Atef A. Shahin, Ph.DWheat Disease Research DepartmentWheat Disease Research Department

Plant Pathology Research InstitutePlant Pathology Research InstituteARC, EgyptARC, Egypt

Email: a.a.shahin@hotmail.comEmail: a.a.shahin@hotmail.com “ “ Rusts never sleep " Rusts never sleep "

- In 2010 African countries spent more than 12.5 billion US$ to import of 32 million tons of wheat.

- Demand for wheat in Africa is growing faster than for any other food crop. This will be a major challenge particularly in cities, where urban population growth is forecasted to increase by 300% by 2050.

- Major biotic and abiotic constraints of wheat production in Africa related to climate change.

reminds us of the words of the late Nobel Prize winner, Norman Borlaug that

"rusts never sleep" "rusts never sleep"

Country/YearCrop lossesMillions $USA2000-07

20106.5 million tones2.2 millions tones$US 30 Washington State

Australia2003-2006AU$ 30-90China1950

64, 90,0214.4 million tonesMore than 20 million

Turkey1992199620002009-10

26.5% (Gereck > 1 m ha)1.2 million tones3% Gerek 79

5685310

Iran1992-942007 and 092010

2.5 milliom tones2 million ha650.000 ha spray

258??

Syria2010Cham 8 (80% yield loss)80% of Area

Ethiopia2010$US 3.2 in fungicide application in Ethiopia

Impact of Stripe Rust Epidemics WorldwideImpact of Stripe Rust Epidemics Worldwide

During the last decades, several yellow rust epidemics in most of the wheat-growing areas

Wheat rusts and loose smut are the major diseases of wheat in Egypt. Also, powdery mildew became more dangerous at recent years. So wheat diseases section aims to control these diseases throughout identification of virulent races, evaluation of breeding materials for resistance varieties and fungicides efficacies.

1. 1947 (Giza 144)

2. 1986 (Sakha 8)

3. 1995 (Gemmeiza-1 and Giza163).

4. 1997 (Sakha 69).

Several epidemics of wheat yellow rust have been reported in Egypt causing significant crop losses

Stripe rust caused by Puccinia striiformis f. sp. tritici is widely distributed and dangerous. It affects wheat crop through damaging its respiratory system, kills foliar parts, makes growth of plant stunted, most importantly reduces grain yield by shriveling grain, reducing weight and affecting its quality.

Stripe rust Stripe rust

Also known as Yellow rustPuccinia striiformis Westend. [teleomorph]Uredo glumarum J.C. Schmidt [anamorph]

High yielding new cultivars1. Miser12. Miser 23. Gemmeiza-104. Sids-12

Wheat is one of the most important food crops allover the world and essential in Egypt. The national production of such crop reached to 8 million tons in 2010 obtained from an acreage of 3 million feddans the annual consumption reached to 2/3, consequently the balance amount is imported from high wheat production countries.To fill the gap between consumption and production through both vertical and horizontal extension via increasing the productivity of acreage unit through high yielding varieties and controlling diseases.

The main objectives of the present investigation were to determine the components of slow-rusting in 20 Egyptian wheat cultivars and Little Club as a standard susceptible one against virulent isolates of stripe rust under greenhouse and field conditions to be exploited in the promising lines in the breeding program of wheat for rust resistance.

The ObjectivesThe Objectives

Studied area: Studied area: The studied area is located in

North Delta region, Kafrelsheikh (31 08 North and 30 56 East). Climatic

condition of the studied area is typically arid Mediterranean climate.

Regular field surveys were annually conducted across wheat

growing area in Egypt, especially in area considered source the inoculum

i.e. Northern governorate of Egypt i.e. Kafrelsheikh.

Studied area: Studied area: The studied area is located in

North Delta region, Kafrelsheikh (31 08 North and 30 56 East). Climatic

condition of the studied area is typically arid Mediterranean climate.

Regular field surveys were annually conducted across wheat

growing area in Egypt, especially in area considered source the inoculum

i.e. Northern governorate of Egypt i.e. Kafrelsheikh.

Field surveys and isolate collections

One infected fields in Kafrelsheikh governorate , registration data and collection of samples infected.

Annual survey (Commercial fields and Egyptian Wheat Trap Rust Nursery).

Data of collection location, cultivar, severity, collector and any other relevant information

were recorded for each sample.

Data of collection location, cultivar, severity, collector and any other relevant information

were recorded for each sample.

Twenty cultivars of wheat were used to study both seedling and adult stage to stripe rust were compared with the susceptible hosts

Plants were grown in 10-cm diameter pots

Seedling evaluation wheat accessions against yellow rust

Inoculated pots were incubated at 10 c in darkness and 100% relative humidity for 24h. Then transferred to permanent cabinets at diurnal system.

