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[Objective] Through conducting a in-depth study on the variety diversity of Yunnan big-leaf tea, analyzing the diversity of their biochemical components with corresponding varieties and screening the specific varieties, the purpose of this paper was to provide theoretical guidance for the exploration, utilization, reproduction of those specific varieties. [Method] The biochemical components of autumn tea of 26 Yunnan big-leaf tea varieties were determined, and based on the results, principal component analysis and cluster analysis were carried out. [Result] The biochemical components of 26 varieties had rich diversity and variation, with an average coefficient of variation of 25.53%. Among the four conventional biochemical components, the largest coefficient of variation was amino acid, up to 14.13%. Among the catechin components, catechin had the largest coefficient of variation, reaching 63.51%. Multivariate principal component analysis showed that the first three principal components accounted for 77.179% of the diversity of biochemical components of 26 varieties, the variance accounted for by the first principal component was 50.165%, the contribution of phenol ammonia ratio was the largest; the variance accounted for by the second principal component was 16.894%, the contribution of epicatechin (EC) was the largest; the variance accounted for by the third principal component was 10.120%, and the contribution of epigallocatechin gallate (EGCG) was the largest. Based on the clustering of 12 biochemical components of 26 variety resources, three groups were formed. The first group mainly was Yunkang series variety resources, which were mainly characterized by high contents of water extract, tea polyphenols, phenol ammonia ratio, total catechin, catechin DL-C and epigallocatechin gallate (ECG), and low contents of amino acids and epigallocatechin (EGC) . The second group was Yunnan large leaf population resources, which were characterized by high contents of amino acids, caffeine and EC, and low contents of total catechin, EGCG and ECG, The third group was mainly artificial hybrid variety resources, which were characterized by high contents of EGC and EGCG, and low contents of water extract, tea polyphenols, caffeine, phenol ammonia ratio, catechin DL-C and EC. The contents of four conventional components of the three groups were relatively consistent, and there were differences in phenol ammonia ratio and catechin content. [Conclusion] 26 Yunnan big-leaf tea variety resources have rich genetic diversity, with 26 high tea polyphenol resources, 1 high caffeine resources and 15 high catechin resources were preliminarily screened. [ABSTRACT FROM AUTHOR]

[Objective] The pmpose of this paper is to obtain the basis information of Potyviruses distribution and investigate Potyvirus species between resistant and susceptible tobacco varieties to PVY in field in Yunnan Province. [Method] During 2017 to 2019,497 tobacco samples with typical Potyviral symptoms were collected in 5 cities, 13 tobacco planting counties (districts) in Yunnan Province and the types of Potyviruses on the main susceptible and resistant varieties to PVY were analyzed. [Result] The results showed that 85. 1 % of 497 tobacco samples were infected by Potyviruses in total. Furthermore, the detection rates of TVBMV, ChiVMV, PVY, and TEV were 58. 8 %, 23. 3 %, 14. 9% and 7. 8% respectively. In terms of the rank of detection rates of Potyviruses in the PVY susceptible varieties, the detection rate of TVBMV was the highest in Qujing,and for ChiVMV was in Yuxi,and for PVY was in Zhaotong. The PVY detection rate on the PVY-resistance varieties was 5. 8% around and much lower than that of susceptible varieties (22. 5%). PVY resistant varieties showed a good crop protection for the PVY disease. [ Conclusion] The analysis showed that the resistant varieties which contained va locus dramatically reduced the yield loss in the high incidence areas of PVY, and the increase of TVBMV detection rate in PVY resistant varieties was due to the decrease of PVY incidence rate, and the resistant varieties did not increase the harm of TVBMV and ChiVMV. However, the single va resistant locus had no effect on the TVBMV and ChiVMV. Therefore, the investigation of Potyviruses species should be carried out before introduce va-containing varieties into the area. TVBMV and ChiVMV had been the emerging disease in Yunnan's main tobacco growing areas, resulting in low yield and quality loss. It is necessary to establish new method to detect these causal agents and to screen moreresistant germplasm resources for TVBMV and ChiVMV. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this paper is to explore the relationship between the main chemical components of flue-cured tobacco and soil chemical properties. [Method] All of 235 tobacco leaf samples and soil samples were collected from typical aromatic tobacco growing areas in Yunnan province. The main soil factors affecting the chemical quality of Yunnan fragrant tobacco leaves were studied by correlation analysis, stepwise regression analysis and principal component analysis. [Result] The contents of total sugar and reducing sugar in Yunnan tobacco were 30.87% and 27.21, respectively ;the contents of total nitrogen, nicotine and potassium were in the appropriate range, which were 1.91, 2.63% and 1.91% respectively ;The results showed that the pH value of the main tobacco planting soils in Yunnan was moderate, with an average of 6.3. The contents of total nitrogen, total phosphorus, available molybdenum and available sulfur were in the rich level. The contents of total potassium and humic acid were on the low level. The contents of organic matter, fulvic acid, available boron, water-soluble chloride ion, salt content and CEC (total amount of cation exchange) were in the middle level. The contents of total sugar, reducing sugar, starch and potassium in tobacco leaves were significantly positive correlation with total potassium in soil. Two sugar difference and sugar alkali ratio were significantly positive correlation with soil available molybdenum content. Two sugar difference was significantly positive correlation with soil humic acid content, and was significantly negative correlation with soil chloride ion content. [Conclusion] The contents of total potassium, available molybdenum, humic acid and water-soluble chloride ion in tobacco growing soil of Yunnan tobacco growing areas are the most important indicators affecting the chemical quality of tobacco leaves in Yunnan. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to investigate occurrence and distribution of Potato virus A(PVA), and analyze genetic variation of PVA in Yunnan Province. [Method] Using DAS-ELISA, 389 potato samples from 19 potato-growing regions of Yunnan Province were tested.Using RT-PCR, P3 protein genes of PVA from 5 positive potato samples were amplified, cloned and sequenced.P3 protein gene sequences of 5 PVA isolates from different regions of Yunnan Province and other 13 PVA isolates were analyzed by DNAMAN and DNAStar, and phylogenetic tree was constructed by Neighbor-joining(NJ) method of MEGA6.0. [Result] The positive sample detertion rates of PVA were 20.82 % among 389 samples. The DNA fragments of 1041 bp were amplified from 5 positive samples of PVA from different regions of Yunnan Province by RT-PCR with the specific primers for P3 protein gene. The sequence analysis results showed that there were higher amino acid sequence identities 98.8 %-99.7 % and 97.6%-100.0 % of P3 and PIPO proteins between 5 Yunnan PVA isolates than amino acid sequence identities 90.8 %-99.1 % and 90.5 %-100.0 % of P3 and PIPO proteins between Yunnan 5 PVA isolates and other 13 PVA isolates.Phylogenetic tree results showed that genetic relationship was the most close between 5 Yunnan isolates andthe Hunan isolate of PVA(KF977085).Contrastly, genetic relationship was most far between PVAisolates from potato and those from tamarillo. [Conclusion] PVA was prevalent in Yunnan province. There was genetic variation between PVA isolates in Yunnan Province. The phylogenetic tree analysis showed that PVA isolates had host adaptability. [ABSTRACT FROM AUTHOR]