New molecular tools for the detection of potato virus x in potato crop of Pakistan

By  Muhammad Fahim Abbas


Potato (Solanum tuberosum L.) is a valuable plant of the family Solanaceae and the world’s most widely grown tuber crop ranking fourth in production in the world after rice, wheat and maize and fifth in acreage among the staple food crops grown for human consumption.

The potato has two compensations over the other crops i.e. its production and calories per unit area are higher than wheat and rice and in term of total production it gives 12-15 times more yield per hectare as compared with cereals. Potato tuber is an excellent source of carbohydrates, protein, and vitamins. Due to favorable soil and climatic conditions prevalent in Pakistan, three crops of potato are produced in a year, i.e. autumn and spring crops in the plain and summer crop in the hills. During the year 2011, potato crop produced 3726.5 thousand tons on 127.7 thousand hectares area which is comparatively low rather than other potato growing developing countries of the world due to different biotic and a biotic factors. Fungus, bacteria (Ashraf et al., 2012), virus (Abbas and Hameed 2012), nematode (Parveen et al., 2013) along with different pests are much responsible in yield reduction and can be easily transferred to next generation through vegetative material. Introduction of new foreign and high yielding varieties without any check and balance and agronomic practices have certainly enhanced potato yield in Pakistan, but at the same time many new diseases were also emerged.

In Pakistan, Mughal et al. (1986) reported Potato virus A, S, M, X, Y, Potato leaf roll virus and Potato mop top virus in autumn, spring and summer potato crop. Among the viral diseases, the incidence of Potato virus Y (Abbas et al., 2012) and Potato virus X (Abbas and Hameed 2012) is increasing in the main potato growing areas of Pakistan. A large number of potato samples were certified in plant diagnostic labs through Enzyme linked Immunosorbant Assay (ELISA) because these techniques are less expensive and more samples can be certified with in short period of time but ELISA is unable to detect low concentration of virus during early stage of infection. The viron of PVX (theoretically one) presented at initial stage of infection multiplied into billions of copies within few days or weeks and dispersed to the healthy plant by mean of agricultural tools along with the inset vector. It is one of the reasons that ELISA negative plants sometime show typical symptoms of PVX at later stages of their growth.

The Polymerase Chain Reaction (PCR) has already revolutionized research in molecular biology and it increasingly applied in most molecular biology laboratories. New applications of PCR are being published at an increasing rate and it is evident that it will be used in may field of basic and applied research. Reverse transcriptase PCR methods are introduced and the main advantage of these methods is that viruses can be detected from total RNA using sap from dormant potato tubers. PCR is having the ability to detect the virus at initial stage of infection where ELISA is unable to detect the virus. The nucleotide evidence of PVX coat protein gene from a Pakistani isolate exhibiting the maximum genetic homology with UK isolate. The application of these molecular techniques for the potato certification will play a vital role to reduce the dispersal of PVX. The high yield of potato crop will enhance farmer’s income and it can play a significant role in the Gross Domestic Product (GDP) of Pakistan.

References: Abbas, M.F., S. Hammed, A. Rauf, Q. Nosheen, A. Ghani, A. Qadir and S. Zakia. 2012. Incidence of six viruses in potato growing areas of Pakistan. Pak. J. Phytopath., 24 (1): 44 – 47.  Abbas, M.F and S. Hameed. 2012. Identification of disease free potato germplasm against potato viruses and PCR amplification of potato virus X. Int. J. Biol. Biotech., 9 (4): 335-339. Ashraf, A., A. Rauf, M.F. Abbas and R. Rehman. 2012. Isolation and identification of Verticillium dahliae causes wilt on potato in Pakistan. Pak. J. Phytopath., 24 (2): 112-116.  Mughal S. M., S. Khalid and Z. Hussain. 1986. Isolation, identification and prevalence of tobacco viruses in Pakistan. Pak. Tobacco. 10(1 & 2): 5-9. Parven, N., T. Mukhtar, M.F. Abbas and C.A. Rauf. 2013. Management of root knot nematode with marigold (Tagetes erecta L.) and antagonistic fungus Paecilomyces lilacinus (Thom) Samson in tomato crop. Int. J. Biol. Biotech., 10 (1): 61-66. Courtesy Hortist

About author: Muhammad Fahim Abbas Qureshi is a Ph.D scholar at Department of Plant Pathology
PMAS Arid Agriculture University, Rawalpindi, Pakistan. To know further details and contact him, please visit:

Solanum tuberosum L.
Solanum tuberosum L.

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