Differences in Blossom-end Rot Resistance in Tomato Cultivars is Associated with Total Ascorbate rather than Calcium Concentration in the Distal End Part of Fruits <i>per se</i>

Abstract

Calcium is widely accepted as the main factor responsible for blossom-end rot (BER) appearance in tomato (Solanum lycopersicum L.) fruit. However, reactive oxygen species (ROS), which can damage plant tissues have also been proposed to initiate BER appearance in tomatoes and other fruit-bearing vegetables. Ascorbate, the major antioxidant in tomato fruit, is generally lower during green fruit development, which corresponds to the stage of BER appearance. Accordingly, one hypothesis is that tomato cultivars with a lower susceptibility to BER under salt stress have higher ascorbate contents and thus better control of ROS levels. In this study, to clarify the relationship between BER incidence and oxidative stress, two BER resistant cultivars, 'Managua RZ' and 'House Momotaro' and one BER-susceptible cultivar 'Reiyoh', were cultivated under salinity or standard nutrient solution (control) conditions. Calcium, potassium, magnesium, total hydro-soluble antioxidants, and ascorbate concentrations were measured in the distal pericarp 1 to 2 days prior to symptom appearance and during symptom appearance in healthy and affected fruits. When salt stress was applied, only BER-resistant cultivars showed a significant increase in ascorbate contents prior to BER appearance as compared with their levels under the control condition. In contrast, pre-BER Ca concentrations. A similar tendency was also observed in apple "bitter pit". The ability to increase the fruit antioxidant capacity and maintain mineral balance under salt stress conditions may explain the resistance to BER development in highly resistant cultivars, probably by the avoidance of oxidative-induced cell necrosis and stabilization of the cell membranes, respectively.

Silicon spraying alleviates calcium deficiency in tomato plants, but Ca‐EDTA is toxic

“…It is possible that the 19 spray applications of Ca-EDTA, both with and without Si, did not result in an increase in Ca accumulation in the shoots and fruits ( Fig. 2E, F) due to the low concentration that we used in the present experiment (1 g L -1 or 25 mM of Ca-EDTA) compared to the recommended, that is, 1.8 g L -1 or 45 mM Ca (Ho and White, 2005) With respect to the non-occurrence of BER in our experiment, although other authors have found BER in the MT cultivar (Gaion et al, 2019), it was found that tomatoes with this disorder at the beginning of development had a distribution and concentration of Ca similar to normal fruits, suggesting that Ca deficiency may not be the primary and exclusive cause of apical rot in tomatoes (Nonami et al, 1995;Rached et al, 2018).…”

“…With respect to the non‐occurrence of BER in our experiment, although other authors have found BER in the MT cultivar ( Gaion et al, 2019), it was found that tomatoes with this disorder at the beginning of development had a distribution and concentration of Ca similar to normal fruits, suggesting that Ca deficiency may not be the primary and exclusive cause of apical rot in tomatoes ( Nonami et al, 1995; Rached et al, 2018).…”

Temporal Relationship between Calcium and Fruit Growth and Development in Bell Pepper (Capsicum annuum L.)

“…In future studies, it is important to determine localized cellular calcium deficiency by investigating subcellular [Ca 2+ ] partitioning in fruit sections (de Freitas et al, 2011). Furthermore, the lack of a direct link between [Ca 2+ ] deficiency and the BER incidence in several studies also suggests a role for antioxidant levels in the distal part of the fruit in the development of BER symptoms (Hagassou et al, 2019;Nonami et al, 1995;Rached et al, 2018;Saure, 2001).…”

Identification of blossom-end rot loci using joint QTL-seq and linkage-based QTL mapping in tomato

“…Even though a central role for Ca 2+ in the development of BER has been postulated for many years, neither a consistent solution nor a direct link to fruit Ca 2+ concentration has been conclusively demonstrated (Ho and White 2005 ). Therefore, other physiological links to the causes of BER such as reactive oxygen species (ROS) formation have recently gained prominence (Rached et al 2018 ). Because of its destructive activity, excessive ROS release upon exposure of plants to stress conditions causes cell membrane lipid peroxidation, membrane leakage, and subsequently cell death, which can lead to the development of BER (Aktas et al 2003 ; Rached et al 2018 ; Van Breusegem and Dat 2006 ).…”

“…Therefore, other physiological links to the causes of BER such as reactive oxygen species (ROS) formation have recently gained prominence (Rached et al 2018 ). Because of its destructive activity, excessive ROS release upon exposure of plants to stress conditions causes cell membrane lipid peroxidation, membrane leakage, and subsequently cell death, which can lead to the development of BER (Aktas et al 2003 ; Rached et al 2018 ; Van Breusegem and Dat 2006 ). Moreover, ROS production reaches a maximum, when the rate of cell expansion during fruit growth is at its maximum (Aktas et al 2003 ).…”