Identification of host plant resistance to pepper leaf curl virus in chilli (Capsicum species)

Three hundred and seven genotypes belonging to four cultivated and one wild species of Capsicum were screened against pepper leaf curl virus (PepLCV) causing devastating leaf curl disease of chilli (Capsicum annuum). Initial screening was done under field conditions based on coefficient of infection (CI), disease reaction to each genotype was assigned. Subsequently, selfed progenies of eight symptom-less and highly resistant lines were challenged by viruliferous white fly under glasshouse conditions, out of which only three genotypes, viz. GKC-29, BS-35 and EC-497636 showed no symptom. Using scion and root stalk of susceptible genotype (Pusa Jwala), these three putative symptom-less genotypes were further challenged by grafting and alternate grafting. The resistant reactions of GKC-29, BS-35, EC-497636 were confirmed because even after 50 days of successful grafting/alternate grafting, no viral symptom appeared on all the grafted plants of these genotypes. When subjected to PCR amplification with degenerate primers deigned to detect gemnivirus like PepLCV, the three symptom-less genotypes did not show any amplification, suggesting that the resistant reaction in three identified symptom-less resistant sources was because of the absence of viral genome and they are not symptom-less carrier.     

Detecting potential IgE-reactive sites on food proteins using a sequence and structure database, SDAP-food

The high incidence of food allergies, including oral allergy syndrome, represent major considerations when introducing new crops and foods. A new structural database of allergenic proteins, SDAP-Food, http://fermi.utmb.edu/SDAP/, has been developed to aid in predicting the IgE-binding potential of novel food proteins and cross-reactivities among known allergens. The site is designed to facilitate the first steps of a decision tree approach to determine the allergenicity of a given protein, based on the sequence and structural similarity to known allergens and their IgE binding sites. Immunological tests can then be used to confirm the predictions. A hierarchical procedure for identifying potential allergens, using a physical property-based sequence similarity index, has been designed to identify regions that resemble known IgE binding sites. As an example, SDAP tools were used to find food allergen sequences similar to an IgE binding site of the Jun a 3 allergen from mountain cedar pollen. The SDAP sequence similarity search matched the Jun a 3 epitope to regions in several food allergens, including cherry (Pru av 2), apple (Mal d 2) and pepper (Cap a 1), which are, like Jun a 3, members of the plant pathogenesis-related (PR-5) protein family. Homology modeling, using our EXDIS/DIAMOD/FANTOM program suite, indicated a similar surface location and structure for the potential epitope region on all of these allergens. The quantitative approach presented here can be used as part of a screening process for potential allergenicity of recombinant food products.     

Antioxidant phytochemicals in cabbage (Brassica oleracea L. var. capitata)

Eighteen different cabbage cultivars were assayed for variability between the cultivars for the antioxidant phytonutrients. The Vitamin C content ranged from 5.66 to 23.50 mg/100 g fresh weight. The maximum Vitamin C content was recorded in cultivar Sprint Ball (23.50 mg/100 g), followed by cv. Gungaless (12.86 mg/100 g). The β-carotene content in cabbage ranged from 0.009 to 0.124 mg/100 g fresh weight. The maximum β-carotene content was recorded in cv. Quisto (0.124 mg/100 g), followed by Green Challenger (0.115 mg/100 g) and Rare Ball (0.114 mg/100 g). The minimum values for β-carotene was noted in cv. Pusa Mukta (0.009 mg/100 g). Lutein content was also recorded in the cabbage cultivars, which ranged from 0.021 to 0.258 mg/100 g fresh weight. Maximum lutein content was recorded in Quisto (0.258 mg/100 g) and minimum in Pusa Mukta (0.021 mg/100 g). Vitamin E (dl-α-tocopherol) was estimated only in 14 cabbage cultivars, which ranged from 0.030 to 0.509 mg/100 g fresh weight. Maximum α-tocopherol content was recorded in Rare Ball (0.509 mg/100 g) and minimum in Green Cornell (0.030 mg/100 g). Total phenol content was also estimated only in 14 cultivars and the values ranged from 12.58 to 34.41 mg/100 g fresh weight. Amongst the three different cultivated forms of cabbage, red cabbage had higher Vitamin C (24.38 mg/100 g), dl-α-tocopherol (0.261 mg/100 g) and phenolic content (101.30 mg/100 g) as compared to the white cabbage and savoy cabbage.     

