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FRIDAY′S NEWSLETTER 15-01-2021
15/01/2021 WORLD NEWS 21
 
 
No 1

Expert Proposes Techniques to Address Regulatory Concerns in Gene Editing

ISAAA News - January 13, 2021
 
Martin Lema, Adjunct Professor at the National University of Quilmes, released an article containing a detailed review of evidence on off-target effects and unintended DNA insertions in gene editing. The document, published in the Journal of Regulatory Science, is a useful resource in proposing concrete regulatory criteria to address the issues.
According to Lema, there is an increasing number of regulatory systems worldwide that consider applications for the authorization of activities involving the use of gene editing for agri-food use. Several countries have progressed in creating regulatory criteria and collecting practical experiences in the field, but there is still a general need for regulatory cooperation on capacity building and forming with harmonized criteria. Thus, the article included a simplified introduction of genome editing from a regulatory perspective.
A pragmatic and proportionate approach for addressing off-target effects and unintended DNA insertions was proposed. If the proposed techniques would be adopted, it is expected that there will be a harmonized approach that could also help developers enhance the safety of their experimental design and protocols, which can lead to cheaper costs and lesser complications in the regulatory assessment.
Download the article from the Journal of Regulatory Science.
 
  
 
 
 
No 2

Chinese Scientists Discover Rice Gene for Adaptation to Low Soil Nitrogen

Scientists from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences (CAS) have found a gene that plays an important role in helping rice adapt to low soil nitrogen. Nitrogen fertilizer has an indispensable role in increasing crop yields, but on the other hand, it creates a severe threat to ecosystems. For this reason, breeding new crop varieties with high nitrogen use efficiency (NUE) is a high priority for both agricultural production and environmental protection.
Using a diversified rice population from different regions, the scientists carefully evaluated how various agronomic traits responded to nitrogen in fields with different nitrogen supply conditions. They further performed a genome-wide association study (GWAS), with one very significant GWAS signal identified. The detailed mechanisms of how OsTCP19 works in regulating rice tillering were also characterized.
The researchers found that OsTCP19-H, the high NUE allele, was highly preserved in rice types grown in nitrogen-poor regions, but has been lost in rice types grown in nitrogen-rich regions. They also found that OsTCP19-H is also highly prevalent in wild rice which was grown in natural soil without artificial fertilizer input, and concludes that OsTCP19-H introgression into modern cultivars can improve nitrogen use efficiency 20-30% under conditions of decreased nitrogen supply.
For more details, read the article on the Chinese Academy of Sciences website.
 
 
 
Science news
 

Transgenic chickpea (Cicer arietinum L.) harbouring AtDREB1a are physiologically better adapted to water deficit

BMC Plant Biology volume 21, Article number: 39 (2021)

Background

Chickpea (Cicer arietinum L.) is the second most widely grown pulse and drought (limiting water) is one of the major constraints leading to about 40–50% yield losses annually. Dehydration responsive element binding proteins (DREBs) are important plant transcription factors that regulate the expression of many stress-inducible genes and play a critical role in improving the abiotic stress tolerance. Transgenic chickpea lines harbouring transcription factor, Dehydration Responsive Element-Binding protein 1A from Arabidopsis thaliana (AtDREB1a gene) driven by stress inducible promoter rd29a were developed, with the intent of enhancing drought tolerance in chickpea. Performance of the progenies of one transgenic event and control were assessed based on key physiological traits imparting drought tolerance such as plant water relation characteristics, chlorophyll retention, photosynthesis, membrane stability and water use efficiency under water stressed conditions.

Results

Four transgenic chickpea lines harbouring stress inducible AtDREB1a were generated with transformation efficiency of 0.1%. The integration, transmission and regulated expression were confirmed by Polymerase Chain Reaction (PCR), Southern Blot hybridization and Reverse Transcriptase polymerase chain reaction (RT-PCR), respectively. Transgenic chickpea lines exhibited higher relative water content, longer chlorophyll retention capacity and higher osmotic adjustment under severe drought stress (stress level 4), as compared to control. The enhanced drought tolerance in transgenic chickpea lines were also manifested by undeterred photosynthesis involving enhanced quantum yield of PSII, electron transport rate at saturated irradiance levels and maintaining higher relative water content in leaves under relatively severe soil water deficit. Further, lower values of carbon isotope discrimination in some transgenic chickpea lines indicated higher water use efficiency. Transgenic chickpea lines exhibiting better OA resulted in higher seed yield, with progressive increase in water stress, as compared to control.

Conclusions

Based on precise phenotyping, involving non-invasive chlorophyll fluorescence imaging, carbon isotope discrimination, osmotic adjustment, higher chlorophyll retention and membrane stability index, it can be concluded that AtDREB1a transgenic chickpea lines were better adapted to water deficit by modifying important physiological traits. The selected transgenic chickpea event would be a valuable resource that can be used in pre-breeding or directly in varietal development programs for enhanced drought tolerance under parched conditions.
 
 
 figure1 
Figure 1:
Molecular analysis of transgenic chickpea lines a: PCR analyses of four transgenic chickpea events (T0); b: PCR analyses of transgenic chickpea progenies (T1) derived from E5c: PCR analyses of transgenic chickpea progenies (T1) derived from E17d: PCR analyses of transgenic chickpea progenies (T1) derived from E19e: PCR analyses of transgenic chickpea progenies (T1) derived from E22; [L1–100 bp DNA ladder and L2–1 kb DNA ladder]; f: Southern blot analysis (L: DIG-labelled DNA ladder; I-IV: Four independent transgenic chickpea lines E5, E17, E19 and E22 (T1 stage); N: Non-transformed chickpea (DCP 92–3); P: Positive control (Binary plasmid). g: RT-PCR analysis (L1: 1Kb plus DNA ladder; P: Positive control; N: Negative control; I-IV: Transgenic chickpea lines (T1 stage); V–X: Transgenic chickpea lines (T2 stage); NTC: No Template Control; C: RNA as Template; L2: 100 bp DNA ladder) [Mean SM 11.8% and mean LWP −0.82 MPa]
 
 
 
 
 
 
 
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