Tag Archives: genetics

New ‘Tomato Expression Atlas’ dives deep into the fruit’s flesh

Researchers have published a ‘spatiotemporal map’ of gene expression for all tissues and all the developmental stages of tomato fruit which highlights how a fruit changes from inside to out as it ripens.

How a fruit ripens has long been an important question for breeders, and with the global tomato market worth around $55 billion a year, tomato is an important subject for understanding the genetic basis of commercially important traits, such as size, colour, flavour, and nutritional content.

“We needed unbiased sampling that was as representative as possible. For that purpose, we harvested in total more than 400 samples from more than 60 randomly selected individual tomato plants,” explained postdoctoral scientist Philippe Nicolas who was involved in the multi-partner project.

The researchers carefully dissected the tomato tissues by hand and with lasers to isolate and sequence RNA from individual tissues and even cells. The sequence data was then compiled, parsed, and organized into the Tomato Expression Atlas (TEA), where it can be analyzed to investigate the various biological processes important for fruit development.

“The TEA database offers an unprecedented level of interactivity and novel ways to visualize complex, multidimensional expression data,” added scientist Lukas Mueller, referring to the TEA’s graphic interface that allows users to visualize gene expression through heat maps and fruit pictographs.

Photo Caption: Tomato fruit at the different developmental stages used for this study.

Photo Credit: The Tomato Expression Atlas

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Should gene edited crops be exempt from GMO rules?

The European court’s Advocate General has determined that organisms derived by gene editing technologies are exempt from wider EU rules on growing and marketing genetically modified (GM) food.

In a release last week, Advocate General Michel Bobek suggested that the EU’s GMO Directive ‘does not … apply to organisms obtained through certain techniques of genetic modification, such as mutagenesis (‘the mutagenesis exemption’).’

Unlike transgenesis, mutagenesis does not, in principle, entail the insertion of foreign DNA into a living organism. It does, however, involve an alteration of the genome of a living species. The mutagenesis techniques have made it possible to develop seed varieties with elements resistant to a selective herbicide.

Dr Michael Antoniou, the head of the molecular genetics department at King’s College London, said exempting new plant-breeding technologies from GM laws was “wrong and potentially dangerous”.

“None of these gene editing methods are perfect,” he told the Guardian. “They have ‘off target’ effects that can inadvertently disturb the biochemistry of organisms leading to unintended outcomes which – if you’re making a new gene edited food crop, for example – could result in the unexpected production of a new toxin or allergenic substance.”

However, John Brennan, secretary-general of the biotechnology lobby group EuropaBio, said, “The advocate general’s opinion demonstrates that necessary steps are being taken towards clarifying the regulatory status of products that have been developed using the latest biotechnological tools and applications. We trust that the forthcoming ruling will contribute to establishing regulatory clarity.”

The Advocate General’s Opinion is not binding on the Court of Justice.

Photo Credit: Wikipedia

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One step closer to crops with twice the yield

Scientists from Wageningen University & Research (WUR) who have identified natural genetic variation for photosynthesis in plants say that unravelling the differences in DNA at a genetic level could help to breed crops which capture more CO2 and produce higher yields.

A team of scientists led by Mark Aarts and Jeremy Harbison used the model plant thale cress to spot various genes involved in the adaptation to changes in the amount of light to which plants are exposed.

The discovery shows that it is possible to improve photosynthesis based on natural genetic variation, something which some scientists have doubted until now. In the long term, breeding on improved photosynthesis could make crops produce more yield with the same amount of soil, water and nutrients.

While photosynthesis is an essential process it demands a high level of control: if a plant is suddenly exposed to too much light, it has to adapt to the new situation. Adaptation generally takes several days, but this new study shows that some plants can adapt quicker than others, and are thus able to adapt their photosynthesis system to their environment sooner.

“We measured the photosynthesis of all plants in the experiment at various times of day and via an identical method, and only applied a single stress factor: a one-off increase in the amount of light. This allowed us to precisely determine the genetic contribution to how plants adapted to the new stressful situation,” explained Mark Aarts.

Photo Caption: The work shows that plant genetics determine how they control photosynthesis.

Photo Credit: Wageningen University & Research

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