Abscisic acid and polyamines coordinately regulate strawberry drought responses

Abstract

Abscisic acid (ABA) and polyamines (PAs) play an important role in plant stress responses; however, their cooperative mechanisms are not fully understood. Here, using the detached-, PEG 6000- and pot-drought strawberry leaves, we investigated the expression changes of genes key to ABA and PA homeostasis by a combination of qRT-PCR, western blotting, RNA-sequencing, physiological analyses, and pharmacological tests. The results showed that early drought may promote the production of both putrescine (Put) by FaADC1 and ABA by FaNCED1, then these productions could be further facilitated by the accumulated Put. Meanwhile, the high accumulation of ABA not only further accelerated ABA biosynthesis by FaNCED3, but also controlled PA homeostasis by a decrease in FaADC1 expression and an increase in FaSAMDC1 and FaPAO5 expression. Based on our RNA-seq data, Put was involved in photosynthesis and oxidative phosphorylation, while ABA was implicated in sugar and flavonoid metabolism, both of which were linked to auxin (IAA). Altogether, in response to strawberry drought stress, FaNCED1/3 and FaADC1/FaSAMDC1 participated separately in ABA and PA accumulation, mostly FaNCED1/FaADC1 was induced by stress and FaNCED3/FaSAMDC1 was induced by ABA. Finally, a balance between ABA and PAs for the cooperative control of plant growth and adaptation is proposed through IAA, photosynthesis, oxidative phosphorylation, and flavonoid metabolism, among which ABA may act in a Put-dependent manner.

Keywords

• Drought
• ABA
• Polyamines
• Strawberry
• Biosynthesis
• Metabolism