Oxidative Stress and Changes in Antioxidant and Biochemical Constituents in Papaya (Carica papaya L.) under Salt Stress

Six papaya cultivars viz., Pusa Dwarf, Surya, Solo, CO5, Tainan and Red Lady were subjected to saline water salt stress continuously for a period of six months with saline water irrigation having an EC value of 0.6, 2.0 and 4 dsm-1. Among these, Red Lady was more sensitive while Tainan resisted salt stress. Under salt stress of 4 dsm-1, yield reduced by 10% in Tainan and by 24% in Red Lady compared to unstressed controls. T.S.S. measurement showed that quality of fruits was not affected by saline irrigation in both cvs. Malondialdehyde levels estimated after six months period of stress, as thiobarbituric acid reacting substances, did not increase in Tainan in contrast to substantial increase in Red Lady under stress conditions. There was substantial increase in levels of antioxidant compounds namely, carotenoids, phenols and flavonoids in Tainan compared to Red Lady. In Tainan there were significant increases in reducing and total sugars and sucrose under conditions of stress in contrast to sharp decreases in Red Lady. Under conditions of stress, there was considerable accumulation of total and reducing sugars and sucrose, across the varieties, possibly contributing to osmotic adjustment. Association of salt stress tolerance in Tainan with soluble sugar accumulation could be used as a breeding tool for selecting salt tolerant papaya genotypes

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Not AvailableA study was conducted to assess the physiological and biochemical changes associated with aril browning of pomegranate. Aril browning is identified by flattened, brown arils with off-flavour and lower firmness. Brown arils were found to have higher respiration, starch, acidity, pyruvic acid and amino acids when compared to healthy arils. Total and reducing sugars, ascorbic acid and anthocyanins were lower in brown arils. Malondialdehyde content and the activities of superoxide dismutase, peroxidase and polyphenol oxidase enzymes were found to be significantly higher in brown arils. Results indicated that the browning of arils was due to oxidative damage of membranes leading to higher enzymatic browning by polyphenol oxidase and peroxidase.Not Availabl

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Not AvailableThrips palmi (Thysanoptera: Thripidae) is the predominant tospovirus vector in Asia-Pacific region. It transmits economically damaging groundnut bud necrosis virus (GBNV, family Tospoviridae) in a persistent propagative manner. Thrips serve as the alternate host, and virus reservoirs making tospovirus management very challenging. Insecticides and host plant resistance remain ineffective in managing thrips–tospoviruses. Recent genomic approaches have led to understanding the molecular interactions of thrips–tospoviruses and identifying novel genetic targets. However, most of the studies are limited to Frankliniella species and tomato spotted wilt virus (TSWV). Amidst the limited information available on T. palmi–tospovirus relationships, the present study is the first report of the transcriptome-wide response of T. palmi associated with GBNV infection. The differential expression analyses of the triplicate transcriptome of viruliferous vs. nonviruliferous adult T. palmi identified a total of 2,363 (1,383 upregulated and 980 downregulated) significant transcripts. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed the abundance of differentially expressed genes (DEGs) involved in innate immune response, endocytosis, cuticle development, and receptor binding and signaling that mediate the virus invasion and multiplication in the vector system. Also, the gene regulatory network (GRN) of most significant DEGs showed the genes like ABC transporter, cytochrome P450, endocuticle structural glycoprotein, gamma-aminobutyric acid (GABA) receptor, heat shock protein 70, larval and pupal cuticle proteins, nephrin, proline-rich protein, sperm-associated antigen, UHRF1-binding protein, serpin, tyrosine–protein kinase receptor, etc., were enriched with higher degrees of interactions. Further, the expression of the candidate genes in response to GBNV infection was validated in reverse transcriptase-quantitative real-time PCR (RT-qPCR). This study leads to an understanding of molecular interactions between T. palmi and GBNV and suggests potential genetic targets for generic pest control.Not Availabl