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Novel candidate genes influencing natural variation in potato tuber cold sweetening identified by comparative proteomics and association mapping.

Fischer M, Schreiber L, Colby T, Kuckenberg M, Tacke E, Hofferbert HR, Schmidt J, Gebhardt C - BMC Plant Biol. (2013)

Bottom Line: The molecular basis of CIS in potato tubers is of interest not only in basic research on plant adaptation to environmental stress but also in applied research, since high amounts of reducing sugars affect negatively the quality of processed food products such as potato chips.We compared by two-dimensional polyacrylamide gel electrophoresis the tuber proteomes of cultivars highly diverse for CIS.Novel SNP's diagnostic for increased tuber starch content, starch yield and chip quality were identified, which are useful for selecting improved potato processing cultivars.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Plant Breeding and Genetics, Max-Planck-Institute for Plant Breeding Research, Cologne, Germany. fischer@mpipz.mpg.de

ABSTRACT

Background: Higher plants evolved various strategies to adapt to chilling conditions. Among other transcriptional and metabolic responses to cold temperatures plants accumulate a range of solutes including sugars. The accumulation of the reducing sugars glucose and fructose in mature potato tubers during exposure to cold temperatures is referred to as cold induced sweetening (CIS). The molecular basis of CIS in potato tubers is of interest not only in basic research on plant adaptation to environmental stress but also in applied research, since high amounts of reducing sugars affect negatively the quality of processed food products such as potato chips. CIS-tolerance varies considerably among potato cultivars. Our objective was to identify by an unbiased approach genes and cellular processes influencing natural variation of tuber sugar content before and during cold storage in potato cultivars used in breeding programs. We compared by two-dimensional polyacrylamide gel electrophoresis the tuber proteomes of cultivars highly diverse for CIS. DNA polymorphisms in genomic sequences encoding differentially expressed proteins were tested for association with tuber starch content, starch yield and processing quality.

Results: Pronounced natural variation of CIS was detected in tubers of a population of 40 tetraploid potato cultivars. Significant differences in protein expression were detected between CIS-tolerant and CIS-sensitive cultivars before the onset as well as during cold storage. Identifiable differential proteins corresponded to protease inhibitors, patatins, heat shock proteins, lipoxygenase, phospholipase A1 and leucine aminopeptidase (Lap). Association mapping based on single nucleotide polymorphisms supported a role of Lap in the natural variation of the quantitative traits tuber starch and sugar content.

Conclusions: The combination of comparative proteomics and association genetics led to the discovery of novel candidate genes for influencing the natural variation of quantitative traits in potato tubers. One such gene was a leucine aminopeptidase not considered so far to play a role in starch sugar interconversion. Novel SNP's diagnostic for increased tuber starch content, starch yield and chip quality were identified, which are useful for selecting improved potato processing cultivars.

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Reducing sugar content (RSC) in tubers of 40 cultivars during cold storage. RSC represents the amounts of glucose and fructose in freeze dried tuber tissue. Cultivars are coded by numbers shown in Additional file 1: Table S1. (A) RSC before cold storage. Cultivars are ranked according to increasing RSC. (B) RSC after 1, 2, 4 and 12 weeks of cold storage. Cultivars are ranked according to increasing RSC after 4 weeks of cold storage. The arrows indicate cultivars that contain at least one dosage of a leucine aminopeptidase allele, for which the SNP allele A2746 is characteristic. SNP2746 associated highly significant with tuber starch content, starch yield and chip quality after storage at 4°C (Table 3). The inset presents a magnification of the data obtained for cultivar 17 to cultivar 8.
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Figure 1: Reducing sugar content (RSC) in tubers of 40 cultivars during cold storage. RSC represents the amounts of glucose and fructose in freeze dried tuber tissue. Cultivars are coded by numbers shown in Additional file 1: Table S1. (A) RSC before cold storage. Cultivars are ranked according to increasing RSC. (B) RSC after 1, 2, 4 and 12 weeks of cold storage. Cultivars are ranked according to increasing RSC after 4 weeks of cold storage. The arrows indicate cultivars that contain at least one dosage of a leucine aminopeptidase allele, for which the SNP allele A2746 is characteristic. SNP2746 associated highly significant with tuber starch content, starch yield and chip quality after storage at 4°C (Table 3). The inset presents a magnification of the data obtained for cultivar 17 to cultivar 8.

Mentions: Tuber RSC was determined before and after cold treatment in 40 cultivars pre-selected for high (No.1 to 20, Additional file 1: Table S1) and low (No. 21 to 40, Additional file 1: Table S1) chip quality. Before cold storage, RSC varied from 0.02 to 3.58 percent dry weight (Figure 1A). The ranking of cultivars corresponded to their prior allocation based on chip quality with two exceptions (cultivars 2 and 31). During twelve weeks of storage at 4°C, RSC increased in all cultivars (Figure 1B). Cultivars exhibiting low RSC values before cold storage showed a higher increase in RSC during cold storage compared to cultivars with high initial RSC values. However, the ranking of cultivars according to RSC before and after 4 weeks cold storage was in high agreement with their assignment to high and low chip quality. In conclusion, RSC was highly indicative for chip quality and vice versa.


