What’s new in botany?

Image information: Novel by Nick Youngson CC BY-SA 3.0 Pix4free

Use, relevance, and meaning of the word ‘novel’ in science has been much discussed (e.g. Jian Wang et al.; Barak Cohen; Sotaro Shibayama et al.; Michael Black; Derek Lowe), as have terms such as ‘new’ and ‘unique’. A lot of that conversation was aimed at use of such words in relation to application for funding of research not yet undertaken. But, those terms are also applied in the context of published work. Maybe it’s to attract the attention of readers who have no end of reports that they could read, or to promote research groups keen to secure future funding or employment. Whatever the reason for such word choice, this item celebrates three botanical discoveries variously described as new or novel or unique [my emphasis for those key words].

First, “The Orchid and the Fruit Fly – Scientists Discover Unique New Plant-Animal Relationship”, which was the heading of the press report relating to the scientific paper entitled “A novel nursery pollination system between a mycoheterotrophic orchid and mushroom-feeding flies” by Kenji Suetsugu.

‘Translating’ the title for you, the orchid in question is Gastrodia foetida (Kenji Suetsugu et al.). As a non-photosynthetic plant it acquires its nutrition from a connection with a fungus, the phenomenon known as mycoheterotrophy (Vincent Merckx). Nursery pollination is a unique mutualistic relationship [co-operation between two species in which both partners benefit] (Regina Bailey; Carole Landry) where plants provide pollinators with brood sites in return for pollination (Shoko Sakai]. The mushroom-feeding flies were fruit flies, Drosophila (Therese Markow) species, D. bizonata and D. rufa in particular.

In the interests of retaining some mystery [I can’t do all the work for you, plus this item already has the feel of a long read…], I encourage interested readers to access the paper – or one of the pieces that interpret the work (here, here, or here) for the details. But, suffice it to say here that Suetsugu reports the “first evidence of nursery pollination not only in mycoheterotrophic plants but also in orchids as a whole”.

Second, “Researchers unearth a new process by which algae pass on nutrients to their coral host”. Which headline, I think you’ll agree, is much more eye-catching and attention-grabbing than the understated and rather restrained title that Yuu Ishii et al. (2023) gave to their work, “Environmental pH signals the release of monosaccharides from cell wall in coral symbiotic alga”. It’s long been known that it is the algal partner – called a zooxanthella (Hayley Gorsuch) – within the coral polyp that supplies the latter with food (Catherine Zandonella). Indeed, were it not for this essential nutritional flow, there would be no coral reef; it’s the alga – by dint of its photosynthetic prowess and production of photosynthates (Haley Zanga et al.) – that contributes the lion’s share to this mutually-beneficial relationship. How the transfer of food is achieved is therefore of considerable importance to the longevity of the relationship, and to the long-term survival of the coral reef as an ecosystem and habitat.

Ishii et al‘s contribution to understanding this phenomenon is the discovery that algae that are found as symbionts [Breviolum sp. ] within coral polyps release simple sugars – such as glucose and galactose – into their surroundings from their cell walls when the pH of their external environment is lowered, when grown ‘in a host-independent manner’, i.e. on their own in culture. This release appears to be related to cell wall breakdown by cellulase (The Protein Man), because genes for the production of this enzyme were also activated by the reduced pH. Although the acidic pH of 5.5 used for the work matched that within the polyp tissues (Elizabeth Hambleton) it is not known if this mechanism of carbohydrate release operates within the intact coral symbiosis. And, if it does, an additional method(s) of carbohydrate release by the alga is not excluded (Ishii et al., 2023).

