Dynamic Alternations in Cellular and Molecular Components during Blossom-End Rot Development in Tomatoes Expressing sCAX1, a Constitutively Active Ca2+/H+ Antiporter from Arabidopsis    

Abstract

Although calcium (Ca) concentration in cellular compartments has been suggested to be tightly regulated, Ca deficiency disorders such as blossom-end rot (BER) in tomato (Solanum lycopersicum) fruit may be induced by abnormal regulation of Ca partitioning and distribution in the cell. The objectives of this work were to analyze the effects of high expression of the constitutively functional Arabidopsis (Arabidopsis thaliana) Ca 2+ /H + exchanger (sCAX1) tonoplast protein in tomato fruit on cellular Ca partitioning and distribution, membrane integrity, and the transcriptional profile of genes potentially involved in BER development. Wild-type and sCAX1-expressing tomato plants were grown in a greenhouse. Wild-type plants did not develop BER, whereas sCAX1-expressing plants reached 100% BER incidence at 15 d after pollination. The sCAX1-expressing fruit pericarp had higher total tissue and water-soluble Ca concentrations, lower apoplastic and cytosolic Ca concentrations, higher membrane leakage, and Ca accumulation in the vacuole of sCAX1-expressing cells. Microarray analysis of healthy sCAX1-expressing fruit tissue indicated down-regulation of genes potentially involved in BER development, such as genes involved in membrane structure and repair and cytoskeleton metabolism, as well as up-regulation of genes that may have limited BER damage expansion, such as genes coding for heat shock proteins, glutathione S-transferases, and peroxidases. The results indicate that the high expression of the sCAX1 gene reduces cytosolic and apoplastic Ca concentrations, affecting plasma membrane structure and leading to BER symptom development in the fruit tissue.

PRODUCTION AND QUALITY VARIABLES OF THREE SELECTIONS OF RIBBED TOMATO (Solanum lycopersicum L.)

“…This characteristic in tomato fruits decreases as they mature (Schouten et al, 2007), so one of the reasons for the lack of firmness in ribbed tomato fruit is that it was harvested when it had an advanced state of maturation and was still on the plant. Although fruit firmness is low, it can be increased by foliar sprays of Ca ++ or harvesting in the early stages of maturation to resist the handling and extend the life shelf, although this last depends on the market destination (Ho and White, 2005).…”

Arabidopsis thaliana PRL1is involved in low-calcium tolerance

“…(Conn et al 2011). Transgenic tobacco (Nicotiana tabacum L.) and tomato constitutively expressing CAX1 displayed Ca-deficiency symptoms under the normal Ca condition (Hirschi 1999;De Freitas et al 2011). The cax1 mutant of A. thaliana shows low-Ca tolerant phenotypes (Cheng et al 2003).…”

Physiological Mechanisms Accounting for the Lower Incidence of Blossom-end Rot in Tomato Introgression Line IL8-3 Fruit

“…ut.ee/), and the primer sequence and description of each gene are given in Table 1. Some primer sets were from de Freitas et al (2011), and primer sets for SlActin as a control were from Mohammed et al (2012).…”

“…The risk of BER occurrence becomes critical when Ca 2+ in the distal portion of the immature fruit decreases to less than 0.20 μmol·g −1 fresh weight (Yoshida et al, 2014). Moreover, Ca 2+ -movement-related genes and Ca 2+ concentration have been shown to be important in the incidence of BER in transgenic studies with their genes (de Freitas et al, 2011;Park et al, 2005 BER is induced within 15 days after flowering (DAF) when fruit growth is most rapid (de Freitas et al, 2011;Saure, 2001 (Ho and White, 2005). High irradiance, temperature, and gibberellin, which promote early fruit growth, could result in the induction of BER (Ho et al, 1993;Saure, 2014).…”

“…In particular, BER exhibits necrosis and discoloring in the distal portion of the tomato fruit and causes serious economic losses in tomato production (Taylor and Locascio, 2004). Initial BER symptoms of tomato fruits are membrane leakage of cell solutes, cell plasmolysis, and membrane breakdown (de Freitas et al, 2011;Ho and White, 2005;Saure, 2001). Subsequently, the fruit surface exhibits symptoms of water soaking, and the tissue of the distal portion of the fruit becomes discolored and necrotic.…”