Tracking costs of virulence in natural populations of the wheat pathogen, Puccinia striiformis f.sp.tritici

Table 2 Success of virulent isolates in pairwise competition experiments in the field

Avir/vircompetition	Pair	Avir	vir	Year 1		Year 2		Selective value of *Avir*
				Cultivar 1*	Cultivar 2**	Cultivar 1*	Cultivar 2**
Avir9/vir9	A	i1	i5	38 ± 2.7	26 ± 0.2	24 ± 1	32 ± 10.2	0.15
	E	i2	i5	-	-	26 ± 9.8	32 ± 0.2	0.16
	B	i2	i6	80 ± 3.5	46 ± 6.4	74 ± 0.2	76 ± 0.3	-0.17
	F	i1	i6	-	-	71 ± 0.9	83 ± 0.3	-0.27
	C	i3	i7	85 ± 4.4	70 ± 11.6	74 ± 5.3	83 ± 3.3	-0.29
	D	i4	i8	83 ± 8.6	72 ± 5	70 ± 3.2	85 ± 5.1	-0.28
Avir4/vir4	G	i9	i11	-	-	22 ± 0.1	18 ± 0.9	0.24
	H	i10	i12	23 ± 0.8	44 ± 6.3	28 ± 5.1	20 ± 0.3	0.17
Avir6/vir6	I	i13	i15	17 ± 1.4	14 ± 1.9	25 ± 6.1	25 ± 0.9	0.24
	J	i14	i16	29 ± 14.5	28 ± 9.9	20 ± 2.2	12 ± 1.9	0.22

Mean (± S.E.) frequencies (%) of virulent (vir) isolates relative to avirulent (Avir) isolates, measured at the end of the growing season. Different pairs (A-J) were set up for each of 3 virulence genes (9, 4, 6). Each pair was started from an initial 50:50 ratio and competed on two host cultivars and in two field seasons (year). Selective values of Avir isolates were estimated according to Leonard [28] and represent averages over cultivars and years. *Cultivar 1 correspond to cv. Thésée for Avir9/vir9 and cv. Audace for Avir4/vir4 and Avir6/vir6, respectively. ** Cultivar 2 correspond to cv. Récital for Avir9/vir9 and cv. Baltimore for Avir4/vir4 and Avir6/vir6, respectively.

ISSN: 2730-7182