Whilst we await the necessary investigation into whether this does happen within the polyp, it hasn’t escaped my notice that there is potential link to concerns over enhanced CO₂ levels in the atmosphere here. A consequence of this is that more CO₂ is absorbed by the oceans, which leads to a well-documented reduction of the seawater’s pH, i.e. the seas become more acidic. If this acid-induced cell wall breakdown is something general to algae, that would have nutrition-enrichment consequences in the immediate area of those algae so affected, which might lead to local eutrophication-like (Michael Chislock et al.) episodes with potentially proliferation of life-forms able to use the liberated carbohydrates as a food source. [Although, if ocean pH drops to 5.5 – as used in the experiments – humankind has probably got a lot worse to worry about than a little bit of eutrophication!] And, if the severity and/or duration of such acidification events were extensive, maybe the algal cell walls will be completely degraded in which case one might worry about survival of the ’naked’ algae. Quite where that takes us is unclear, but maybe this bit of algal physiology has relevance well beyond the immediate coral reef symbiosis? [Because this work wasn’t carried out on the coral polyp symbiosis one is tempted to amend the science news outlet’s headline to “Researchers unearth a new process by which algae might pass on nutrients to their coral host”.]

Third, we have “A new type of cell related to organ movement for selfing in plants” by Yin-Zheng Wang et al.. Because cells are rather small – and you usually need a microscope to see them at all – finding a new one is quite an achievement*. But, that is what Wang et al. have announced. Termed contractile cells, this new cell type was found in the stigmas of the gesneriad Chirita pumila]. A distinctive feature is the rough endoplasmic reticulum [RER] (Kara Rogers; V Kriechbaumer & F Brandizzi), which is continuously distributed throughout the entirety of cells, and which configuration s distinct from the organelle commonly found within plant cells.

Wang et al. (2023) propose that the contractile cells drive circadian closing-bending movements of the stigmas in response to day-to-night moisture changes. The ‘engine’ for this movement appears to be a water-sensitive RER that becomes extremely elongated upon absorption of water – rather than the usual situation of water uptake into the vacuole (Michael Davidson; Xiaona Tan et al.), which organelle appears absent from these cells. The inferred hydrostatic pressure that’s generated by water-imbibed RER promotes upto an 8-fold increase in length of the contractile cells – i.e. they expand [which gives cause for pause as to why they’re termed contractile cells, unless they do contract as well…] – within so-called stigma laminae at the tip of the style. Because of the cells’ location within the stigma, the resulting elongation is one-sided and the stigma laminae bend over the anther which is mechanically squeezed. As a consequence, it is thought that pollen grains are forcibly ejected from the pollen channel and fall onto the stigma receptive surface causing self-pollination.

It’s worth pointing out that not only has a new plant cell type been identified, but this is also – to the best of Wang et al‘s knowledge – the first report of this specialised form of RER in plants. Furthermore, this process in Chirita “represents a novel type of plant movement and is distinct from the general features of other organ movements in plants without deformation of the motion organs themselves”. A total of three new discoveries in a most singular scientific paper.

That novel work on self-pollination nicely links with the previous study by Mohamed Abdelaziz et al. announcing “Anther Rubbing, a New Mechanism That Actively Promotes Selfing in Plants” in the crucifer (Dmitry German et al.) Erysimum incanum.

Three [four including the 2019 work; five if you look right to the end of this piece…] quite different discoveries, which – assuming that there are no prior published papers to contradict any of those claims – all qualify as new, unique, or novel. Which proves that there is much to discover about the botanical world in its broadest sense. But, in fairness, all work that is published should be new – not necessarily novel or unique, but new. Otherwise, there’s no point in it being published. So, maybe use of new or novel in the title of a paper is actually unnecessary, superfluous, and redundant..? Unless, it helps to distinguish such work from all of the rest and gets your paper read and cited more, and greater kudos and prestige for the research team involved. Hmmm, discuss.

* If finding a new cell – which needs a microscope – is quite hard, imagine how difficult it must be to identify a whole new organ – which almost by definition is readily-visible to the naked eye and no doubt seen by many people. Yet, that is what was reported a few years ago by Timothy Gookin & Sarah Assmann in their article entitled “Cantil: a previously unreported organ in wild-type Arabidopsis regulated by FT, ERECTA and heterotrimeric G proteins”. Is this the definition of ‘hiding in plain sight’? Anyway, there’s more on that discovery from Jamie Chambers, and here.

