Bereimipour, A. | Search bioRxiv

bioRxiv2026

RAP2.3 is required for MYB51 and SIGMA3 expression during the response of Arabidopsis thaliana to multifactorial stress combination

In nature, plants are subjected to multiple environmental stress factors simultaneously or sequentially. Recent studies revealed that when three or more stress factors impact a plant simultaneously (termed multifactorial stress combination; MFSC), plant survival declines, even if the intensity of each individual stress involved in the MFSC is low. We previously identified RAP2.3 as a key transcription factor (TF) required for Arabidopsis thaliana survival, specifically under a MFSC of salt+excess light+heat stress (i.e., S+EL+HS). Here we report that RAP2.3 is required for the expression of SIGMA3, a nuclear-encoded factor that directs plastid RNA polymerase to specific plastid promoters, and MYB51, a key stress response TF involved in glucosinolate metabolism and oxidative stress responses, specifically during a MFSC of S+EL+HS. Like rap2.3 mutants, myb51 and sig3 mutants display significantly low survival rate specifically under the MFSC of S+EL+HS. Based on MYB51 gene regulatory network analysis and characterization of jasmonic acid (JA) mutants, we further reveal that suppression of JA signaling could play an important role in promoting plant survival under conditions of S+EL+HS. Our findings uncover an additional layer of the response of plants to MFSC, as well as identify potential targets for breeding crops with enhanced tolerance to climate change.

plant biology↗

bioRxiv2025

bHLH35 mediates specificity in plant responses to multiple stress conditions

How biological systems respond to stress is a fundamental question in biology, primarily addressed using the reductionist approach of applying one stress condition at a time. In nature, however, organisms experience a multitude of stresses, simultaneously or sequentially, questioning the validity of the reductionist approach for predicting plant responses to stress under natural conditions. Here, we reveal that in the flowering plant Arabidopsis thaliana, the transcriptional regulator bHLH35 is required for plant survival under a specific set of stress conditions that includes a combination of salinity, excess light, and heat, occurring simultaneously (but not for each of these stresses applied individually or in any other combination). Under these conditions, bHLH35 interacts with NAC069 and binds the promoter of LBD31, also specifically required for survival under the 3-stress combination. Our findings uncover a high degree of specificity in the response of organisms to stress, a specificity that would not have been revealed using the reductionist approach, and one that should be taken into consideration when developing agronomically important crops with heightened resilience to climate change.

plant biology↗