Author: Wa Ode Kamillah*, Hermin Pancasakti Kusumaningrum, Rejeki Siti Ferniah , Azalia Puspa Herida, Garinda Linggar Nasansia

Photo by Rhoberazzi from Getty Images/Canva

In this study, the response of Dieng red potato plants to frost exposure was evaluated physiologically by testing electrolyte leakage and chlorophyll content, and molecularly by detection of Inh2 gene. The physiological response shows an increased electrolyte leakage rate and a significant decrease in chlorophyll content in plants exposed to frost compared to those grown in normal temperatures. Sequencing of Inh2 gene identifies four homologous Solanum tuberosum alleles. The difference in the order of Inh2 lies in the gap of 12 bp. Phylogenetic analysis shows that inh2 gene is in a cluster with INH2α*C allele and has evolved slowly from a common ancestor with S. lycopersicum. This is the first study on the physiological mechanisms of frost tolerance and the sequencing of Inh2 gene in Dieng red potatoes. Hopefully, this study will provide useful information for the breeding of low-sugar Dieng red potatoes.

Keywords: Dieng, electrolyte leakage, chlorophyll, Inh2, frost

Potato (Solanum tuberosum L.) includes thousands of varieties that vary in size, shape, pigment, and other characteristics. One of the pigmented potatoes that has been widely cultivated is red potato plant. The glycemic index (GI) value of potato tubers varies widely and depends on the type, storage and serving. Red potato tubers have a lower GI value than other types of potato tubers. The low GI value in red potato tubers reaches 56 when served by boiling and consumed when cold (Eleazu, 2016). Red potato tubers also contain potential nutritional sources in the form of carbohydrates, minerals, vitamins C and B1 (Beals, 2019). Therefore, choosing red potato tubers to serve as diet food is the best choice. Furthermore, there are pre-harvest factors that affect red potato tubers, namely the temperature of their growing period. Potato plants are very sensitive to frost, so temperature is one of the factors that affect the productivity of red potatoes.

Potato plants cannot tolerate low temperatures and will immediately show symptoms of freezing damage (Che et al., 2020). Potato plants are not able to tolerate the formation of ice in its tissues, either extracellular or intracellular. Leakage of electrolytes from cells often occurs after frost injury (Arvin and Donnelly, 2007; Rooy et al., 2017). Another damage that occurs after an electrolyte leak is a reduction in photosynthesis. Chlorophyll content of plants has a good correlation with the ability of photosynthesis. The reduction in chlorophyll contents in potato plants has been shown to slow down the rate of photosynthesis (Harb and Lahham, 2013; Li et al., 2021).

Potato plants exposed to low temperatures will also cause the accumulation of reducing sugars, namely glucose and fructose or cold-induced sweetening, CIS (Datir et al., 2019). Acid invertase activity was the most significant factor in determining the accumulation of fructose and glucose (Stein and Granot, 2019). Acid invertase activity can be controlled post translation by invertase inhibitors. Invertase inhibitor is of two types, the apoplastic invertase inhibitor encoded by Inh1 gene and the vacuolar invertase inhibitor encoded by Inh2 gene (Datir, 2020). According to Liu et al. (2010), the interaction between acid invertase and vacuolar invertase inhibitor may play an important role in controlling reducing sugars.

Understanding the response of potato plants to frost is essential for the development of cold-resistant crops. Red potatoes used in this research come from the Dieng. This is because air temperature in Dieng during the dry season (June-August) is very low and can reach freezing point in the morning, thus causing frost. The objectives of this study was to determine the physiological response of red potato plants to the amount of electrolyte leakage and chlorophyll content based on its resistance after exposure to frost and to analyze the sequence and compile the phylogenetic tree of Inh2 gene of Dieng red potato plants. The results of this study are expected to be used as supporting data and a first step to breed cold-tolerant red potato plants so that they can be used as diet food by producing low-sugar potatoes through the mechanism of potato plants in inhibiting the formation of reducing sugar.

Wa Ode Kamillah*, Hermin Pancasakti Kusumaningrum, Rejeki Siti Ferniah , Azalia Puspa Herida, Garinda Linggar Nasansia

Department of Biology, Faculty of Science and Mathematics, Diponegoro University, Semarang 50275, Indonesia

To appear in: Jordan Journal of Biological Sciences

Volume 15, Number 1,March 2022
ISSN 1995-6673
Pages 101 – 106

DOI: https://doi.org/10.54319/jjbs/150113

Received Date: December 8, 2020
Revised Date: March 9, 2021
Accepted Date: April 4, 2021

* Corresponding author. e-mail: no corresponding author.