Integrative analysis of the metabolome and transcriptome reveals the potential mechanism of fruit flavor formation in wild hawthorn(Crataegus chungtienensis)

Hawthorns are important medicinal and edible plants with a long history of health protection in China.Besides cultivated hawthorn,other wild hawthorns may also have excellent medicinal and edible value,such as Crataegus chungtienensis,an endemic species distributed in the Southwest of China.In this study,by integrating the flavor-related metabolome and transcriptome data of the ripening fruit of C.chungtienensis,we have developed an understanding of the formation of hawthorn fruit quality.The results show that a total of 849 metabolites were detected in the young and mature fruit of C.chungtienensis,of which flavonoids were the most detected metabolites.Among the differentially accumulated metabolites,stachyose,maltotetraose and cis-aconitic acid were significantly increased during fruit ripening,and these may be important metabolites affecting fruit flavor change.Moreover,several flavonoids and terpenoids were reduced after fruit ripening compared with young fruit.Therefore,using the unripe fruit of C.chungtienensis may allow us to obtain more medicinal active ingredients such as flavonoids and terpenoids.Furthermore,we screened out some differentially expressed genes(DEGs)related to fruit quality formation,which had important relationships with differentially accumulated sugars,acids,flavonoids and terpenoids.Our study provides new insights into flavor formation in wild hawthorn during fruit development and ripening,and at the same time this study lays the foundation for the improvement of hawthorn fruit flavor.

Directional neighbor discovery in mmWave wireless networks

The directional neighbor discovery problem,i.e,spatial rendezvous,is a fundamental problem in millimeter wave(mmWave)wireless networks,where directional transmissions are used to overcome the high attenuation.The challenge is how to let the transmitter and the receiver beams meet in space under deafness caused by directional transmission and reception,where no control channel,prior information,and coordination are available.In this paper,we present a Hunting based Directional Neighbor Discovery(HDND)scheme for ad hoc mmWave networks,where a node follows a unique sequence to determine its transmission or reception mode,and continuously r0-tates its directional beam to scan the neighborhood for other mmWave nodes.Through a rigorous analysis,we derive the conditions for ensured neighbor discovery,as well as a bound for the worst-case discovery time and the impact of sidelobes.We validate the analysis with extensive simulations and demonstrate the superior perfor-mance of the proposed scheme over several baseline schemes.

Cultivated hawthorn(Crataegus pinnatifida var.major)genome sheds light on the evolution of Maleae(apple tribe)

Cultivated hawthorn(Crataegus pinnatifida var.major)is an important medicinal and edible plant with a long history of use for health protection in China.Herein,we provide a de novo chromosomelevel genome sequence of the hawthorn cultivar“Qiu Jinxing.”We assembled an 823.41 Mb genome encoding 40571 genes and further anchored the779.24 Mb sequence into 17 pseudo-chromosomes,which account for 94.64%of the assembled genome.Phylogenomic analyses revealed that cultivated hawthorn diverged from other species within the Maleae(apple tribe)at approximately 35.4 Mya.Notably,genes involved in the flavonoid and triterpenoid biosynthetic pathways have been significantly amplified in the hawthorn genome.In addition,our results indicated that the Maleae share a unique ancient tetraploidization event;however,no recent independent whole-genome duplication event was specifically detected in hawthorn.The amplification of non-specific long terminal repeat retrotransposons contributed the most to the expansion of the hawthorn genome.Furthermore,we identified two paleo-sub-genomes in extant species of Maleae and found that these two sub-genomes showed different rearrangement mechanisms.We also reconstructed the ancestral chromosomes of Rosaceae and discussed two possible paleopolyploid origin patterns(autopolyploidization or allopolyploidization)of Maleae.Overall,our study provides an improved context for understanding the evolution of Maleae species,and this new highquality reference genome provides a useful resource for the horticultural improvement of hawthorn.