In this blog post I will
analyse an in vitro cultivation experiment of the plant Camellia japonica L.
conducted by Seglie et al.[1]
Treatments in the experiment
The scientists used a set of different treatments to
examine the impact of them on the in vitro multiplication and rooting of 19 Japanese
genotypes and 4 commercial cultivars of Camellia japonica.
In a first step they varied the plant hormones in the
substrate, one group with 6-benzyladenine (BA) and the other with BA and gibberellic
acid (GA3). BA is a cytokinin which stimulates the cell division and
inhibits apical dominance.[2] GA promotes the germinability
and the elongation of plants.[3] Plants with these two
substrates where then held in darkness or in a 16/8 h photoperiod (16 hours
light and 8 hours darkness).
In a second experiment the plants were first multiplied
on a substrate with BA and then placed on a medium with or without indole-3-butyric
acid (IBA) to bring them in the rooting stage. IBA is an auxin, these plant
hormones promote the rooting of plants and the apical dominance.[4] So they work as an
antagonist to the cytokinins. In one group the IBA was included in a nanosponge
and in the other not.
Bacterial contamination rate
In darkness the explants from auxiliary buds showed a bacterial
contamination rate of 94.8%, explants
from shoot tips just 54%. This is no surprise because auxiliary meristems fall
in a dormancy after they are built, they only start to make a side branch when
they get the signal by plant hormones.[5] In this timespan bacteria
can penetrate into the meristem, in contrast the growing apical meristems let
no time for the bacteria to wander to the tip of the meristem. During dormancy
there is also not a high rate of metabolic activity as in the active apical
meristem, so the bacteria is not much inhibited. As a conclusion I would say
they took meristems from not activated auxiliary meristems and growing apical
meristems, this would explain the huge difference in bacterial contamination.
Nanosponges
Nanosponges are nanocarriers, the word nano refers to materials
between 1 and 100 nm, these very small carriers can be used to absorb, release
and transport molecules.[6] Nanosponges are relatively
new and promising, there is a wide field of applications like in medicine or in
water cleaning.[7]
With this small scale technique it is possible to engineer on a molecular level.
As an example, toxins anywhere in human bodies can be captured and transported
to the liver.[8]
In the study of Seglie et al. they used the nanosponge
β-CD-NS 1:4, it is based on a β-Cyclodextrine (CD) molecule. β-CD is a ring of seven glucose molecules, it is polar on the outside and apolar on the inside, this makes it perfect to
transport an apolar molecules like IBA and bring it into the plant where it
gets dissolved in the polar cell water (see Image 1).[9] With this setting the IBA
can be transported into the plant more efficient because the hormone does not
get lost in the apolar substrate and the release of the IBA extend on a longer interval.[10]
 |
| Image 1: β-Cyclodextrine Ring (CD) with an indole-3-butyric
acid (IBA) inside (assembled from www.trc-canada.com and http://commons.wikimedia.org). |
[1] Seglie, L., Caser,
M. Berruti, A., Scariot,V. (2011). Investigations on In Vitro Multiplication
and Rooting in Camellia japonica L.VII International Symposium on In Vitro
Culture and Horticultural Breeding.
[2] Siddiqui, W., Bhattacharjya, A.,
Chakraborty, I., Dhua,R.(2011). 6-Benzylaminopurine improves shelf life,
organoleptic quality and healthpromotingcompounds of fresh-cut broccoli florets.
Journal of Scientific & Industrial Reserch 70, S.461-465.
[3] Vandenbussche, F., Fierro, A.C.,
Wiedemann, G., Reski, R., Van Der Straeten, D. (2007). Evolutionary conservation of plant
gibberellin signalling pathway components. BMC Plant Biology 7:65.
[4] Campbell & Reece (2006). Biologie.
München: Pearson Studium. S.971.
[5] Campbell & Reece (2006). Biologie.
München: Pearson Studium. S.874 f.
[6] Cristina, B., Pacheco, I.,
Robbie K. (2007). Nanomaterials
and nanoparticles: Sources and toxicity. Biointerphases 2:1.
[7]
Hu, C.M.J, Fang, R.H., Copp, J., Luk, B.T., Zhang, L. (2013). A
biomimetic nanosponge that absorbs pore-forming toxins. Nature
Nanotechnology 8, S. 336-340.
[8] Jesse Emspak (2011). Nanosponges
To Suck Up Toxins. From:http://news.discovery.com/tech/nanotechnology/universal-antidote-in-a-sponge-130414.htm
[9] Seglie, L., Martina, K., Devecchi,
M., Roggero, C., Trotta, F., Scariot, V. (2011). β-Cyclodextrin-based nanosponges as
carriers for 1-MCP in extending the postharvest longevity of carnation cut
flowers: an evaluation of different degrees of cross-linking. Plant Growth
Regulation 65:3 S. 505-511.
[10] Roggero, C.M., Di Stefano, D.,
Tumiatti, V., Tumiatti, M., De Vecchi, M., Scariot,V., Kapila, S. (2012). Use of
functionalised nanosponges for the growth, conservation, protection and
disinfection of vegetable organisms. Patent WO 2013046165 A1.
