Natural variations of growth thermo‐responsiveness determined by SAUR26/27/28 proteins in Arabidopsis thaliana

Abstract

Summary How diversity in growth thermo‐responsiveness is generated for local adaptation is a long‐standing biological question. We investigated molecular genetic basis of natural variations in thermo‐responsiveness of plant architecture in Arabidopsis thaliana. We measured the extent of rosette architecture at 22°C and 28°C in a set of 69 natural accessions and determined their thermo‐responsiveness of plant architecture. A genome‐wide association study was performed to identify major loci for variations in thermo‐responsiveness. The SAUR26 subfamily, a new subfamily of SAUR genes, was identified as a major locus for the thermo‐responsive architecture variations. The expression of SAUR26/27/28 is modulated by temperature and PIF4. Extensive natural polymorphisms in these genes affect their RNA expression levels and protein activities and influence the thermo‐responsiveness of plant architecture. In addition, the SAUR26 subfamily genes exhibit a high variation frequency and their variations are associated with the local temperature climate. This study reveals that the SAUR26 subfamily is a key variation for thermo‐responsive architecture and suggests a preference for generating diversity for local adaptation through signaling connectors.

Genetic variation associated with plastic and homeostatic growth responses to drought in Arabidopsis

“…Relevant to the non-discrete distribution of the plastic responses in the accessions that we studied, variation in transcript abundance of SAUR26 explained 17% of the observed plastic response in leaf area to drought in our study (Figure 2F, G). The importance of SAUR26 is supported by previous work that revealed natural genetic variation in SAUR26 associated with growth thermo□responsiveness of the rosette compactness index (Wang et al, 2019) and cis□elements in the 5’ upstream region or the 3’UTR region of SAUR26 that were responsible for this response (Wang et al 2021). This conclusion is also supported by our meta-analysis of the larger Iberian population with transcriptome data, which also identified SAUR26 transcript abundance as positively correlated with higher water use efficiency (Fig.…”

“…2g, h). The importance of SAUR26 is supported by previous work that revealed natural genetic variation in SAUR26 associated with growth thermoresponsiveness of the rosette compactness index (Wang et al, 2019), and cis-elements in the 5' upstream region or the 3'UTR region of SAUR26 that were responsible for this response (Wang et al 2021). This conclusion is also supported by our meta-analysis of the larger Iberian population with transcriptome data, which also identified SAUR26 transcript abundance as positively correlated with higher WUEi (Fig.…”

Polymorphisms in cis‐elements confer SAUR26 gene expression difference for thermo‐response natural variation in Arabidopsis

“…1e). Consistent with a previous study (Wang et al ., 2019), the Col‐0 accession that carries the Group A haplotype has a lower expression of SAUR26 compared to the Ang‐0 accession that carries the Group B haplotype. Taken together, variation in SAUR26 gene expression is determined by polymorphisms within its own gene, and the variations in the promoter and 5′UTR as well as the 3′UTR all have strong association with SAUR26 expression.…”

“…ICARUS 1 and ICARUS 2 , members of the tRNA His guanylyl transferase (Thg1) superfamily, are found to influence thermo‐responsive rosette growth (Zhu et al ., 2015; Méndez‐Vigo et al ., 2019). In addition, a SMALL AUXIN UP RNA ( SAUR ) gene cluster, SAUR26–SAUR28 , is shown to modulate thermo‐responsive rosette architecture in Arabidopsis natural accessions (Wang et al ., 2019). Natural polymorphisms in SAUR26–SAUR28 cause variations of thermo‐responsive rosette architecture via affecting mRNA abundance and protein activity, and expression variations in SAUR26–SAUR28 likely play a large role in conferring growth variations (Wang et al ., 2019).…”

The SAUR41 subfamily of cell expansion-promoting genes modulates abscisic acid sensitivity and root touch response: a possible connection to ion homeostasis regulation

“…8,9 Briefly, a variety of functional studies in Arabidopsis (Arabidopsis thaliana) SAUR genes have reported the following findings: SAUR10 is expressed in the stems and inflorescence branches to control shoot architecture; SAUR16/50 are light responsive in order to modulate cotyledon opening during de-etiolation; SAUR19s regulate hypocotyl growth in response to auxin and brassinosteroid (BR) signals; SAUR26/27/28 have extensive natural genetic polymorphisms that are associated with the thermo-responsiveness of the plant architecture; SAUR36 is involved in the promotion of leaf senescence; SAUR62/75 are required for pollen tube growth; and SAUR76/77/78 may affect ethylene receptor signaling during seedling growth. [8][9][10] The SAUR41 subfamily of Arabidopsis SAURs consists of four members, including SAUR41 (At1g16510), SAUR40 (At1g79130), SAUR71 (At1g56150), and SAUR72 (At3g12830). We have reported that artificial expression of SAUR41 by promoters of auxin transporter genes and root meristem patterning genes differentially modulate root cell expansion and root development.…”