MaDREB1F confers cold and drought stress resistance through common regulation of hormone synthesis and protectant metabolite contents in banana

Adverse environmental factors severely affect crop productivity.Improving crop resistance to multiple stressors is an important breeding goal.Although CBFs/DREB1s extensively participate in plant resistance to abiotic stress,the common mechanism underlying CBFs/DREB1s that mediate resistance to multiple stressors remains unclear.Here,we show the common mechanism for MaDREB1F conferring cold and drought stress resistance in banana.MaDREB1F encodes a dehydration-responsive element binding protein(DREB)transcription factor with nuclear localization and transcriptional activity.MaDREB1F expression is significantly induced after cold,osmotic,and salt treatments.MaDREB1F overexpression increases banana resistance to cold and drought stress by common modulation of the protectant metabolite levels of soluble sugar and proline,activating the antioxidant system,and promoting jasmonate and ethylene syntheses.Transcriptomic analysis shows that MaDREB1F activates or alleviates the repression of jasmonate and ethylene biosynthetic genes under cold and drought conditions.Moreover,MaDREB1F directly activates the promoter activities of MaAOC4 and MaACO_(2)0 for jasmonate and ethylene syntheses,respectively,under cold and drought conditions.MaDREB1F also targets the MaERF11 promoter to activate MaACO_(2)0 expression for ethylene synthesis under drought stress.Together,our findings offer new insight into the common mechanism underlying CBF/DREB1-mediated cold and drought stress resistance,which has substantial implications for engineering cold-and drought-tolerant crops.

Allele-defined genome reveals biallelic differentiation during cassava evolution

Dear Editor,Generation of heterozygous genomes by hybridization between or within species can help maintain plant diversity and serve as a potential source of new species(Baek et al.,2018).Moreover,genomic heterozygosity is associated with genomic coadaptation,developmental stability,and heterosis.Accurate definition of alleles in haplotypes is necessary to precisely characterize allelic variation controlling agriculturally important traits(Shi et al.,2019).Currently,most released genomes have mosaic assembly of haplotypes due to random selection or collapse of alleles during genome assembly(Shi et al.,2019),which masked allelic variation and functional differentiation of divergent alleles in heterozygous species.