Characterization of Slow Rusting Resistance against Puccinia striiformis f. sp. tritici in Candidate and Released Bread Wheat Cultivars of Pakistan

Syed Jawad Ahmad Shah

doi:10.4172/2157-7471.1000223

Abstract

A set of 50 candidate and released bread wheat cultivars of Pakistan were studied to identify slow rusting resistance against yellow rust caused by Puccinia striiformis f. sp. tritici (PST). Seedling tests were done under glasshouse conditions at Thiverval-Grignon, INRA, France while slow rusting resistance was evaluated during 2005-07 in field plots using epidemiological variables at Peshawar, Pakistan. Twenty nine cultivars (58%) displayed susceptibility against the two PST races used in the seedling tests. Epidemiological parameters of resistance at the adult-plant stage were significantly (P<0.01) different for years, cultivars and cultivar x year interactions over three years. Analyses were done for sequence tagged site (STS) marker, csLV34 at INRA and revealed that 40% of the tested cultivars possessed adult plant resistance gene Yr18 linked allele of 150 bp. Of the 50 cultivars evaluated under field trials, 11 were highly resistant to both PST races as in the seedling tests and 39 showed different levels of slow rusting. Cultivars Bakhtawar-93, Punjab-96, Bahawalpur-95, V-00183 and V-00125 were relatively more stable over 3-years as Final Rust Severity (FRS), Area Under Disease Progress Curve (AUDPC) and Infection Rate (r) values were 74, 81, and 63% less of the susceptible control, Morocco, respectively. These cultivars also possessed the marker linked to Yr18 and could be exploited for the deployment of Yr18 in breeding for slow rusting in wheat. Both FRS and ACI are suitable parameters and can be used for phenotypic selection in a wheat breeding program for slow rusting resistance.

Highlights

Characteristics of race non-specific resistance in the wheatPuccinia system include a non-hypersensitive and partial resistance response with variable disease severity levels under field conditions across locations and years [13]
Highly significant (P
For FRS was significantly lower compared to previous two years. This decrease in FRS could be due to rainfall which was more during March and April in 2006-07 (259 mm) when compared with 2005-06 (49 mm) and 2004-05 (112 mm) and this may be one of the major reasons for lower FRS since extended or heavy rain showers might have exhausted available spore stocks and inhibited further sporulation process for hours

Summary

Introduction

Characteristics of race non-specific resistance in the wheatPuccinia system include a non-hypersensitive and (or) partial resistance response with variable disease severity levels under field conditions across locations and years [13]. In many cereal-rust pathosystems, quantitative aspects of cultivar resistance have been investigated by disease severity at a certain crop development stage, the area under the disease progress curve (AUDPC) or by apparent infection rate ‘r’ and average coefficient of infection (ACI) values for adult plant resistance (APR) [11,21,22,23,24]. Yellow rust remains a major constraint in Asia, threatening 43 million ha of wheat. In Southeast Asia, Pakistan is second in terms of wheat area, but its national average yield is stagnant at around 2 t. Diseases are one of the major production constraints in Pakistan, and 1% loss in production accounts for a loss of 36.6 million US dollars [4]. Yellow rust is a high profile, economically important disease capable of attacking

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Conclusion