Expression profile of genes coding for carotenoid biosynthetic pathway during ripening and their association with accumulation of lycopene in tomato fruits

Fruit ripening process is associated with change in carotenoid profile and accumulation of lycopene in tomato (Solanum lycopersicum L.). In this study, we quantified the β-carotene and lycopene content at green, breaker and red-ripe stages of fruit ripening in eight tomato genotypes by using high-performance liquid chromatography. Among the genotypes, lycopene content was found highest in Pusa Rohini and lowest in VRT-32-1. To gain further insight into the regulation of lycopene biosynthesis and accumulation during fruit ripening, expression analysis of nine carotenoid pathway-related genes was carried out in the fruits of high lycopene genotype—Pusa Rohini. We found that expression of phytoene synthase and β-carotene hydroxylase-1 was four and thirty-fold higher, respectively, at breaker stage as compared to red-ripe stage of fruit ripening. Changes in the expression level of these genes were associated with a 40% increase in lycopene content at red-ripe stage as compared with breaker stage. Thus, the results from our study suggest the role of specific carotenoid pathway-related genes in accumulation of high lycopene during the fruit ripening processes.     

<Emphasis Type="Italic">LIG1</Emphasis> polymorphisms: the Indian scenario

Elucidation of the genetic diversity and relatedness of the subpopulations of India may provide a unique resource for future analysis of genetic association of several critical community-specific complex diseases. We performed a comprehensive exploration of single nucleotide polymorphisms (SNPs) within the gene DNA ligase 1 (LIG1) among a multiethnic panel of Indian subpopulations representative of the ethnic, linguistic and geographical diversity of India using a two-stage design involving DNA resequencing-based SNP discovery followed by SNP validation using sequenom-based genotyping. Thirty SNPs were identified in LIG1 gene using DNA resequencing including three promoter SNPs and one coding SNP. Following SNP validation, the SNPs rs20580/C19008A and rs3730862/C8804T were found to have the most widespread prevalence with noticeable variations in minor allele frequencies both between the Indian subpopulation groups and also from those reported on other major world populations. Subsequently, SNPs found in Indian subpopulations were analysed using bioinformatics-based approaches and compared with SNP data available on major world populations. Further, we also performed genotype–phenotype association analysis of LIG1 SNPs with publicly available data on LIG1 mRNA expression in HapMap samples. Results showed polymorphisms in LIG1 affect its expression and may therefore change its function. Our results stress upon the uniqueness of the Indian population with respect to the worldwide scenario and suggest that any epidemiological study undertaken on the global population should take this distinctiveness in consideration and avoid making generalized conclusions.     

Metabolism of Dihydrozeatin in Floral Buds of Wild-Type and a Genic Male Sterile Line of Rapeseed (Brassica napus L.)

The metabolism of [³H]dihydrozeatin (DZ) in floral buds of threedevelopmental stages, and endogenous cytokinin (CK) levels inmature stamens were investigated in wild-type (WT) and a geniemale sterile (GMS) line of rapeseed (Brassica napus L.). Floralbuds were fed [³H]DZ and subsequently different metabolites,namely nucleotides, ribosides and glucosides, were analysedby 2DTLC and HPLC. The GMS buds exhibited a higher initial uptakeof [³]DZ than wild-type buds, but the total uptake after 12h was either similar or less in GMS buds. [³]Dihydrozeatin wasmetabolized more efficiently in WT than in GMS buds, as moreof [³]DZ was retained in the latter. This was especially thecase in stage 2 buds, when in GMS anthers microspores fail toseparate from tetrads, thereby causing sterility. [³H]Dihydrozeatinwas converted to dihydrozeatin nucleotide (DZNT), dihydrozeatinriboside and O-glucosides by both WT and GMS buds. However,all these metabolites were relatively low in GMS buds. The majordifference was in the reduced formation of DZNT by stage 2 GMSbuds. The GMS stamens also contained low levels of various cytokinins,including the nucleotides. These observations, along with earlierreports, suggest that low levels of endogenous CKs, and, inparticular, the reduced formation of CK nucleotides are partlyresponsible for the breakdown of microsporogenesis in GMS anthers. Key words: Cytokinin, metabolism, male sterility, rapeseed, Brassica napus     

Association of <Emphasis Type="Italic">IL-10</Emphasis> gene (−1082A&gt;G, −819C&gt;T and −592C&gt;A) polymorphism and its serum level with metabolic syndrome of north Indian subjects

Metabolic syndrome (MetS) is an inflammatory disorder, in which various cytokines play important role in tilting balance towards disease state. Interleukin-10 (IL-10) is an important antiinflammatory cytokine, but its genetic polymorphisms and serum levels in Indian MetS subjects are unknown. Three IL-10 gene polymorphisms (?1082A >G (rs1800896), ?819C >T (rs1800872) and ?592C >A (rs1800871)) were genotyped with PCR-RFLP in MetS subjects (n = 384) and age/sex matched control subjects (n = 386). Serum IL-10 was measured using enzyme-linked immunosorbent assay. Serum IL-10 level was significantly low in MetS subject and significantly correlated with clinicobiochemical parameters of MetS. Of three investigated promoter polymorphisms, IL-10 –819C > T and –592C >A were significantly associated with risk of MetS. The mutant alleles ?819T and ?592A of IL-10 gene polymorphism were significantly higher in MetS subjects compared to controls. Of the four different haplotypes obtained, common ACC haplotype and rare GTA haplotype of IL-10 polymorphisms were associated with MetS. The mean of fasting insulin and HOMA-IR were significantly different between the genotypes of both ?819 C >T and ?592C >A polymorphisms of IL-10 in MetS subjects. These results suggested that polymorphisms in IL-10 gene (?819C >T and ?592C >A), haplotypes (ACC and GTA) and serum level are significantly associated with risk of MetS. IL-10 ?819C >T and ?592C >A polymorphic variants are also significantly associated with insulin level and homeostasis model assessment-insulin resistance in north Indian MetS subjects.