READ THE ARTICLES

Abdelaziz, M., Bakkali, M., Gómez, J.M., Olivieri, E. and Perfectti, F. (2019) “Anther rubbing, a new mechanism that actively promotes selfing in plants,” The American Naturalist, 193(1), pp. 140–147. Available at: https://doi.org/10.1086/700875.

Cohen, B.A. (2017) “How should novelty be valued in science?,” eLife, 6, p. e28699. Available at: https://doi.org/10.7554/elife.28699.

German, D.A., Hendriks, K.P., Koch, M.A., Lens, F., Lysak, M.A., Bailey, C.D., Mummenhoff, K. and Al-Shehbaz, I.A. (2023) “An updated classification of the Brassicaceae (Cruciferae),” PhytoKeys, 220, pp. 127–144. Available at: https://doi.org/10.3897/phytokeys.220.97724.

Gookin, T.E. and Assmann, S.M. (2021) “Cantil: a previously unreported organ in wild-type Arabidopsis regulated by FT, ERECTA and heterotrimeric G proteins,” Development (Cambridge, England), 148(11), p. dev195545. Available at: https://doi.org/10.1242/dev.195545.

Hambleton, E.A. (2023) “How corals get their nutrients,” eLife, 12, p. e90916. Available at: https://doi.org/10.7554/elife.90916.

Ishii, Y., Ishii, H., Kuroha, T., Yokoyama, R., Deguchi, R., Nishitani, K., Minagawa, J., Kawata, M., Takahashi, S. and Maruyama, S. (2023) “Environmental pH signals the release of monosaccharides from cell wall in coral symbiotic alga,” eLife, 12, p. e80628. Available at: https://doi.org/10.7554/elife.80628.

Kriechbaumer, V. and Brandizzi, F. (2020) “The plant endoplasmic reticulum: an organized chaos of tubules and sheets with multiple functions,” Journal of Microscopy, 280(2), pp. 122–133. Available at: https://doi.org/10.1111/jmi.12909.

Markow, T.A. (2015) “The secret lives of Drosophila flies,” eLife, 4, p. e06793. Available at: https://doi.org/10.7554/elife.06793.

Sakai, S. (2002) “A review of brood-site pollination mutualism: plants providing breeding sites for their pollinators,” Journal of Plant Research, 115(3), pp. 161–168. Available at: https://doi.org/10.1007/s102650200021.

Shibayama, S., Yin, D. and Matsumoto, K. (2021) “Measuring novelty in science with word embedding,” PLoS One, 16(7), p. e0254034. Available at: https://doi.org/10.1371/journal.pone.0254034.

Suetsugu, K. (2023) “A novel nursery pollination system between a mycoheterotrophic orchid and mushroom‐feeding flies,” Ecology. Available at: https://doi.org/10.1002/ecy.4152.

Suetsugu, K., Aoki, R. and Kaneko, S. (2023) “Resurrection and emended description of Gastrodia foetida (Orchidaceae),” Phytotaxa, 583(3), pp. 251–259. Available at: https://doi.org/10.11646/phytotaxa.583.3.3.

Tan, Xiaona, Li, K., Wang, Z., Zhu, K., Tan, Xiaoli and Cao, J. (2019) “A review of plant vacuoles: Formation, located proteins, and functions,” Plants, 8(9), p. 327. Available at: https://doi.org/10.3390/plants8090327.

Wang, J., Veugelers, R. and Stephan, P. (2016) Bias against novelty in science: A cautionary tale for users of bibliometric indicators. Cambridge, MA: National Bureau of Economic Research.

Wang, Y.-Z., Lin, Y.-X., Liu, Q., Liu, J. and Barrett, S.C.H. (2023) “A new type of cell related to organ movement for selfing in plants,” National Science Review, 10(9), p. nwad208. Available at: https://doi.org/10.1093/nsr/nwad208.