De novo assembly of a new Olea europaea genome accession using nano pore seque ncing

Olive(Olea europaea L.)is internationally renowned for its high-end product,extra virgin olive oil.An incomplete genome of O.europaea was previously obtained using shotgun sequencing in 2016.To further explore the genetic and breeding utilization of olive,an updated draft genome of olive was obtained using Oxford Nanopore third-generation sequencing and Hi-C technology.Seven different assembly strategies were used to assemble the fi nal genome of 1.30 Gb,with contig and scaffold N50 sizes of4.67 Mb and 42.60 Mb,respectively.This greatly increased the quality of the olive genome.We assembled 1.1 Gb of sequences of the total olive genome to 23 pseudochromosomes by Hi-C,and 53,518 protein-coding genes were predicted in the current assembly.Comparative genomics analyses,including gene family expansion and contraction,whole-genome replication,phylogenetic analysis,and positive selection,were performed.Based on the obtained high-quality olive genome,a total of nine gene families with 202 genes were identi fi ed in the oleuropein biosynthesis pathway,which is twice the number ofgenes identi fi ed from the previous data.This new accession of the olive genome is of suf fi cient quality for genome-wide studies on gene function in olive and has provided a foundation for the molecular breeding of olive species.

Transcriptome-wide effect of Salix SmSPR1 in etiolated seedling of Arabidopsis

Microtubules and their regulatory proteins are involved in the regulation of plant cell morphology.SPIRAL1(SPR1),a plant-specific microtubule-binding protein,is critical in regulating the anisotropic growth of plant cells.Our previous study showed that overexpressed S alix SmS PR1 genes in Arabidopsis thaliana caused right-handed spiral elongation in etiolated seedlings,but there were no morphological differences between wild-type and transgenic seedlings under varied light conditions.We then studied the transcriptional regulation patterns in transgenic plants engineered with the S mSPR1 gene.Transcriptomic results showed that a large number of differentially expressed genes were involved in plant light signal reception,chlorophyll synthesis and photosystem structure.Eleven gene families with 42 photosynthesis-related genes and 6 light-responsive genes were involved in regulation of cell morphology.Our results showed that these genes in the SmSPR1-ox line were particularly down-regulated under dark conditions.In addition,33 TFs showed differences between S mSPR1-ox and wild-type lines.Taken together,the transcriptome analysis provides new insight into investigating the molecular mechanisms of light-induced cell morphological changes mediated by the microtubule binding protein SPR1.