Screening Of Wheat Varieties With Adult-Plant Resistance To Stripe Rust And Study On Its Resistance Mechanism

Stripe rust, caused by puccinia striiformis f.sp. tritici, is one of the most serious diseases of wheat in the worldwide. Planting resistance cultivars is the most effective methods for disease control. Up to now lots of cultivars with major-gene resistance lost their resisatance soon after releasing because of emergence of new stipe rust races. Therefore finding durable resistance wheat cultivars is very important. Most of durable resistance wheat cultivars showed adult-plant resistance(APR) which were susceptible at seedling stage and resistant at adult stage. This paper centered on the screening and identification of wheat cultivars with APR, and the possible resistant mechanisms involved in APR.Wheat varieties and germplasms of 492 from the wheat production regions of Yellow River and the Huaihe River were tested to identify their resistance to CY32 in the seedling stage in greenhouse and in the adult stage in field. The results showed that 58 varieties expressed adult-plant resistance to CY32, which percentage was 10.98%. And within them 17 cultivars showed high resistance or near immune, 38 cultivars showed moderate resistance, 3 cultivars showed between high resistance to moderate resistance.APR varieties of 58 were tested to identify their resistances to stripe rust race CY29, CY31 and Shui14 in the seedling stage and the adult-plant stage. The results showed that in the seedling stage the varieties resistant to the races CY29, CY31 and Shui14 accounting for 17.50%,64.58% and 41.67% of all the tested varieties. And in the adult plant stage the varieties resistant to the races CY29, CY31 and Shui14 accounting for 85.42%, 77.08% and 87.5% of all the tested varieties. In the adult plant stage the varieties showed resistance to all of the races CY29, CY31 CY32 and Shui14 accounting for 82.76%. Most of APR varieties showed resistance to predominant stripe rust races.APR wheat varieties of 48 was inoculated with CY32 in the seedlings stage and adult stage and growed during 12~16℃, after appearance of symptom they treated by high temperature 12~16℃and normal temperature 19~21℃, respectively. The characteristica of APR to stripe rust in these varieties was as follows: some varieties didn't express high temperature resistance which accounting for 60.42% of all the tested varieties, some varieties expressed high temperature resistance at all stages of growth which accounting for 2.08%, some varieties expressed high temperature resistance at seedling stage which accounting for 20.83%, some varieties expressed high temperature resistance at adult stage which accounting for 6.25% and others expressed resistacne and susceptible with high temperature treatment which accounting for 10.42%. The result provide basis to the reasonable utility of APR.In the seedling and adult-plant stage Qinnong142 and Zhongyu5 , which were adult-plant resistance to CY32, and susceptible variety Mingxian169 were inoculated with CY32. PAL, PPO, POD andβ-1,3- glucanase activity in TEE of the leaves in 12 days after inoculation were detected with spectrophotometer assay. The results with ANOVA as follows: in seedlings stage and adult stage PAL, PPO, POD andβ-1,3-glucanase in the inoculated varieties were higher than that of control. In the seedling stage the activity of PPO and POD in the APR increased higher than the susceptible variety,while in the adult stage the activity of PAL, PPO, POD andβ-1,3-glucanase increased higher than the susceptible variety, too. The results showed that the expression of APR in the adult-plant stage was relative to the increasing of the activity of PAL, PPO, POD andβ-1,3-glucanase, while the ARP variety was relative to the increasing of the activity of PPO and POD.