RNAi-directed downregulation of betaine aldehyde dehydrogenase 1 (OsBADH1) results in decreased stress tolerance and increased oxidative markers without affecting glycine betaine biosynthesis in rice (Oryza sativa)

Abstract

As an important osmoprotectant, glycine betaine (GB) plays an essential role in resistance to abiotic stress in a variety of organisms, including rice (Oryza sativa L.). However, GB content is too low to be detectable in rice, although rice genome possesses several orthologs coding for betaine aldehyde dehydrogenase (BADH) involved in plant GB biosynthesis. Rice BADH1 (OsBADH1) has been shown to be targeted to peroxisome and its overexpression resulted in increased GB biosynthesis and tolerance to abiotic stress. In this study, we demonstrated a pivotal role of OsBADH1 in stress tolerance without altering GB biosynthesis capacity, using the RNA interference (RNAi) technique. OsBADH1 was ubiquitously expressed in different organs, including roots, stems, leaves and flowers. Transgenic rice lines downregulating OsBADH1 exhibited remarkably reduced tolerance to NaCl, drought and cold stresses. The decrease of stress tolerance occurring in the OsBADH1-RNAi repression lines was associated with an elevated level of malondialdehyde content and hydrogen peroxidation. No GB accumulation was detected in transgene-positive and transgene-negative lines derived from heterozygous transgenic T0 plants. Moreover, transgenic OsBADH1-RNAi repression lines showed significantly reduced seed set and yield. In conclusion, the downregulation of OsBADH1, even though not causing any change of GB content, was accounted for the reduction of ability to dehydrogenate the accumulating metabolism-derived aldehydes and subsequently resulted in decreased stress tolerance and crop productivity. These results suggest that OsBADH1 possesses an enzyme activity to catalyze other aldehydes in addition to betaine aldehyde (the precursor of GB) and thus alleviate their toxic effects under abiotic stresses.

Proteomic analysis of soybean root including hypocotyl during recovery from drought stress

“…Yang et al [56] reported that overexpressing aldehyde dehydrogenase gene confers drought and salt tolerance in tobacco. Consistent with this finding, overexpressing aldehyde dehydrogenase 7 improved the drought tolerance in Arabidopsis [43], and increased aldehyde dehydrogenase activity is linked with improved stress tolerance in rice [57]. The results of the present study are in agreement with these previous reports, suggesting that aldehyde dehydrogenase has an essential role in drought stress tolerance and recovery in soybean.…”

Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics

“…BADH converts betaine aldehyde to glycine betaine, which mediates osmotic homeostasis, and has positive effects on plant adaptation to drought stress [164]. RNAi-directed downregulation of OsBADH1 resulted in a decrease of stress tolerance and an increase of oxidative stress [165], implying its important role in plant drought tolerance.…”

Leaf proteome analysis provides insights into the molecular mechanisms of bentazon detoxification in rice

“…The up-regulation of catalase isozyme B (U301, D0D9C4) by bentazon is beneficial in protecting cells from the toxic effects of hydrogen peroxide; catalase is a typical antioxidant and is strongly up-regulated by other stresses [32]. ALDH (aldehyde dehydrogenase) (U285, Q9FRX7) and STR (strictosidine synthase) (U904, Q75LL5) are also biomarkers of biotic stress [33][34][35]. ALDH induction has been observed in a variety of plant species exposed to heat, dehydration, salinity, oxidants, ultraviolet radiation, pesticides, or metals [36].…”