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In vitro shoot tip culture of N. campanulata

Here's the result so far of my recent attempt at propagating N. campanulata by culturing the shoot tips in vitro. I used small basal shoots as explant source and referred to these links for disinfection methods:
http://icps.proboards.com/thread/4891
http://www.flytrapcare.com/phpBB3/nepenthes-meristem-introduction-t19147.html
Having referred to the links above, I made adjustments and came with my own disinfection method: 1-h in Benlate, followed by 15-min in bleach solution, and then briefly in sterile distilled water (i.e. no alcohol, no PPM).

I tried two types of explants, single 'cone' of unexpanded leaf containing the shoot tip meristem or intact basal shoot. I harvested eight basal shoots in total. For three of them, I cultured them intact, and for the remaining five, I excised only the shoot tips as explants. Both methods seem to work for obtaining sterile cultures, and here's some results I'd like to share.

After three weeks of culture, all the shoot tips cultured were free from contamination (first five tubes from the left). Two of the intact shoot cultures were contaminated with fungus within a week of culture and were discarded, leaving one remaining (last tube on the right).
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Based on my observation so far, the tiny shoot tips can be damaged easily during disinfection. The one in the leftmost tube is completely blackened, while the rest show varying amount of blackening, but at least there's still some green on them. Intact shoots seem to withstand the disinfection process better, but are more difficult to disinfect completely (2 out of 3 were contaminated).

Here are two explants that have shown positive growth after three weeks of culture:
35407227394_081f9489c9_b.jpg


One of them was a shoot tip explant. It was a completely tight 'cone' when cultured. Now it has begun to unfurl, revealing a cream-colored 'cone' within.
35407225604_d4cc95dfeb_b.jpg


The other one was an intact shoot explant. It had two expanded leaves with a tight 'cone'. Now after three weeks that 'cone' has unfurled to become the largest leaf on the left. In addition, another leaf and a new 'cone' was produced.
35407226114_1db292d502_b.jpg


I used hormone-free half-strength MS medium for the first three weeks of culture. Now that these remaining explants seem free from microbial contamination, I've transferred them to multiplication medium containing 1 ppm BAP and 0.1 ppm NAA.
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Just as an aside, tissue culture of nepenthes with leaf explant is possible.
It has been done:
http://www.tbg.org.tw/tbgweb/cgi-bin/topic.cgi?forum=19&topic=9227
Apparently it involves the use of 2,4-D, but the details of the protocol remain undisclosed. :)

Yeah, so that's it for now. Will update when something interesting happens with my N. campanulata cultures.
 
very nice to see. thanks for sharing!
 
Congratulations on your success so far. I too have managed to introduce meristematic tissues and leaf primordia in vitro; and I do agree that those explants are particularly sensitive to sterilization.

I did find PPM to be useful however . . .
 
Thank you, BigBella. When searching the net for information a while back, PPM sounds like THE thing to have for some particular sterilization work. And now hearing you say it, hm, it might be worth the effort to import the stuff in I guess.
 
This morning I harvested five more basal shoots from my plant and cultured the shoot tips in vitro. This time round I managed to take some photos of the disinfection process, so here they go.

The tiny basals were soaked in Benlate solution immediately after they were cut.
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I removed all scales from the shoots and also any leaves that have unfurled.
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Then I put the shoots in fresh Benlate solution to soak further for a total of 1 h.
35407218184_c29c66bc27_b.jpg


From Benlate solution they went straight into bleach solution for 15 mins. Finally they were rinsed briefly with sterile distilled water. After this final rinsing I discarded the basal portion of the shoots.
35407213364_d0652bd65b_b.jpg


The excised shoot tips were then cultured in hormone-free half-strength MS medium.
35407217524_88220da4cd_b.jpg


I made a slight modification to the disinfection procedure by halving the concentration of the bleach solution. This time round I used 3 mL household bleach in 100 mL water, instead of 6 mL bleach in 100 mL water. The explants were looking good and the lower concentration of the bleach solution clearly did less damage to these tender shoot tips.
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Sounds like a very sound protocol and continued good luck to you; though I would be cautious, in the long run, of 1:2 MS, since the ammonium nitrate concentration, toxic to Nepenthes, is quite high -- some 1650 mg / L at full strength in some formulations. I generally limit it to 1:4 or 1:3; or make my own media . . .
 
