Rapid starch degradation in the wood of olive trees under heat and drought is permitted by three stress-specific beta amylases

Mor Tsamir-Rimon, Shifra Ben-Dor, Ester Feldmesser, Yaara Oppenhimer-Shaanan, Rakefet David-Schwartz, Alon Samach, Tamir Klein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Carbon reserve use is a major drought response in trees, enabling tree survival in conditions prohibiting photosynthesis. However, regulation of starch metabolism under drought at the whole-tree scale is still poorly understood. To this end, we combined measurements of nonstructural carbohydrates (NSCs), tree physiology and gene expression. The experiment was conducted outside on olive trees in pots under 90 d of seasonal spring to summer warming. Half of the trees were also subjected to limited water conditions for 28 d. Photosynthesis decreased in dehydrating trees from 19 to 0.5 µmol m−2 s−1 during the drought period. Starch degradation and mannitol production were a major drought response, with mannitol increasing to 71% and 41% out of total NSCs in shoots and roots, respectively. We identified the gene family members potentially relevant either to long-term or stress-induced carbon storage. Partitioning of expression patterns among β amylase and starch synthase family members was observed, with three β amylases possibly facilitating the rapid starch degradation under heat and drought. Our results suggest a group of stress-related, starch metabolism genes, correlated with NSC fluctuations during drought and recovery. The daily starch metabolism gene expression was different from the stress-mode starch metabolism pattern, where some genes are uniquely expressed during the stress-mode response.

Original languageAmerican English
Pages (from-to)1398-1414
Number of pages17
JournalNew Phytologist
Volume229
Issue number3
DOIs
StatePublished - Feb 2021

Bibliographical note

Publisher Copyright:
© 2020 The Authors New Phytologist © 2020 New Phytologist Trust

Keywords

  • carbon source
  • drought response
  • drought tolerance
  • mannitol
  • starch degradation
  • starch synthesis

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