Thioredoxin <i>h</i>2 and <i>o</i>1 Show Different Subcellular Localizations and Redox-Active Functions, and Are Extrachloroplastic Factors Influencing Photosynthetic Performance in Fluctuating Light

• Main Authors: Liang-Yu Hou (Author), Martin Lehmann (Author), Peter Geigenberger (Author)
• Format: Book
• Published: MDPI AG, 2021-04-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Arabidopsis contains eight different <i>h</i>-type thioredoxins (Trx) being distributed in different cell organelles. Although Trx <i>h</i>2 is deemed to be confined to mitochondria, its subcellular localization and function are discussed controversially. Here, cell fractionation studies were used to clarify this question, showing Trx <i>h</i>2 protein to be exclusively localized in microsomes rather than mitochondria. Furthermore, Arabidopsis <i>trxo1</i>, <i>trxh2</i> and <i>trxo1h2</i> mutants were analyzed to compare the role of Trx <i>h</i>2 with mitochondrial Trx <i>o</i>1. Under medium light, <i>trxo1</i> and <i>trxo1h2</i> showed impaired growth, while <i>trxh2</i> was similar to wild type. In line with this, <i>trxo1</i> and <i>trxo1h2</i> clustered differently from wild type with respect to nocturnal metabolite profiles, revealing a decrease in ascorbate and glutathione redox states. Under fluctuating light, these genotypic differences were attenuated. Instead, the <i>trxo1h2</i> double mutant showed an improved NADPH redox balance, compared to wild type, accompanied by increased photosynthetic efficiency, specifically in the high-light phases. Conclusively, Trx <i>h</i>2 and Trx <i>o</i>1 are differentially localized in microsomes and mitochondria, respectively, which is associated with different redox-active functions and effects on plant growth in constant light, while there is a joint role of both Trxs in regulating NADPH redox balance and photosynthetic performance in fluctuating light.

Item Description

10.3390/antiox10050705
2076-3921