Novel candidate genes influencing natural variation in potato tuber cold sweetening identified by comparative proteomics and association mapping.

Fischer M, Schreiber L, Colby T, Kuckenberg M, Tacke E, Hofferbert HR, Schmidt J, Gebhardt C - BMC Plant Biol. (2013)

Reducing sugar content (RSC) in tubers of 40 cultivars during cold storage. RSC represents the amounts of glucose and fructose in freeze dried tuber tissue. Cultivars are coded by numbers shown in Additional file 1: Table S1. (A) RSC before cold storage. Cultivars are ranked according to increasing RSC. (B) RSC after 1, 2, 4 and 12 weeks of cold storage. Cultivars are ranked according to increasing RSC after 4 weeks of cold storage. The arrows indicate cultivars that contain at least one dosage of a leucine aminopeptidase allele, for which the SNP allele A2746 is characteristic. SNP2746 associated highly significant with tuber starch content, starch yield and chip quality after storage at 4°C (Table 3). The inset presents a magnification of the data obtained for cultivar 17 to cultivar 8.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750364&req=5

Figure 1: Reducing sugar content (RSC) in tubers of 40 cultivars during cold storage. RSC represents the amounts of glucose and fructose in freeze dried tuber tissue. Cultivars are coded by numbers shown in Additional file 1: Table S1. (A) RSC before cold storage. Cultivars are ranked according to increasing RSC. (B) RSC after 1, 2, 4 and 12 weeks of cold storage. Cultivars are ranked according to increasing RSC after 4 weeks of cold storage. The arrows indicate cultivars that contain at least one dosage of a leucine aminopeptidase allele, for which the SNP allele A2746 is characteristic. SNP2746 associated highly significant with tuber starch content, starch yield and chip quality after storage at 4°C (Table 3). The inset presents a magnification of the data obtained for cultivar 17 to cultivar 8.
Mentions: Tuber RSC was determined before and after cold treatment in 40 cultivars pre-selected for high (No.1 to 20, Additional file 1: Table S1) and low (No. 21 to 40, Additional file 1: Table S1) chip quality. Before cold storage, RSC varied from 0.02 to 3.58 percent dry weight (Figure 1A). The ranking of cultivars corresponded to their prior allocation based on chip quality with two exceptions (cultivars 2 and 31). During twelve weeks of storage at 4°C, RSC increased in all cultivars (Figure 1B). Cultivars exhibiting low RSC values before cold storage showed a higher increase in RSC during cold storage compared to cultivars with high initial RSC values. However, the ranking of cultivars according to RSC before and after 4 weeks cold storage was in high agreement with their assignment to high and low chip quality. In conclusion, RSC was highly indicative for chip quality and vice versa.

Bottom Line: The molecular basis of CIS in potato tubers is of interest not only in basic research on plant adaptation to environmental stress but also in applied research, since high amounts of reducing sugars affect negatively the quality of processed food products such as potato chips.We compared by two-dimensional polyacrylamide gel electrophoresis the tuber proteomes of cultivars highly diverse for CIS.Novel SNP's diagnostic for increased tuber starch content, starch yield and chip quality were identified, which are useful for selecting improved potato processing cultivars.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Plant Breeding and Genetics, Max-Planck-Institute for Plant Breeding Research, Cologne, Germany. fischer@mpipz.mpg.de

ABSTRACT

Background: Higher plants evolved various strategies to adapt to chilling conditions. Among other transcriptional and metabolic responses to cold temperatures plants accumulate a range of solutes including sugars. The accumulation of the reducing sugars glucose and fructose in mature potato tubers during exposure to cold temperatures is referred to as cold induced sweetening (CIS). The molecular basis of CIS in potato tubers is of interest not only in basic research on plant adaptation to environmental stress but also in applied research, since high amounts of reducing sugars affect negatively the quality of processed food products such as potato chips. CIS-tolerance varies considerably among potato cultivars. Our objective was to identify by an unbiased approach genes and cellular processes influencing natural variation of tuber sugar content before and during cold storage in potato cultivars used in breeding programs. We compared by two-dimensional polyacrylamide gel electrophoresis the tuber proteomes of cultivars highly diverse for CIS. DNA polymorphisms in genomic sequences encoding differentially expressed proteins were tested for association with tuber starch content, starch yield and processing quality.

Results: Pronounced natural variation of CIS was detected in tubers of a population of 40 tetraploid potato cultivars. Significant differences in protein expression were detected between CIS-tolerant and CIS-sensitive cultivars before the onset as well as during cold storage. Identifiable differential proteins corresponded to protease inhibitors, patatins, heat shock proteins, lipoxygenase, phospholipase A1 and leucine aminopeptidase (Lap). Association mapping based on single nucleotide polymorphisms supported a role of Lap in the natural variation of the quantitative traits tuber starch and sugar content.

Conclusions: The combination of comparative proteomics and association genetics led to the discovery of novel candidate genes for influencing the natural variation of quantitative traits in potato tubers. One such gene was a leucine aminopeptidase not considered so far to play a role in starch sugar interconversion. Novel SNP's diagnostic for increased tuber starch content, starch yield and chip quality were identified, which are useful for selecting improved potato processing cultivars.

Show MeSH
Related in: MedlinePlus