Biology and life table of Diaeretiella rapae against Brevicoryne brassicae on different cultivars of cauliflower

Phytoparasitica - Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) is one of the most promising, effective and a common endoparasitoid of different aphid species including cabbage aphid,...     

Genetic diversity of bitter gourd (Momordica charantia L.) genotypes revealed by RAPD markers and agronomic traits

Bitter gourd or bitter melon (Momordica charantia L.) is considered as minor cucurbitaceous vegetable in spite of having considerable nutritional and medicinal properties. Although some reports on genetic diversity based on morphological characterization are available, no work has been conducted to estimate genetic diversity using molecular markers in this crop. In the present study, 38 genotypes of M. charantia including few commercially cultivars collected from different parts of India based on agro-ecological zones were analysed for diversity study both at morphological and molecular levels. Genomic DNA was extracted from young healthy leaves following the procedure of Doyle and Doyle [Doyle, J.J., Doyle, J.L., 1990. A rapid DNA isolation procedure from small quantity of fresh leaf material. Phytochem. Bull. 119, 11–15]. Pair-wise comparison of genotypes was calculated as per the procedure of Jaccard [Jaccard, P., 1908. Nouvelles recherches sur la distribution florale. Bull. Soc. Vaud. Sci. Nat. 44, 223–270]. Dendrogram was constructed using the unweighted pair group method with arithmetic averages (UPGMA) and the computation for multivariate analysis was done using the computer programme NTSYS-pc Version 2.0 [Rohlf, F.J., 1998. NTSYS-pc Numerical Taxonomy and Multivariate Analysis System, Version 2.01. Exeter Software, Setauket, NY, USA]. Diversity based on yield related traits and molecular analysis was not in consonance with ecological distribution. Among 116 random decamer primers screened 29 were polymorphic and informative enough to analyse these genotypes. A total of 208 markers generated of which 76 (36.50%) were polymorphic and the number of bands per primer was 7.17 out of them 2.62 were polymorphic. Pair-wise genetic distance (GD) based on molecular analysis ranged from 0.07 to 0.50 suggesting a wide genetic base for the genotypes. The clustering pattern based on yield related traits and molecular variation was different.     

Genetic analysis and pyramiding of two gall midge resistance genes (Gm-2 and Gm-6t) in rice ( Oryza sativa L.)

Asian rice gall midge (Orseolia oryzae) is a major pest across much of south and southeast Asia. This pest is genetically diverse and many gall midge biotypes are known to exist in each country. During the last three decades, host plant resistance has proved to be the most effective mechanism of controlling the Asian rice gall midge. Seven genes conditioning resistance to gall midge larvae have been identified in rice (Oryza sativa) and are being used in cultivar improvement programs. However, some of these genes are rendered ineffective by new gall midge biotypes. Increased understanding of genetics, inheritance, allelic relationships and linkage is necessary to maximise the durability of major gene resistance by the pyramiding of these genes. The two genes, Gm-2 and Gm-6(t), are known to confer resistance against a number of biotypes in India and China, respectively. An F₃ population derived from a cross between Duokang #1 (donor of Gm-6(t)) and Phalguna (donor of Gm-2) was screened against Chinese gall midge biotype 4 at Guangdong, China, and Indian gall midge biotype 1 at Raipur, India. At each location, separately,a single gene governed resistance. The parallel segregation of 417 F₃progenies for both biotypes at two locations revealed that recombination had occurred between the two genes, establishing that the two genes are not allelic. However, the two genes Gm-2 and Gm-6(t), were found to be linked with a distance of ∼16.3 cM. A number of lines homozygous at one locus and segregating for the other locus were identified and selected. These lines were selfed to obtain lines homozygous for the favourable alleles at both loci (two locus pyramids). This is the first report on use of conventional host-pest interaction method for pyramiding two closely located Gm-resistance loci of dissimilar effects. The implications of deployment of these pyramids within and across country borders, with reference to the prevailing gall midge populations are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification of a diverse mini‐core panel of Indian rice germplasm based on genotyping using microsatellite markers

Identification of a small core germplasm set representing the available genetic diversity is essential for its proper evaluation and subsequent utilization in rice improvement programmes. For constituting a small diverse mini‐core panel of Indian rice germplasm, a representative set of 6912 accessions drawn based on their geographic origin from the whole rice germplasm collection available in the National Gene Bank was genotyped using 36 microsatellite markers. Automated fragment analysis of amplicons yielded a total of 435 alleles, with an average 12.4 and range of 3–29 alleles per locus. Polymorphism information content (PIC) ranged from 0.08 (RGNMS190) to 0.86 (RM552) with an average of 0.528. Based on genotyping data, a mini‐core consisting of 98 genotypes was identified. Ninety‐four per cent of the alleles present in the core set were present in the mini‐core. The identified small but diverse panel will be useful for further intensive trait‐specific evaluation and utilization in allele mining.     

