Mating Type and Aggressiveness of Phytophthora infestans (Mont.) de Bary in Potato-Growing Areas of Punjab, Pakistan, 20
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Mating Type and Aggressiveness of Phytophthora infestans (Mont.) de Bary in Potato-Growing Areas of Punjab, Pakistan, 2017–2018 and Identification of Genotype 13_A2 in 2019–2020 Waqas Raza 1 & Muhammad Usman Ghazanfar 1 & Louise Sullivan 2 & David E. L. Cooke 2 & Louise R. Cooke 3 Received: 23 August 2019 / Accepted: 17 July 2020/ # The Author(s) 2020
Abstract Samples of blighted potato leaves were collected from fields in six potato-growing districts of the Punjab Province of Pakistan in 2017–2018. A total of 149 isolates of Phytophthora infestans were obtained from six potato cultivars (Asterix, Barsenna, Burana, Caroda, Mazika, Sante). Of these isolates, 73% were A1 mating type, 23% were A2 mating type and 4% were self-fertile. Both mating types of P. infestans occurred in all six districts sampled, but in every case, the A1 mating type predominated. The foliar aggressiveness of 104 of these isolates (weakly pathogenic isolates were excluded) was tested on detached leaflets of potato cv. Caroda, and a composite aggressiveness index (CAI) calculated from lesion area (measured after 10 days), latent period and infection frequency was used to compare isolates. There was no difference in CAI between isolates obtained from different districts or cultivars. The A2 mating type isolates had significantly greater CAIs than A1 isolates but this does not imply a genetic linkage nor a general association between mating type and aggressiveness. It may be that the A2 isolates belonged to an aggressive clonal lineage such as 13_A2 that has been reported in other countries in the region. While it was not possible to test the isolates collected in 2017–2018, genotyping of samples collected in 2019–2020 showed the widespread occurrence of the EU_13_A2 clonal lineage in the same districts of Pakistan and supported this hypothesis. This is the first report of EU_13_A2 from Pakistan. The implications for potato late blight management in the Punjab are discussed. Keywords Aggressiveness . Late blight . Mating type . Phytophthora infestans population
* Waqas Raza [email protected] * Louise R. Cooke [email protected] Extended author information available on the last page of the article
Potato Research
Introduction Potato (Solanum tuberosum L.) is the most important vegetable crop worldwide and the third most important food crop after wheat and rice (Jansky et al. 2019); its tubers are a globally important dietary source of starch, protein, antioxidants and vitamins (Burlingame et al. 2009). Potatoes grow in a wide range of habitats from sea level to 4000 m altitude and from 47° S to 65° N latitude (Hijmans 2001). While potato consumption has been declining in Europe and North America, it has been steadily increasing in the developing world; now, more potato production takes place in developing countries than in the developed world and potatoes have an important role in food security of developing countries (Wijesinha-Bettoni and Mouillé 2019). Late blight of potato caused by Phytophthora infestans (Mont.) de Bary is the most d
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