Cloning of an H+-PPase gene from Thellungiella halophila and its heterologous expression to improve tobacco salt tolerance

Abstract

An H 1 -pyrophosphatase (PPase) gene named TsVP involved in basic biochemical and physiological mechanisms was cloned from Thellungiella halophila. The deduced translation product has similar characteristics to H 1 -PPases from other species, such as Arabidopsis and rice, in terms of bioinformation. The heterologous expression of TsVP in the yeast mutant ena1 suppressed Na 1 hypersensitivity and demonstrated the function of TsVP as an H 1 -PPase. Transgenic tobacco overexpressing TsVP had 60% greater dry weight than wild-type tobacco at 300 mM NaCl and higher viability of mesophyll protoplasts under salt shock stress conditions. TsVP and AVP1, another H 1 -PPase from Arabidopsis, were heterologously expressed separately in both the yeast mutant ena1 and tobacco. The salt tolerance of TsVP or AVP1 yeast transformants and transgenic tobacco were improved to almost the same level. The TsVP transgenic tobacco lines TL3 and TL5 with the highest H 1 -PPase hydrolytic activity were studied further. These transgenic tobacco plants accumulated 25% more solutes than wild-type plants without NaCl stress and 20-32% more Na 1 under salt stress conditions. Although transgenic tobacco lines TL3 and TL5 accumulated more Na 1 in leaf tissues, the malondialdehyde content and cell membrane damage were less than those of the wild type under salt stress conditions. Presumably, compartmentalization of Na 1 in vacuoles reduces its toxic effects on plant cells. This result supports the hypothesis that overexpression of H 1 -PPase causes the accumulation of Na 1 in vacuoles instead of in the cytoplasm and avoids the toxicity of excessive Na 1 in plant cells.

Overexpression of Thellungiella halophila H+-PPase (TsVP) in cotton enhances drought stress resistance of plants

“…This may be due to the diVerence between TsVP and AVP1 or diVerent kinds of transgenic plants. Gao et al (2006) reported that the expression patterns in non-transgenic plants were diVerent between TsVP and AVP1 under salt stress. The expression of TsVP was salt induced while AVP1 was constitutively expressed, which may imply something except diVerent promoters (we have done some work, unpublished).…”

“…AY436553) from Thellungiella halophila (Gao et al 2006) into two cotton cultivars (Lumianyan19 and Lumianyan 21) via Agrobacterium-mediated transformation, and the transgenic cotton plants from Lumianyan19 were proved to exhibit improved salt tolerance (Lv et al 2008). Here, performance of the transgenic cotton under drought stress at three developmental stages (seedling, squaring and Xowering stages) was investigated using four transgenic lines from the two cotton genotypes.…”

Genome Structures and Transcriptomes Signify Niche Adaptation for the Multiple-Ion-Tolerant Extremophyte Schrenkiella parvula

“…Many studies have associated high AVP1 and SALT OVERLY SENSITIVE1 (SOS1) expression levels with increased salt tolerance (Park et al, 2005;Gao et al, 2006;Oh et al, 2009). AVP1 exist as two copies in S. parvula, with their combined expression higher than AtAVP1 (Table II).…”

Life at the extreme: lessons from the genome

“…Genomic regions containing homologs of NHX8 , encoding a plasma membrane Li + transporter [42], and AVP1 , encoding a vacuolar proton transporter [79], were compared between T. parvula (Tp) and Arabidopsis thaliana (At). Shown are five colinear genes adjacent to NHX8 and AVP1 in the two species.…”