The tin1 gene retains the function of promoting tillering in maize

Abstract

Sweet maize and popcorn retain tillering growth habit during maize diversification. However, the underlying molecular genetic mechanism remains unknown. Here, we show that the retention of maize tillering is controlled by a major quantitative trait locus (QTL), tin1, which encodes a C2H2-zinc-finger transcription factor that acts independently of tb1. In sweet maize, a splice-site variant from G/GT to C/GT leads to intron retention, which enhances tin1 transcript levels and consequently increases tiller number. Comparative genomics analysis and DNA diversity analysis reveal that tin1 is under parallel selection across different cereal species. tin1 is involved in multiple pathways, directly represses two tiller-related genes, gt1 and Laba1/An-2, and interacts with three TOPLESS proteins to regulate the outgrowth of tiller buds. Our results support that maize tin1, derived from a standing variation in wild progenitor teosinte population, determines tillering retention during maize diversification.

Variation in maize chlorophyll biosynthesis alters plant architecture

“…The Oy1-N1989 allele suppressed tillering conditioned by tin1 variant in P39 (Figure 9). The suppression of tillering in gt1 mutants in Oy1-N1989/+ backgrounds (Figure 10) is consistent with tin1 acting upstream of gt1 (Zhang et al 2019) to regulate tiller bud out growth. Oy1-N1989 also suppressed tb1 despite the fact that tb1 acts independently of tin1, suggests that loss of chlorophyll regulates branching upstream of the branch point between tb1 and tin1-gt1 (Figures 9 and 10; Table S10).…”

“…The maize gene, tiller number1 (tin1) encodes a C2H2-zinc-finger transcription factor which is a dominant factor responsible for increased tiller growth in the Purdue sweetcorn line P51 (Zhang et al 2019). TIN1 is upstream of GT1, but acts independently of TB1 (Kebrom and Brutnell 2015;Zhang et al 2019).…”

“…The maize gene, tiller number1 (tin1) encodes a C2H2-zinc-finger transcription factor which is a dominant factor responsible for increased tiller growth in the Purdue sweetcorn line P51 (Zhang et al 2019). TIN1 is upstream of GT1, but acts independently of TB1 (Kebrom and Brutnell 2015;Zhang et al 2019). The high tillering Purdue Sweetcorn line P39, encodes the same tin1 allele as P51 (Zhang et al 2019) possibly due to their common derivation from 'Golden Bantam' (www.ars-grin.gov).…”

“…TIN1 is upstream of GT1, but acts independently of TB1 (Kebrom and Brutnell 2015;Zhang et al 2019). The high tillering Purdue Sweetcorn line P39, encodes the same tin1 allele as P51 (Zhang et al 2019) possibly due to their common derivation from 'Golden Bantam' (www.ars-grin.gov). The Oy1-N1989 allele suppressed tillering conditioned by tin1 variant in P39 (Figure 9).…”

“…The levels of sucrose and other reducing sugars are lower in Oy1-N1989 and further modified by vey1 (Khangura et al 2019b). We tested if Oy1-N1989 modulated tiller outgrowth by crossing the mutant to well characterized prolific tillering genetic stocks such as (a) the maize inbred P39 which carries the high tillering allele at tiller number1 (Zhang et al 2019), (b) the classical dominant tillering mutant Tillering1, and (c) a semi-dominant tb1 in a mixed background. The tillering of the F1 hybrids between B73 and all three high tillering lines (sweet corn inbred P39, Tlr1, and tb1) was suppressed by Oy1-N1989 allele (Figure 9 and Table S10).…”