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Abstract

The plant V-type H+-ATPase (V-ATPase) does not only serve basic housekeeping functions but is also involved in stress-induced NaCl sequestration during salinity stress. To address the question whether the same isoforms conferring housekeeping functions are equally involved in the response to high salinity, we have isolated cDNA clones for subunits A and c, as representing the peripheral V1 complex and the membrane-integral V0 complex, respectively, from the halotolerant sugar beet (Beta vulgaris L., diploid variety). RNA blot analysis with gene-specific probes revealed a coordinate expression of the cloned subunit A and c isoforms during plant development and in response to high salinity. Also, in rapidly dividing suspension-cultured cells with 10-fold increased transcript amounts as compared to young leaf tissue, the ratio of transcripts for both genes was similar to the ratio found for transcripts in leaves of different age. We have then isolated partial genomic clones (BVA/70 for Beta V-ATPase 70 kDa subunit; BVA/16-1 for Beta V-ATPase 16 kDa subunit), including the promoter regions. Transcription start mapping revealed long 5'-UTR leader sequences (230 and 172 bases, respectively) for both genes. Both promoters contain putative G-box motifs in similar distance to the TATA boxes. For a quantitative comparison of relative promoter strength, the BVA/70 and BVA/16-1 promoters linked to the luciferase reporter gene (LUC) were delivered to sugar beet suspension-cultured cells by particle bombardment. The BVA/16-1 promoter showed a 1.7-fold higher activity as compared with the BVA/70 promoter. Salt treatment induced an increase of BVA/70 (+70%) and BVA/16-1 (+57%) promoter activities, concomitant with increased transcript amounts. The following sequences have been deposited at the EMBL database X98767: Beta vulgaris V-ATPase subunit A, cDNA clone; X98851, B. vulgaris V-ATPase subunit c isoform 1, cDNA clone; Y11038, B. vulgaris V-ATPase subunit A, partial genomic clone; Y11037, B. vulgaris V-ATPase subunit c isoform 1, partial genomic clone.

Wheat V-H+-ATPase Subunit Genes Significantly Affect Salt Tolerance in Arabidopsis thaliana

“…Salt-stressed and salt-adapted tobacco suspended cell culture also showed an increased level of A subunit mRNA [8]. In Beta vulgaris L. and its suspended cell culture, NaCl stimulated coordinated changes of A and c subunits [9]–[10]. In S. salsa (L.) Pall, salt stress increased the transcription and translation of B and c subunits [11].…”

Overexpression of ThVHAc1 and its potential upstream regulator, ThWRKY7, improved plant tolerance of Cadmium stress

“…However, when the leaves fully expanded, only the c subunit was induced in reaction to salt 66 . Sugar beet VHA-A and VHA-c were coordinately expressed during plant development and are induced in response to high salinity 67 . The subunit E was also induced after treatment with salt for 3 d in mature common ice plant leaves, but it was not induced in juvenile leaves under the same conditions 68 .…”

A single cytosine deletion in theOsPLS1gene encoding vacuolar-type H+-ATPase subunit A1 leads to premature leaf senescence and seed dormancy in rice

“…Antisense-mediated inhibition of VHA-A2 gene expression was reported to retard seed formation in tomato ( Amemiya et al , 2006 ). In sugar beet, VHA-A gene expression declines in aging leaves ( Lehr et al , 1999 ). In Arabidopsis , deficiency in VHA-A leads to complete male and partial female gametophytic lethality ( Dettmer et al , 2005 ).…”