I've just been doing either seeds or small seedlings, so this is encouraging. It would be nice to develop a good disinfecting protocol. I been trying out various
disinfectants/times with a diluted solution of live bacteria and some trichoderma fungal spores, since it hard to judge the methods even side by side, if the explants/seeds etc are relatively clean. I think using a standard solution of known contaminates would be useful in determining how effective a method is. Any opinions concerning this?
steve
 
Sounds like a very sound protocol and continued good luck to you; though I would be cautious, in the long run, of 1:2 MS, since the ammonium nitrate concentration, toxic to Nepenthes, is quite high -- some 1650 mg / L at full strength in some formulations. I generally limit it to 1:4 or 1:3; or make my own media . . .

Wow, I didn't know that. Thanks so much for the pointer!

I've just been doing either seeds or small seedlings, so this is encouraging. It would be nice to develop a good disinfecting protocol. I been trying out various
disinfectants/times with a diluted solution of live bacteria and some trichoderma fungal spores, since it hard to judge the methods even side by side, if the explants/seeds etc are relatively clean. I think using a standard solution of known contaminates would be useful in determining how effective a method is. Any opinions concerning this?
steve

Hm, that sounds interesting! Yes, I think it'll be great if the minimum concentration required to kill the microbes could be determined, in order to minimize damage to the explants/seeds. When I used 6 mL bleach in 100 mL water to sterilize the shoot tip explants, all were free from contamination, but the explants themselves were quite damaged, so I was wondering if that was an overkill. Which is why I decided to reduce the bleach in half for my second attempt.
 
  • #10
Oh, and it also depends so much on what stuff of interest is to be disinfected. A sterilization protocol that is too harsh for one type of explant, may be perfectly fine for others.... For instance, here are shoot tip cultures of chocolate cosmos sterilized with 6 mL household bleach in 100 mL water for 15 min. After just a week of culture, they are growing strongly and seem to be unharmed at all.
35407223864_916b983d86_b.jpg


35407222944_0c68c0ef1e_b.jpg
 
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  • #11
Quick update:

One-week old shoot tip cultures, using 3% instead of 6% household bleach (v/v) as surface sterilant


Three of the cultures look pretty good.
35407233054_3371965e8f_b.jpg


Two have bacterial contamination, not sure if it's internal infection or just some bacteria that the surface sterilization simply missed.
36243493195_e4ee36c44c_b.jpg




Five-week old culture of shoot tips, using 6% household bleach (v/v) as surface sterilant

After 3 weeks in hormone-free medium, plus 2 weeks in multiplication medium, only the lower right explant shows definite growth.
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Progress of 5-week old culture using intact shoot as explant

Before and after photos, after 2 weeks in multiplication medium.
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35848515500_abe7fb5a79_m.jpg

Cloudiness in the "after" photo is condensation on test tube surface. The black patch on the leaf is 5-week old damage incurred during surface-sterilization of the explant with bleach.

Here's a clearer shot taken from a different angle.
35848515630_2c1407f6a6.jpg
 
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  • #12
Very nice work -- and I would expect that the contamination was simply a surface sterilization issue. I don't think that I've ever seen internal bacterial issues from with a dissected plant or basal . . .
 
  • #13
(Hardy is taking down notes and really grateful for the input....)

Thank you :)
 
  • #14
An update:

3-week old shoot tip cultures, using 3% instead of 6% household bleach (v/v) as surface sterilant

Out of five explants, only two sterile cultures are obtained. The one on the left has begun to grow. The other one still looks pretty good.
36241238405_c63b046867_b.jpg


The contaminated cultures.
36241237495_013d23eb3d_b.jpg

The leftmost culture seemed clear of any infection in the first 2 weeks of culture, but later developed fungal growth from within the explant itself. The whole tube was taken over within a week. The other two developed bacterial growth within the first week of culture, but the infection seems benign. In fact one of the explants is positively growing despite the bacterial contamination.
36241236425_979951ca3d_b.jpg




7-week old culture of shoot tips, using 6% household bleach (v/v) as surface sterilant

After 3 weeks in hormone-free medium, plus a month in multiplication medium, some of the shoot tips are dead and the surviving ones definitely don't look happy. Perhaps I shouldn't have transferred these to the multiplication medium so soon.
36241239555_05b770a4b6_b.jpg




7-week old culture using intact shoot as explant

After 3 weeks in hormone-free medium, plus a month in multiplication medium, there is one confirmed axillary shoot, which I'm very glad to see :) There are other protuberances on adjacent leaf bases, but it's still too early to tell if those are axillary shoot or callus.
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  • #15
Good accessible thread :) Thanks for also documenting those that failed.

