Abstract
Soil salinity is being perceived as a major threat to agriculture. Plant breeders and molecular biologist are putting their best efforts to raise salt-tolerant crops. The discovery of the Saltol QTL, a major QTL localized on chromosome I, responsible for salt tolerance at seedling stage in rice has given new hopes for raising salinity tolerant rice genotypes. In the present study, we have functionally characterized a Saltol QTL localized cytoskeletal protein, intermediate filament like protein (OsIFL), of rice. Studies related to intermediate filaments are emerging in plants, especially with respect to their involvement in abiotic stress response. Our investigations clearly establish that the heterologous expression of OsIFL in three diverse organisms (bacteria, yeast and tobacco) provides survival advantage towards diverse abiotic stresses. Screening of rice cDNA library revealed OsIFL to be strongly interacting with metallothionein protein. Bimolecular fluorescence complementation assay further confirmed this interaction to be occurring inside the nucleus. Overexpression of OsIFL in transgenic tobacco plants conferred salinity stress tolerance by maintaining favourable K+/Na+ ratio and thus showed protection from salinity stress induced ion toxicity. This study provides the first evidence for the involvement of a cytoskeletal protein in salinity stress tolerance in diverse organisms.
Highlights
Abiotic stresses pose a major threat to agriculture worldwide
We focused our study on chromosome 1 localized OsIFL (LOC_Os01g18840), since it is residing within Saltol QTL of rice
We studied transcript abundance of four key stress marker genes, viz. glutathione S-transferase (GST), early-responsive to dehydration stress (ERD10), metallothionein (MT) and late embryogenesis abundant protein (LEA), in the wild type and transgenic tobacco plants by qRT-PCR
Summary
Abiotic stresses pose a major threat to agriculture worldwide. At the same time, it is known that these stresses affect the yield, which mostly depends on the genetic makeup of the crops[1,2,3]. As an effort to survive under these unfavourable conditions, plants reprogram various molecular, biochemical and physiological pathways within their cells Thorough understanding of these adaptive responses in plants, especially employing the contrasting genotypes and using the tools of functional genomics is must to achieve the target of raising salinity stress tolerant crop plants. Of rice has been used as a salt sensitive check in our studies These efforts have resulted in mining of a few novel genes, some of which have been validated for their roles in stress tolerance by using functional genomics tools[16,17,18]. As salinity tolerance is a quantitative trait, understanding the physiological mechanisms of salt responses in plants, their biochemical basis and inheritance is a daunting, but an essential task, to be achieved for developing salt tolerant high yielding rice genotypes. The objectives of the current study were to (1) isolate the full length gene encoding OsIFL, from O. sativa cv IR64 (2) test, whether the overexpression of OsIFL improves salinity tolerance in model systems such as bacteria, yeast and tobacco, (3) find out the interacting partners of OsIFL protein and (4) comment on possible mechanism responsible for OsIFL-mediated stress response
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