VIRULENCE ANALYSIS OF PUCCINIA TRlTICINA POPULATION AND GENE POSTULATION IN CURRENT GENOTYPES OF WHEAT AGAINST LEAF RUST IN P MOST AN

Abstract

For the virulence analysis of Puccinia /rilicina population and gene postulation In current genotypes of wheat against rust in Pakistan, two surveys were conducted during 2002·03 and 2003·04 in different districts of Sindh, Balochislan, Punjab and North West Province. The leaf rust incidence in Sindh province ranged from 30·42 percent during 2002·03 with severity ranged from 608·738. While during 2003·04 incidence ranged from 28·40 percent, with severity ranged from 45S· 80S. In Balochistan province one district was surveyed with 35 percent mean incidence and 64S severity during 2002·03 whilc 20 percent incidence with 40S severity was observed during 2003·04. In Punjab incidence ranged from 21·37 percent with mean severity 60S during 2002·03, whereas, incidence ranged from 20-42 percent with severity during 2003·04. In North West Province incidence ranged from 10·15 percent with mean severity 308 during 2002·03, while, incidence of I percent with mean severity 408 during 2003·04 was Oh''''MJM The virulence frequency in 2002·03 and 2003·4 was found in Pakistan for the genes Lr2a, Lr2b, Lr2c, Lr3, Lr3ka, Lr3bg, LrlO, Lrll, Lr14a, Lr14b, Lr15, 7, Lr18, Lr20, I, Lr23, Lr26, Lr30, Lr32, Lr33, Lr35, Lr37, LrB and Lr27+31. The virulence analysis of resistance genes in 8indh, Baluchistan, Punjab and NWFP during 2002·03 and 2003·04 showed virulence frequency 0·20 percent having the genes Lr9, Lrl9, Lr34 with the difference of genes Lr34 in Punjab only. The virulence frequencies different provinces viz. 8indh, Baluchistan, Punjab and NWFP for the Lrl, Lr2a, Lr2b, Lr2c, Lr3, Lr3ka, Lr3bg, LrlO, Lrll, Lrl3, Lrl4a, Lrl4b, Lrl5, Lr18, Lr20, Lr21, Lr23, Lr24, Lr25, Lr26, Lr27+31, Lr30, Lr32,Lr33, XII Lr35, Lr37 and LrB fell in the range of 51-100 percent. Among commercial varieties only the MaxiPak showed susceptibility at all the locations during 2002-03 and 2003- 04. A total of II genes, Lri (in 12 lines), Lr3 (4), Lr9 (2), LrlO (28), Lrl3 (27), Lrl4a (2), Lrl6 (9), Lrl7 (8), Lr23 (18), Lr26 (36), Lr27+31 (5) for leaf rust resistance were postulated either singly or in combination in 76 Pakistani wheats. Lr26 was the most frequent by Lr9 among the Pakistani wheats.