5.1 Transcription factors
Previous reviews had identified several transcription factor families as hubs for plant responses to multiple stresses (Fujita et al., 2006; Atkinson & Urwin, 2012; Rivero et al., 2022). MYC2 is a central player in plant responses to biotic and abiotic stress (Anderson et al., 2004), and plays a role in JA-induced defense genes and is a key regulator by which ABA controls signaling related to biotic stress (Atkinson & Urwin, 2012). MYB transcription factors are also a key group, as they have been shown to be induced by drought, UV-B radiation, cold stress as well as biotic stress (Atkinson & Urwin, 2012). Additionally, NAC and AP2/ERF transcription factors have broad spectrum responses to biotic and abiotic stress in multiple species (Atkinson & Urwin, 2012). More targets for future research include WRKY, bZIP, TCP, and calmodulin-binding transcription factor activator (CAMTA) transcription factors (Atkinson & Urwin, 2012; Kissoudis et al., 2014 Rivero et al., 2022). Several members of these transcription factor families (ERF, MYB, bHLH, NAC, and WRKY) have been suggested to act as switches controlling transcriptional reprogramming during plant development as well as in tolerance to biotic and abiotic stresses. These transcription factors are ideal candidates for engineering stress-tolerant plants (Erpen et al. 2017, Baillo et al. 2019)
Furthermore, understanding post-translational regulation of transcription factors is important, as this impacts expression of downstream genes that can be key regulators of plant stress response. These downstream genes include proline-rich proteins. For example, when proline-rich proteins from pigeonpea (Cajanus cajan L.) were constitutively expressed in Arabidopsis they provided enhanced tolerance to multiple abiotic stresses such as osmotic, salt, and heat stress. Meta-analyses of transcriptome datasets have revealed additional core abiotic stress responsive genes (Dossa et al., 2019, Saidi et al., 2022), include genes belonging to a member of the late embryogenesis abundant family (LEA) (Huang et al. 2016, Chen et al. 2019), and alcohol dehydrogenase (ADH) family members (Shi et al. 2017). Additionally, the resistance gene, Xa7 , conferring bacterial blight resistance in rice functions better at high temperatures, indicating elevated temperature can have a positive impact on plant defense responses to pathogens (Cohen et al., 2017). These genes could be key targets for future research efforts.