瓠瓜KNOX基因家族全基因组鉴定及组织表达分析

Genome-wide identification and expression of KNOX gene family in bottle gourd

【目的】探明瓠瓜KNOX基因家族特征,在瓠瓜全基因组水平上对KNOX基因家族成员进行鉴定和分析,研究其组织表达模式。【方法】利用生物信息学方法,对瓠瓜KNOX家族基因成员进行鉴定、编码蛋白理化性质分析及家族成员结构域和保守基序分析,利用MEGA 5.05软件构建系统进化树,采用实时荧光定量PCR技术,分析KNOX基因在瓠瓜不同组织(根、茎、叶、花、果实)中的表达情况。【结果】鉴定到12个瓠瓜KNOX家族基因,这些基因分布在6条染色体上,且均定位于细胞核。大多数瓠瓜KNOX家族蛋白含有同源异型盒蛋白特有的4种结构域KNOX1、KNOX2、ELK和Homeobox_KN。系统进化分析将瓠瓜KNOX基因分为KNOX ClassⅠ和KNOX ClassⅡ2大类群,2个类群又可进一步分为5个分支,其中ClassⅠ-C为瓠瓜特有的进化分支。KNOX基因启动子区有多个激素响应元件和植物生长相关元件。组织表达分析发现,瓠瓜KNOX基因具有不同的表达模式,KNOX ClassⅠ类基因表达具有组织特异性,在根、茎和果实中表达量较高,在其余组织中表达量较低或不表达,其中Lsi04G014450在根和茎中表达量最高,Lsi11G006380在果实中表达量最高;KNOX ClassⅡ类基因在所有组织中均有较高表达。【结论】瓠瓜KNOX基因家族有12个成员,分布于6条染色体上,在进化关系上可分为5组,具有瓠瓜特有的进化分支,在不同组织中的表达具有特异性。

【Objective】This study investigated the characteristics of KNOX gene family in bottle gourd,identified bottle gourd KNOX gene family through genome-wide analysis,and analyzed their expression patterns in different organs.【Method】Genome-wide identification of bottle gourd KNOX gene family members,their coding protein physicochemical properties,and conserved domains and motifs were analyzed via bioinformatics tools.Phylogenetic tree was constructed by MEGA 5.05 software.Gene expre-ssion profiles in different organs(root,stem,leaf,flower and fruit)were conducted by real-time PCR technique.【Result】A total of twelve KNOX gene family members were identified from the bottle gourd genome.The twelve KNOX genes were distributed on six of eleven chromosomes,and all of them were located in the nucleus.Multiple sequence alignment showed that most genes contained four conserved plant KNOX domains of KNOX1,KNOX2,ELK and Homeobox_KN.Phylogenetic analysis showed that bottle gourd KNOX proteins were classified into two evolutionary groups of KNOX ClassⅠand KNOX ClassⅡ,which were further divided into five branches.ClassⅠ-C was a specific evolutionary branch.There were multiple phytohormone responsive elements and plant growth and development cis-elements in the promo-ter region of KNOX genes.The qRT-PCR showed that bottle gourd KNOX genes exhibited different expression profiles.The expression of KNOX ClassⅠgene was tissue-specific,with the highest expression in roots,stems and fruits but low or no expression in other tissues.Lsi04G014450 had the highest expression in roots and stems and Lsi11G006380 had the highest expression in fruits.KNOX ClassⅡgene was highly expressed in all tissues.【Conclusion】A total of 12 KNOX members distributed on 6 chromosomes were identified from the bottle gourd genome.They could be divided into 5 groups with a specific branch ClassⅠ-C and they exhibited diverse and specific tissue expression patterns.