Molecular and morphometric analyses reveal discrete grouping of pomegranate (Punica granatum) genebank accessions away from cultivars

Management of germplasm in the field genebanks is greatly assisted by genetic analysis. Estimation of genetic diversity and assessment of genetic relationships among 45 accessions of pomegranate (Punica granatum L.) that included cultivars and germplasm collections were carried out using nine morphometric, 241 ISSR and six SSR markers. The average genetic distance values based on ANOVA sum of squares (Ward) were 3.94 and 5.10 for morphometric and DNA markers respectively. Hierarchical clustering based on genetic distances grouped the accessions into at least three distinct clusters; the two-way clustering showing the contribution of individual markers in genetic grouping. Discrete grouping of field genebank accessions (with IC numbers) away from cultivars was evident based both on quantitative traits data as well as DNA marker data. The findings suggested the possibility of broadening genetic base of cultivated varieties by augmenting the breeding programmes in India with diverse as well as trait- specific pomegranate germplasm

Molecular basis of flower initiation—A review

455-465Plants have many differences, like protandry, protogyny, etc. However, amidst these differences, all angiosperms have a common mechanism of flowering, i.e. concentric pattern of flowering (sepal, petal, stamen and carpel). The mechanism or the genes thorough which plants maintain boundaries between the four, sepal-petal-stamen-carpel, are also given due importance. Once a plant attains competence, flowers may be produced through the reorganization of SAM directly to floral meristem, or through the inflorescence or co-inflorescence meristem, in response of exogenous and endogenous signals. Initiation, determination and differentiation are classed into four stages and this is the region which is studied here in detail. Some organ specificity genes, like MALE STERILITY (MS) and BICAUDAL (BIC), move us towards a better understanding of the mechanism like male sterility and self-incompatibility in plants. Models like ABC, biophysical, MCDK, etc., help in explaining the mechanism of flowering on a molecular basis. However, in general, the path towards flowering is laid when the floral repressor genes are down regulated. Recently identified miRNAs in plants authenticate them and also give out the mechanism by which they down regulate. It has also been found out that MADS-box gene family and CArG-box genes (where those MADS domain protein binds) are highly conserved. Their role in flower development is also touched upon

Genetic Diversity and Population Structure Analysis to Construct a Core Collection from Safflower (<i>Carthamus tinctorius</i> L.) Germplasm through SSR Markers

Genetic resources are the fundamental source of diversity available to plant breeders for the improvement of desired traits. However, a large germplasm set is difficult to preserve and use as a working collection in genetic studies. Hence, the present study evaluates the genetic diversity of 3115 safflower accessions from the Indian National Gene Bank, including Indian cultivars, to develop a manageable set of accessions, with similar genetic variations of germplasm studied. A total of 18 polymorphic SSR markers were used. The genetic diversity analysis revealed that germplasm accessions were highly diverse and there is no correlation between genetic diversity and the geographical collection of germplasm or sourcing of germplasm. A core set was developed using a core hunter software with different levels of composition, and it was found that 10% of the accessions showed maximum gene diversity and represented an equal number of alleles and major allele frequency in the germplasm studied. The developed core consisted of 351 accessions, including Indian cultivars, and they were validated with various genetic parameters to ascertain that they were a true core set for the studied accessions of safflower germplasm

Characterization of capsaicin synthase and identification of its gene (csy1) for pungency factor capsaicin in pepper (Capsicum sp.)

Capsaicin is a unique alkaloid of the plant kingdom restricted to the genus Capsicum. Capsaicin is the pungency factor, a bioactive molecule of food and of medicinal importance. Capsaicin is useful as a counterirritant, antiarthritic, analgesic, antioxidant, and anticancer agent. Capsaicin biosynthesis involves condensation of vanillylamine and 8-methyl nonenoic acid, brought about by capsaicin synthase (CS). We found that CS activity correlated with genotype-specific capsaicin levels. We purified and characterized CS (≈35 kDa). Immunolocalization studies confirmed that CS is specifically localized to the placental tissues of Capsicum fruits. Western blot analysis revealed concomitant enhancement of CS levels and capsaicin accumulation during fruit development. We determined the N-terminal amino acid sequence of purified CS, cloned the CS gene (csy1) and sequenced full-length cDNA (981 bp). The deduced amino acid sequence of CS from full-length cDNA was 38 kDa. Functionality of csy1 through heterologous expression in recombinant Escherichia coli was also demonstrated. Here we report the gene responsible for capsaicin biosynthesis, which is unique to Capsicum spp. With this information on the CS gene, speculation on the gene for pungency is unequivocally resolved. Our findings have implications in the regulation of capsaicin levels in Capsicum genotypes