以银杏雌树成熟叶为材料构建cDNA文库,随机挑取2 324个克隆进行5′端测序,并将所得序列与核酸数据库进行同源性比较。结果显示:银杏叶光合作用基因ESTs为97条,占能量代谢相关的基因ESTs总数的75%;与光反应相关的基因主要有PSII捕光叶绿素a/b结合蛋白、放氧复合体蛋白、质体蓝素(PC)、PSI捕光叶绿素a/b结合蛋白、PSI反应中心亚单位、铁硫蛋白、铁氧蛋白还原酶、ATP合成酶等;与暗反应相关的基因主要有核酮糖二磷酸羧化酶/加氧酶(RuBisCO)、核酮糖二磷酸羧化酶/加氧酶激酶RuBisCO activase(RA)、甘油醛—3—磷酸脱氢酶、核桐糖—5—磷酸异构酶、丙糖磷酸异构酶等;RuBisCO基因表达相当丰富,与落叶松Larix laricinaRuBisCO同源。这些结果为揭示银杏光合作用过程中的基因表达和生理过程提供了科学依据。
Based on 5′-sequencing of the 2 324 clones from cDNA library of female Gingko mature leaves,a homology comparison the obtained sequence to genes from the GenBank at NCBI was carried out.Analysis of the Ginkgo biloba EST library revealed a number of ESTs with high BLAST similarity to genes with known roles in higher plant photosynthesis process.These genes consisted of those involved in the light-reaction and dark-reaction of the plant photosynthesis,and the ESTs was 97.75% of the total ESTs from energy metabolization.The former was similar to genes related to light harvesting chlorophyll a/b binding protein of photosystem II gene as well as protein of oxygen-evolving complex gene,plastocyanin precursor gene,chlorophyll a/b binding protein of LHCI type II precursor gene,PSI reaction center subunit II,subunit of photosystem I,ferredoxin-NADP oxidoreductase(FNR) and ATP synthase alpha chain etc..The latter had homologies to genes that regulate the dark reaction,including RuBisCO small subunit,RuBisCO activase(RA) gene,glyceraldehyde-3-phosphate dehydrogenase(GAPDH) gene,ribulose-5-phosphate-3-epimerase gene,and Triosephosphate isomerase(TIM) gene.The expression of RuBisCO gene was quite rich,and most similar to Larix laricina RuBisCO.The findmgs provide a scientific basis for revealing the physilogical process and gene expression in the photosynthetic course of G.biloba.