IC4R  Rice Literature Database

A two-staged model of Na+ exclusion in rice explained by 3D modeling of HKT transporters and alternative splicing.

The HKT family of Na(+) and Na(+)/K(+) transporters is implicated in plant salinity tolerance. Amongst these transporters, the cereal erm' data-tid='9021' href='#term-9021'>HKT1;4 and HKT1;5 are responsible for Na(+) exclusion from photosynthetic tissues, a key mechanism for plant salinity tolerance. It has been suggested that Na(+) is retrieved from the xylem transpiration stream either in the root or the leaf sheath, protecting the leaf blades from excessive Na(+) accumulation. However, direct evidence for this scenario is scarce. Comparative modeling and evaluation of rice (Oryza sativa) HKT-transporters based on the recent crystal struc='term' data-tid='9023' href='#term-9023'>ture of the bacterial TrkH K(+) transporter allowed to reconcil='term' data-tid='9025' href='#term-9025'>e transcriptomic and physiological data. For OsHKT1;5, both transcript abundance and protein structural features within th='term' data-tid='9027' href='#term-9027'>e selectivity filter could control shoot Na(+) accumulation in a range of rice varieties. For OsHKT1;4, alternative splicing of transcript and the anatomical complexity of the sheath needed to be taken into account. Thus, Na(+) accumulation in a specific leaf blade seems to be regulated by abundance of a correctly spliced OsHKT1;4 transcript in a corresponding sheath. Overall, allelic variation of leaf blade Na(+) accumulation can be explained by a complex interplay of gene transcription, alternative splicing and protein structure.