Pyramiding Ty‐2 and Ty‐3 genes for resistance to monopartite and bipartite tomato leaf curl viruses of India

Breeding resistance to whitefly‐transmitted begomoviruses is an important goal of tomato breeding programmes worldwide. So far, resistance to begomoviruses in tomato has been achieved using wild species, and at least five resistance genes (Ty genes) have been studied. The present study was undertaken to combine Ty‐2 and Ty‐3 and to determine the effect of pyramiding on infection of tomato by three diverse begomovirus species. The diagnostic ability of the markers linked to Ty genes was assessed and marker‐assisted selection was used to develop pyramided tomato lines from the crosses between Ty stocks. Five stable pyramided tomato lines that differ in fruit morphology and yield potential were developed. The horticultural performance of pyramided lines in field trials showed that the yield and horticultural traits are well maintained in the plants. The response of these lines was assessed using agroinoculation and field tests in a disease hotspot. The pyramided lines and Ty‐3‐carrying lines exhibited a high level of resistance to the monopartite and two bipartite begomoviruses tested. The pyramided tomato lines developed in this study could be important genetic resources for sustainable tomato production in areas affected by tomato leaf curl virus disease. The combined results of disease resistance tests also showed that Ty‐3 is critical for achieving broad‐spectrum resistance. The limitations of relying on a single gene and the importance of pyramiding are discussed in the light of available evidence on frequent recombination in begomoviruses.     

Divergent evolution of wild and cultivated subspecies of <Emphasis Type="Italic">Triticum timopheevii</Emphasis> as revealed by the study of <Emphasis Type="Italic">PolA1</Emphasis> gene

Triticum timopheevii (genome symbol AAGG) comprises two subspecies, cultivated ssp. timopheevii, and wild ssp. armeniacum. These two subspecies are considered as allotetraploids of AA genome from Triticum diploid species and SS genome from Aegilops species. The difference in genome symbol (G vs. S) is due to wide genetic variations among four SS genome species, Ae. bicornis, Ae. longissima, Ae. searsii, and Ae. speltoides. In order to study the origin of T. timopheevii, we compared 19th intron (PI19) sequence of the PolA1 gene, encoding the largest subunit of RNA polymerase I. Two different sized DNA fragments containing PI19 sequences (PI19A and PI19G) were amplified both in ssp. timopheevii and ssp. armeniacum. Shorter PI19A (112 bp) sequences of both subspecies were identical to PI19 sequences of two AA species, T. monococcum and T. urartu. Interestingly, the longer PI19G (241–243 bp) sequences of ssp. armeniacum showed more similarity to PI19 sequences of Ae. speltoides whereas ssp. timopheevii showed more similarity to PI19 sequences of other three SS genome species. The results indicated that two subspecies of T. timopheevii, ssp. armeniacum or ssp. timopheevii, might have arisen independently by allotetraploidization of AA genome with Ae. speltoides or one of the remaining three Aegilops species, respectively.     

Effects of land-use change on soil microbial C, N and P in a Himalayan watershed

Soil microbial C, N and P as affected by land-use change were studied in a Himalayan watershed at Sikkim, India. The major land-uses considered were forests (dense and open), agroforestry types (large cardamom and mandarin), open cropped and wasteland areas covering subtropical and temperate zones. Across the land-use, microbial C ranged from 219 to 864 μg g⁻¹, microbial N from 30 to 142 μg g⁻¹, and microbial P from 12 to 43 μg g⁻¹ soils. The microbial C, N and P were positively related to each other. The microbial C:N ratio in these soils ranged from 6 to 11 and the microbial C:P ratio from 18 to 27. The conversion of forests into other land-uses resulted in a remarkable decline in the amounts of soil nutrients and microbial C, N and P. The microbial nutrients in the Himalayan region are very sensitive to land-use/cover changes. Therefore, the conversion of forest to agricultural land should be reversed. Agroforestry systems should be included in agricultural land in mountainous regions.     

Effect of SO2 and NH3 on growth behavior of some phylloplane fungi of wheat in in vitro

The colony growth of some phylloplane fungi of wheat viz. Alternaria alternata, Aspergillus favus, Amiger, Cladosportium cladosporioides, Curvularia lunata, Drechslera australiensis, Epicoccum purpurascens, Fusarium oxysporum, Penicillium chrysogenum and P. citrinum were studied in chamber fumigation experiments exposed to 2669 ± 105 μg SO₂ m^?3 and 708.33 ± 55 μg NH3 m^?3 air, separately, for 10, 30 and 60 min. The colony growth of all the test fungi was significantly (P=0.01/0.005) inhibited on prolonged period of SO₂/NH₃ exposure. However, some of the test fungi namely A. favus, A. niger, E. purpurascens and F. oxysporum showed growth stimulation after 10 min exposure of SO₂. Similarly, the growth of C. lunata and F. oxysporum increased only after 10 min exposure of NH3. The inhibitory effect of SO₂/NH₃ was directly correlated with the exposure times.     

