| Light is basic element for plant growth and development.Light is not only the energy source of photosynthesis,but also as a kind of signal activate light receptors to control gene expression,protein synthesis and cells metabolism by signal transduction,which plays a very important role on plant physiological metabolic activity.Different illumination factors regulate plant growth and development,which form the adaptation of different plant species to light.To clarify the physiological and molecular mechanism for light regulating plant growth has important theoretical and practical significance.In this study,poplar 741 was taken as the test material,The poplar 741 were treated with different light quality(blue light,white light)at different times(1 day,2 days and 5 days),to study the effects of the growth and physiological characteristics of poplar 741.The transcriptome datas of different light quality at different times to deal with poplar 741 were compared by RNA-seq technique,to investigate the genes related to the growth and physiological characteristics of poplar 741.The main results are as follows:1.The effect of different light quality on the growth of poplar 741 was significant.The leaf length,leaf width and leaf area under the blue light were less than that of the white light at 1 day,2 days and 5 days;the leaf length/width ratio under the blue light was larger than that of white light,but there was no significant difference between them.The plant height under the blue light treatment was higher than that of white light,and there was significant difference between them.The growth of plant height under the blue light treatment increased by 79.17%,68.33%and 63.36%,respectively,compared with white light at 1 day,2 days and 5 days.Under the blue light treatment,the internode distance was higher than that of white light,and the internode distance were increased by 2.43%,10.13%and 52.16%,respectively,at 1 day,2 days and 5 days,but the ground diameter of poplar 741 under blue light treatment was lower than that of white light,the results indicated that the blue light treatment was beneficial to the growth of poplar 741.Under the same treatment time,the biomass and root/shoot ratio of poplar 741 under the blue light treatment were lower than that of white light,and with the increase of treatment time,the difference of biomass and root/shoot ratio of poplar 741 treated with blue and white light became smaller.In general,the white light is favorable for the accumulation of dry matter on the aerial part of poplar 741,and the blue light is favorable for the accumulation of dry matter in the underground part of poplar 741 at the same time.2.The effect of different light quality on the photosynthetic pigments of poplar 741leaves was significant.The poplar 741 was respectively treated with blue and white light at1 day,2 days and 5 days,compared with white light,compared with white light,chlorophyll a,chlorophyll b,chlorophyll a+b and carotenoid content were higher under blue light treatment,except for chlorophyll a/b,the chlorophyll a,chlorophyll b,chlorophyll a+b and carotenoid contents increased sharply when treated with blue light for1 day,and reached the maximum at 2 days under blue light treatment.Indicating that blue light is favorable for the formation of photosynthetic pigments of poplar 741 leaves.3.The effect of different light quality on the photosynthesis of poplar 741 leaves was significant.The poplar 741 was respectively treated with blue and white light at 1 day,2days and 5 days,compared with white light,the Pn,Gs and Tr under the blue light treatment were higher than that of white light,except Ci.Under the white light,Pn,Gs,Ci and Tr all increased first and then decreased with the increase of treatment time,and reached the maximum value at 2 days.Under the blue light,Pn increased first and then decreased with the increase of treatment time,and reached the maximum at 2 days,and Gs,Ci and Tr showed a decreasing trend.4.The effect of different light quality on chlorophyll fluorescence parameters of poplar 741 leaves was different.The F_v/F_m values of the poplar 741 leaves were increased by 10.18%,4.31%and 4.78%,respectively,compared with the white light at 1 day,2 days and 5 days.The results indicated that the blue light was beneficial to the absorption of light energy by poplar 741 leaves,and had higher photosynthetic capacity.Under the blue light treatment,theΦPSⅡis higher than that of white light,that is,theΦPSⅡwas 5.65%,7.81%and 15%higher than that of the white light at 1 day,2 days and 5 days.At the same time,the difference ofΦPSⅡbetween blue light and white light was significant.Under the blue light treatment,the q P were increased by 0.46%,19.60%and 8.43%,respectively,compared with the white light at 1 day,2 days and 5 days.And the light energy of photochemical electron transport was much more than that of white light at 2 days,and the electron transfer activity of PSⅡwas the highest,that is,poplar 741 had the highest photosynthetic activity.With the increase of treatment time,the q N of blue light and white light treatment showed a decreasing trend,which indicated that the part of the light absorbed by PSⅡantenna was dissipated in the form of heat after the different light quality.5.Analysis of poplar 741 transcriptome changes at different time under different light quality treatment using RNA-seq technology.Reads of each sample were compared with the reference genome,the comparison rate of each sample was more than 86%.The results of NR database showed that the homology and similarity of novel coding transcripts were very high in the library,and the matched genome sequence was the highest.The results of the egg NOG database showed that a total of 18731 genes were annotated into cellular processes and signaling,information storage and processing,metabolism.The difference of gene expression under different light quality at the same treatment time showed that 505,755 and 680 genes were differentially expressed at 1day,2days and 5days,respectively.The difference expression genes were compared with GO database and KEGG database.The results showed that the enrichment of GO was most significant in the biological process,followed by the molecular function,and the least in the cellular component.Through KEGG significant enrichment analysis showed that 259 significant differentially expressed genes were annotated into 83 KEGG Pathways at 1day;349 significant differentially expressed genes were annotated into 90 KEGG Pathway at 2days;268significant differentially expressed genes were annotated to 74 KEGG Pathway at 5days.There are 15 photosynthetic genes,6 photosynthetic genes,1 plant auxin-related gene and 3blue-light receptor-related genes were find out by analyzing differentially expressed genes.Four genes were selected by fluorescence quantitative PCR.The results showed that the quantitative results were consistent with those of transcriptome.The discovery of these genes in order to study the different light quality of poplar 741 growth regulation mechanism to provide a reference. |
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