| Apis cerana cerana in Changbai Mountain is an ecological type of eastern honey bees(Apis cerana)formed by long-term natural selection under the ecological conditions of Changbai Mountain,which bears excellent traits such as rapid reproduction,strong maintenance of colonies,collection capability,resistance to adversity,and cold tolerance.Unfortunately,the biotic and abiotic factors,such as ecological invasion of Apis mellifera,habitat loss and fragmentation,overexploitation of biological resources,intensive agricultural development,pathogenic microbial infection,overuse of pesticides,global warming,and atmospheric pollution,have caused a massive decline in the population size and distribution density of A.cerana cerana in Changbai Mountain.The population are in an endangered-sustained state.The protection,evaluation and utilization of the germplasm genetic resources are imminent.In this study,the germplasm resources of A.cerana cerana in Changbai Mountain were evaluated from the aspects of resource traits,genetic diversity and cold-resistance adaptability,in order to provide technical support for the scientific protection of this resource.The main results are as follows:1.Based on the determination of the indexes of production performance and biological characteristics of A.cerana cerana in Changbai Mountain during the blooming period of Tilia.The results showed that the nectar collecting ability,colony fecundity and colony development rate were reached the peak at the florescence stage,and there were significant differences among different time stages(P<0.05).There was a very significant negative correlation between nectar collecting ability and environmental temperature(P<0.01),and significant negative correlation between colony development rate and environmental temperature(P<0.05).It can be concluded that the A.cerana cerana in Changbai Mountain has strong collecting ability and good environmental adaptability during the blooming period of Tilia.2.Based on the geometric morphometric analysis of 300 wing specimens of eastern honey bees from 30 populations in 5 geographical regions,including North,Northwest,Qinghai-Tibet,South and Changbai Mountain.The results showed that A.cerana cerana in Changbai Mountain had larger wings,and the average CS value was significantly correlated with latitude and altitude,which increased with the increase of latitude and altitude(P<0.05);The main positions of the variation of the forewing are LM9-10 and LM1-3,and the main positions of the variation of the hindwing are LM3-6;There was a certain degree of wing morphological differentiation was observed within A.cerana cerana in Changbai Mountain,with no signifcant diferentiation observed between the individuals from Jilin and Heilongjiang,and signifcant diferentiation observed between Liaoning individuals.3.Based on the whole-genome resequencing of 130 individuals in 5 geographic regions,the genetic structure,genetic differentiation,genetic diversity and population history of A.cerana cerana in Changbai Mountain were analyzed.The results showed that when K=2-5,Jilin individuals except Ji’an area and all Heilongjiang individuals were came from the same ancestor,while Liaoning individuals and Ji’an individuals were mixed,which was consistent with the results of PCA and phylogenetic tree;The mean Fst was 0.2294 between the individuals from Changbai Mountain and the A.cerana from the northern,northwestern,southern,and Qinghai-Tibetan regions,showing a high degree of genetic diferentiation.The average Fst between the individuals from Heilongjiang and Jilin was 0.1002,which indicated moderate to low diferentiation.Notably,the individuals from Liaoning reached a high degree of genetic diferentiation,with an average Fst of 0.1506.A.cerana cerana in Changbai Mountain had the lowest π,lowest He,highest Ho,highest F,and the slowest LD decay;The quantitative variation in the effective population size of A.cerana cerana in Changbai Mountain coincided with the cyclical variation in historical global temperature;From the MIS4 to the Holocene period,the A.cerana population in Changbai Mountain experienced two signifcant population contractions and one signifcant population expansion compared with populations in other regions;The selective sweep analysis between Changbai Mountain individuals and Hainan individuals obtained 273 selected genes in Changbai Mountain population,which were significantly enriched to 99 GO items and 5 KEGG pathways(P<0.05),5 highly enriched functional categories such as serine/threonine protein kinase were identified.4.Based on the measure of the activities of protective enzymes and physiological indexes related to cold tolerance,including SOD,CAT and POD,as well as the contents of total amino acids,glycogen,glucose and glycerol of A.cerana cerana in Changbai Mountain and Italian honeybee(Apis mellifera L.)during overwintering,and preliminarily explored the physiological mechanism of the difference in cold tolerance between Changbai Mountain population and Italian honeybee.The results showed that the overall performance of SOD,CAT and POD activities in A.cerana cerana in Changbai Mountain were better than that of Italian honeybee(P?0.05),indicating that the protective enzyme system might play an important role in defense.The contents of total amino acids,glycogen,glucose and glycerol of A.cerana cerana in Changbai Mountain fluctuated obviously in each periods,and the contents of total amino acids,glucose and glycerol were generally higher than those of Italian honeybee,which might be the key antifreeze protective substances of A.cerana cerana in Changbai Mountain during overwintering period.5.Based on Oxford nanopore sequencing technology,the full-length transcriptome data of A.cerana cerana in Changbai Mountain during overwintering were obtained,17398 transcripts were obtained,and 5941 complete ORFs,1193 Lnc RNAs,10866 SSRs,and 619 TFs were predicted.The results showed that the AS events and the number of genes with APA in the overwintering period were significantly more than those in the non-overwintering period(P?0.05),indicating that honeybee would produce more AS events and APA mechanisms to deal with the adverse environment under cold stimulation;The statistics and analysis of DETs and DEGs showed that their upregulated expression in the Hippo and Fox O signal pathway and downregulated expression in the MARK pathway were important aspects of the molecular mechanism of A.cerana cerana in Changbai Mountain during overwintering period.In conclusion,our study provided basic data and useful insights for the evaluation of germplasm resources,genetic diversity,adaptive evolution,molecular mechanism of cold-resistance of A.cerana cerana in Changbai Mountain,as well as the scientific conservation of this population. |
PDF Full Text Request