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Is this the future of food? 'Sexless' seeds that could transform farming

raphmercier.bsky.social @raphmercier.bsky.social · Sep 8

www.nature.com/articles/d41...

Interesting journalist piece on apomixix. With pieces of MiMe inside :-)

Scientists are tinkering with plant genes to create crops that seed their own clones, with a host of benefits for farmers.

www.nature.com

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Reposted

Schnittger Lab @schnittger-lab.bsky.social · Aug 25

Six more years—plus a lot of blood, sweat, and tears—later, we are thrilled to finally share it: a cytological framework of female meiosis in Arabidopsis!

www.biorxiv.org/content/10.1...

A cytological framework of female meiosis in Arabidopsis

Female and male meiosis often differ in many aspects, such as their duration and the frequency as well as the positioning of crossovers. However, studying female meiosis is often very challenging and ...

Unlocking meiotic crossovers near plant centromeres

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raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

Thank you and congrats to all contributors in Versailles @ijpb-versaillescly.bsky.social and Cologne @mpipz.bsky.social and in particular to Dipesh Singh, Alexander Mahland, Rigel Salinas, Joiselle Fernandes and Qichao Lian.

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raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

The identification of the very conserved CTF18, SGO2 and SPF2 as suppressors of centromere-proximal crossovers highlights the importance of cohesin turnover in this process and opens up new possibilities for plant breeding. Much more in the paper : www.biorxiv.org/content/10.1...

Crossovers (COs) ensure proper chromosome segregation during meiosis and generate genetic diversity. COs are non-uniformly distributed along chromosomes and almost universally suppressed in centromere...

two women are sitting next to each other and one is pointing at the camera

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raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

and guess what, some did! The cohesion regulators CTF18 and SGO2, and the deSUMOylase SPF2 actively limit centromere proximal crossover. Their mutation allows both the formation of crossover where they were completely absent in the wild-type, and enhance their frequency where they were rare!

ALT: two women are sitting next to each other and one is pointing at the camera

a close up of a woman 's face with a triangle and a mathematical formula .

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

We reasoned that the changes in the organization of the centromere-proximal region that affect kinetochore orientation in the identified mutants (see above and the first preprint) may also affect crossover formation near centromeres.

ALT: a close up of a woman 's face with a triangle and a mathematical formula .

a close up of a person 's hand touching a plant in a field .

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

But there are genes in these regions, which are thus innacissible to recombinatiion. This creates a significant bottleneck for plant breeding.

ALT: a close up of a person 's hand touching a plant in a field .

a little girl wearing a shirt that says " til to " is eating a snack

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

An now the SECOND story.
Meiotic crossover shuffle genetic information. But, they are non-uniformly distributed along chromosomes and almost universally suppressed in centromere-proximal regions. How crossover are prevented next to centromere is unclear.

ALT: a little girl wearing a shirt that says " til to " is eating a snack

Monopolar orientation of kinetochores at meiosis is enforced by COHESINS and their regulators, CENP-C, and the deSUMOylase SPF2

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

Our findings demonstrate that cohesion establishment and protection, kinetochore, and deSUMOylation enforce monopolar orientation in plants. This support a cohesion-driven model of kinetochore orientation at meiosis I that is conserved across kingdoms. Take a look: www.biorxiv.org/content/10.1...

The first division of meiosis is unique in its capacity to halve the ploidy of the future gametes. To this end, one key innovation compared to mitosis is the monopolar orientation of the pairs of sist...

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

We show that monopolar orientation involves all four cohesin subunits (REC8, SCC3, SMC1, SMC3), the cohesion establishment factors CTF18 and DCC1, and the cohesin protectors SGO1/2 and PANS1, the inner kinetochore protein CENP-C, and the desumoylase SPF2.

a cartoon of a duck with the words " i 'm on the case "

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

We performed a large forward genetic screen in Arabidopsis thaliana, specifically designed to identify the molecular components imposing monopolar orientation. The design is a bit crasy, see in the paper 🤪. But we found many mutants!

ALT: a cartoon of a duck with the words " i 'm on the case "

a hamster wearing a pink hat that says grind on it

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

One key innovation of meiosis compared to mitosis is the monopolar orientation of the centromere of sister chromotid at metaphase I. Rather than being separated, like at mitosis, the two go together at meiosis I.

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raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

The first division of meiosis is unique in its ability to separate homologous chromosomes. This is essential for maintaining the stable number of chromosomes in sexual reproduction. Without this, the number of chromosomes would double with each generation.

ALT: a hamster wearing a pink hat that says grind on it

Monopolar orientation of kinetochores at meiosis is enforced by COHESINS and their regulators, CENP-C, and the deSUMOylase SPF2

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

Preprint Alert! 🚨🧬
Not one, but two preprints!

Meiotic orientation of kinetochore at meiosis is inforced by...[see below]
www.biorxiv.org/content/10.1...

and

Unlocking meiotic crossovers next to plant centromere
www.biorxiv.org/content/10.1...

#meiosis4ever
#everythingisconnected

a thread👇

The first division of meiosis is unique in its capacity to halve the ploidy of the future gametes. To this end, one key innovation compared to mitosis is the monopolar orientation of the pairs of sist...