Recent Advances in Assembly of Complex Plant Genomes

Over the past 20 years,tremendous advances in sequencing technologies and computational algorithms have spurred plant genomic research into a thriving era with hundreds of genomes decoded already,ranging from those of nonvascular plants to those of flowering plants.However,complex plant genome assembly is still challenging and remains difficult to fully resolve with conventional sequencing and assembly methods due to high heterozygosity,highly repetitive sequences,or high ploidy characteristics of complex genomes.Herein,we summarize the challenges of and advances in complex plant genome assembly,including feasible experimental strategies,upgrades to sequencing technology,existing assembly methods,and different phasing algorithms.Moreover,we list actual cases of complex genome projects for readers to refer to and draw upon to solve future problems related to complex genomes.Finally,we expect that the accurate,gapless,telomere-totelomere,and fully phased assembly of complex plant genomes could soon become routine.

Innovative computational tools provide new insights into the polyploid wheat genome

Bread wheat(Triticum aestivum)is an important crop and serves as a significant source of protein and calories for humans,worldwide.Nevertheless,its large and allopolyploid genome poses constraints on genetic improvement.The complex reticulate evolutionary history and the intricacy of genomic resources make the deciphering of the functional genome considerably more challenging.Recently,we have developed a comprehensive list of versatile computational tools with the integration of statistical models for dissecting the polyploid wheat genome.Here,we summarize the methodological innovations and applications of these tools and databases.A series of step-by-step examples illustrates how these tools can be utilized for dissecting wheat germplasm resources and unveiling functional genes associated with important agronomic traits.Furthermore,we outline future perspectives on new advanced tools and databases,taking into consideration the unique features of bread wheat,to accelerate genomic-assisted wheat breeding.

Digital Karyotyping with Whole Genomic Sequencing for Complex Congenital Disorder

Complex congenital disorders may be caused by multiple genetic alterations and/or environmental hazards. Diagnosis and management of these diseases are usually difficult. Robust next-generation sequencing （NGS） technologies provide unprecedented opportunities to maximize mutation detection and improve genetic counseling and clinical management. Targeted or whole exome sequencing （WES） mainly detects protein-coding DNA sequence aberrations and is the major DNA sequencing technology that is entering clinical practice （Liu et al., 2014）.

A High-throughput Genomic Tool： Diversity Array Technology Complementary for Rice Genotyping

Diversity array technology （DART^TM） was a genotyping tool characterized gel-independent and high throughput. The main purpose of present study is to validate DArT for rice （Oryza sativa L.）genotyping in a high throughput manner. Technically, the main objective was to generate a rice general purpose gene pool, and optimize this genomic tool in order to evaluate rice germplasm genetic diversity. To achieve this, firstly, a generalpurpose DArT array was developed. Ten representatives from 24 varieties were hybridized with the general-purpose array to determine the informativeness of the clones printed on the array. The informative 1 152 clones were re-arrayed on a slide and used to fingerprint 17 of 24 germplasms. Hybridizing targets prepared from the germplasm to be assayed to the DNA array gave DNA fingerprints of germplasms. Raw data were normalized and transformed into binary data, which were then analyzed by using NTSYSpc （Numerical taxonomy system for cluster and ordination analysis, v. 2.02j） software package. The graphically displayed dendrogram derived from the array experimental data was matched with simple sequence repeats genotyping outline and varieties＇ pedigree deviation of the different varieties. Considering DArT is a sequence-independent genotyping approach, it will be applied in studies of the genetic diversity and the gene mapping of diverse of organisms, especially for those crops with less-developed molecular markers.