IGI Paper Delivery: Rice that reproduces as a clone is agricultural breakthrough


A male-expressed rice embryogenic trigger redirected for asexual propagation through seeds Traditional hybrid breeding is a process that generates crops with high yield and
other desirable characteristics by breeding two different high-performing
plants together we can generate seeds that grow into a so-called hybrid plant
that grows even better. For some crops the hybrids can produce double the yield!
Unfortunately, when the hybrid plant self-fertilizes or is bred with an identical
hybrid plant its seeds will produce plants with lower yields. This is why
farmers have to buy new hybrid seeds every year. So why aren’t offspring
identical to their parents? Let’s zoom into their cells to find out. sexual reproduction begins at the mother egg cell. In a hybrid plant the mother egg cell contains special versions of different genes that in combination give
the hybrid its high yield. A process called meiosis divides the DNA into
separate egg cells. The male cell or sperm then fertilizes one of the egg
cells and the fertilized egg begins to grow into an embryo eventually forming a
whole seed. The resulting seeds inherit different combinations of genes and will
have a very different genetic makeup from the parents, just like you’d expect
for human children. If the offspring ends up losing its
powerful combination of high-yield genes it will have lower yields than its
hybrid parent. In this breakthrough study, Dr. Sundaresan and his team have
managed to engineer rice plants that create seeds that are exact clones of
the parent. The engineered plants reproduce asexually yielding clonal
seeds with all of the parents desirable traits. So how did they achieve this
remarkable feat? To enable asexual reproduction, Sundaresan and his team
first used CRISPR genome editing to turn off three genes and stop meiosis. This
produces egg cells that carry all of the mother’s genes without any of the
shuffling and gene loss that normally happens.
Next the researchers added a gene called baby boom 1, or BBM1, which triggers
the egg cell to develop into an embryo without the need for sperm eventually
producing a full seed. In the end each seed carries a perfect clone of the
original plant. This breakthrough means that hybrid plants with desirable traits
will produce seeds that can be planted and grown into plants that are exact
clones with high yields year after year. Even great-grand plants will still be
clones of the original rice plant. Currently, not all of the seeds from the
same engineered plant are identical clones but now that the big technical
barrier has been overcome the team is working to increase the efficiency. Excitingly, since all of the key genes involved in
this approach are found in other plants the same strategy could potentially be
used in other important crops like corn, tomatoes, and wheat. Right now most
farmers do not grow hybrid rice crops due to the high cost of the seeds. This
IGI project could transform the world one day giving farmers in developing
countries access to all the benefits of hybrid rice without having to buy
expensive seeds every year.

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