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postgraduate thesis: Functional analysis of anther-specific genes essential for pollen exine development and male fertility in tobacco

TitleFunctional analysis of anther-specific genes essential for pollen exine development and male fertility in tobacco
Authors
Advisors
Advisor(s):Lo, CSC
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Lin, Y. C. [林映辰]. (2012). Functional analysis of anther-specific genes essential for pollen exine development and male fertility in tobacco. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053417
AbstractIn flowering plants, pollen grains are surrounded by extremely strong outer walls providing solid and firm structure for protecting pollen and species-specific interactions with female stigma. The outer wall of pollen, referred to as exine, is composed of sporopollenin polymer, but the composition and synthesis of sporopollenin remains poorly understood. Previous studies have indicated that several genes such as Fatty Acyl-CoA Synthetase (ACOS5), Polyketide Synthases (PKSA and PKSB), and Tetraketide α-Pyrone Reductase (TKPR1) take part in the biosynthesis of sporopollenin in Arabidopsis thaliana. The existence of ancient biochemical pathways for sporopollenin biosynthesis has been widely proposed but experimental evidence from plant species other than Arabidopsis is not extensively available. In this study, two homologous PKS genes, NtPKS1 and NtPKS2, were found in tobacco (Nicotiana tabacum). Results of RT-PCR and in situ hybridization revealed that NtPKS1 and NtPKS2 are specifically and transiently expressed in tapetal cells during microspore development in tobacco anthers. RNAi plants of NtACOS1 and NtPKS1 were investigated. Comparing with wild-type tobacco (SR1), abnormal pollens, defect exine structure, and male sterility were found in the RNAi lines. Enzymatic assays show that NtPKS1 and NtPKS2 encode anther-specific enzymes using fatty acyl-coenzyme A and p-coumaroyl coenzyme A as substrates to yield tri- and tetra- ketide α-pyrone and bisnoryangonin respectively. In this study, the metabolic steps catalyzed by the anther-specific acyl- CoA synthetase (ACOS), polyketide synthase (PKS), and tetraketide α-pyrone reductase (TKPR) were investigated. Using fatty acids as starting substrates, sequential activities of heterologously-expressed tobacco enzymes NtACOS1, NtPKS1, and NtTKPR1 resulted in the production of reduced tetraketide α- pyrones which propose to contribute to the biosynthesis of sporopollenin precursors in tobacco.
DegreeMaster of Philosophy
SubjectTobacco - Genetics.
Tobacco - Reproduction - Molecular aspects.
Dept/ProgramBiological Sciences
Persistent Identifierhttp://hdl.handle.net/10722/188298

 

DC FieldValueLanguage
dc.contributor.advisorLo, CSC-
dc.contributor.authorLin, Ying Chen.-
dc.contributor.author林映辰.-
dc.date.accessioned2013-08-27T08:03:25Z-
dc.date.available2013-08-27T08:03:25Z-
dc.date.issued2012-
dc.identifier.citationLin, Y. C. [林映辰]. (2012). Functional analysis of anther-specific genes essential for pollen exine development and male fertility in tobacco. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053417-
dc.identifier.urihttp://hdl.handle.net/10722/188298-
dc.description.abstractIn flowering plants, pollen grains are surrounded by extremely strong outer walls providing solid and firm structure for protecting pollen and species-specific interactions with female stigma. The outer wall of pollen, referred to as exine, is composed of sporopollenin polymer, but the composition and synthesis of sporopollenin remains poorly understood. Previous studies have indicated that several genes such as Fatty Acyl-CoA Synthetase (ACOS5), Polyketide Synthases (PKSA and PKSB), and Tetraketide α-Pyrone Reductase (TKPR1) take part in the biosynthesis of sporopollenin in Arabidopsis thaliana. The existence of ancient biochemical pathways for sporopollenin biosynthesis has been widely proposed but experimental evidence from plant species other than Arabidopsis is not extensively available. In this study, two homologous PKS genes, NtPKS1 and NtPKS2, were found in tobacco (Nicotiana tabacum). Results of RT-PCR and in situ hybridization revealed that NtPKS1 and NtPKS2 are specifically and transiently expressed in tapetal cells during microspore development in tobacco anthers. RNAi plants of NtACOS1 and NtPKS1 were investigated. Comparing with wild-type tobacco (SR1), abnormal pollens, defect exine structure, and male sterility were found in the RNAi lines. Enzymatic assays show that NtPKS1 and NtPKS2 encode anther-specific enzymes using fatty acyl-coenzyme A and p-coumaroyl coenzyme A as substrates to yield tri- and tetra- ketide α-pyrone and bisnoryangonin respectively. In this study, the metabolic steps catalyzed by the anther-specific acyl- CoA synthetase (ACOS), polyketide synthase (PKS), and tetraketide α-pyrone reductase (TKPR) were investigated. Using fatty acids as starting substrates, sequential activities of heterologously-expressed tobacco enzymes NtACOS1, NtPKS1, and NtTKPR1 resulted in the production of reduced tetraketide α- pyrones which propose to contribute to the biosynthesis of sporopollenin precursors in tobacco.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.source.urihttp://hub.hku.hk/bib/B50534178-
dc.subject.lcshTobacco - Genetics.-
dc.subject.lcshTobacco - Reproduction - Molecular aspects.-
dc.titleFunctional analysis of anther-specific genes essential for pollen exine development and male fertility in tobacco-
dc.typePG_Thesis-
dc.identifier.hkulb5053417-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplineBiological Sciences-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5053417-
dc.date.hkucongregation2013-

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