Novel role for a serine/arginine-rich splicing factor, AdRSZ21 in plant defense and HR-like cell death
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A splicing factor gene belonging to the serine/arginine (SR)-rich protein family was cloned from Arachis diogoi, a wild relative of peanut in a study on differential gene expression and was designated as AdRSZ21. AdRSZ21 exhibits a RNA recognition motif (RRM), a CCHC type zinc finger domain (Zinc Knuckle, ZnK) and a C-terminal RS domain that is rich in arginine and serine. Multiple sequence alignment of AdRSZ21 with putative orthologs from diverse taxa including lower plants and monocots showed that the RRM and ZnK domains are evolutionarily conserved. Phylogenetic studies revealed that AdRSZ21 belongs to the RSZ subfamily and is closely related to the Arabidopsis ortholog AtRSZ22. Transient constitutive and conditional heterologous expression of AdRSZ21 resulted in HR-like cell death in tobacco leaves. The presence of a functional RRM domain, but not ZnK domain was essential for AdRSZ21 induced HR-like cell death phenotype. On the other hand, expression of AdRSZ21 with mutated ZnK domain lead to accelerated cell death. The cell death induced by AdRSZ21 was found to be associated with specific upregulation of patatin-like protein gene and other defense related gene transcripts suggesting a role for AdRSZ21 in plant defense and HR-like cell death.
KeywordsSerine/arginine-rich protein Alternative splicing Arachis diogoi Programmed cell death Patatin-like protein Ribosomal protein Phaeoisariopsis personata
The work was supported by a grant (BT/PR6853/PBD/16/627/2005) from the Department of Biotechnology, Government of India. Arachis wild germplasm used in this study has been kindly provided by ICRISAT, Patancheru, India. The authors thank Prof. Nam-Hai Chua, Rockefeller University, New York, USA for pER8 vector. The authors would like to thank Dr. K. Uma Mahendra Kumar, IGCAR, Kalpakkam for helping with the analysis of IDRs. The authors also acknowledge the research facilities supported by DST-FIST, UGC-CAS etc. to the Department of Plant Sciences, University of Hyderabad. KRRK was supported by Dr. D.S.Kothari Postdoctoral Fellowship from University Grants Commission (UGC), Government of India.
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