The linkage between the stem rust resistance gene Sr2 and pseudo-black chaff in wheat can be broken

Recessively inherited gene Sr2 has provided the basis of durable resistance to stem rust (caused by Puccinia graminis tritici) in wheat (Triticum aestivum L.) worldwide. The associated earhead and stem melanism or ‘pseudo‐black chaff’ is generally used as a marker for this gene. Sr2 has been postulated in many wheat cultivars of India including ‘Lok 1’, based on associated pseudo‐black chaff in adult plants, and leaf chlorosis in seedlings. However, dominant inheritance of the resistance factor operating in ‘Lok 1’, and a 13 : 3 (resistant : susceptible) F₂ segregation in the ‘Sr2‐line’ (‘Chinese Spring’⁶ × ‘Hope’ 3B) × ‘Lok 1’ cross confirmed that Sr2 was absent in ‘Lok 1’. Susceptible plants with a pseudo‐black chaff phenotype were observed in F₂ populations of ‘Agra Local’ (susceptible) × ‘Lok 1’, and the ‘Sr2‐line’ × ‘Lok 1’ crosses. Most of the F₃ families derived from the susceptible F₂ segregants with pseudo‐black chaff phenotypes were true breeding for the expression of pseudo‐black chaff with susceptibility to stem rust. Thus, linkage of pseudo‐black chaff with Sr2 in wheat can be broken, and hence, caution may be exercised in using pseudo‐black chaff as a marker for selecting Sr2 in breeding programmes.     

Simulation of salt and water movement and estimation of water productivity of rice crop irrigated with saline water

The HYDRUS-ID model was experimentally tested for water balance and salt build up in soil under rice crop irrigated with different salinity water (ECiw) of 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ in micro-lysimeters filled with sandy loam soil. Differences of means between measured (M) and HYDRUS-1D predicted (P) values of bottom flux (Q _o) and leachate EC as tested by paired t test were not found significant at P = 0.05 and a close agreement between RMSE values showed the applicability of the HYDRUS-1D to simulate percolation and salt concentration in the micro-lysimeters under rice crop. Potential ET values of rice as obtained from CROPWAT matched well with model predicted and measured one at all ECiw treatments. The model predicted root water uptake varied from 66.1 to 652.7 mm and the maximum daily salt concentration in the root zone was 0.46, 2.3, 4.5, 6.7, 8.4 and 10.2 me cm⁻³ in 0.4, 2, 4, 6, 8 and 10 dS m⁻¹ ECiw treatments, respectively. The grain production per unit evapotranspiration ( \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} ) value of 2.56 in ECiw of 0.4 dS m⁻¹ treatment declined to 1.31 with ECiw of 2 dS m⁻¹. The \textWP_{\textET\texta} {\text{WP}}_{{{\text{ET}}_{\text{a}} }} reduced to one-fifth when percolation was included in the productivity determination. Similarly, the water productivity in respect of total dry matter production (TDM) was also reduced in different treatments. Therefore, the model predicted values of water balance can be effectively utilized to calculate the water productivity of rice crop.     

Study of resistance against some ionophores in Eimeria tenella field isolates.

Three Eimeria tenella field isolates from Gurgaon district of Haryana (north India) were studied in a battery test for evaluating drug resistance against two currently used ionophores; maduramicin (5ppm) and salinomycin (60ppm). Broiler birds (Ross strain) were infected with 10(5) sporulated oocysts each at the age of 2 weeks and prophylactic medication commenced 2 days prior to infection. Drug resistance was assessed by calculating the global index for individual ionophore compounds based on weight gain, feed conversion ratio, oocyst index, lesion score and mortality. Present studies revealed no resistance of the ionophores in any of the field isolates. Both the drugs showed varying degree of efficacy, e.g. maduramicin exhibited limited efficacy against all the three field isolates, whereas salinomycin showed limited efficacy against Gurgaon isolate (GrI)-I, good efficacy against GrI-II and partial resistance against GrI-III.     

