Virulence Spectrum of Phytophthora infestans and Spatial Distribution of Physiological Races in Northwestern Ethiopia

አህፅሮትድንች ለምግብና ለአመጋግብ ዘዴ ዋስትና በተለይም የምግብ ዋስትና ችግር ባለበት አካባቢ ዋነኛ ምግብ ነው፡፡ ምንም እንኳን ድንች ከፍተኛ ጠቀሜታ ያለው ቢሆንም ፋይቶፍቶራ ኢንፌስታንስ በሚባል ተዋስያን አማካኝነት የሚከሰተው የድንች ምች በሽታ ከፍተኛ ጉዳት በማድረስ ለድንች ማምረት ትልቅ  ማነቆ ነው፡፡ ጥናቱ በሰሜን ምዕራብ ኢትዮጵያ ዋና ዋና የድንች አብቃይ በሆኑ አካባቢዎች ላይ የፋይቶፍቶራ ኢንፌስታንስ በሽታ አምጭ የዝርያ ዓይነቶችን እና ስርጭታቸውን ለመለየት በ2018 የተካሄደ ነው፡፡ በአጠቃላይ 74  ናሙናዎች ተሰብስበው በድንች ቁርጥራጮች ላይ በማባዛት በብላክስ በሽታ ተቋቋሚ የድንች ዘረመሎች ላይ በሽታ አምጭነታቸው ተገምግሟል፡፡ ናሙናዎቹ በሽታውን በሚቋቋሙ ዘረመሎች ላይ ተሞክረው በአሳዩት አፀፋዊ መልስ መሠረት 6፣ 11 እና 16 የተለያዩ ዓይነት በሽታ አምጭ ዝርያዎች በአዊ፣ በደቡብ ጎንደር እና በምዕራብ ጎጃም በቅደም ተከል መሠረት እንደሚገኙ አሳይቷል፡፡ የሻኖን የአይነት ብዛት መለኪያ ውጤት ለሁሉም ናሙናዎች በአጠቃላይ 0.8 ሲሆን ለአዊ፣ ለደቡብ ጎንደር እና ምዕራብ ጎጃም ዞኖች ለየራሳቸው ደግሞ 0.75፣ 0.84 እና 0.92 በቅደም ተከተላቸው መሠረት ነው፡፡ በአጠቃላይ 74ቱም ናሙናዎች የሦስቱም ዞኖች ፑል ተደርገው ሲታይ 27 የተለያዩ ዓይነት በሽታ አምጭ ዝርያዎች እንዳሉ ተለይተዋል፡፡ ምንም አይነት የዝርያ ውስብስብነት የሌለው ናሙና በደቡብ ጎንደር እና ምዕራብ ጎጃም ዞኖች የተገኘ ቢሆንም ከፍተኛ የዝርያ ውስብስብነት 10 የበሽታ አምጭነት ነገር ያላው ዝርያ በደቡብ ጎንደር ተገኝቷል፡፡ በሽታውን ከሚቋቋሙ ዘረመሎች ውስጥ R3, R5, R8 እና R9 አጠቃላይ ከታየው ልዩነት ከፍተኛ አስተዋፅኦ ያበረከቱ ሲሆን R9 እና R5 በጣም ውጤታማ የነበሩ 95% እና 92%  የሚሆኑትን ናሙናዎች በቅደም ተከተል መቋቋም የቻሉ ዘረመሎች ናቸው፡፡ በጠቅላላው ዋና ተቋቋሚ ዘረመል የያዙ የድንች ዝርያዎችን በመጠቀም በሽታውን መከላከል አዳጋች ነው፡፡ ምክንያቱም ሁሉንም ናሙናዎች መቋቋም የቻለ ዘረመል ባለመኖሩ እና ውስብስብ በሽታ አምጭ የዝርያ ዓይነቶች በአካባቢው ተሰራጭተው ስለሚገኙ፡፡  AbstractDespite the importance of potato the late blight disease, caused by the oomycete Phytophthora infestans is most destructive disease for potato production. The study was conducted to identify virulent races and spatial distribution of Phytophthora infestans populations in major potato growing areas of northwestern Ethiopia in 2018. Seventy-four isolates (samples) were collected and multiplied on potato tuber slices and virulence was assessed on Black’s potato differentials. Isolates reaction to differentials revealed 6, 11, and 16 race types at Awi, South Gondar and West Gojam, respectively. Shannon diversity index was 0.80 for the entire isolates but it was 0.75, 0.84 and 0.92 for isolates collected from Awi, South Gondar and West Gojam, respectively. Tewnty-seven physiological races were detected in the pooled population when the 74 isolates from the three populations were combined. Absence of race complexity was found in isolates of South Gondar and West Gojam while the highest race complexity with virulence factors of 10 was found in South Gondar. Differentials, R3, R5, R8, and R9 had larger contribution to the total variability of isolates and R9 and R5 genes were most effective withstood 95% and 92% of isolates. It is concluded that potato varieties resistant to major genes are hardly possible to be used as disease management option due to the absence of R genes resistant to all isolates, the complexity, and distribution of races in the region

Protocol for assessing bacterial wilt resistance in greenhouse and field conditions. International cooperators’ guide

This protocol is an updated version of “Assessing potato clone field resistance to bacterial wilt” issued in The International Cooperators’ Guide (CIP 2007). The first edition of the protocol presented a standard procedure for field assessment of resistance to bacterial wilt for documenting levels of resistance of advanced potato germplasm. This second edition has included a standardized procedure for greenhouse screening of potato seedlings for bacterial wilt resistance useful for perform genetic studies, parental selection or identification of new sources of resistance in accessions of wild species propagated or maintained as true see

Current diversity of Phytophthora infestans infecting cultivated potato in the Peruvian Andes

Late blight caused by P. infestans is the most devastating disease of potato worldwide. To understand the current P. infestans population structure in the Peruvian Andes, 701 single-lesion samples were collected from cultivated potato in different agroecological zones at 2016-2017. Genetic diversity was analyzed using the 12-plex SSR markers kit and mtADN. Phenotypic diversity was characterized for mating type, metalaxyl resistance and virulence. SSR analysis showed that population consists of EC-1 and PE-3 clonal lineages variants, that have the mtADN IIa and Ia, respectively. All isolates were A1 mating type. 94% of the EC-1 variant isolates were resistant to metalaxil, whereas the sensitive proportion (47%) in the PE-3 variants was bigger than the resistant (35%). Furthermore, virulence assays detected 41 complex physiological races from 142 selected isolates, the most frequent physiological race was 1,3,4,7,10,11 in both EC-1 and PE-3 variants. Phylogenetic analysis evidenced that isolates share identical SSR genotypes and physiological races in distant regions, that suggests that migration could have occurred. Additionally, no detection of A2 mating type indicate that population reproduction must be asexual. EC-1 clonal lineage continues to dominate across the Peruvian Andes, since 91% of the isolates were variants of this clonal lineage. The US-1 clonal lineage reported at 2001, appears to be displaced as it was no longer detected infecting cultivated potato