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Short Short Ug99—Ug99— AgricultureThreatThreat toto

PALLABI ROY, SNIGDHA MAJUMDER AND SIRAJ DATTA

1960s by developing high yielding crop Predicted Pathway strains said: “Ug99 has immense potential The FAO has already alerted Afghanistan, for social and human destruction. It is India, Pakistan, Turkmenistan, Uzbekistan capable of severely damaging virtually all and Kazakhstan about the dangerous of the world’s commercial bread . It wheat that may cause a huge loss g99 is a virulent strain of old crop is a problem that goes far beyond wheat to wheat production by destroying entire disease “Black Stem ” that has production in developing countries.” fields. evolved to overcome the resistance U outbreak caused by Ug99 prevalent in wheat varieties during the Threat to World Wheat Crops depends on the following key factors: area Green Revolution of the 1960s. Black Stem Ug99 was first observed in in 1999. and distribution of susceptible material; Rust is a disease caused by a fungi It has overcome many wheat-resistant degree of susceptibility; optimum graminis in wheat. Puccinia is a temperatures and moisture; amount of fungus that belongs to the class genes like Sr24, Sr25, Sr26, Sr27 Sr31, and initial inoculum, and air movement. An Basidiomycetes. This rust fungus of wheat Sr38 that the other races could not. After additional sub-factor that might be added resembling rusted iron rods in wheat stem, Uganda, the spores of Ug99 spread to to this list is the historical precedence of plugs the vascular system such that through wind current, followed by the movement of spores through known nutrients can not travel from the leaves to , , , southern regions. the grain resulting in plants producing thereby threatening regions of the near The Ug99 spores can attack India fewer tillers and seeds, and in cases of east, eastern , central and southern following either of the two routes: severe infection the plants may even die. Asia. It not only spreads rapidly but also Route A: East Africa directly to Like most rust fungi it requires two generates new variants able to break the southern Pakistan/western India (has no hosts to complete its life cycle—Wheat resistance of the wheat varieties grown in (Triticum aestivum L.) and Barberry (Berberis these regions. known precedent and of much lower vulgaris). The urediniospores (fungal spore) The deleterious effect of Ug99 is more probability). spread over long distances through wind pronounced (upto100%) with respect to Route B: East Africa––West currents rapidly and can affect fields of the stem rust that too may reduce crop Asia–South Asia (has higher probability). distant countries within a short time period. yield. About 80% yield losses were recently Conditions favourable for outbreaks of Huge crop loss due to this infection can recorded in Kenya and Uganda, though epidemics currently exist in the migration lead to severe in countries where fortunately neither of these countries path of highest probability. wheat is the major staple crop. depends totally on wheat as a staple crop. Nobel prize-winner Norman E. But for countries like India, where wheat is Indian Approach Borlaug, who helped India and many other the major staple crop, Ug99 is a big threat The Indian Council of Agricultural Research countries to avoid the food crisis in the that can lead to a serious food crisis. (ICAR) scientists, engaged in wheat 23 SCIENCE REPORTER, NOVEMBER 2011 Short Feature

“Ug99 has immense potential for social and human destruction. It is capable of severely damaging virtually all of the world’s commercial bread wheat. It is a problem that goes far beyond wheat production in developing countries.”

improvement programme, are trying to The ICAR, in collaboration with the trifloxystrobin and fluoxastrobin are protect the crop from Ug99 as wheat International Wheat and Maize Research effective for controlling cereal rust directly impacts the country’s . Centre (CIMMYT), Mexico started a testing diseases. The country has not faced any epidemic programme of wheat at Njoro in Kenya There is a need to study the since the last four decades because since 2005. The tests have shown that there molecular mechanism of wheat and regular countrywide surveys have been are 13 Indian wheat varieties with pathogen interaction of susceptible as carried out to safeguard the wheat crop resistance to Ug99 and its variants. This well as resistant varieties in order to against destructive pathogens like Ug99. diverse resistance in wheat varieties will elucidate the biochemical or signaling Wheat Varieties help them fight against the deadly pathway of the defense mechanism. pathogen and other future threats of this Analysis of this study can help in the Resistant to magnitude. The resistant wheat varieties development of broad-spectrum Ug99 are being multiplied. disease-resistant transgenic plants. This It takes a few seasons for the race to will render a cost effective and 1. GW 273 build up and appear on a large scale to environmentally friendly approach to cause economic losses. Thus, by the time combat the threat of Ug99 unlike the 2. GW 322 Ug99 reaches India, the already identified chemical treatment that is costly and 3. HI 1500 resistant varieties should be multiplied might have deleterious effect on plants. 4. HD 2781 rapidly, bred and then aggressively distributed to cultivators to avoid any loss 5. MP 4010 in the farmer’s field. As an immediate relief 6. HUW 510 measure, chemical control technology is Dr Siraj Datta, an M.Tech. from the Department of 7. MACS 2846 (durum) also available to ensure that this race does Agricultural and Food Engineering, IIT-Kharagpur, not spread and cause damage. is a faculty member at the School of Biotechnology 8. HI 8498 (durum) and Life Sciences, Haldia Institute of Technology, Some fungicides have been identified ICARE Complex, Haldia, West Bengal-721657; 9. UP 2338 that can be effective against stem rust. Email: [email protected] 10. DL 153-2 Stem rust can be effectively controlled by 11. HW 1085 some azole fungicides such as Pallabi Roy ([email protected]) and Snigdha tebuconazole, cyproconazole, Majumder ([email protected]) are B.Tech 12. Raj 4120 fluquinconazole, prothioconazole and students of School of Biotechnology & Life Sciences, 13. PBW 343 triadimenol. Strobilurins such as Haldia Institute of Technology, Haldia. SCIENCE REPORTER, NOVEMBER 2011 24