Comprehensive Mechanism of Gene Silencing and Its Role in Plant Growth and Development

Abstract

Gene silencing is a negative feedback mechanism that regulates gene expression to define cell fate and also regulates metabolism and gene expression throughout the life of an organism. In plants, gene silencing occurs via transcriptional gene silencing (TGS) and post-transcriptional gene silencing (PTGS). TGS obscures transcription via the methylation of 5′ untranslated region (5′UTR), whereas PTGS causes the methylation of a coding region to result in transcript degradation. In this review, we summarized the history and molecular mechanisms of gene silencing and underlined its specific role in plant growth and crop production.

Heat Stress-Mediated Constraints in Maize (Zea mays) Production: Challenges and Solutions

“…Recently, several gene families have been identified and subsequently characterized in maize involved in heat stress response, such as heat shock protein-70 and heat shock factor ( Casaretto et al, 2016 ; Jagtap et al, 2020 ; Jiang et al, 2021 ). Additionally, transcriptomic profiling of maize seedlings exposed to heat stress showed several differentially expressed genes employed in developing improved heat-tolerant maize varieties using robust genome editing techniques, such as RNAi and CRISPR/Cas9 ( El-Sappah et al, 2021 ; Razzaq et al, 2021 ; Singh et al, 2021 ). Integration of robust genetic engineering techniques has accelerated conventional breeding of maize by reducing the time of variety development with the application of genetic markers in the early detection of desired traits in F1 ( Ahmar et al, 2020 ).…”

Using field evaluation and systematic iteration to rationalize the accumulation of omega‐3 long‐chain polyunsaturated fatty acids in transgenic Camelina sativa

“…Firstly, in the case of DHA2015.2 (the simplest iteration) resulted in the unexpected accumulation of C18 Δ6‐desaturated fatty acids such as GLA and SDA and an absence of EPA and DHA (Figure 3; Figure S1; see also Figure S4 for side‐by‐side comparison of the different iterations). However, we believe that this phenomenon is an event‐specific example of transgene‐silencing (reviewed by El‐Sappah et al., 2021 and citations therein), most likely because of the (random) site of insertion of the T‐DNA in the host genome, as opposed to the replacement of the Piw3 ω3‐desaturase with the Hpw3 activity. Evidence for this specific fatty acid profile being as a consequence of post‐transcriptional gene silencing (PTGS) is given further weight by comparison of the field data for T4 and from the T3 GH‐grown seeds with the initial T2 seeds (Figure S6), in which the latter clearly shows high levels of EPA + DHA.…”

Development of a High Oleic Cardoon Cell Culture Platform by SAD Overexpression and RNAi-Mediated FAD2.2 Silencing

“…The obtained transformed calli populations, CcSAD overexpressing, and CcFAD2.2 knocked out lines, based on their respective transgene transcript abundance, showed various degrees of expression compared with WT and empty vector controls (Figures 4A,B). Since the constitutive introduction of foreign DNA may cause silencing side effects due to excessive transcription of the engineered gene (Gazzani et al, 2004), and effective silencing is not strictly linked to the lowest transcript levels (El-Sappah et al, 2021), the selection of the most efficient independent transformants was made based on fatty acid content. In both gene manipulation strategies, a modification of the fatty acids flux in favor of oleic acid production was positively reached, and this was more evident for FAD silenced lines (Supplementary Figures 3A,B).…”