Virulence Spectrum of Puccinia graminis f. sp. tritici in Northwest Ethiopia

Abstract

 አህፅሮት

ኢትዮጵያ ውስጥ ስንዴን ከሚያጠቁ በሽታዎች መካከል የግንድ ዋግ አንዱ እና ዋነኛው ነው፡፡ ይህንን በሽታ የሚያመጣው ተዋስያን አካል የአየሩን ምቹ ሁኔታ በመጠቀም እራሱን እየቀያየረ በሽታ የሚቋቋሙ የስንዴ ዝርያዎችን በማጥቃት ከፍተኛ የሆነ የምርት ቅነሳ ያደርጋል፡፡ የዚህ ጥናት ዓላማ የነበረው በሰሜን ምዕራብ ኢትዮጵያ ውስጥ ያለውን የስንዴ የግንድ ዋግ ዝርያ መለየት ነው፡፡ ሰማንያ ስድስት ናሙናዎች በ2010 እና በ2011 የምርት ዘመን ተሰብስበው 20 ድፍሬንሻሎችን በመጠቀም አራት (TTTTF, TKTTF, TKPTF, and TTRTF) የስንዴ ግንድ ዋግ ዝርያዎችን ለመለየት ተችሏል፡፡ ከእነዚህ አራት ዝርያዎች ውስጥ በ2010ና በ2011 በተከታታይ በአማካይ በመቶኛ TTTTF 60.4 እና 60 የሚሆነውን የሚሸፍን ሲሆን በሁለተኛነት ደረጃ TKTTF 38.7 እና 37.3 ሸፍኖ ታይቷል፡፡ ሌሎች የግንድ ዋግ ዝርያዎች በሁለቱም የምርት ዘመን በአማካይ በመቶኛ 1 የሚሆነውን የሸፈኑ ሲሆን እነዚህ ሁለት ዝርያዎች የተገኙትም፤ TKPTF በ2010 ከደቡብ ጎንደር ፋርጣ ሲሆን TTRTF በ2011 ከሰሜን ጎንደር አምባ ጊዎርጊስ ላይ ብቻ ነው፡፡ የግንድ ዋግ የሚቋቋሙ ዘረመልን የያዙ ድፍሬንሻሎች እንደ Sr5, Sr21, Sr9e, Sr7b, Sr6, Sr8a, Sr9g, Sr36, Sr17, Sr9a, Sr9d, Sr10, SrTmp, Sr38 እና SrMcN ሁሉም በተለዩ የዋግ ዝርያዎች የተጠቁ ሲሆን Sr24 እና Sr31 ዋግ የሚቋቋሙ ዘረመልን የያዙ ድፍሬንሻሎች ግን ሙሉ በሙሉ የተለዩትን የዋግ ዝርያዎችን መቋቋም ችለዋል፡፡ በአሁኑ ጥናት Sr31  እና በአሁኑና ከዚህ በፊት ኢትዮጵያ ውስጥ በተደረጉ ጥናቶች Sr24  ዘረመልን የሚያጠቃ የግንድ ዋግ ዝርያ ያለመኖሩ ስለተረጋገጠ  እነዚህን ዘረመሎች ከሌሎች የግንድ ዋግ መቆጣጠሪያ መንገዶች ጋር በመጠቀም አሁን ያለውን የግንድ ዋግ ዝርያ መቋቋም የሚችል የስንዴ ዝርያ ማዳቀል ይቻላል፡፡

Abstract

Stem rust caused by Puccinia graminis f. sp. tritici is one of the most important diseases of wheat in Ethiopia. The pathogen can produce new races that can overcome resistant varieties and cause epidemic under favorable environmental conditions resulting in serious yield losses. The study was carried out to determine the virulence spectrum of Puccinia graminis f. sp. tritici in northwest Ethiopia. Eighty-six stem rust samples were collected during 2017 and 2018 cropping seasons and analyzed on 20 standard stem rust differential lines which resulted in the identification of four races (TTTTF, TKTTF, TKPTF, and TTRTF). Of these races, 60.4 and 60% of the isolates were TTTTF followed by 38.7 and 37.3% of TKTTF (Digalu race) in 2017 and 2018, respectively.  These two races accounted for almost 99% of the stem rust population. The least virulent races were TKPTF and TTRTF that accounted 1% in both seasons and were detected only at single location (Farta in South Gondar in 2017 and Amba Giorgis in North Gondar in 2018). The differential hosts carrying resistance genes Sr5, Sr21, Sr9e, Sr7b, Sr6, Sr8a, Sr9g, Sr36, Sr17, Sr9a, Sr9d, Sr10, SrTmp, Sr38 and SrMcN were susceptible to the four races identified in northwest Ethiopia. Two differential hosts carrying the resistant genes Sr24 and Sr31 were effective against all the four races identified in this study. Absence of virulence against lines carrying Sr31 in the present and Sr24 in the present and previous studies suggests that these genes may serve as a source of resistance in combination with other wheat stem rust management systems to the current rust races in northwest Ethiopia.