Research on Two Main Economical Characters in Potato Using Molecular Approach

论文摘要

Potato is the third most important food crop in the world after wheat and rice, which are grown in nearly 125 countries on more than 48 million acres worldwide. Potato consumption has increased steadily in developing countries, which now account for more than half of the global harvest. Due to potato’s ease of cultivation and its high energy content, potato has been a valuable cash crop for millions of farmers.Accumulation of reducing sugars during cold storage is a persistent and costly problem for the potato processing industry. High temperature processing of potato tubers with elevated amounts of reducing sugars results in potato chips, fries and other products that are unacceptable to consumers because of their bitter taste and unappealing dark color. More problematically, such products contain increased amounts of acrylamide, a neurotoxin and a potential carcinogen. Silencing of the potato vacuolar acid invertase gene VInv can prevent reducing sugar accumulation in cold-stored tubers. Using this approach we developed Vlnv gene silencing lines using RNA interference （RNAi） from four potato cultivars grown currently for potato chip production in North America. Accumulation of reducing sugars during cold storage was reduced by-93% or more in all RNAi lines that had>90% reduction of VInv transcript. Potato chips produced from these lines were light colored and significantly lower in acrylamide than controls. Changes in growth and tuber yield were not associated with VInv suppression using RNAi. We demonstrate that silencing of the VInv gene is an effective approach to control the cold-induced sweetening problem in potato.Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is considered as the No.1 potato disease that is costly to control. RB gene, cloned from the wild potato species Solanum bulbocastanum, confers broad-spectrum resistance to potato late blight. To better understand the expression patterns and regulation of RB gene, the RB gene was transformed into potato cultivar Katahdin, drive by 35S promoter. Among 11 transgenic potato lines used in this study,5 lines showed single genomic insertion of the RB gene,4 lines showed 4 or 5 copies of RB gene, and 2 lines contained more than 8 copies. It is confirmed that the RB trangene driven by 35S promoter could confer resistance to late blight. The results indicate that no significant correlation was observed among RB transgene copy number and late blight resistance in 35S.RB lines. The results also showed a different pattern for RB gene expression among 35S promoter-driven transgenic lines compared to transgenic RB lines driven by native promoter.

论文目录

• Abstract
• Chapter 1. Introduction
• 1.1 Potato is an important crop in the world
• 1.2 Cold-induced sweetening is a serious issue in potato industry
• 1.3 RB-mediated resistance to potato late blight disease
• References
• Chapter 2. Developing cold chipping potato varieties by silencing the vacuolarinvertase gene
• 2.1 Abstract
• 2.2 Introduction
• 2.3 Materials and methods
• 2.3.1 Plant materials
• 2.3.2 Silencing constructs for the potato vacuolar acid invertase gene
• 2.3.3 Development and characterization of transgenic plants
• 2.3.4 Measurement of VInv gene transcription
• 2.3.5 Assessment of chip color, tuber sugar contents and chip acrylamide levels
• 2.4 Results
• 2.4.1 Development of VInv gene silencing lines in four potato chipping varieties
• 2.4.2 Sugar contents of the RNAi lines
• 2.4.3 Processing quality of the RNAi lines
• 2.5 Discussion
• References
• Tables
• 附图
• Chapter 3.Constitutive expression of the RB gene and its impact on potato late blightresistance
• 3.1 Abstract
• 3.2 Introduction
• 3.3 Materials and methods
• 3.3.1 Plant materials
• 3.3.2 Southern blot hybridizations
• 3.3.3 Late blight resistance evaluation
• 3.3.4 Quantification of RB gene transcription
• 3.4 Results
• 3.4.1 Copy number of the RB gene among 35S:RB transgenic potato plants
• 3.4.2 Late blight resistance evaluation of 35S:RB transgenic potato lines
• 3.4.3 No significant correlation was observed among RB transgene copy number and late blight resistance
• 3.4.4 Transcript evaluation of RB gene among different 35S:RB transgenic lines
• 3.5 Discussion
• References
• Tables
• 附图
• Publication
• Acknowledgement