Early communication

Early communication

Like plants, plant cells cannot change their place. For forming functioning organs, good communication is a must. To tell the cell when to divide, and what its job is. This communication is most important at the verry start. During the development of the embryos the growth regions are established. When this does not happen correctly, the root or shoot will not grow. Verry important, having good communication.

Still, we don not know much about it. Researchers from France studied how communication is regulated during the development of the root-growth region. While most of a plant embryo has no direct contact with the mother plant, the embryonic root has. It can get instructions from the embryo itself, but also from the mother plant.

Good communication is important, when you don’t speak up, instructions from others get a chance

The researchers noticed that the WIP-gene family has a crucial role during the development of the embryogenic root-growth region. The interesting part of this gene family is that half of its genes are only turned on in the embryo, while the other half is only turned on in the mother plant. A cell can use this to know if it is part of the mother plant or the embryo.

When the cell believes it is part of the embryo, then it will follow the embryo development instructions. The cell will undergo the precise cell divisions needed for proper root-growth region development. Are the embryo-WIP genes turned off, then the cell does not know which instructions to follow. The mother-plant WIP genes can now convince the cells that they do not have to divide that precisely. The root-growth region doesn’t develop.

The WIP genes show us: good communication is important. When you don’t speak up, instructions from others get a chance. Before you know it, it will be one big mess. But when you follow the example of plants, by having good communication from the start, things will bloom.

Literature

Yujuan Du, Maria Victoria Gomez Roldan, Aimen Haraghi, Nawel Haili, Farhaj Izhaq, Marion Verdenaud, Adnane Boualem and Abdelhafid Bendahmane (2022) Spatially expressed WIP genes control Arabidopsis embryonic root development. Nat. Plants 8, 635–645. https://doi.org/10.1038/s41477-022-01172-4

Prille communicatie

Prille communicatie

Plantencellen kunnen, net zomin als planten, niet van plaats veranderen. Voor het vormen van functionerende organen is goede communicatie tussen cellen een vereiste. Om te vertellen hoe te delen en wat de taak van de cel is. In het beginstadium is deze communicatie het allerbelangrijkst. Tijdens de ontwikkeling van de embryo worden de groeikernen aangelegd. Gebeurt dit niet goed, dan kan de wortel of stengel niet groeien. Heel belangrijk dus, die communicatie.

Toch weten we er niet veel vanaf. Onderzoekers uit Frankrijk onderzochten regulatie van de communicatie tijdens de ontwikkeling van de wortelgroeikern. Waar de rest van de planten-embryo niet in contact staat met de moederplant, staat de prille wortelgroeikern dat wel. Het kan dus instructies van de embryo zelf maar ook die van de moederplant ontvangen.

Goede communicatie is belangrijk, zeg je niets dan krijgen andere instructies een kans

De onderzoekers ontdekte dat de WIP-genenfamilie een cruciale rol speelt in de ontwikkeling van de wortelgroeikern. Het interessante aan deze genenfamilie is dat de helft van de genen aan staat in de embryo terwijl de andere helft alleen aan is in de moederplant. Zo weet de cel dus of het deel is van de moederplant of juist van de embryo.

Denkt de cel dat het deel is van de embryo, dan volgt het de embryo vorming instructies op. De cel gaat het de precieze celdelingen maken die onderdeel zijn van de wortelgroeikern ontwikkeling. Staan de embryo-WIP genen uit, dan weet de cel niet welke instructies het moet volgen. De moederplant-WIP genen kunnen nu de cellen overtuigen dat ze niet zo precies hoeven te delen. De wortelgroeikern vormt zich niet.

De WIP-genen laten zien: goede communicatie is belangrijk. Zeg je niets dan krijgen andere instructies een kans. Voordat je het in de gaten hebt loopt alles in de soep. Volg je het voorbeeld van de plant op en zorg je vanaf het begin voor goede communicatie, dan bloeit alles op.

Literatuur

Yujuan Du, Maria Victoria Gomez Roldan, Aimen Haraghi, Nawel Haili, Farhaj Izhaq, Marion Verdenaud, Adnane Boualem and Abdelhafid Bendahmane (2022) Spatially expressed WIP genes control Arabidopsis embryonic root development. Nat. Plants 8, 635–645. https://doi.org/10.1038/s41477-022-01172-4

Flourishing with a little bacterial help

Flourishing with a little bacterial help

Bacteria and fungi in the soil unlock mineral sources of nitrogen, sulphate, and iron. Transforming these minerals into a form that plants can uptake. While these microorganisms are always useful, they are essential in arid soils that have accumulated huge mineral quantities. Such as the Atacama Desert. Here large groves of the Atacama Desert giant horsetail (Equisetum xylochaetum) grow in the valley streambeds. Researchers wondered if these large plants got some microbial help to flourish in such harsh environment.