Seedlings of 10 days old, inoculation was conducted by spraying of them with mixture of spores and talcum powder (in 1:4 proportions).

seedling infection type in response to wheat stripe rust . This greenhouse test helps to detect seedling resistance. This greenhouse test helps to detect seedling resistance. If a wheat line shows a susceptible response it may either be susceptible to the disease or carry adult plant resistance (APR). APR often indicates the presence of slow rusting genes that can be combined through breeding to produce materials with durable rust resistance.

Infection Type (IT) was recorded based on the 0-4 scale with ITs 3 and 4combined as 3 (the most susceptible reaction) in field data. Generally IT 0-2 areconsidered resistant, 2-3 intermediate, and 3-4 susceptible. Heterogenous reactions of an entry were indicated by two or more ITs separated by "," for most plants with the first IT and few plants with the second IT or connected with "-" for entries containing plants with continuous ITs. Entries with a high IT in the first note, but a low IT in the second note may indicate that they have high-temperature, adult-plant (HTAP) resistance.

Resistance reaction was recorded

based on McIntosh et al. (1995) using the scale 0-4,0 = no visible uredia, 1 = small uredia with necrosis, 2 = small to medium sized uredia with green islands and surrounded by necrosis or chlorosis, 3 = medium sized uredia with or without chlorosis and 4 = large uredia without chlorosis). Infection Types (ITs) of 3+ or higher were regarded as susceptible, whereas ITs of 3 or lower were regarded as resistant.

Stripe rust (L to R):

IT 0, ; , ;N , 1+ , 2C , 3 , 4

Artificial inoculation was carried out with a mixture of races by spraying all tested entries and spreader rows with a mixture of spores and talcum powder (in 1:20 proportions), two times after the sun set. Percent severity was recorded four times, starting when Morocco reached 30% severity according to the modified Cobb scale (Peterson et al., 1948) and reaction based on (Roelfs et al., 1992).

Artificial inoculation was carried out with Sakha races by spraying all test entries and spreader rows with mixture of spores and talcum powder (in 1:20 proportions), two times after the sun set. Percent severity was recorded four times, starting when Morocco reached 30% severity according to the modified Cobb scale (Peterson, 1948) and reaction based on Roelfs et al. (1992). Coefficient of Infection (CI) which are calculated by combination of Disease Severity (DS) and Infection Type (IT), was used for estimating of Area Under Disease Progress Curve (AUDPC) after converting by formula; . Constant values for infection types were used based on (immune = 0, R = 0.2, MR = 0.4, M = 0.6, MS = 0.8, S = 1; Stubbs et al., 1986). Estimation of AUDPC and rAUDPC was performed as follows (Milus and Line, 1986):

where, X1, X2 and X3, X4 are the rust intensities recorded on the first, second, third and fourth recording dates. N1 is interval day between X1, X2 and N2 is interval day between X2, X3 and N3 is interval day between X3 and X4:

Coefficient of Infection (CI) which is calculated by combinations of Disease Severity (DS) and Infection Type (IT), was used for estimating of Area Under Disease Progress Curve (AUDPC).

Constant values for infection types were used based on (immune = 0, R = 0.2, MR = 0.4, M = 0.6, MS = 0.8, S = 1; (Stubbs et al., 1986). Estimation of AUDPC and rAUDPC was performed according to the following equation adopted by (Milus and Line, 1986).

Adult plant infection type, seedling reaction and mean comparison for coefficient of infection, AUDPC and rAUDPC in Egyptian wheat

cultivars to yellow rust

Adult plant infection type, seedling reaction and mean comparison for coefficient of infection, AUDPC and rAUDPC in Egyptian wheat

cultivars to yellow rust

Cultivars

Mean comparison based on Duncan multiple testing*

Seedling reaction

Adult plant reaction

Mean of coefficient of infection

Mean of AUDPC

Mean of rAUDPC

Misr1I-R1304.462

Misr2R-MR1.4426.253

Giza 167MS-S4546068.544

Giza168MR-MS107210.713

Sakha61R1304.463

Sakha93MS32168253

Sakha94MR-MS7787.143

Gemmeiza5MS-S41.536053.573

Gemmeiza7MR-MS79614.283

Gemmeiza10I-R1365.351+

Gemmeiza11I-R1324.761+

Sids1 MS-S2336053.574

Sids12R1.9527.733+

Sids13I-R1345.051+

Shandaweel1MR6.4527.732+

Beni Sweif1MS-S2222833.924

Beni Sweif4I-R1426.253

Beni Sweif5I-R1365.353

Beni Sweif6MR6649.254

Sohag3I-R1365.352+

MoroccoS94.556721004

Monthly precipitation, mean temperature and moisture during the growing seasons 2010/2011 and 2011/2012 at Sakha station, Kafrelsheikh.

