundaries and specifies meristem fates despite not being expressed within them. TSH4 accomplishes this by using a double-negative feedback loop that targets and represses the very same microRNAs that negatively regulate it. TSH4 functions redundantly with a pair of homologs to positively regulate a suite of domestication loci while specifying the meristem that doubled seed yield in modern maize. TSH4 has a critical role in yield gain and helped generate ideal crop plant architecture, thus explaining why it was a major domestication target. Maize transcription factor TASSELSHEATH4 establishes the leaf versus meristem cell boundary and vegetative versus floral axillary meristem fates as part of a domestication gene network.