玉米木质素合成途径基因ZmCCoAOMT1功能研究及转录组分析

Functional Study and Transcriptome Analysis of Corn Gene ZmCCoAOMT1 Involved in Lignin Synthesis Pathway

青贮玉米是一种优良的饲料作物,是畜牧业的优质粗饲料来源。咖啡酰辅酶A-O-甲基转移酶(caffeoyl-CoA-O-methyltransferase,CCoAOMT)是木质素合成途径中的关键甲基转移酶。从玉米自交系B73的EMS突变体库获得了ZmCCoAOMT1基因的单碱基突变体,通过表型分析、生理生化分析、基因表达分析验证了ZmCCoAOMT1的功能。研究发现,ZmCCoAOMT1突变造成茎秆木质化程度降低、木质素含量显著减少、G型木质素(guaiacyl lignin)和S型木质素(syringa lignin)含量下降、体外干物质消化率提高。此外,突变体茎秆中ZmCCoAOMT1的表达量也显著低于野生型。转录组分析表明,ZmCCoAOMT1基因的突变可能调控苯丙烷代谢途径中相关基因的表达,进而引起木质素含量和单体组成发生变化。因此,ZmCCoAOMT1基因是培育高消化率优质青贮玉米品种的重要基因资源,研究结果为木质素合成代谢途径遗传机理研究提供了重要理论依据。

Silage corn with high-quality roughage source for animal husbandry is an excellent forage crop.Caffeoyl-CoA-O-methyltransferase(CCoAOMT),a key methyltransferase,plays an important role in the lignin synthesis.In this study,the EMS single-base mutant of ZmCCoAOMT1 gene was obtained from EMS mutant library of corn inbred line B73,and the function of ZmCCoAOMT1 was demonstrated based on phenotypic analysis,physiological and biochemical analysis and gene expression analysis.It was found that the mutation of ZmCCoAOMT1 reduced the degree of lignification,significantly decreased the stem lignin content,and declined G(guaiacyl lignin)and S(syringa lignin)monomers contents,whereas increased in vitro digestibility of dry matter.The expression of ZmCCoAOMT1 in the stalks of the mutant was significantly reduced compared to the wild type.Transcriptome analysis analysis showed that the mutation of ZmCCoAOMT1 gene might change the expression of related genes involved in the phenylpropanoid metabolic pathway,leading to variation in lignin content and monomer composition.Therefore,ZmCCoAOMT1 gene would be valuable in corn breeding for high-digestibility and high-quality silage,and above results provided an important genetic basis for elucidating the mechanism of lignin anabolic pathway.