Molecular markers for late blight resistance breeding of potato: an update

Late blight is the most devastating disease of the potato crop that can be effectively managed by growing resistant cultivars. Introgression of resistance (R) genes/quantitative trait loci (QTLs) from the Solanum germplasm into common potato is one of the plausible approaches to breed resistant cultivars. Although the conventional method of breeding will continue to play a primary role in potato improvement, molecular marker technology is becoming one of its integral components. To achieve rapid success, from the past to recent years, several R genes/QTLs that originated from wild/cultivated Solanum species were mapped on the potato genome and a few genes were cloned using molecular approaches. As a result, molecular markers closely linked to resistance genes or QTLs offer a quicker potato breeding option through marker‐assisted selection (MAS). However, limited progress has been achieved so far through MAS in potato breeding. In near future, new resistance genes/QTLs are expected to be discovered from wild Solanum gene pools and linked molecular markers would be available for MAS. This article presents an update on the development of molecular markers linked to late blight resistance genes or QTLs by utilization of Solanum species for MAS in potato.     

Efficacy of ‘indigenous vaccine’ using native ‘Indian bison type’ genotype of Mycobacterium avium subspecies paratuberculosis for the control of clinical Johne’s disease in an organized goat herd

Therapeutic efficacy of a new ‘Indigenous vaccine’ prepared from native highly pathogenic ‘Indian Bison Type’ genotype of Mycobacterium avium subspecies paratuberculosis (MAP) of goat origin has been evaluated with respect to control of clinical Johne’s disease in naturally infected Mehsana breed of goat in North Gujarat. Fifty goats from Sheep and Goats Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, were randomly divided into 2 groups viz.,‘Vaccinated’(n?=?35) and ‘Control’(n?=?15). After vaccination, goats were monitored for physical condition, morbidity, mortality, body weights, shedding of MAP in feces, internal condition, gross lesions and humoral immune responses up to 120 days (at each interval of 30 days). At the end of 120 days trial, there was marked overall improvement in physical condition and body weights of vaccinated goats as compared to ‘Control’ goats. Vaccinated goats gained significantly (P?<?0.05) higher body weights, hardly exhibited any lesions characteristic of JD, had significantly higher (P?<?0.01) antibody titers and shedding of MAP was significantly (P?<?0.01) reduced. Few of the vaccinated goats were positive for MAP DNA in faecal PCR and blood PCR before vaccination. However, all were found as negative at 120 days post vaccination (DPV). Overall vaccine exhibited effective in restriction of MAP infection and significant improvement in production parameters and reduction in mortality and morbidity due to JD. The trial in the herd will be continued.     

Occurrence of Peanut stripe virus on patchouli and raising of virus-free patchouli plants by meristem tip culture

Journal of Plant Diseases and Protection - Patchouli (Pogostemon cablin) was found infected with a viral disease showing mosaic symptoms on the leaves in the Chand-pur farm at Institute of...     

Comparison of the Standard AGID Test and Competitive ELISA for Detecting Bluetongue Virus Antibodies in Camels in Gujarat,India

The performance of the standard agar gel immunodiffusion (AGID) test and the competitive enzyme-linked immunosorbent assay (cELISA) for the detection of serum antibody against bluetongue virus (BTV) in clinically healthy and diseased camels in Gujarat state were compared. Out of 176 sera tested, 22 (12.5%) and 34 (19.3%) were positive for group-specific bluetongue antibodies by AGID and cELISA, respectively. Maximum seropositivities of 18.0% by AGID and 25.8% by cELISA were recorded in the Kutchhi breed, and of 6.9% and 12.6%, respectively, in the Marwari breed. The seroprevalence detected by AGID and cELISA in clinically healthy and diseased camels did not differ significantly with regard to bluetongue disease in these breeds.     

The potential of entomopathogens in biological control of white grubs

Abstract

White grubs are highly polyphagous and most destructive soil pests inflicting damage to a wide variety of crops. In India, more than 1000 species of white grubs are known of which over 40 species attack wide range of plants. White grubs are naturally infected by various entomopathogens which include fungi, bacteria and nematodes. Entomopathogenic fungi offer great potential and members of genera Beauveria and Metarhizium are widely used against white grubs. Several commercial products of entomopathogenic fungi like Bio Green, ORY-X, Grub X 10G, Betel, Biotrol FMA and Meta-Guard have been developed for the control of white grubs. In India, good control of white grubs in paddy, ginger and sugarcane has been achieved with different entomofungi. Among EPNs, Heterorhabditis bacteriophora is moderately effective against Popillia japonica and Rhizotrogus majalis. H. indica and H. bacteriophora are effective against potato white grubs in India. Paenibacillus popilliae cause milky disease in P. japonica grubs. The bacterium is pathogenic to Holotrichia consanguinea, H. serrata and Leucopholis lepidophora. In north-western Himalaya, B. cereus is highly toxic to the grubs of H. seticollis and Anomala dimidiata.