Enrichment of Intrinsically Disordered Residues in Ohnologs Facilitate Abiotic Stress Resilience in Brassica Rapa

Abstract

Background: Arabidopsis thaliana and Brassica rapa shared a common evolutionary clade but Brassica species experienced an extra whole genome triplication (WGT) event compared with the model plant A. thaliana. This extra round of WGT confers B. rapa more abiotic stress resistant. The study aims to unravel how the consequences of whole genome duplication steer the variation in stress adaptation competency between the two species.Result: Comparing the duplication status between abiotic stress resistant (ASR) genes in the two species, significant increase in the number of paralogs in ASR genes of B. rapa than A. thaliana was found. Investigation on the proteomic features suggests that the ohnologs pairs in both species are more enriched with intrinsically disordered residues (IDRs) than other duplicated pairs but IDRs only in B. rapa have showed a significant positive correlation with functional divergence between the duplicated pairs. The functional divergence helps to mediate more stress adaptation functions in the ohnologs of B. rapa than that of A. thaliana. Moreover, domain ontology analysis has revealed that the new domains with stress functions are significantly more enriched in the ohnologs of B. rapa. Interestingly, majority of these stress tolerant domains are found to be present in the intrinsically disordered regions of the proteins. Statistical analysis along with these observations make it reasonable to speculate that IDRs expedite stress adaption potentiality in B. rapa by enriching more stress related functions and accommodating stress specific domains in ohnologs of this plant species.Conclusion: With the occurrence of WGT in the Brassica species the stress resilience features of B. rapa as compared to A. thaliana is less studied. This study unveils the role of intrinsically disordered residues (IDRs) of ohnologs in optimizing more stress resilience in B. rapa than A. thaliana. Thus, it will open new avenues in understanding the mechanism of succeeding stress adaptation potentiality in B. rapa over evolutionary time.