Introduction
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the key enzyme for carbon fixation and four different holoenzyme form of Rubisco are found in different organisms (Tabita et al., 1999; Tabita et al., 2007). Most abundant Rubisco forms 1 consist of eight large subunits and eight small subunits are found in algae, cyanobacteria and higher plants (Shively et al., 1973). The multiple nuclear gene encoding small subunits of Rubisco is called rbcS. rbcS exists only in Rubisco form 1 so that it is not absolutely essential for carboxylate activity, however it is apparent that rbcS influence catalyze indirectly as following possibilities (Spreitzer et al., 2002). rbcS could have a role to determine the carboxylation efficiency …show more content…
Pichersky (1986) and Thomas-Hall (2007) reported that paralogous gene copies of rbcS are closely related to each other than orthologous gene copies in different species, therefore they concluded this observed pattern as concerted evolution of rbcS in Solanum lycopersicum and Musa acuminata. Some species specific investigations about evolutionary process of rbcS have done, however, the characteristics and evolutionary mechanisms of rbcS among subfamilies have not elucidated.
This study will examine the evolutionary mechanism and diversification of rbcS among Angiosperms family level and discuss the model of evolution. I will address ; 1) The evolutionary mechanism of rbcS in different species of Angiosperms; 2) The mechanism of evolutionary events results in multiple copies of rbcS, and differentiation of copy number depends on species; 3) The divergence of roles between different RBCS …show more content…
This can be explained by concerted evolution as a result of unequal crossover and gene conversions among gene copies. I examined gene conversion events among Angiosperms, and identified different patterns in different subfamilies. I detected simple duplication events followed by speciation in Solanaceae, loss of gene copies in Grass, and old gene duplication followed by independent gene conversions in different two clades of Brassicaceae. However, these observed gene conversion events differs from the expected evidence of concerted evolution. Besides that, I observed Long Branch lengths, frequent gene duplication and many duplicated genes subsequently become nonfunctional. These evidences suggest that the hypothesis of concerted evolution is not the best model fits to observed pattern of rbcS phylogeny in Angiosperms. Regarding the results, I hypothesize that the birth and death model (Nei and Hughes 1992, Ota and Nei 1994) of evolution can explain this pattern of rbcS evolution. In this model, new genes are created by repeated gene duplications, and some duplicate genes are maintained in the genome for a long time, but others are deleted or have become nonfunctional through deleterious mutations. I need further investigation to conclude that the observed pattern of rbcS
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the key enzyme for carbon fixation and four different holoenzyme form of Rubisco are found in different organisms (Tabita et al., 1999; Tabita et al., 2007). Most abundant Rubisco forms 1 consist of eight large subunits and eight small subunits are found in algae, cyanobacteria and higher plants (Shively et al., 1973). The multiple nuclear gene encoding small subunits of Rubisco is called rbcS. rbcS exists only in Rubisco form 1 so that it is not absolutely essential for carboxylate activity, however it is apparent that rbcS influence catalyze indirectly as following possibilities (Spreitzer et al., 2002). rbcS could have a role to determine the carboxylation efficiency …show more content…
Pichersky (1986) and Thomas-Hall (2007) reported that paralogous gene copies of rbcS are closely related to each other than orthologous gene copies in different species, therefore they concluded this observed pattern as concerted evolution of rbcS in Solanum lycopersicum and Musa acuminata. Some species specific investigations about evolutionary process of rbcS have done, however, the characteristics and evolutionary mechanisms of rbcS among subfamilies have not elucidated.
This study will examine the evolutionary mechanism and diversification of rbcS among Angiosperms family level and discuss the model of evolution. I will address ; 1) The evolutionary mechanism of rbcS in different species of Angiosperms; 2) The mechanism of evolutionary events results in multiple copies of rbcS, and differentiation of copy number depends on species; 3) The divergence of roles between different RBCS …show more content…
This can be explained by concerted evolution as a result of unequal crossover and gene conversions among gene copies. I examined gene conversion events among Angiosperms, and identified different patterns in different subfamilies. I detected simple duplication events followed by speciation in Solanaceae, loss of gene copies in Grass, and old gene duplication followed by independent gene conversions in different two clades of Brassicaceae. However, these observed gene conversion events differs from the expected evidence of concerted evolution. Besides that, I observed Long Branch lengths, frequent gene duplication and many duplicated genes subsequently become nonfunctional. These evidences suggest that the hypothesis of concerted evolution is not the best model fits to observed pattern of rbcS phylogeny in Angiosperms. Regarding the results, I hypothesize that the birth and death model (Nei and Hughes 1992, Ota and Nei 1994) of evolution can explain this pattern of rbcS evolution. In this model, new genes are created by repeated gene duplications, and some duplicate genes are maintained in the genome for a long time, but others are deleted or have become nonfunctional through deleterious mutations. I need further investigation to conclude that the observed pattern of rbcS