Effects Of UV-B And UV-C On Tobacco Seedlings

Rational utilization of ultraviolet ray,can improve the quality of the crops and agricultural products,extend the storage period,etc.The research that using UV cultivated strong seedlings had been conducted on cucumber,pepper and tomato;Research direction mainly concentrated in the agronomic traits and physiological indexes,or the transcriptome data,however,the researches that combined the agronomic traits,physiological indexes and transcriptome into together analysis were less.On band,UV-A、UV-B and UV-C were used,but did not compare the effects of two or more wavelengths.To screen out the tobacco seedlings cultivation of the better UV band,and explore the UV for tobacco seedlings mechanism,the text that tobacco seedlings were exposed in 100μW/cm2 UV from cross period to stocking stage was maaeCln test duration,agronomic index,chlorophyll,malondialdehyde,free proline,plant total polyphenol and the volatile substances were measured,furthermore,effects caused by UV-B and UV-C wree analyzed.In the end,differential expression genes were analyzed by gene chip technology.The results showed as follows:1.UV-B and UV-C can alleviate tobacco seedlings vain growth,thicken leaves,promote roots growth.Tobacco seedlings’ leaves that exposed in100 μW/cm2 UV-C Chronically were margins curled up and uneven,whereas UV-B had no morphological damage on tobacco seedlings.2.In the early stage of the seedlings(ultraviolet irradiated 10 days),UV-B and UV-C can significantly reduce the tobacco seedlings chlorophyll content.When into stocking stage,the effect of UV-B on chlorophyll is not significant,but UV-C still significantly reduced tobacco seedlings chlorophyll content.UV-B and UV-C irradiation 10 days,tobacco seedlings’ malonaldehyde content was significantly higher than that of control,but in the stocking stage(ultraviolet irradiation 30 days),UV-B and UV-C had no effect on malondialdehyde content,that showed tobacco seedlings had resistance on UV-B and UV-C by means of exposing in it,and better suited to field environment.Free proline and plant total polyphenol contents of Seedlings that exposed in UV-B and UV-C were higher than CK,that indicated UV were beneficial to enhance tobacco seedlings’resistance.3.After exposed in UV-B and UV-C,Tobacco seedlings’ green leaf volatiles contents were higher than CK significantly.The resisitance inducer substance hexenal,linalool,nerol were improved,that were beneficial to enhance tobacco seedlings’ stress resistance.4.Microarray data were analyzed.There were 28 differential expression genes,up regulation 10,down regulation 18 in UV-B,these genes that related to photosynthesis、starch and sugar metabolism were down regulation,that related amino sugar and nucleotide sugar degradation,flavoniods synthesis,inositol phosphate metabolism were up regulation.There were 619 differential expression genes,up regulation 266,down regulation 353 in UV-C,these genes that related to photosynthesis matter accumulation,gibberellic acid synthesis were down regulation,that related synthesis of antiviral defense and physiological active substances,signal factor activation on cell wall metabolism were up regulation.In conclusion,UV irradiation had effects on tobacco morphology,photosynthetic capacity,antiviral defense and physiological active substances,taken together,UV-B was more suitable than UV-C on strong seedling cultivation.