Monthly precipitation, mean temperature and moisture during the growing seasons 2010/2011 and 2011/2012 at Sakha station, Kafrelsheikh.

MonthsTemperature CPrecipitation (mm)RH%

2010/20112011/20122010/20112011/20122010/20112011/2012

November 18.9117.06--73.6370.43

December15.5613.3114.6020.672.5873.56

January13.5009.2020.7332.4871.3868.88

February15.4010.4712.732.7470.5068.83

March14.7013.2615.3542.7569.3168.47

April18.2118.0411.1-66.1463.53

May21.6021.67--58.1162.87

CultivarsReaction

2010/20112011/2012

Misr1RR

Misr2R5MR

Giza 16750MS50S

Giza16810MR20MS

Sakha9340MS40MS

Sakha9410MR-MS10MS

Gemmeiza540MS50S

Gemmeiza710MR-MS10MS

Sids-120MS30S

Sids12RR

Beni Sweif130MS20S

Beni Sweif4I-RI-R

Morocco80S90S

Adult plant infection type

Thousand kernel weight (g.), and their reduction % of different wheat genotypes in the presence and absence of stripe rust during 2010/2011

and 2011/2012 at Sakha station, Kafrelsheikh.

Thousand kernel weight (g.), and their reduction % of different wheat genotypes in the presence and absence of stripe rust during 2010/2011

and 2011/2012 at Sakha station, Kafrelsheikh.

Cultivars

1000 Kernel weight (g.)

2010/2011 season2011/2012 season

PIReduction %PIReduction%

Misr148.8046.604.5145.2042.206.64Misr242.7539.607.3740.8036.809.80Giza16747.8041.9012.344.7839.2012.5Giza16841.4639.005.9340.4837.886.42

Sakha6151.7947.687.9449.4245.907.12Sakha9344.1140.338.5740.2038.703.73Sakha9447.4345.583.9043.9639.879.30Gemmeiza548.3244.517.8845.7141.509.21

Gemmeiza753.9049.308.5350.8746.338.92Gemmeiza1053.3051.603.1945.3042.605.96

Sids1250.2048.802.7948.3046.302.90Sids1341.0638.306.7237.9035.107.39Shandaweel144.6039.9010.541.5037.709.16Beni Sweif154.7351.266.3448.5446.763.67

Beni Sweif652.6050.503.9949.2047.204.07Morocco43.2030.4029.6039.1527.9028.70

Misr2Shandaweel1Beni Sweif6

Giza 167Gemmeiza5Sids1 Beni Sweif1Sakha93

Misr1Sakha61Gemmeiza10Gemmeiza11Sids12Sids13Beni Sweif4Beni Sweif5Sohag3

Giza168Sakha94Gemmeiza7

Yield parameters were taken into consideration i.e. 1000 kernel weight (g.) and reduction % in certain yield

components.

Yield parameters were taken into consideration i.e. 1000 kernel weight (g.) and reduction % in certain yield

components.

As regarded to the thousand k.w. within the completely protected plots, the present

data showed slight significance between the tested entries. Wheat cultivar Beni Sweif-4

was significantly differentiated from the other entries followed by both Sohag-3 (55.38) Beni

Sweif-1 (54.73) Gemmeiza-7 (54.68), Gemmeiza-11(51.58) and Sakah61(50.79).

On the other hand, the highest reduction (%) was observed in the Sids-1 cultivar, however, the least value of reduction was recorded with Sids12 and Misr1

Fig.(a) Association between rAUDPC and coefficient of infection for assessment of slow rusting and (b) association between final disease severity and coefficient of infection for assessment of slow rusting

Association between slow rusting parameters: Field assessment of slow rusting resistance was evaluated through final disease severity, rAUDPC and coefficient of infection. CI is the mostly used parameter for the purpose (Ali et al., 2008). During in this study, an attempt was made to elucidate the relationship between these parameters. Positive relation of coefficient of infection was found with final disease severity and rAUDPC with a strong R2 value that was 98 and 91%, respectively (Fig. 1a, b). These results were agreed with the results of other researchers (Ali et al., 2008; Sandoval-Islas et al., 2007). Regarding to good relation of AUDPC with quantitative resistance components, i.e., latent period and infection frequency (Sandoval-Islas et al., 2007), we can use rAUDPC or CI for measuring slow rusting or partial resistance.

CONCLUSIONThe results of current study showed that the lines had diversity regarding resistance reaction, ranging from immunity to partially resistant lines. Most of the evaluated lines exhibited better performance under high disease pressure shown by susceptible check. Resistance of all categories including immune to partial resistance Giza 168, Sakha94 and Gemmeiza7) were supposed to be having genes for varying degrees of slow rusting can be used for future manipulation in wheat improvement program after confirmatory studies. However, these lines should be assessed over years and locations for yellow rust along with other desirable characters before approval.

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