Screening of wheat germplasm for slow rusting traits
During the present studies thirty-one genotypes of wheat were screened for their resistance and susceptibility response against stripe rust disease under subtropical agro climatic conditions of Jammu. The disease was first observed on 4^th Feb., on a susceptible host Agra Local. Subsequently, the disease was recorded in other tested genotypes as well, but it was on 25^th Feb. that the disease engulfed all the test genotypes and the disease severity ranged from 5-25 per cent. Thereafter the disease severity increased at a steady pace till 25^th Mar. which was considered as the Final Rust Severity (FRS). The FRS ranged from 25 to 95 per cent, with maximum disease severity (95%) in Agra Local and minimum of 25 per cent each in K9351, NIAW301, PBW 12 and HUW213 (Table 1). Bariana et al. (2002) screened 176 doubled haploid lines derived from CD87/Katepwa (CD/K) for stripe rust resistance. Both parental lines, CD87 and Katepwa, showed stripe rust resistance. Both lines were susceptible to 110 E143A+ at seedling stage. The presence of susceptible segregates indicated the genetic independence of resistance in CD87 and Katepwa. Data in Table 1 further exhibited that AURPC value in 9 genotypes (Raj 4037, Sonara 64, HS 1097, NP 823, HPW 42, K 9351, NIAW 301, PBW 12 and HUW 213) ranged from 0-800 and in 21 genotypes (Tawa, KRL, RW 346, Utkalia, HD 2643, NP 825, WH 291, HP 1633, HUW 12, PBW 226, PV 18, K 8434, NI 179, NI 5439, K 9644, HD1925, PBW 65, Ajanta, K 9533, GW 503 and Sharbati Sonara) from >800 to 1600, however, in Agra Local it was highest (2340). While calculating the CI, a value of 6.25 to 8.25 was observed in Sonara 64, NIAW 301, PBW 12, HUW 213, Ajanta, NP 823, K8434, K9533, Sharbati Sonara, HP 1633, HPW 42, K9351 and Raj 4037 and 30 to 33.75 in Tawa, KRL, RW 346, Utkalia, HD2643, HS 1097, NP 825, WH 291, PBW 226, PV 18, NI 179, NI 5439, K9644, HD 1925, PBW 65 and GW 503 , whereas, in Agra Local the CI value (95) was the highest. Similarly, the infection rate (r) varied from 0.014 in case of NP 825 to 0.122 in Agra Local. Among them six germplasm (NP 825, HP 1633, K8434, PBW 12, Ajanta and K9533) exhibited a range of 0.014-0.019, whereas, in eight genotypes (KRL, NP 823, HD1925, NIAW 301, PBW 65, HUW 213, GW 503, and Sharbati Sonara) the infection rate ranged from 0.021 to 0.028. In case of TAWA, RW 346, Sonara 64, Utkalia, HD 2643, WH 291, HUW 12, PBW 226, PV 18, NI 179, HPW 42, NI 5439, K9644, and K9351 the infection rate ranged from 0.036 to 0.049. However, the infection rate in case of HS 1097, Raj 4037 and Agra Local was comparatively high (0.056, 0.084 and 0.122, respectively). The result was in conformity with the findings of other workers who reported that breeding lines with low value of AURPC, CI and r were expected to possessed genes that conferred partial resistance (Ali etal.,2012). Data in Table 2 indicate that genotypes were categorized as moderately resistant (Sonara 64, Utkalia, NI 5439, NIAW 301, PBW 12, HUW 213, Ajanta, NP 823, K8434, K9533, Sharbati Sonara, Raj 4037, HP 1633, HPW 42 and K9351), moderately susceptible (Tawa, KRL, RW 346, HD 2643, HS 1097, NP 825, , WH 291, HUW 12, PBW 226, NI 179, NI 5439, K9644, HD1925, PBW 65, PV 18 and GW 503) and susceptible (Agra Local), whereas, none of the tested genotypes showed resistant response against stripe rust

Molecular validation of stripe rust resistance gene in wheat germplasm:
The Yr18 locus confers partial and durable adult plant resistance against stripe rust fungus. In order to track Yr18, PCR was carried out with an allele specific primer cssfr2 which resulted in the amplification of 523 bp fragment, which exhibited the presence and absence of banding pattern. Nine wheat genotypes (Sonara 64, K9351, HP 1633, Raj 4037, Sharbati Sonara, K9533, K8434, NP 823 and Ajanta) amplified a band of 523 bp fragments which indicated the presence of Yr18 gene (Table 3, Fig., 1). Five allele-specific markers (cssfr1–cssfr5) were developed by Lagudah (2009) based on a 3 bp deletion in exon 11 of the Yr18-gene which were closely linked to the Lr34/Yr18/Ltn1/Pm38 locus and have been shown to provide a much wider diagnostic ability for this multi-pathogen resistance trait in diverse wheat cultivars. The validation of results are in accordance with the findings of Laugdah et al. (2009).

Assessment of losses caused by stripe rust
While assessing the losses while evaluating thirty one genotypes at tillering, flowering and dough phonological stages, though there was no loss at the initial stage of tillering, but the per cent losses at flowering stage ranged from 11.95 to 36.15. In case of Raj 4037, NIAW 301, PBW 12 and HUW 213 the per cent losses estimated were 11.95, whereas, the per cent losses estimated were 20.75 (HD 2643 and NP 825), 22.95 (PBW 65) and 36.15 (Agra Local). Similarly, at the dough stage the per cent losses estimated in K9351, NIAW 301, PBW 12 and HUW 213 was 14.15, whereas, in case of PBW 65 and Agra Local the losses recorded were 25.15 and 44.95 per cent, respectively. Chen (2005) have reported that the disease may cause 40-78 per cent losses under normal conditions, but if the conditions were favorable for disease spread the loss might rise to 84 per cent (Murray et al., 1994). The predicted losses may be less if the wheat varieties were resistant or slow rusting against rust diseases (Salman et al., 2006). Similarly, the wheat varieties which showed less area under disease progress curve normally bear less yield losses (Hussain et al., 1996).

Table (1):
Evaluation of wheat germplasm for slow rusting parameters against Puccinia striiformis.

Table (2):
Response of wheat germ plasm against stripe rust under field conditions.

Table (3):
Molecular validation of Yr18 for yellow rust.

Table (4):
Assessment of losses in wheat germplasm due to stripe rust (Puccinia striiformis) of at different growth stages.