橡胶树橡胶生物合成调控相关基因表达丰度比较

Comparison of expression abundance of genes related to rubber biosynthesis regulation in Hevea brasiliensis

关键词:  巴西橡胶树,橡胶生物合成调控,基因丰度,比较

Key words:  Hevea brasiliensis, rubber biosynthesis regulation, gene abundance, comparison

摘要:

蛋白质是构成生命系统的基本元件之一,是大部分生物学功能的执行者。蛋白质丰度与其生物学功能息息相关,其丰度受基因表达过程中各环节严格精密的调控。其中,蛋白质丰度与其相应mRNA丰度存在较强的相关性,蛋白质丰度差异的40%可由mRNA丰度来解释。茉莉酸信号途径调节巴西橡胶树中的天然橡胶生物合成,但相关基因彼此间的表达丰度差异尚待阐明。该文比较了S/2Dd3割胶制度下,15个橡胶生物合成调控相关基因COI1、JAZ1、JAZ2、JAZ3、MYC1、MYC2、MYC3、MYC4、MYC5、GAPDH、HMGR1、SRPP、REF、HRT1、HRT2以及2个常用内参基因18S、ACTIN1在10个橡胶树种质胶乳中的表达丰度差异;将ACTIN1的表达丰度设定为1,以此为标准计算出样品中其他基因的表达丰度。结果表明:相同个体中不同基因的转录丰度差异明显,不同个体中相同基因集的丰度大小排序存在一定差异;同一基因在不同个体中的转录丰度差异明显,这16个基因的最大丰度分别是最低丰度的9.43、6.04、10.02、12.29、18.82、9.22、38.46、112.83、121.36、15.34、19.09、13.54、10.05、19.80、24.83、11.82倍,他们的变异系数分别为73.05%、55.19%、69.09%、67.37%、66.59%、53.87%、83.25%、122.02%、166.34%、59.89%、70.59%、75.67%、74.20%、68.34%、84.23%、78.59%;总的来说,在群体水平上,16个基因的转录丰度从高到低依次为18S>SRPP>HMGR1>REF>MYC2/HRT1>COI1>MYC1/MYC4>GAPDH/JAZ1/MYC5>JAZ2>HRT2/MYC3/JAZ3,他们的群体平均丰度依次为ACTIN1的28382.26、43.64、11.39、7.16、5.47、5.10、1.07、0.75、0.74、0.45、0.42、0.33、0.12、0.06、0.06、0.04倍。值得注意的是,无论在个体水平还是群体水平上,18S的丰度毫无疑问是最大的,在mRNA中,SRPP的丰度最大,JAZ1大于JAZ2和JAZ3,MYC2大于MYC1、MYC3、MYC4、MYC5,HRT1大于HRT2。综上结果表明,结构基因和功能基因的丰度高于调控基因。在基因相对表达分析中,常对目的基因和内参基因作均一化处理,从而掩盖了不同基因间的真实丰度差异,因此,在基因表达分析中,既要关注基因的相对表达量,也要关注基因间的丰度差异,这有助于更全面地理解基因的功能。

Abstract:

Protein is one of the basic components of life system and the executor of most biological functions. Protein abundance is closely related to its biological function, and its abundance is strictly and precisely regulated by each link in the process of gene expression. Among them, there is a strong correlation between protein abundance and its corresponding mRNA abundance, about 40% of the difference in protein abundance can be explained by mRNA abundance. Jasmonic acid signaling pathway regulates the biosynthesis of natural rubber in Hevea brasiliensis, but the difference of expression abundance among related genes needs to be elucidated. In the present study, the expression abundance differences of 15 rubber biosynthesis regulatory genes COI1, JAZ1, JAZ2, JAZ3, MYC1, MYC2, MYC3, MYC4, MYC5, GAPDH, HMGR1, SRPP, REF, HRT1, HRT2, and 2 common internal reference genes 18S, ACTIN1 in 10 rubber tree germplasms latex following tapping them with S/2D d3 tapping system were compared. The expression abundance of ACTIN1 in each sample is set to 1, and the expression abundance of other genes in the sample is calculated according to the standard. The results were as follows: The transcriptional abundance of different genes in the same individual was significantly different, and the abundance order of the same gene set was different in different individuals; The transcription abundance of the same gene was significantly different in different individuals, the maximum abundance of the 16 genes were 9.43, 6.04, 10.02, 12.29, 18.82, 9.22, 38.46, 112.83, 121.36, 15.34, 19.09, 13.54, 10.05, 19.80, 24.83, 11.82 times of the lowest abundance, and the coefficient of variation were 73.05%, 55.19%, 69.09%, 67.37%, 66.59%, 53.87%, 83.25%, 122.02%, 166.34%, 59.89%, 70.59%, 75.67%, 74.20%, 68.34%, 84.23%, 78.59%, respectively; Overall, at the population level, the transcription abundance of the 16 genes from high to low was 18S>SRPP>HMGR1>REF>MYC2/HRT1>COI1>MYC1/MYC4>GAPDH/JAZ1/MYC5>JAZ2>HRT2/MYC3/JAZ3, correspondingly, the average abundance were 28 382.26, 43.64, 11.39, 7.16, 5.47, 5.10, 1.07, 0.75, 0.74, 0.45, 0.42, 0.33, 0.12, 0.06, 0.06, 0.04 times than that of ACTIN1, respectively. It is worth noting that, the abundance of 18S is undoubtedly the highest, and in mRNA, SRPP is the largest, JAZ1 is greater than that of JAZ2 and JAZ3, MYC2 is greater than that of MYC1, MYC3, MYC4 and MYC5, HRT1 is greater than HRT2 at both the individual and population levels. The results showed that, the abundance of structural genes and functional genes is higher than that of regulatory genes. In the analysis of gene relative expression, the target gene and the internal reference gene are usually homogenized, thus masking the real abundance difference between different genes, therefore, in the gene expression analysis, we should pay attention not only to the relative expression of genes, but also to the abundance difference between genes, which is helpful for understanding the function of genes in a more comprehensive way.