- 著者
- Yong-Gen Yin Atsuko Sanuki Yukihisa Goto Nobuo Suzui Naoki Kawachi Chiaki Matsukura
- 出版者
- Japanese Society for Plant Biotechnology
- 雑誌
- Plant Biotechnology (ISSN:13424580)
- 巻号頁・発行日
- vol.40, no.4, pp.345-351, 2023-12-25 (Released:2023-12-25)
- 参考文献数
- 32
In early developing tomato (Solanum lycopersicum L.) fruit, starch accumulates at high levels and is used by various primary metabolites in ripening fruits. ADP-glucose pyrophosphorylase is responsible for the first key step of starch biosynthesis. Although it has been reported that AgpL1 and AgpS1 isoforms are mainly expressed in early developing fruit, their regulatory mechanism has not been elucidated. The present study investigated the transcriptional response of AgpL1 and AgpS1 to various metabolizable sugars, nonmetabolizable sugar analogues, hexokinase inhibitors and proline by an experimental system using half-cut fruits. AgpL1 was upregulated in response to sucrose and constituted hexoses such glucose, whereas the AgpS1 gene almost did not exhibit a prominent sugar response. Further analyses revealed that other disaccharides such maltose and trehalose did not show a remarkable effect on both AgpL1 and AgpS1 expressions. These results indicate that there are two distinct regulatory mechanisms, namely, sugar metabolism-dependent and -independent, for the regulation of AGPase gene expression. Interestingly, the ADP treatment, a hexokinase inhibitors, cancelled the sugar response of AgpL1, indicating that hexokinase-mediated sugar signaling should be involved in the sugar response of AgpL1. These results suggest that sugar-dependent (AgpL1) and sugar-independent (AgpS1) pathways coordinatively regulate starch biosynthesis in immature tomato fruit.
- 著者
- Moalla Rached Baldet Pierre Gibon Yves Chiaki Matsukura Toru Ariizumi Hiroshi Ezura Naoya Fukuda
- 出版者
- The Japanese Society for Horticultural Science
- 雑誌
- The Horticulture Journal (ISSN:21890102)
- 巻号頁・発行日
- pp.OKD-150, (Released:2018-02-16)
- 被引用文献数
- 14
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 Ca2+ concentrations did not associate with the BER susceptibility of each cultivar. Interestingly, ‘Reiyoh’ showed much higher K+/Ca2+ and (K++Mg2+)/Ca2+ ratios than the two other cultivars in healthy fruits due to a strong tendency towards lowered Ca2+ 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.