The Proteome of Fruit Peroxisomes: Sweet Pepper (Capsicum annuum L.) as a Model.

Despite of their economical and nutritional interest, the biology of fruits is still little studied in comparison with reports of other plant organs such as leaves and roots. Accordingly, research at subcellular and molecular levels is necessary not only to understand the physiology of fruits, but also to improve crop qualities. Efforts addressed to gain knowledge of the peroxisome proteome and how it interacts with the overall metabolism of fruits will provide tools to be used in breeding strategies of agricultural species with added value.

Physiology of pepper fruit and the metabolism of antioxidants: chloroplasts, mitochondria and peroxisomes.

Background And Aims: Pepper (Capsicum annuum) contains high levels of antioxidants, such as vitamins A and C and flavonoids. However, information on the role of these beneficial compounds in the physiology of pepper fruit remains scarce. Recent studies have shown that antioxidants in ripe pepper fruit play a key role in responses to temperature changes, and the redox state at the time of harvest affects the nutritional value for human consumption.

Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration.

Background And Aims: Pepper (Capsicum annuum, Solanaceae) fruits are consumed worldwide and are of great economic importance. In most species ripening is characterized by important visual and metabolic changes, the latter including emission of volatile organic compounds associated with respiration, destruction of chlorophylls, synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyanins), formation of pectins and protein synthesis. The involvement of nitric oxide (NO) in fruit ripening has been established, but more work is needed to detail the metabolic networks involving NO and other reactive nitrogen species (RNS) in the process.

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+ /K+ homeostasis.

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na(+) ] and [K(+) ] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na(+) -selective class I-HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single-nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2.

Overexpression of SlSOS2 (SlCIPK24) confers salt tolerance to transgenic tomato.

The Ca(2+)-dependent SOS pathway has emerged as a key mechanism in the homeostasis of Na(+) and K(+) under saline conditions. We have identified and functionally characterized the gene encoding the calcineurin-interacting protein kinase of the SOS pathway in tomato, SlSOS2. On the basis of protein sequence similarity and complementation studies in yeast and Arabidopsis, it can be concluded that SlSOS2 is the functional tomato homolog of Arabidopsis AtSOS2 and that SlSOS2 operates in a tomato SOS signal transduction pathway.

The plasma membrane Na+/H+ antiporter SOS1 is essential for salt tolerance in tomato and affects the partitioning of Na+ between plant organs.

We have identified a plasma membrane Na(+)/H(+) antiporter gene from tomato (Solanum lycopersicum), SlSOS1, and used heterologous expression in yeast to confirm that SlSOS1 was the functional homolog of AtSOS1. Using post-transcriptional gene silencing, we evaluated the role played by SlSOS1 in long-distance Na(+) transport and salt tolerance of tomato. Tomato was used because of its anatomical structure, more complex than that of Arabidopsis, and its agricultural significance.