Mutations inHUA2restore flowering in the Arabidopsistrehalose 6-phosphate synthase1(tps1) mutant

Abstract

AbstractPlant growth and development are regulated by many factors, including carbohydrate availability and signaling. Trehalose 6-phosphate (T6P), which is synthesized by TREHALOSE-6-PHOSPHATE SYNTHASE 1 (TPS1), is positively correlated with and functions as a signal that informs the cell about the carbohydrate status. Mutations inTPS1negatively affect the growth and development ofArabidopsis thalianaand complete loss-of-function alleles are embryo lethal, which can be overcome using inducible expression ofTPS1(GVG::TPS1) during embryogenesis. Using EMS mutagenesis in combination with genome re-sequencing we have identified several alleles in the floral regulatorHUA2that restore flowering and embryogenesis intps1-2 GVG::TPS1. Genetic analyses using aHUA2T-DNA insertion allele,hua2-4, confirmed this finding. RNA-seq analyses demonstrated thathua2-4has widespread effects on thetps1-2 GVG::TPS1transcriptome, including key genes and pathways involved in regulating flowering. Higher order mutants combiningtps1-2 GVG::TPS1andhua2-4with alleles in the key flowering time regulatorsFLOWERING LOCUS T(FT),SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1(SOC1), andFLOWERING LOCUS C(FLC) were constructed to analyze the role ofHUA2during floral transition intps1-2in more detail. Taken together, our findings demonstrate that loss ofHUA2can restore flowering and embryogenesis intps1-2 GVG::TPS1in part through activation ofFT, with contributions of the upstream regulatorsSOC1andFLC. Interestingly, we found that mutation ofFLCis sufficient to induce flowering intps1-2 GVG::TPS1. Furthermore, we observed that mutations inHUA2modulate carbohydrate signaling and that this regulation might contribute to flowering inhua2-4 tps1-2 GVG::TPS1.