Phenotypic and genetic attributes conferring non-specific resistance genes against leaf and stripe rusts on wheat

Abstract

A comprehensive germplasm evaluation study of wheat elite lines was conducted at Wheat Research Institute Faisalabad to identify new sources of leaf and stripe rust resistance and high yield potential during crop seasons 2015-2017. The parents’ lines were selected on the basis of phenotypic characteristics and slow rusting history of race non-specific resistance genes by the selection of desirable parents used in a filial generation (F1-F5). In primary evaluation, total 855 head rows (F6 generation) were selected among F5 generation and screened. Among these, 112 lines were found to be resistant and these were further assayed for leaf and stripe rust resistance, yield performance and the presence of race non-specific rust resistance genes through phenotypic and molecular markers. The second round of evaluation identified 44 lines potentially resistant to both leaf and stripe rust under field conditions. Environmental factors played a great role on the progress of leaf and stripe rust disease severities during both crop seasons 2015-2017. Maximum lines showed statistically significant correlation with all environmental conditions. A positive linear relationship was observed between temperature (minimum and maximum), relative humidity, rainfall and wind speed and leaf and stripe rust disease severity. The phenotypic and molecular investigation confirmed 10 elite lines demonstrating the linkage of three designated slow rusting/race non-specific resistance genes (Lr34/Yr18, Lr46/Yr29, and Sr2/Yr30). Among 112 advanced lines, under yield testing trial 14 lines (cluster-V) demonstrated highest mean values for all traits i.e. plant height (cm), grain yield (Kg ha-1), protein (%), 1000 grain weight (g), spike length (cm) and number of spikelet per spike as compared to all check varieties. It was concluded that CHENAB2000/INQ.91/5/WBLL1*2/ 4/SNI/TRAP#1/3/KAUZ*2/TRAP//KAUZ; PB-36259-0A-0A-0A-12A-0A (V-70003), 87094/ERA// PAK-81/2*V-87094/3/SHAFAQ-06/4/MAYA/PVN; PB-36369-0A-0A-0A-11A-0A (V-70034), FSD.08/6/BABAX/3/FASAN/Y//KAUZ/4/BABAX/5/LU26/HD2179/7/PB.96/87094/MH.97; PB. 37082-0A-0A-0A-19A-0A (V-70054), CNDO/R143//ENTE/MEXI_2/3/AEGILOPSSQUARROS A(TAUS)/ 4/WEAVER/5/PICUS/6/TROST/7/TACUPETOF2001/8/ CROW'S'/NAC//BOW'S'; PB No.36830-0A-0A-0K-12A-0A (V-70070); WHEAR/KRONST ADF2004//KAUZ/SITE; PBNo.36880-0A-0A-0K-11A-0A (V-70085), CNDO/R143//ENTE/MEXI_2/3/AEGILOPSSQUAR ROSA(TAUS)/4/WEAVER/5/IRENA/6/LERKE/7/TAN/PEW//SARA/3/CBRD; PBNo.369760 A-0A-0K-4A-0A (V-70103) and CNDO/R143//ENTE/MEXI_2/3/AEGILOPSSQUA RROSA(TAUS)/4/WEAVER/5/IRENA/6/LERKE/7/TAN/PEW//SARA/3/CBRD; PB No. 36976-0A-0A-0K-10A-0A) (V-70104) were most prominent crosses yielded lines and showed the combination of three slow rusting genes. None of these lines showed race specific/complete resistance, but were of slow rusting type and were suitable for commercial cultivation. Virulences analysis of leaf and stripe rust race populations was carried out to observe virulence pattern in the country through avirulence/virulence formula. The surveys were carried out on the rust traps nurseries consisted of 39 leaf and 27 stripe rust near-isogenic lines planted at different locations in Pakistan. The results showed that there were no virulence patterns for genes Lr18, Lr19, Lr23+(GAZA), Lr28, Lr29, Lr32, Lr34, Lr35, Lr36 and Lr37 and Yr1, Yr3, Yr4, Yr5, Yr8, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr28, Yr29, Opata, Yrcv, Yrsp, Super Kauz, PBW-343 and Aoc+Yra. Among varieties FSD-08, PB-11, AARI-2011, Millat-11 and AAS-11 exhibited effective resistance to both leaf and stripe rust pathotypes.