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Polyploidy complicates transcriptional regulation and increases phenotypic diversity in organisms. The dynamics of genetic regulation of gene expression between coresident subgenomes in polyploids remains to be understood. Here we document the genetic regulation of fiber development in allotetraploid cottonGossypium hirsutumby sequencing 376 genomes and 2,215 time-series transcriptomes. We characterize 1,258 genes comprising 36 genetic modules that control staged fiber development and uncover genetic components governing their partitioned expression relative to subgenomic duplicated genes (homoeologs). Only about 30% of fiber quality-related homoeologs show phenotypically favorable allele aggregation in cultivars, highlighting the potential for subgenome additivity in fiber improvement. We envision a genome-enabled breeding strategy, with particular attention to 48 favorable alleles related to fiber phenotypes that have been subjected to purifying selection during domestication. Our work delineates the dynamics of gene regulation during fiber development and highlights the potential of subgenomic coordination underpinning phenotypes in polyploid plants.

 

Abstract. In the summer of 2017, heavy ozone pollution swamped most of the North ChinaPlain (NCP), with the maximum regional average of daily maximum 8 h ozoneconcentration (MDA8) reaching almost 120 ppbv. In light of the continuingreduction of anthropogenic emissions in China, the underlying mechanisms forthe occurrences of these regional extreme ozone episodes are elucidated fromtwo perspectives: meteorology and biogenic emissions. The significantpositive correlation between MDA8 ozone and temperature, which is amplifiedduring heat waves concomitant with stagnant air and no precipitation,supports the crucial role of meteorology in driving high ozoneconcentrations. We also find that biogenic emissions are enhanced due tofactors previously not considered. During the heavy ozone pollution episodesin June 2017, biogenic emissions driven by high vapor pressure deficit(VPD), land cover change and urban landscape yield an extra mean MDA8 ozoneof 3.08, 2.79 and 4.74 ppbv, respectively, over the NCP, which togethercontribute as much to MDA8 ozone as biogenic emissions simulated using theland cover of 2003 and ignoring VPD and urban landscape. In Beijing, thebiogenic emission increase due to urban landscape has a comparable effect onMDA8 ozone to the combined effect of high VPD and land cover change between2003 and 2016. In light of the large effect of urban landscape on biogenicemission and the subsequent ozone formation, the types of trees may becautiously selected to take into account of the biogenic volatile organic compound (BVOC) emission during the afforestation of cities. This study highlights the vital contributions ofheat waves, land cover change and urbanization to the occurrence of extremeozone episodes, with significant implications for ozone pollution control ina future when heat wave frequency and intensity are projected to increaseunder global warming.