Mesophyll abscisic acid restrains early growth and flowering but does not directly suppress photosynthesis

Boaz Negin, Adi Yaaran, Gilor Kelly, Yotam Zait, Menachem Moshelion*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Abscisic acid (ABA) levels increase significantly in plants under stress conditions, and ABA is thought to serve as a key stressresponse regulator. However, the direct effect of ABA on photosynthesis and the effect of mesophyll ABA on yield under both well-watered and drought conditions are still the subject of debate. Here, we examined this issue using transgenic Arabidopsis (Arabidopsis thaliana) plants carrying a dominant ABA-signaling inhibitor under the control of a mesophyll-specific promoter (FBPase::abi1-1, abbreviated to fa). Under normal conditions, fa plants displayed slightly higher stomatal conductance and carbon assimilation than wild-type plants; however, these parameters were comparable following ABA treatment. These observations suggest that ABA does not directly inhibit photosynthesis in the short term. The fa plants also exhibited a variety of altered phenotypes under optimal conditions, including more vigorous initial growth, earlier flowering, smaller flowers, and delayed chlorophyll degradation. Furthermore, under optimal conditions, fa plant seed production was less than a third of that observed for the wild type. However, under drought conditions, wild-type and fa seed yields were similar due to a significant reduction in wild-type seed and no reduction in fa seed. These findings suggest that endogenous basal ABA inhibits a stress-escape response under nonstressed conditions, allowing plants to accumulate biomass and maximize yield.

Original languageAmerican English
Pages (from-to)910-925
Number of pages16
JournalPlant Physiology
Issue number2
StatePublished - Jun 2019

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© 2019 American Society of Plant Biologists. All Rights Reserved.


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