Enhanced Accumulation of BiP in Transgenic Plants Confers Tolerance to Water Stress

Abstract

The binding protein (BiP) is an important component of endoplasmic reticulum stress response of cells. Despite extensive studies in cultured cells, a protective function of BiP against stress has not yet been demonstrated in whole multicellular organisms. Here, we have obtained transgenic tobacco (Nicotiana tabacum L. cv Havana) plants constitutively expressing elevated levels of BiP or its antisense cDNA to analyze the protective role of this endoplasmic reticulum lumenal stress protein at the whole plant level. Elevated levels of BiP in transgenic sense lines conferred tolerance to the glycosylation inhibitor tunicamycin during germination and tolerance to water deficit during plant growth. Under progressive drought, the leaf BiP levels correlated with the maintenance of the shoot turgidity and water content. The protective effect of BiP overexpression against water stress was disrupted by expression of an antisense BiP cDNA construct. Although overexpression of BiP prevented cellular dehydration, the stomatal conductance and transpiration rate in droughted sense leaves were higher than in control and antisense leaves. The rate of photosynthesis under water deficit might have caused a degree of greater osmotic adjustment in sense leaves because it remained unaffected during water deprivation, which was in marked contrast with the severe drought-induced decrease in the CO 2 assimilation in control and antisense leaves. In antisense plants, the water stress stimulation of the antioxidative defenses was higher than in control plants, whereas in droughted sense leaves an induction of superoxide dismutase activity was not observed. These results suggest that overexpression of BiP in plants may prevent endogenous oxidative stress.

Changes in the root proteome of Triticosecale grains germinating under osmotic stress

“…Small HSPs interact with HSP100/HSP70 and participate in the protection of other proteins (Sarkar et al 2009). A high tolerance to osmotic stress of plants has been correlated with a production of large amounts of HSPs (Alvim et al 2001;Mohammadi et al 2012a). The small HSP identified in the roots of triticale probably prevents unfolding of other proteins and facilitates plant defense against stress.…”

Genetic approaches towards overcoming water deficit in plants - special emphasis on LEAs

“…Histone H1-S antisense transgenic plants showed remarkable differences in leaf anatomy and physiological activities (Scippa et al, 2004). The expression of other proteins involved in stress response such as molecular chaperones (Alvim et al, 2001); NAD + dependent glyceraldehyde-3-phosphate dehydrogenase (Jeong et al, 2000) have also conferred tolerance against water stress.…”

The STT3a Subunit Isoform of the Arabidopsis Oligosaccharyltransferase Controls Adaptive Responses to Salt/Osmotic Stress

“…It remains to be determined if regulating the consequences of UPR signaling can modulate adaptation. However, water stress tolerance of BiP-overexpressing tobacco plants suggests that this is plausible (Alvim et al, 2001). Dissection of the networking UPR (Koizumi et al, 2001), SOS, and mitogen-activated protein kinase pathways (Mizoguchi et al, 2000) under salt/osmotic stress will provide further insights regarding integrated plant mechanisms that can lead to tolerance.…”