The crossability between Brassica carinata (BBCC, 2n=34) and Brassica rapa (AA, 2n=20), and the cytomorphology of their F1 hybrids were studied. Hybrids between these two species were only obtained when B. carinata was used as the female parent. The hybrid plants exhibited intermediate leaf and flower morphology, and were found to be free from white rust and Alternaria blight diseases. One of the four F1 plants was completely male sterile, while the remaining plants had 4.8, 8.6, and 10.9% stainable pollen, respectively. No seed was produced on hybrid plants under self pollination or in backcrosses; but seed was obtained from open pollination. The occurrence of the maximum of 11 bivalents as well as up to 44.8%) of cells with multivalent associations in the form of trivalents (0‐2) and a quadrivalent (0‐1) in the trigenomic triploid hybrid (ABC, 2n = 27) revealed intergenomic homoeology among the A, B and C genomes. Meiotic analysis of F1 hybrids indicated that traits of economic importance, such as disease resistance, could be transferred from B. carinata to B. rapa through interspecific crosses.

Interspecific hybridization is an important tool to elucidate intergenomic relationships, transfer characters across species and develop synthetic amphidiploids, and it has been widely applied for improving brassicas. The objective of the present study was to create genetic variability in Brassica through interspecific hybridization. Crosses between Brassica juncea (AABB, 2n ¼ 36), and Brassica rapa (AA, 2n ¼ 20) vars toria, yellow sarson, and brown sarson were attempted, and the hybrid derivatives were advanced to the F 4 generation. Hybrids were obtained from the crosses B. juncea · toria and B. juncea · yellow sarson. The F 1 plants were vigorous and intermediate to the parents in many morphological traits. The meiotic study of AAB hybrids showed 10 II + 8 I in the majority (71.8%) of cells analysed. A maximum of 12 and a minimum of seven bivalents were also observed in a few cells. The occurrence of multivalent associations (trivalents to pentavalents) at diakinesis/metaphase I and a bridgefragment configuration at anaphase I were attributed to homoeology between A and B genomes. A high percentage of plants resembling B. juncea was observed in the F 2 generation. Transgressive segregation in both directions was found for plant height, primary branches, main raceme length, siliquae on main raceme, siliqua intensity, seeds per siliqua and seed yield. There were significant differences for the 14 characters in the F 4 derivatives. Moderate to high estimates of phenotypic and genotypic coefficients of variation, broad-sense heritability, and expected genetic advance were found for seed yield, 1000-seed weight, siliquae per plant, seeds per siliqua and days to flowering. Intergenomic recombination, reflected as wide variation in the hybrid progenies, permitted the selection of some useful derivatives.

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Host plant resistance is an important component for management of the melon fruit fly, Bactrocera cucurbitae (Coquillett), owing to difficulties associated with its chemical and biological control. Various biochemical traits including total sugar, reducing sugar, non-reducing sugar, tannins, phenols, alkaloids, flavinoid and pH contents of fruit were studied on 11varieties/ genotypes of muskmelon, Cucumis melo L., in relation to resistance against B. cucurbitae under field conditions. Significant differences were found in tested varieties/ genotypes for fruit infestation and larval density per fruit. AHMM/BR-1, RM-50 and AHMM/BR-8 were the most resistant; MHY-5, Durgapura Madhu and Pusa Sarabati were moderately resistant; AHMM/BR-13, Pusa Madhuras and Arka Jeet were susceptible; whereas Arka Rajhans and GMM-3 were the highly susceptible varieties/ genotypes to fruit fly in both seasons, 2011 and 2012. The larval density per fruit increased with an increase in percent fruit infestation and there was a significant positive correlation (r = 0.97) between percent fruit infestation and larval density per fruit. Total sugar, reducing sugar, non-reducing sugar and pH were lowest in resistant and highest in susceptible varieties/ genotypes, whereas tannins, phenols, alkaloids and flavinoid contents were highest in resistant and lowest in susceptible varieties/ genotypes. Total alkaloid and pH contents explained 97.96% of the total variation in fruit fly infestation and 92.83% of the total variation in larval density per fruit due to alkaloids and total sugar contents.

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Summary Reciprocal crosses between Brassica carinata (BBCC, 2n=34) and B. tournefortii (TT, 2n=20) were attempted in order to determine crossability between the species, carry out chromosomal associations among the B, C and T genomes, and to study morphology of the interspecific hybrids. A hybrid between these 2 species was obtained only when B. carinata was used as a female parent. Morphologically, the hybrid was intermediate between the progenitor species but its leaves resembled B. carinata. The F 1 plant was tall but grew very slowly. The hybrid was almost male sterile, showing only 2.3% pollen stainability. Meiotic studies of trigenomic triploid hybrid (BCT, 2n=27) showed various chromosome configurations including quadrivalents (0-1), trivalents (0-2), bivalents (2-9) and univalents (5-23). Only 5 univalents were recorded to have occurred; otherwise trivalents and bivalents were observed in pollen mother cells of the BCT hybrid. A few chromosomal association could be expected through allosyndesis which suggests the possibility of transferring genes across the species through interspecific hybridization.

The inheritance of siliqua locule number and seed coat colour in Brassica juncea was investigated, using three lines each of tetralocular brown seeded and bilocular yellow seeded. Three crosses of tetralocular brown seeded · bilocular yellow seeded lines were attempted and their F 1 , F 2 and backcross generations were examined for segregation of these two traits. Brown seed colour and bilocular siliqua characters were found to be dominant over yellow seed and tetralocular siliqua, respectively. Chi-square tests indicated that each trait is controlled by different sets of duplicate pairs of genes. Bilocular siliquae or brown seeds can result from the presence of either of two dominant alleles, whereas tetralocular siliquae or yellow seeds are produced when alleles at both loci are recessive. A joint segregation analysis of F 2 data indicated that the genes governing siliqua locule number and seed colour were inherited independently.

Out of 103 microsatellite markers used for studying the genetic diversity among local landraces of species, 56 were found polymorphic, including 38 gSSR and 18 eSSR, respectively. A total of 197 amplification products were obtained. The mean number of alleles per locus was 3.52. The PIC ranged from 0.037 to 0.986, while size of amplified product ranged from 105 to 500 bp. Cucumber-derived SSRs were amplified within (68%), (61.16%), and (60.2%), with an average of 63.12% cross-transferability. The Jaccard's coefficient ranged from 0.66 to 0.97, with an average of 0.81. High genetic variability was observed for node of 1st hermaphrodite flower (6.4-17), days to 1st hermaphrodite flower (38-52.1), days to 1st fruit harvest (43-65), number of fruit per cluster (1-5.9), fruit length (3.9-25 cm), fruit weight (18.4-175 g), number of fruit per plant (20-147.5), and yield per plant (2.2-4.7 kg). Two sub-populations were identified including 21 genotypes (sub-population I) and 06 genotypes (sub-population II), these two sub-populations showed 0.608-0.395% of the ancestral relationship to each other. This study provides information for future exploration, collection, and utilization of genotypes, as well as the polymorphic markers identified could be available for the study of landmarks in linkages, genomic structures, evolutionary ecology, and marker-assisted selection (MAS) in species.