A new cytoplasmic-nuclear male sterility system in pearl millet

Among the cytoplasmic-nuclear male sterility (CMS) systems reported in pearl millet, Pennisetum glaucum (L.) R. Br., the A_m= A₄ system produces the highest frequency of male-sterile hybrids. A CMS source identified in a large-seeded gene pool (LSGP) was compared with the A₄ system. Seven diverse restorer lines of the A4 system produced hybrids with 81A4 that were all fertile (pollen-shedding score 4 and 68–89% selfed seedset). In contrast, all the hybrids of these inbreds made with the isonuclear line with the LSGP cytoplasm were sterile (pollen-shedding score 1 and 0–3% selfed seedset). Topcross hybrids of four diverse composites made with 81A4 had 10–35% plants that had good fertility (> 50% selfed seedset). In comparison, no plant of any topcross hybrid with the isonuclear line having LSGP cytoplasm exceeded 20% selfed seedset, and it was rare for a plant to exceed even 10% selfed seedset. These differential fertility restoration patterns of hybrids indicate that the LSGP cytoplasm represents a CMS system that is different from the A4 and, by implication, from all those reported to date. This new CMS system is designated A₅.     

Cutaneous water loss and respiration rates of various breeds of sheep at high ambient temperatures

Summary The sweating and respiratory rates in rams of Rambouillet (R), Chokla (C), Malpura (M), R × C and R × M breed/breed crosses were recorded when housed in sheds or exposed to 20, 25, 30, 35 and 42°C ambient temperatures in a climatic chamber. The sweating (cutaneous moisture) was higher (P<0.05) in Rambouillet and its crosses than the natives, the Malpura sheep producing the least sweat at all temperatures. There was no breed difference in the response of increase in sweating up to 35°C but at 42°C the Chokla showed a considerable increase. Sweating was more pronounced on the shoulder than on the mid-side region. Sweating and respiratory rates increased (P<0.05) with the increase in ambient temperature. The Rambouillet exhibited the highest increase in respiration rate at 25°C and the trend continued up to 42°C. The relationship between fleece characteristics, evaporative heat loss and heat tolerance of sheep is discussed.

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Perdida Cutanea De Agua Y Frecuencia Respiratoria De Varias Razas De Ovejas Sometidas A Temperaturas Ambientales Altas

Resumen Se registraron las frecuencias sudorípara y respiratoria en carneros de las razas Rambouillet (R), Chokla (C), Malpura (M), R × C y R × M, alojados en cobertizos o expuestos a temperaturas ambientales de 20, 25, 30, 35 y 42°C en una cámara climática. El sudor (humedad cutánea) fue mayor (P<0.05) en carneros Rambouillet y sus cruces que en animales nativos, siendo la raza Malpura la que menos sudor produjo bajo todas las temperaturas. No se presentaron diferencias significativas entre las diferentes razas respecto a la humedad cutánea hasta los 35°C, pero a los 42°C la raza Chokla presentó un aumento considerable. El sudor fue más notorio en la espalda que en la región média. Las frecuencias respiratoria y sudorípara aumentaron (P<0.05) directa y paralelamente a la temperatura ambiental. La raza Rambouillet tuvo la frecuencia respiratoria más alta a los 25°C, incrementandose esta paulatinamente hasta los 42°C. Se discute la relación entre las caracteristicas del vellon, la pérdida de calor por evaporación y tolerancia al calor de las ovejas.

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Niveau Des Pertes D'eau Par Transpiration, Et Rhythme Respiratoire De Differentes Races De Moutons Soumis A Des Temperatures Ambiantes Elevees

Résumé Les pertes par transpiration et le rythme respiratoire de béliers de Rambouillet (R), Chokla (C), Malpura (M) et de croisements R × C et R × M ont été relevés lorsque les animaux étaient en bergerie ou exposés à des températures ambiantes, dans une chambre climatique, à 20, 25, 30 et 42°C. Les pertes d'eau par transpiration ont été plus importantes (P<0.05) chez les mérinos de Rambouillet et les métis par rapport aux animaux de race locale, les Malpura manifestant les déperditions d'eau moindre à toutes les températures.Il n'y a pas eu de différences raciales dans la réponse à l'accroissement de la transpiration jusqu'à 35°C mais à 42°C les Chokla ont manifesté une augmentation considérable.La déperdition d'eau par transpiration cutanée a été plus prononcée au niveau des épaules que sur le côté du milieu du corps. La transpiration et le rythme respiratoire ont augmenté (P<0.05) avec l'accroissement de la température ambiante. Les mérinos de Rambouillet ont montré la plus importante augmentation du rythme respiratoire à 25°C, température qui a continué de s'accroître jusqu'à 42°C, limite supérieure de l'expérimentation.Les relations entre l'influence de la température sur les pertes d'eau par évaporation et al tolérance des moutons à la chaleur sont discutées.