Genetics and distribution of fertility restoration associated RAPD markers in inbreds of pepper (Capsicum annuum L.)

Experiments were conducted to study genetics of fertility restoration and to examine distribution of RAPD markers (OPW19₈₀₀ and OPP13₁₄₀₀) linked with fertility restoration gene (Rf) in pepper (Capsicum annuum L.) inbreds. Forty-two hot and five sweet pepper inbreds were crossed on a cytoplasmic male sterile (cms) line CCA-4261 and F₁s were evaluated for fertility restoration under open field conditions. DNA of 5 plants of CCA-4261 and individual plants of 47 inbreds was isolated and PCR reaction was performed using OPW19 and OPP13 primers. The results revealed that most of the hot pepper lines posses Rf gene. The Rf gene associated two markers, viz., OPW19₈₀₀ and OPP13₁₄₀₀ were not frequently distributed in the restorer inbred lines because presence of marker bands often does not coincide with the presence of Rf gene identified in many restorer inbreds. The case specific applications of both the RAPD markers have been described.     

Comparative study of chlorophyll content in diploid and tetraploid black wattle (Acacia mearnsii)

The effects of the number of chromosome sets on chlorophyllcontent in diploid and tetraploid black wattle were assessedthrough chlorophyll absorbance. Seedlings of 8 months of age,1-year-old trees in polybags and 2-year-old field material wereselected for this investigation. Three families per ploidy levelcomprising of 10 half-sibs per family were used in the analysis.An analysis of variance revealed significant differences (P< 0.05) in chlorophyll absorbance between diploid and tetraploidmaterials ( = 0.375 and = 0.653, respectively). Significantdifferences (P < 0.05) between treatments (seedling, baggedmaterial and field material) within each ploidy level were recorded,where chlorophyll absorbance increased from diploid bagged trees( = 0.343) to seedlings ( = 0.375) to field trees ( = 0.408). Similar significant increases were recordedfor the tetraploid seedlings ( = 0.629) to bagged trees ( = 0.644) to field trees ( = 0.686). Significant differences (P < 0.05) were also recordedbetween genetic lines within both ploidy levels. However, whencomparing families within each ploidy level, with respect totreatment differences, in most cases, two of the three familiesshowed no significant differences (P > 0.05). Within eachfamily, significant differences (P < 0.05) were recordedbetween each of the three treatments tested, with the fieldmaterial consistently having significantly (P < 0.05) greateramounts of chlorophyll.     

Genetic diversity in Indian ash gourd (Benincasa hispida) accessions as revealed by quantitative traits and RAPD markers

In present study, an attempt has been made to assess the genetic diversity among 34 accessions of Benincasa hispida using quantitative traits and RAPD data. Variability was observed for characters like days to first female flower, fruit weight, equatorial and polar diameter. Cluster analysis based on quantitative traits revealed a high degree of diversity among the accessions. RAPD-based dendrogram showed dissimilarity values 0.64–0.943 suggesting that the accessions represent a genetically diverse population. A non-significant correlation was observed between the clustering based on quantitative traits and RAPD markers. But the accessions like IVAG-107 and IVAG-81 clearly separated from rest of the accessions based on the quantitative traits and as well as RAPD primers. Both the dendrogram revealed that the accessions from northeastern region of India are diverse from the accessions of other parts of India, as they cluster together in both the dendrogram. The information generated could be utilized in developing cultivars/hybrids for specific traits.