The high-quality sequencing of the Brassica rapa‘XiangQingCai’genome and exploration of genome evolution and genes related to volatile aroma

‘Vanilla’(XQC,brassica variety chinensis)is an important vegetable crop in the Brassica family,named for its strong volatile fragrance.In this study,we report the high-quality chromosome-level genome sequence of XQC.The assembled genome length was determined as 466.11 Mb,with an N50 scaffold of 46.20 Mb.A total of 59.50%repetitive sequences were detected in the XQC genome,including 47570 genes.Among all examined Brassicaceae species,XQC had the closest relationship with B.rapa QGC(‘QingGengCai’)and B.rapa Pakchoi.Two whole-genome duplication(WGD)events and one recent whole-genome triplication(WGT)event occurred in the XQC genome in addition to an ancient WGT event.The recent WGT was observed to occur during 21.59-24.40 Mya(after evolution rate corrections).Our findings indicate that XQC experienced gene losses and chromosome rearrangements during the genome evolution of XQC.The results of the integrated genomic and transcriptomic analyses revealed critical genes involved in the terpenoid biosynthesis pathway and terpene synthase(TPS)family genes.In summary,we determined a chromosome-level genome of B.rapa XQC and identified the key candidate genes involved in volatile fragrance synthesis.This work can act as a basis for the comparative and functional genomic analysis and molecular breeding of B.rapa in the future.

Genome assembly of Polygala tenuifolia provides insights into its karyotype evolution and triterpenoid saponin biosynthesis

Polygala tenuifolia is a perennial medicinal plant that has been widely used in traditional Chinese medicine for treating mental diseases.However,the lack of genomic resources limits the insight into its evolutionary and biological characterization.In the present work,we reported the P.tenuifolia genome,the first genome assembly of the Polygalaceae family.We sequenced and assembled this genome by a combination of Illumnina,PacBio HiFi,and Hi-C mapping.The assembly includes 19 pseudochromosomes covering∼92.68%of the assembled genome(∼769.62 Mb).There are 36463 protein-coding genes annotated in this genome.Detailed comparative genome anal-ysis revealed that P.tenuifolia experienced two rounds of whole genome duplication that occurred∼39–44 and∼18–20 million years ago,respectively.Accordingly,we systematically reconstructed ancestral chromosomes of P.tenuifolia and inferred its chromosome evolution trajectories from the common ancestor of core eudicots to the present species.Based on the transcriptomics data,enzyme genes and transcription factors involved in the synthesis of triterpenoid saponin in P.tenuifolia were identified.Further analysis demonstrated that whole-genome duplications and tandem duplications play critical roles in the expansion of P450 and UGT gene families,which contributed to the synthesis of triterpenoid saponins.The genome and transcriptome data will not only provide valuable resources for comparative and functional genomic researches on Polygalaceae,but also shed light on the synthesis of triterpenoid saponin.

Evaluation on ChatGPT for Chinese Language Understanding

ChatGPT has attracted extension attention of academia and industry.This paper aims to evaluate ChatGPT in Chinese language understanding capability on 6 tasks using 11 datasets.Experiments indicate that ChatGPT achieved competitive results in sentiment analysis,summary,and reading comprehension in Chinese,while it is prone to factual errors in closed-book QA.Further,on two more difficult Chinese understanding tasks,that is,idiom fill-in-the-blank and cants understanding,we found that a simple chain-of-thought prompt can improve the accuracy of ChatGPT in complex reasoning.This paper further analyses the possible risks of using ChatGPT based on the results.Finally,we briefly describe the research and development progress of our ChatBIT.