Genome-wide in silico characterization and stress induced expression analysis of BcL-2 associated athanogene (BAG) family in Musa spp.

Programmed cell death (PCD) is a genetically controlled process for the selective removal of damaged cells. Though understanding about plant PCD has improved over years, the mechanisms are yet to be fully deciphered. Among the several molecular players of PCD in plants, B cell lymphoma 2 (Bcl-2)-associated athanogene (BAG) family of co-chaperones are evolutionary conserved and regulate cell death, growth and development. In this study, we performed a genome-wide in silico analysis of the MusaBAG gene family in a globally important fruit crop banana. Thirteen MusaBAG genes were identified, out of which MusaBAG1, 7 and 8 genes were found to have multiple copies. MusaBAG genes were distributed on seven out of 11 chromosomes in banana. Except for one paralog of MusaBAG8 all the other 12 proteins have characteristic BAG domain. MusaBAG1, 2 and 4 have an additional ubiquitin-like domain whereas MusaBAG5-8 have a calmodulin binding motif. Most of the MusaBAG proteins were predicted to be localized in the nucleus and mitochondria or chloroplast. The in silico cis-regulatory element analysis suggested regulation associated with photoperiodic control, abiotic and biotic stress. The phylogenetic analysis revealed 2 major clusters. Digital gene expression analysis and quantitative real-time RT-PCR depicted the differential expression pattern of MusaBAG genes under abiotic and biotic stress conditions. Further studies are warranted to uncover the role of each of these proteins in growth, PCD and stress responses so as to explore them as candidate genes for engineering transgenic banana plants with improved agronomic traits.

Coordinated Epigenetic Regulation in Plants: A Potent Managerial Tool to Conquer Biotic Stress

Plants have evolved variable phenotypic plasticity to counteract different pathogens and pests during immobile life. Microbial infection invokes multiple layers of host immune responses, and plant gene expression is swiftly and precisely reprogramed at both the transcriptional level and post-transcriptional level. Recently, the importance of epigenetic regulation in response to biotic stresses has been recognized. Changes in DNA methylation, histone modification, and chromatin structures have been observed after microbial infection. In addition, epigenetic modifications may be preserved as transgenerational memories to allow the progeny to better adapt to similar environments. Epigenetic regulation involves various regulatory components, including non-coding small RNAs, DNA methylation, histone modification, and chromatin remodelers. The crosstalk between these components allows precise fine-tuning of gene expression, giving plants the capability to fight infections and tolerant drastic environmental changes in nature. Fully unraveling epigenetic regulatory mechanisms could aid in the development of more efficient and eco-friendly strategies for crop protection in agricultural systems. In this review, we discuss the recent advances on the roles of epigenetic regulation in plant biotic stress responses.

AtERF60 negatively regulates ABR1 to modulate salt, drought, and basal resistance in Arabidopsis

ABSCISIC ACID REPRESSOR-1 (ABR1), an APETALA2 (AP2) domain containing transcription factor (TF) contribute important function against variety of external cues. Here, we report an AP2/ERF TF, AtERF60 that serves as an important regulator of ABR1 gene. AtERF60 is induced in response to drought, salt, abscisic acid (ABA), salicylic acid (SA), and bacterial pathogen PstDC3000 infection. AtERF60 interacts with DEHYDRATION RESPONSE ELEMENTS (DRE1/2) and GCC box indicating its ability to regulate multiple responses. Overexpression of AtERF60 results in the drought and salt stress tolerant phenotype in both seedling and mature Arabidopsis plants in comparison with the wild type (WT-Col). However, mutation in AtERF60 showed hyperactive response against drought and salt stress in comparison with its overexpression and WT. Microarray and qRT-PCR analysis of overexpression and mutant lines indicated that AtERF60 regulates both abiotic and biotic stress inducible genes. One of the differentially expressing transcripts was ABR1 and we found that AtERF60 interacts with the DRE cis-elements present in the ABR1 promoter. The mutation in AtERF60 showed ABA hypersensitive response, increased ABA content, and reduced susceptibility to PstDC3000. Altogether, we conclude that AtERF60 represses ABR1 transcript by binding with the DRE cis-elements and modulates both abiotic and biotic stress responses in Arabidopsis.