The ARF2–ANT–COR15A gene cascade regulates ABA-signaling-mediated resistance of large seeds to drought in Arabidopsis

Abstract

Seedlings of large-seeded plants are considered to be able to withstand abiotic stresses efficiently. The molecular mechanisms that underlie the involved signaling crosstalk between the large-seeded trait and abiotic tolerance are, however, largely unknown. Here, we demonstrate the molecular link that integrates plant abscisic acid (ABA) responses to drought stress into the regulation of seed mass. Both loss-of-function mutants of the Auxin Response Factor 2 (ARF2 encoding a transcription factor) and lines overexpressing AINTEGUMENTA (ANT; a transcription factor) under the 35S promoter exhibited large seed and drought-tolerant phenotypes as a result of abnormal ABAauxin crosstalk signaling pathways in Arabidopsis. The target gene COLD-REGULATED15A (COR15a) was identified as participating in the regulation of seed development with ABA signaling through a negative regulation mechanism that is mediated by ANT. The molecular and genetic evidence presented indicate that ARF2, ANT and COR15A form an ABA-mediated signaling pathway to link modulation of seed mass with drought tolerance. These observations indicate that the ARF2 transcription factor serves as a molecular link that integrates plant ABA responses to drought stress into the regulation of seed mass.

Why are Seedlings of Large-Seeded Plants Considered to Withstand Drought Stresses Efficiently?

“…However, high concentrations of ABA can suppress root growth by suppressing cell division [9]. Our observation in leaf development also support this notion [1]. Together, in our model, ARF2 transcription repressor integrates ABA signals into regulatory of seed mass and drought tolerance by negatively modulating ANT-mediated regulation of COR15A genes.…”

“…We also found that AN3 modulates seed mass (our unpublished data). Thus, AN3 integrates an unknown signal into seed mass and drought tolerance by negatively modulating YODA-mediated regulation.Taken together, our current research not only demonstrated the first direct evidence for ARF2 mediated both seed mass and drought tolerance by negatively regulating the expression of ANT and COR15A, enriched the regulation network of both seed mass and drought tolerance, but also provided a novel insight in understanding the mechanism underlying why are seedlings of large-seeded plants considered to withstand drought stresses efficiently [1]. However, it remain unknown how ABA signaling induces the activity of ARF2 and ANT, and what relationships between ABA receptors and ARF2 or ANT.…”

“…Recently, our reports revealed that ARF2-ANT-COR15A form a ABA signal-mediated gene cascade for regulating both drought tolerance and seed mass. Together, this work presents a large body of work and provides a new insight on the link between auxin and ABA in seed size and abiotic tolerance regulation, and thus this is original and relevant study with important impacts for the basic science as well as agriculture [1].Similar to this study, currently we reported that ANGUSTIFOLIA3 (AN3), a transcription coactivator, regulates Arabidopsis plant drought tolerance by modifying root system and stomatal density via transrepressing YODA expression [15,16]. We also found that AN3 modulates seed mass (our unpublished data).…”

“…On the other hand, seed size can be altered intraspecifically in response to environmental cues [1]. Ecologists and evolutionary biologists had early observed this phenomenon [1][2][3][4].…”

“…Genetic evidence indicates ARF2-ANT-COR15A forms ABA (abscisic acid) signaling-mediated gene cascade for regulation of both drought tolerance and seed mass, which has cross talk with the auxin signal pathway. Together, our proposed model provides a better understanding of seed mass and drought tolerance regulation, which may in turn lead to better increased crop yield and crop breeding [1].In this model, what signaling molecule performs a key relationship between drought tolerance (stress) and seed mass (growth and development)? We found that the phytohormone abscisic acid (ABA) plays a key role.…”