CROP BIOTECH UPDATE
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A weekly summary of world developments in agri-biotech for developing countries, produced by the Global Knowledge Center on Crop Biotechnology, International Service for the Acquisition of Agri-biotech Applications SEAsiaCenter (ISAAA)
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September 30, 2026
In This Week’s Issue:
News
New Breeding Technologies
• CRISPR-Cas9 Editing Opens New Paths for Forage Improvement
• Study Identifies Genes That Control Dwarf Apple Growth
• Scientists Fine-tune Rice Texture Using Prime Editing
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NEWS
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New Breeding Technologies
CRISPR-CAS9 EDITING OPENS NEW PATHS FOR FORAGE IMPROVEMENT
Scientists from China have established a CRISPR-Cas9 gene-editing system in black medic (Medicago lupulina), a high-protein leguminous forage crop used as livestock feed and a nitrogen-fixing cover crop. By targeting and knocking out the MlPINNA1 gene, which is involved in compound leaf development, the researchers converted the species' typical trifoliate leaves into pinnate pentafoliate leaves. The established gene-editing system could enable the modification of other forage-related traits for developing improved forage crops and supporting the genetic improvement of related species such as alfalfa.
To establish the gene-editing and plant regeneration system, the researchers optimized culture conditions and designed a CRISPR-Cas9 construct targeting the MlPINNA1 gene. Three independent gene-edited plants were obtained, with insertions and deletions at the target sites confirmed through sequencing. All three edited lines developed pentafoliate leaves, confirming the role of MlPINNA1 in leaf development.
While further studies will be needed to determine whether the pentafoliate trait itself leads to greater biomass, the successful modification of MlPINNA1 demonstrated the potential of gene editing to precisely alter traits in black medic. The established framework could be utilized to investigate and manipulate genes involved in forage production and quality, potentially improving the quantity and nutritional value of forage and supporting more nutritious feed and sustainable livestock production.
You may read the study in the Journal of Integrative Plant Biology to learn more.
Researchers from Hebei Agricultural University and the Hebei Provincial Key Laboratory of Forest Tree Germplasm Resources and Forest Protection have identified a molecular pathway that regulates plant height in apple trees. The study investigated MdKNOX15, a gene highly active in dwarf and spur-type apple varieties, to gain insights into developing dwarf apple trees suitable for high-density orchards.
The study revealed that increasing MdKNOX15 activity produced shorter plants with lower levels of the growth hormone gibberellin (GA), while reducing the gene increased GA levels and plant height. Further analyses showed that MdKNOX15 directly regulates two GA-related genes, MdGA2ox7 and MdGA20ox2. The study also found that MdKNOX15 interacts with the DELLA homolog MdSLR1b, which affects the stability and activity of MdKNOX15.
The findings showed that MdGA2ox7 suppresses apple growth, while MdGA20ox2 promotes it. The study also found that MdSLR1b further strengthened the effects of MdKNOX15 on these genes. The researchers proposed that the MdKNOX15-MdSLR1b-MdGA2ox7/MdGA20ox2 pathway plays a central role in controlling apple plant height and could support breeding efforts for dwarf apple varieties.
For more information, read the study from The Plant Journal.
Scientists from China leveraged prime editing to develop rice with lower amylose content that could improve texture and cooking quality. The promoter of the Wx (Waxy) gene controls the production of a starch component that affects how rice cooks and feels when eaten. By making targeted changes to the promoter of the Wx (Waxy) gene, the researchers produced two new rice lines with amylose reductions of up to 3.95 percentage points without disrupting existing agronomic characteristics.
Rather than completely knocking out the gene, which can produce excessively sticky glutinous rice, the regulatory region of the Wx gene was precisely modified using prime editing to reduce its expression. In laboratory tests, the resulting rice lines showed longer gel consistency, higher breakdown viscosity, and improved instrumental taste values, characteristics associated with softer texture and improved eating quality after cooking.
Field evaluations found no significant differences in the agronomic traits evaluated between the edited rice and the original variety, while neither of the two edited promoter sequences was found among the 3,032 rice accessions examined. Human sensory evaluation and further field testing will be needed. Nevertheless, this approach demonstrates how prime editing can create new versions of existing genes that are not readily found in natural rice populations, giving breeders more options for fine-tuning cooking and eating quality.
Read the full study in the International Journal of Molecular Sciences to learn more.