| Located in the main part of the Qinghai-Tibet Plateau,Tibet is known as a treasure house of plant resources because of its vast territory,diverse climate types and rich plant resources.In the history,the backward transportation restricted the wide exchange of crop varieties,which created conditions for the evolution and formation of local varieties.Hot pepper has been introduced to Tibet for more than 100 years,and many local varieties have been formed.It has special taste quality and is deeply loved by local farmers and herdsmen.In order to effectively utilize these germplasm resources,this study evaluated the quality of 20 local varieties and studied the genes related to capsaicin synthesis in fruit placenta of three of them by RNA-Seq technology.The main results are as follows:(1)Among 20 local varieties,the average fruit weight and plant height differ greatly among different varieties.According to fruit shape index,they can be divided into three categories,namely,line pepper,finger pepper and cone pepper.(2)Among 20 local varieties,the quality indexes of soluble protein,soluble sugar,VC,VA,free amino acid and capsaicin of pepper fruit varied greatly among different varieties.The highest content of soluble protein was 48(59.03± 5.27 mg/g),10(55.90 ± 10.97 mg/g)and 24(55.37 ± 5.79 mg/g);the highest content of soluble sugar was 53(203.11 ± 1.55g/mg),47(178.68 ± 22.34g/mg),9(159.29 ± 5.24g/mg),28(154.78 ± 24.38g/mg)and 0(153.61 ± 15.72g/mg).the highest VC content was 24(156.65 ± 12.52 mg/g),53(154.26 ± 8.48 mg/g)and 25(149.66 ± 13.09 mg/g);the highest VA content was 48(0.6047 ± 0.0621mg/100g),8(0.5003 ± 0.0393 mg/100g)and 49(0.4967 ± 0.1125 mg/100g);the highest free amino acid content was 53(58.47 ± 0.48 g/100g)and 23(52.42 ±2.61 g/100g);The highest capsaicin content was 6(2934.27 ± 179.14 mg/kg)and 10(2915.64 ± 192.24 mg/kg).Variety 48 had high soluble protein and VA content,while variety 53 had high soluble sugar,high VC and high free amino acid content.(3)According to the difference of capsaicin content,three local varieties,No.6 with the highest capsaicin content,No.25 with the middle capsaicin content and No.4 with the lowest capsaicin content,were selected and analyzed by RNA-Seq technique.A total of 54.41 Gb Raw＿bases were obtained.The total number of Clean＿reads was 37,293,138.67,and the percentage of Q30 base was more than 96%.Through screening,279 up-regulated genes were found in the differentially expressed gene set.After differentially expressed analysis,8differentially expressed genes related to Capsaicins were preliminarily screened out.(4)Design specific primers for differentially expressed genes and validate their expression.It is speculated that seven genes,LOC107857229 、LOC107870553 、 LOC107849953 、 LOC107851643 、 LOC107854372 、LOC107867296 and LOC107843092 are consistent with the results of transcriptome data analysis.Therefore,these genes are positively correlated with the synthesis of capsaicinoids and are important genes regulating the accumulation of capsaicinoids. |
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