Abstract
Background: Potato is the most important staple food in the world. Cold-induced sweetening occurs when potatoes are stored at low temperature for longer period of time. Due to non- enzymatic Millard reaction it causes unwanted changes in colour, taste and in flavor when fried and roasted at high temperature. However, long-term cold storage is mandatory to keep an adequate supply of potatoes throughout the year. The cause of cold-induced sweetening is invertase enzyme.
Methods: Five potato varieties (Hermes (A) Lady Rosetta (B) Oscar (C) Kuroda (D) and Multa (E)) were investigated for invertase activity during two month cold storage at 4°C. Crude protein was extracted by PD Midi Trap G25 column technique. Quantification of mRNA expression was employed through QPCR. Determination of sucrose, reducing sugars and organic acids was simply done by 80% ethanol method and concentration were find out by using HPLC with already set standards. The correlation between invertase enzyme, sugar content and mRNA expression was calculated through Statistical methods.
Results: Significant activity of invertase was observed at 4ºC with up to 6.3 nmol/min/mg of protein in the type-1 & 4 (cv. Hermes and Kuroda); 2.5 times less in type 2 (Rosetta) and 3.5 times less in type 3 (Multa) when compared with same at 4ºC. In addition, malic acid concentration was found positively correlated with invertase activity at 4ºC as compared with its concentration at harvesting time. However, citric acid and oxalic acid concentrations were independent of invertase enzyme activity. The transcript level of invertase enzyme was found significantly high in potato tubers stored at 4ºC in result 1 & 4 type, less in result type 2(C) and negligible in result 3(E) potato variety when revealed through reverse transcription PCR.
Conclusions: In conclusion, Oscar (C) and Multa (E) were found more resistant to CIS at 4ºC storage and may be used for future variety improvement programs for CIS resistant through breeding and molecular approaches.
Arfan Ali, Mazhar Iqbal, Qurban Ali, Abdul Razzaq, Idrees Ahmad Nasir. (2015) Gene Profiling for Invertase Activity: Assessment of Potato Varieties for Resistance towards Cold Induced Sweetening, Advancements in Life Sciences, Volume 3, Issue 2.
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