橡胶草促分裂活化蛋白激酶(MPK)基因家族进化和表达谱分析

Evolutionary and Expression Profile Analyses of Mitogen-activated Protein Kinase(MPK) Gene Family in Taraxacum kok-saghyz

天然橡胶是关系国计民生的重要工业原料,橡胶草(Taraxacum kok-saghyz)是菊科蒲公英属多年生植物,与巴西橡胶树、银胶菊并称为三大产胶植物。我们前期研究发现橡胶树促分裂活化蛋白激酶(MPK)基因家族对天然橡胶合成具有调控作用,但是关于橡胶草MPK基因家族的功能分析还未见报道。在此,我们确定了21个橡胶草MPK基因家族成员,通过多序列比对、系统发生树和蛋白基序分析将这些成员分为4个已知的亚家族,分别含有不同的保守结构域。进一步的分子进化分析发现存在复制关系的成员TkMPK5、TkMPK11和TkMPK14在橡胶草进化中出现了与产胶相关的功能分化。通过实时荧光定量PCR分析21个橡胶草MPK基因的表达谱,揭示了MPK16、MPK8和MPK5是胶乳中表达量最高的3个MPK家族成员。进一步对盐、冷和热处理后的MPK基因家族表达情况分析表明,不同亚家族的MPK成员分别响应不同的胁迫处理。综上,橡胶草MPK家族成员在天然橡胶生物合成中具有多种功能,不同的亚家族成员响应不同的胁迫信号,本研究为利用分子育种技术提高橡胶草胁迫耐受或产量提供了潜在的基因靶标。

Natural rubber is an important industrial material related to the national economy and people's livelihood.Taraxacum kok-saghyz is a perennial herb belongs to genus Taraxacum,which is also known as the three major rubber-producing plants accompany with rubber tree and guayule.Our previous studies have shown that the rubber tree mitogen-activated protein kinase(MPK)gene family involves in regulation of natural rubber biosynthesis.However,the functional analysis of the MPK gene family of T.kok-saghyz has not been reported yet.Here,we identified 21 members of the TkMPK gene family.Multiple sequence alignments,phylogenetic tree and protein motif analyses showed that these MPK gene members could be divided into four known sub-families containing different conserved domains.Further molecular evolutionary analyses revealed that duplicated genes TkMPK5,TkMPK11 and TkMPK14 showed functional differentiation related to rubber production during the evolution of T.kok-saghy.Real-time quantitative PCR analysis of the expression profiles of 21 TkMPK genes revealed that MPK16,MPK8 and MPK5 are the top three MPK family members in latex.Further analysis of the expression of the MPK genes after salt,cold and heat treatment showed that different sub-families of MPK members responded to different stress treatments.In summary,members of the MPK family of T.kok-saghy play multiple roles in natural rubber biosynthesis and different sub-family members respond to different stress signals.This work provides potential gene targets for molecular breeding that would improve stress tolerance or rubber yield in T.kok-saghy.