Introgression of teosinte branched1 gene from wild-progenitor enhances prolificacy in subtropically-adapted maize
摘要
Introgression of the tb1-T allele from teosinte into subtropically adapted maize inbreds led to an ~3-fold enhancement in prolificacy in reconstituted hybrids, underscoring its significant utility in baby corn breeding.
AbstractTraditional maize generally possesses one ear per plant in contrast to >100 ears found in its wild relative - teosinte. The teosinte branched1 (tb1) gene has been identified as the master regulator for prolificacy (>1 ears per plant) in maize. So far, tb1 gene has not been introgressed into subtropical maize germplasm for enhancement of prolificacy using marker-assisted backcross breeding (MABB). Here, tb1-T allele present in teosinte (Zea mays ssp. parviglumis) has been introgressed into seven elite parental inbreds using molecular breeding. Seven inbreds with tb1-M allele were parents of nine popular maize hybrids. We developed an InDel functional marker (MGU-tb1-Hopscotch) that successfully differentiated the tb1-T (722 bp) allele from tb1-M (559 bp) allele, and used in BC1F1, BC2F1 and BC2F2 generations. Severe segregation distortion of tb1 gene was observed in segregating generations across crosses. Background selection using 98–113 simple sequence repeats (SSRs) led to 90.2–97.9% recovery of recurrent parent genome (RPG) among introgressed progenies. The introgressed inbreds possessed a mean of 2.79 (range: 2.27–3.47) ears per plant over 1.56 (range: 1.00–2.07) across recurrent parents. Multi-environment evaluation revealed that the reconstituted hybrids also possessed higher prolificacy (average: 3.22, range: 2.42–3.96) over their original hybrids (average: 1.30, range: 1.00–2.11). MABB-derived hybrids also showed higher prolificacy (2.52-fold) over their introgressed inbreds (1.79-folds). Improved inbreds and hybrids were at par with their original versions for morphological traits. No visible linkage drag was observed among the MABB-derived genotypes. These tb1-T-derived maize hybrids with higher prolificacy possess great potential especially in baby corn breeding. The present study highlighted the role of wild progenitors for genetic improvement in modern maize.