     

Superovulatory Response and Embryo Recovery after Treatment with Different Gonadotrophin during Induced Luteal Phase inCamelus dromedarius

Superovulation, embryo recovery and transfer were attempted in 19 dromedary camels of about 6-10 years of age, and having calved at least once. Superovulation was done using two commercially available porcine FSH preparations, FSH-I (II donors) and FSH-2 (8 donors) during a luteal phase created by inducing ovulation with hCG. The superovulatory response was assessed by ultrasonography. The embryo recovery was attempted non-surgically in sitting position on day 8 and day 7 after first mating in one FSH-1 and one FSH-2 group, respectively. Considerable individual variation in response to the superovulatory stimulus was observed. No significant difference was observed between the two groups in terms of superovulatory response and embryo recovery (p > 0.05). In total 30 embryos were recovered from 17 donors (1.51 embryos/donor). Recipients were synchronized with donors using hCG. Eight embryos were transferred, resulting in two pregnancies and live births.     

Association analysis of novel polymorphisms in 2′, 5′‐oligoadenylate synthetase gene with reproductive traits in indigenous and cross‐bred cattle of Indian Origin

2′, 5′‐Oligoadenylate synthetases (OAS) are important components of an interferon‐mediated antiviral pathway. No polymorphisms in exonic regions of bovine OAS1 gene have been identified and associated with reproduction traits. The objective of the study was to detect and evaluate the effects of mutations in exonic region of bovine OAS1 gene with reproduction traits in cattle. DNA samples collected from 250 individual cows of two Indian dairy breeds (Sahiwal and Frieswal) of cattle were used in the study. The genetic variants of the OAS1 gene were identified with polymerase chain reaction–single‐strand conformation polymorphism (PCR‐SSCP) and sequence analysis using seven set of primer pairs. The PCR‐SSCP analysis revealed polymorphism in the fragments comprising of exon 2, exon 5 and first fragment of exon 6 while the fragments of exons 1, 3, 4 and second fragment of exon 6 were monomorphic in Sahiwal and Frieswal cattle. The mutations in the amplified region comprising of exon 2 were found to have significant association with age at first breeding and calving, service period, dry period and pregnancy rate. Significant associations were found between SNPs in the exon 5 and service and dry periods of the animal, whereas the genetic variants in the first fragment of the exon 6 showed significant association with age at first breeding and calving. To our knowledge, this study demonstrated for the first time that the polymorphisms in OAS1 gene were associated with reproductive traits and it can be chosen as a candidate gene for improvement of reproductive performance of cattle.     

Accuracy of fetal age estimates using transrectal ultrasonography for predicting calving dates in dairy cows in seasonally calving herds in New Zealand

AIM: To describe the accuracy of transrectal ultrasonography for predicting calving dates in dairy cows under typical New Zealand conditions and to assess potential risk factors for differences between predicted and actual calving dates.

METHODS: Data were collected from 116 seasonally calving herds over 2 years in a retrospective single cohort study. Transrectal ultrasonography was undertaken by experienced veterinarians (n=12) to determine if cows were pregnant, and if so to estimate fetal age. Predicted calving date was calculated by adding 282 days to the estimated conception date. Accuracy was assessed using differences between predicted and actual calving dates for each animal. Potential risk factors for animals calving >10 days before or after their predicted calving date were assessed using multinomial logistic regression models.

RESULTS: The study population comprised 83,104 cows over the 2 years of the study; 75,037 (90.3%) cows calved within 10 days of their predicted calving date, 3,683 (4.4%) calved >10 days earlier, and 4,384 (5.3%) >10 days later, than predicted. Risk factors for calving >10 days before or after the predicted calving date included having >1 artificial insemination (AI) before pregnancy diagnosis (p=0.03), where the cow’s most recent AI was <21 days before the end of the herd’s AI period (p<0.01), and where the diagnosis was made at the second or third herd-visit (p<0.01). The probability of calving being >10 days later than predicted also increased when the fetus was ≥13 weeks old at pregnancy diagnosis (p<0.01).

CONCLUSIONS AND CLINICAL RELEVANCE: In this study, >90% of cows diagnosed pregnant by veterinarians using transrectal ultrasonography calved within 10 days of the predicted calving date. In herds where herd reproductive performance is high, it would be expected that more cows would conceive to their first AI, and potentially fewer cows would have AI close to the end of the herd’s AI period, which would increase diagnostic accuracy. Where herd managers rely on accurate predicted calving dates they should be informed about realistic expected accuracy. For greatest accuracy, a complete AI history should be made available to the person performing the pregnancy diagnoses and cows at most risk of having inaccurate predicted calving dates should be identified.