They analysed the bacteria attached to the roots of the giant horsetail. Among the bacteria they found species that specialised in either fixing nitrogen, reducing sulphate or iron. Not only that, but the genes for proteins needed for these reactions were turned on. Suggesting that when the researchers took the sample, these bacteria were busy with fixing nitrogen, reducing sulphate or iron. The close contact of the bacteria with the horsetail roots means that the plants have direct access to these unlocked minerals. Directly benefitting their growth.

Disturbing and mining soils influences the types of bacteria present in those soils

In the past the large mineral quantities in the Atacama Desert were mined, disturbing the soil. The researchers compared the microbes attached to roots from past mining sites with those on roots of plants on less disturbed soils. On both sites the roots had lots of microbes attached. But not the same microbes. While the roots from less disturbed soils had lots of active beneficial bacteria, those of disturbed soils had not so much. Suggesting that disturbing and mining soils influences the types of bacteria present in those soils.

Harsh environments, like the Atacama Desert show us the importance of the interaction between microorganisms and plants. Microorganisms help plants flourish in this stressful environment. And as the researchers say, this is something to keep in mind if we want to protect these ecosystems.

Literature

Anchittha Satjarak, Linda E Graham, Marie T Trest, Joy Zedler, Jennifer J Knack, Patricia Arancibia-Avila, Nitrogen fixation and other biogeochemically important features of Atacama Desert giant horsetail plant microbiomes inferred from metagenomic contig analysis, Annals of Botany, 2022;, mcac060, https://doi.org/10.1093/aob/mcac060

How to predict winter

How to predict winter

It’s a challenge, year after year, to stop growing on time. And, after winter, to start again. Annual plants have it easy. They germinate, grow, flower, set seeds, disperse them, and die. Simple. Easy, first one thing than the next. Being a perennial is not that easy. Every year you need to stop growing before winter arrives. Then start up again, and flower as well. How do they recognise the right moment for this all?

For annuals we now more or less know how they do it. But for perennials it is another story. They do things differently than annual plants, do more things, sometimes even multiple things at once. Take for example growing and flowering. For annuals this is regulated by the gene FT. When the FT gene is turned on, the plant grows, it develops new leaves and stems. Is the FT gene turned off? Then the plant starts flowering. Easy. 

Not in perennials. Perennials, it turned out have multiple FT genes. To understand what these FT genes do, researchers from Sweden studied the FT genes from European aspen, a tree from the poplar family. The FT genes in European aspen come in two types, FT1 and FT2. The researchers followed the genes a whole year and had a look at what happens when these genes are turned off completely.

Growth, but not flowering, is regulated by these two genes

In growing leaves FT2 is turned on. But, during shorter days the researchers noticed that there is less FT2. By the time, in autumn, the tree forms buds, FT2 is turned off. When FT2 is completely switched off, the European aspen start making buds even when the days are still very long. It turns out that FT2, just like FT from annuals, is needed for growth and prevention of starting the next step, bud formation, to early.

The researchers noticed FT1 was only turned on during the winter, in the buds. The colder, the more FT1. When, in spring, the first leaves appeared, FT1 was already turned off. Switching the FT1 gene completely off, and the researchers noted that the first leaves did not appear in spring. The buds remained close. This suggest that FT1 wakes the buds up from hibernation. How exactly? That is still a mystery.

In perennials, the daylength coupled FT2 gene is regulating growth, just like FT in annuals. In contrast in perennials FT1 is coupled to temperature, not daylength. Allowing FT1 to regulate the hibernation of buds. Growth, but not flowering, is regulated by these two genes. FT1 and FT2 help perennials, to stop on time with growing, and, when winter is over, to start growing again.

Literature

Domenique André, Alice Marcon, Keh Chien Lee, Daniela Goretti, Bo Zhang, Nicolas Delhomme, Markus Schmid, Ove Nilsson (2022) FLOWERING LOCUS T paralogs control the annual growth cycle in Populus trees. Current Biology, https://doi.org/10.1016/j.cub.2022.05.023