Effect of Benzyladenine on Transpiration, Water Potential and its Components in Genotypes of Wheat Contrasting in Drought Tolerance

Drought tolerant and susceptible cultivars of wheat, C-306 and Kalyan sona, growing under non-stressed and water-stressed conditions, were sprayed with benzyladenine (BA) at 70 days after sowing (DAS). Observations recorded at 5, 10, 15, 20 and 25 days after spraying revealed that BA increased the rate of transpiration (TR) in C-306 under non-stressed conditions. However, under water stress, the increase was significant only after 5 days of BA spraying. In Kalyan sona BA treatment either decreased TR or did not exhibit significant increase under non-stressed conditions, but caused significant increase in TR under water stress. The increase in TR was elicited through enhanced stomatal opening. Water potential, osmotic potential and pressure potential of both genotypes decreased on account of water stress. The effect of BA was not perceptible on restoration of leaf water potential (LWP) or its components. The effect of BA was possibly confined to stomatal behaviour and transpiration.     

Detection of goat pox antigen and antibody by the counter immunoelectrophoresis test

Summary The counterimmunoelectrophoresis (CIE) test was standardised for the detection of goat pox antigen and antibody using inactivated antigens. The chloroform inactivated and live antigens were equally sensitive for detection of goat pox precipitins. The precipitinogens of goat pox virus (GPV) were found to be soluble in nature. The CIE test was quick as well as more sensitive than the agar gel precipitation test for detection of GPV antibody/antigen. The CIE employing inactivated antigen has been used for the first time in the detection of GPV antibodies/antigens.

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Deteccion Del Antigeno Y Anticuerpos De Viruela Caprina Mediate La Prueba De Contrainmunoelectroforesis

Resumen Se estandarizó la prueba de contrainmunoelectroforesis, para la detección del antígeno y anticuerpos del virus de la viruela caprina, usando antígenos inactivados. El antígeno inactivado con cloroformo y el antígeno vivo, fueron igualmente sensitivos para la detección de precipitinas de viruela caprina. Los precipitógenos del virus de la viruela caprina se encontraron que eran solubles. La prueba de contrainmunoelectroforesis fue más rápida y más sensitiva que la precipitación agar gelatina para la detección de anticuerpos/antígenos del virus de la viruela caprina. La prueba de contrainmunoelectroforesis con antígeno inactivado ha sido utilizada por vez primera en la detección de anticuerpos/antígenos del virus de la viruela caprina.

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Detection De l'Antigene Et De l'Anticorps Variole Caprine Par Un Test De Contrimmuno-Electrophorese

Résumé Le test de contrimmuno-électrophorèse (CIE) a été standardisé pour la détection de l'antigène et de l'anticorps variole caprine avec des antigènes inactivés. Les antigènes vivants et inactivés par le chloroforme sont de sensibilité équivalente pour la détection des précipitines variole caprine. On a montré que ces précipitogènes du virus variole caprine (VVC) étaient de nature soluble. Le CIE est rapide et plus sensible que le test de précipitation en gélose pour la détection des antigènes et anticorps VVC. C'est la première fois que le CIE mettant en oeuvre un antigène inactivé a été utilisé.

     

Experimental Bubalian Fasciolosis: Kinetics of Antibody Response using 28 kDa Fasciola gigantica Cysteine Proteinase as Antigen

Tropical Animal Health and Production -     

Duration of Anthelmintic Effect of Three Formulations of Ivermectin (Oral,Injectable and Pour-on) Against Multiple Anthelmintic-Resistant <Emphasis Type="Italic">Haemonchus contortus</Emphasis> in Sheep

We report the results of investigations that were conducted in a sheep flock in Uttaranchal, India where repeated failure of anthelmintic medication was noted. The study revealed that Haemonchus contortus in sheep had developed resistance to benzimidazoles (fenbendazole, mebendazole and albendazole), imidazothiazole (levamisole) and salicylanide (rafoxanide), while it was fully susceptible to avermectins (ivermectin). Further, the suppression of nematode egg output in faeces of sheep naturally infected with multiple anthelmintic-resistant H. contortus following treatment with ivermectin tablet (0.4 mg/kg body weight (bw), orally), ivermectin injection (1% w/v, 0.2 mg/kg bw, subcutaneously) and ivermectin pour-on (0.5 w/v, 0.5 mg/kg bw) was also studied over a period of 10 weeks post treatment. It was noted that ivermectin tablet after initial clearance of infection (faecal egg count reduction 100%), could not prevent establishment of new patent natural infection for even a single day, while ivermectin pour-on and injection prevented the establishment of new infection for 7 and 14 days post treatment, respectively. Maximum protection period (duration for which mean faecal egg count of sheep reaches 500 eggs per gram of faeces or more) of 68 days was recorded in sheep treated with injectable ivermectin, followed by pour-on (60 days) and oral (53 days) preparations.