Phosphomannose isomerase affects the key enzymes of glycolysis and sucrose metabolism in transgenic sugarcane overexpressing the manA gene.

Muqing Zhang,Rukai Chen,Jihua Wang,Xiaolei Zhuo,Chuanyu Yang,Charles A Powell

doi:10.1007/s11032-015-0295-4

Muqing Zhang, Rukai Chen + Show 4 more

Open Access

https://doi.org/10.1007/s11032-015-0295-4

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Abstract

Sugarcane is one of the most important crops cultivated for the production of sugar and ethanol. In our previous studies, an innovative positive selection system for obtaining transgenic sugarcane, which utilized the E. coli-derived manA gene as the selectable marker and mannose as the selective agent, was developed and patented in China. In this paper, the influence of phosphomannose isomerase (PMI) overexpression on the key enzymes of both glycolysis and sucrose metabolism was investigated in transgenic sugarcane through the manA gene. Overexpressed PMI increased hexokinase activity by approximately 24 % compared with non-transgenic control plants, but pyruvate kinase (PK) activity was reduced by approximately 14 %. In comparison with the non-transgenic control plants, the activities of sucrose synthase, sucrose-phosphate synthase, and acid invertase were also modestly affected in the PMI-overexpressing transgenic plants, but no significant differences were observed at the stalk elongation and maturity stages. However, agronomic and technical traits were not affected by manA gene overexpression in the transgenic sugarcane. In conclusion, PMI overexpression significantly affected the hexokinase and PK activities by catalyzing the reversible interconversion between mannose-6-phosphate and fructose-6-phosphate, which is an intermediate of glycolysis. However, it had no significant effects on sucrose accumulation in sugarcane.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-015-0295-4) contains supplementary material, which is available to authorized users.

Highlights

Sugarcane is a major crop for the production of sucrose and ethanol in the tropical and subtropical regions of more than 100 countries
No phosphomannose isomerase (PMI) enzyme activity was quantified in the non-transgenic plants, indicating that PMI was absent in the nontransgenic sugarcane (Fig. 2)
Selectable marker genes have been pivotal in the development of plant transformation technologies because the marker genes allow scientists to identify or isolate cells that are expressing the cloned DNA (Wilmink and Dons 1993)

Summary

Introduction

Sugarcane is a major crop for the production of sucrose and ethanol in the tropical and subtropical regions of more than 100 countries. 100 Page 2 of 10 methods laborious, and sugarcane is a prime candidate for improvements through genetic engineering (Singh et al 2013; Ming et al 2006). Genetic transformation offers the potential to introduce elite commercial sugarcane varieties with new and desirable characteristics, such as resistance to pathogens and abiotic stress, as well as improvements in their agronomic performance and sugar yield (Groenewald and Botha 2008; Chong et al 2007; Zhang et al 2006). The gene transfer and transgenic method based on the manA gene have been patented for sugarcane transformation in China (Zhang et al 2007). Privalle (2002) and Reed et al (2001) summarized the biochemistry, mode of action, and safety issues associated with PMI, there have been no reports on the influence of manA overexpression on sucrose synthesis/degradation or glycolysis

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