Molecular and genetic characterization of transgenic tomato expressing 3-hydroxy-3-methylglutaryl coenzyme A reductase

Abstract

Mevalonic acid (MVA) pathway, in parallel with methylerythritol phosphate (MEP) pathway, produces precursor metabolites for isoprenoids, and affect fruit development in plants. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is supposed to be a key enzyme in the MVA pathway. To understand the role of HMGR in fruit development, we previously generated transgenic tomato (Solanum lycopersicum) expressing a melon HMGR gene (CmHMGR) and observed increased fruit size in these plants. To further examine this effect, we performed molecular and genetic characterization of the transgenic tomato line in the T 4 generation. The line showed stable expression of CmHMGR mRNA and protein, an effect that could lead to the increase in fruit weight observed, which exceeded 20%. Interestingly, the CmHMGR mRNA was highly expressed during tomato fruit development, whereas expression of the endogenous HMGRs (SlHMGR1, SlHMGR2, and SlHMGR3) was lower than in the wild type, suggesting the presence of a regulatory mechanism at the transcriptional level, as in mammalian systems. A preliminary analysis using cDNA macroarray filters was performed, and genes showing more than 2.5-fold differences in expression between transgenic and wild-type plants were identified. Most of the genes involved in isoprenoid biosynthesis did not show significantly different transcription levels, but 121 annotated genes and 152 genes of unknown function were found to be differentially expressed. These results demonstrate that the transgenic tomato line expressing the HMGR gene is genetically stable and could be used as a comprehensive material to elucidate the roles of HMGRs in tomato fruit development.

Brassinosteroid Regulates 3-Hydroxy-3-methylglutaryl CoA Reductase to Promote Grape Fruit Development

“…For example, in melon fruits, the rapid accumulation of HMGR during the early stage of fruit development and the active cell division determine the size of the fruits . However, in tomatoes, while the use of the HMGR inhibitor lovastatin resulted in a significant decrease in the fruit size, the overexpression of the HMGR gene was found to significantly increase the fruit size. , Second, HMGR can directly affect the synthesis of sesquiterpenes and triterpenes. The expression level of HMGR determines the type and content of downstream terpenoid metabolites. , Terpenes are the main components contributing to grape aroma, among which monoterpenes were synthesized by the MEP pathway and sesquiterpenes and triterpenes were synthesized by the MVA pathway, indirectly and directly regulated by HMGR, respectively. , In this study, the suppression and overexpression of HMGR in strawberries changed their aromatic composition.…”

“…57 However, in tomatoes, while the use of the HMGR inhibitor lovastatin resulted in a significant decrease in the fruit size, the overexpression of the HMGR gene was found to significantly increase the fruit size. 56,58 Second, HMGR can directly affect the synthesis of sesquiterpenes and triterpenes. The expression level of HMGR determines the type and content of downstream terpenoid metabolites.…”

Species-Specific Expansion and Molecular Evolution of the 3-hydroxy-3-methylglutaryl Coenzyme A Reductase (HMGR) Gene Family in Plants

“…As a result, up-regulation of HMGR genes could improve terpenes productivities in the transgenic plants [23] , [24] , [25] , [26] , [27] . Furthermore, it was reported that transgenic tomato plants that constitutively expressed a heterologous HMGR gene from melon showed a significant increase in fruit size [28] .…”

Genetic Manipulation of Tomato (Solanum lycopersicum) cv. PKM-1 using cry2AX1 Gene for Insect Resistance

“…when these modified genes are expressed in them (Mandaokar et al, 2000). Tomato is an excellent plant for stably expressing transgenes, indicating a good target for genetic engineering (Kobayashi et al, 2003;Omura et al, 2007;Sun et al, 2007). These characteristics make it an attractive research target for practical application in food and agricultural industries.…”