SNAC3 Transcription Factor Enhances Arsenic Stress Tolerance and Grain Yield in Rice (Oryza sativa L.) through Regulating Physio-Biochemical Mechanisms, Stress-Responsive Genes, and Cryptochrome 1b

Abstract

Arsenic (As) is one of the toxic heavy metal pollutants found in the environment. An excess of As poses serious threats to plants and diminishes their growth and productivity. NAC transcription factors revealed a pivotal role in enhancing crops tolerance to different environmental stresses. The present study investigated, for the first time, the functional role of SNAC3 in boosting As stress tolerance and grain productivity in rice (Oryza sativa L.). Two SNAC3-overexpressing (SNAC3-OX) and two SNAC3-RNAi transgenic lines were created and validated. The wild-type and transgenic rice plants were exposed to different As stress levels (0, 25, and 50 µM). The results revealed that SNAC3 overexpression significantly improved rice tolerance to As stress and boosted grain yield traits. Under both levels of As stress (25 and 50 µM), SNAC3-OX rice lines exhibited significantly lower levels of oxidative stress biomarkers and OsCRY1b (cryptochrome 1b) expression, but they revealed increased levels of gas exchange characters, chlorophyll, osmolytes (soluble sugars, proteins, proline, phenols, and flavonoids), antioxidant enzymes (SOD, CAT, APX, and POD), and stress-tolerant genes expression (OsSOD-Cu/Zn, OsCATA, OsCATB, OsAPX2, OsLEA3, OsDREB2B, OsDREB2A, OsSNAC2, and OsSNAC1) in comparison to wild-type plants. By contrast, SNAC3 suppression (RNAi) reduced grain yield components and reversed the aforementioned measured physio-biochemical and molecular traits. Taken together, this study is the first to demonstrate that SNAC3 plays a vital role in boosting As stress resistance and grain productivity in rice through modulating antioxidants, photosynthesis, osmolyte accumulation, and stress-related genes expression, and may be a useful candidate for further genetic enhancement of stress resistance in many crops.

From genes to ecosystems: Decoding plant tolerance mechanisms to arsenic stress

“…Similarly, the OsPRX38 auxin-catabolism-related gene, part of the class III peroxidases multigene family of plant-specific peroxidase, enhances As tolerance by activating stress-related mechanisms such as SOD (superoxide dismutase), PRX (peroxidase), GST (glutathione- s -transferase) activity promoting higher lignification in root cells, acting as a barrier to prevent the entry of As during As perception [ 77 ]. It has been reported that SNAC3 overexpression plays a pivotal role in boosting As stress tolerance and grain productivity in O. sativa by antioxidant enzymes, photosynthesis, and osmolyte accumulation [ 78 ].…”

Association between Reactive Oxygen Species, Transcription Factors, and Candidate Genes in Drought-Resistant Sorghum

“…The overexpression of this gene significantly improved drought and salt tolerance in rice, with a 22–34% increase in yield compared to wild-type rice [ 106 ]. Similarly, the overexpression of the SNAC2 gene increased drought resistance in rice yields compared to wild-type rice yields [ 107 , 108 ]. Tran et al, cloned three Arabidopsis NAC family genes, ANAC019 , ANAC055 , and ANAC072 , and they discovered that the overexpression of these genes dramatically increased drought tolerance compared to the wild type, with ANAC072 being engaged in the ABA signaling system [ 109 ].…”

Transcriptional Control of Seed Life: New Insights into the Role of the NAC Family

“…Data from ABA content, SNAC3 expression, and response in mutants suggest that SNAC3 may function mainly in an ABA-independent manner [96], in contrast to some previously reported NAC genes. Finally, last year, two SNAC3-OX lines and two SNAC3-RNAi lines were created and subjected to arsenic stress treatments [201]. Interestingly, SNAC3 overexpression significantly intensified rice tolerance to arsenic stress and boosted grain yield, while the expression elimination generated a contrary response in both parameters.…”

“…Interestingly, SNAC3 overexpression significantly intensified rice tolerance to arsenic stress and boosted grain yield, while the expression elimination generated a contrary response in both parameters. For further clarification, SNAC3 overexpression induced the enzymatic antioxidant levels of transgenic rice lines which in turn scavenge ROS, causing decreased oxidative stress and enhanced arsenic stress tolerance [201].…”