Also, I'm excited and hope this means there will be more campies on the market one of these days!
 
  • #16
Very nice progress. I ran into that same issue, having introduced shoot tips into multiplication media, either too early; or, with an excessive level of cytokinins . . .
 
  • #17
Good accessible thread :) Thanks for also documenting those that failed.

Also, I'm excited and hope this means there will be more campies on the market one of these days!

Thanks for the kind words. Yup yup, I do hope to mass-propagate it and one day spread it far and wide so that everyone can grow this very nice plant :)

36074477842_c35922a35c_z.jpg



Very nice progress. I ran into that same issue, having introduced shoot tips into multiplication media, either too early; or, with an excessive level of cytokinins . . .

Thank you, BigBella. I've been patiently waiting for the shoot tips to grow in hormone-free medium. So far they're still alive but extremely slow....

Here's the only two shoot tip explants that are sterile and still survive after 8 weeks
35407313934_19b7b93819_z.jpg


36074412212_45785790a3_z.jpg

More patience needed I guess!


On the other hand, taking intact basal shoot as explant is so much faster. I did not document this the first time round, but here's the method I use to prepare a basal shoot explant.
35407231344_6d85802c74_b.jpg


35407230594_4b96af3fd6_b.jpg


I cut the basal shoot taking with it a sliver of wood from the mother stem. The sliver of wood was removed from the explant after the last rinse in sterile water, just before the explant was stuck in the agar medium.
35407229664_0bdd86713e_b.jpg


Here's an update of the lone basal shoot explant that survives, looking good so far. When the culture was 3 weeks old, and the same culture 9 weeks later at 12 weeks old.
35848593500_cd9b5b6871.jpg
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In comparison with the shoot tip cultures, this one has grown by leaps and bounds. I've found that the multiplication rate is 4X during these 3 months. Meaning, I can take 4 intact shoot explants from the culture and start the process all over again. But the biomass has definitely more than quadrupled during this period. There's some proliferation of callus on top of the 4 shoots produced. So if I can get the callus to form shoots then the multiplication rate is theoretically greater than 4X.

Strong shoots originating from lateral buds.
35848593330_725eb302c6_b.jpg


There's also some callus near the leaf bases beginning to form what looks like tiny shoots. Possible somaclonal mutants among them?
35848591560_ea20340444_b.jpg


In this pic you can see the lower leaf axils cracked from the expanding stem girth. There's also a couple roots growing from the callus.
35848592540_271d0d595d_b.jpg


Root close-up
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I think this culture will soon be ready to divide. :)
 
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  • #18
This is beautiful work Hardy. What is the strength of your benlate solution? Also if you don't mind me asking, is your "household bleach" 5% NaClO? Lately I've noticed that household bleach in the US is now 8%, instead of the ~5% it used to be. Thanks in advance--
 
  • #19
Thanks for your kind comment :) Well believe it or not, I don't measure the concentration of the benlate solution. I simply strive to prepare a milky suspension so I can't say for sure but it's definitely more than the recommended 1g/L for spray applications. In my experience benlate has very low toxicity to plants. I even generously apply the powder or as concentrated paste to open wounds of my nep, orchid, roses etc with little if any ill effects. If you want to be conservative, then you may like to start with 1 g/L but I think you can safely double or triple that. Here's some old photos, which shows how I prepare benlate solution for rose grafting.

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As you can see, I use much lower concentration in that case and strive to get just cloudy suspension for rose grafting, but for disinfecting nep explants I strive for 'milky'.

As for household bleach I think it's between 5% - 6%? I will have to double check at the lab tomorrow. Will be glad to clarify if you have more questions :)
 
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  • #20
I've checked and the concentration of the household bleach is 5%-6% NaOCl. Cheers.
 
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