Latest / Hydroponics Daily / Florigen - The Flowering Hormone

Transcript

Florigen - The Flowering Hormone · Hydroponics Daily

• 0:00
  Hi, welcome back to Hydroponics Daily with me Dr Russell Sharp and today's topic
• 0:06
  is florigen and florigen is the flowering hormone in plants.
• 0:11
  Now I did a PhD on flowering and I started that in 2000 and it was on flowering in rhododendron.
• 0:19
  So not a model plant species, a very difficult plant to study flowering on.
• 0:23
  A very big plant which doesn't help
• 0:26
  and back then is from 2000
• 0:29
  to 2004 the consensus was that
• 0:32
  florigen probably didn't exist and for
• 0:35
  decades people had been studying flowering
• 0:39
  and and they they'd known that there was a signal that
• 0:42
  was traveling from the leaves to the apical buds
• 0:45
  the apical meristems and initiating flowering when
• 0:48
  in certain day lengths and certain conditions but
• 0:52
  no one had been able to to isolate it and
• 0:55
  characterize it but they knew that it was occurring
• 0:58
  in the leaves what the signal didn't originate in
• 1:02
  the stem because you could cover the the
• 1:05
  apical stems and they would still initiate flowers but if you
• 1:07
  covered the leaves then no flowers would initiate so
• 1:10
  you have short day plants that flower when the days are short
• 1:13
  or long day plants when the days are long and so
• 1:17
  they knew some sort of signal was traveling now the consensus
• 1:20
  back then was maybe it was a consortium of
• 1:23
  different hormones positive ones and negative ones
• 1:26
  interacting on the apical meristem and rather
• 1:29
  than just one signal and one one hormone and
• 1:33
  then when i finished my phd actually they
• 1:36
  discovered that there was a protein
• 1:40
  that was transported from the leaves to the
• 1:43
  stem and in arabidopsis which is
• 1:45
  the model plant species that protein is
• 1:49
  encoded by a gene called flowering locust tea.
• 1:52
  And flowering locust tea or ft protein is the
• 1:55
  the protein that travels from the leaves to the
• 1:57
  apical meristems and it's a it's a fairly interesting
• 2:01
  way it does it there's a gene called constans and
• 2:04
  that has to build up and build up and and build up to the level where it's it's
• 2:09
  being transcribed it's being processed at a level where suddenly bang the ft
• 2:14
  gene is activated and then it generates this protein and then that's translocated and it flowers.
• 2:23
  So that's what happens in Arabidopsis. Arabidopsis is a long day plant,
• 2:27
  so it flowers under long days.
• 2:29
  Some of you will be growing short day plants and in those plants it will be
• 2:33
  different and the gene might have a different name, but the actual genetics
• 2:38
  will probably be something very similar.
• 2:41
  So there are anti-fluorogens as well so there are,
• 2:47
  protein based hormones that,
• 2:50
  and are antagonistic and work as anti-florogens so
• 2:53
  in arabidopsis that's terminal flowering one
• 2:56
  or tfl1 these are just names they don't mean anything necessarily
• 2:59
  i mean some genes you know have crazy
• 3:03
  names like superman or teddy bear and things like this they're
• 3:06
  just the first thing that they were discovered for
• 3:09
  or the scientists wanted to name them that's what they're called
• 3:12
  and then in somato the anti-florogen is
• 3:15
  called self-pruning or sp1 so obviously self-pruning
• 3:18
  doesn't relate to pruning necessarily so there's
• 3:22
  just a bit of interesting you know about florigen
• 3:26
  and the fact that it's a protein and it's
• 3:29
  been characterized now and it's certainly in arabidopsis not
• 3:32
  in other plants in short day plants it'll be very different so in rhododendron
• 3:37
  is an example of that flowers and exposure to short days and then we for a long
• 3:44
  time we thought gibberellins were important and that's because when you apply gibberellins.
• 3:50
  You can get a massive change in flowering now
• 3:53
  this is a great example it shows that just because
• 3:56
  you apply something and it stimulates a response in the
• 3:59
  plant it doesn't mean that that's the endogenous internal
• 4:03
  thing that controls that in the plant it could be
• 4:06
  that that hormone that you're applying or chemical that you're applying is
• 4:09
  stimulating something else and in the case of gibberellins they're
• 4:12
  more now to do thought to be to do with stem
• 4:16
  elongation these are the these are the and cell elongation
• 4:20
  so when people apply growth regulators they're
• 4:23
  preventing stem elongation and that's acting as an antagonist to gibberellins
• 4:28
  so things like paclibutrazole and prohexodione these are fairly toxic well in
• 4:35
  case of prohexodione nasty chemicals you wouldn't want to eat them because they
• 4:40
  do the same in humans as well. So gibberellins are.
• 4:43
  Were thought for a while to be or indicate were
• 4:47
  you know potential candidates for
• 4:49
  florigen certainly in arabidopsis and then in short
• 4:52
  day plants like rhododendron they were
• 4:55
  antagonistic to flowering and there were there's
• 4:59
  about 130 well last time at well
• 5:01
  when i was doing my phd there were about 130 gibberellins and
• 5:05
  ga5 and ga6 i remember were particularly powerful
• 5:09
  in rhododendron but in the Arabidopsis GA20 GA1
• 5:13
  GA3 these are they were
• 5:16
  these were the most powerful and it was good that the first scientists
• 5:20
  to ever study gibberellins gave them numbers rather
• 5:24
  than names like you know we talked about the proteins and
• 5:26
  the genes like terminal flower and self-pruning and
• 5:29
  FT and constans in gibberellins they
• 5:32
  gave them numbers and that would have been good because the first
• 5:35
  people to to characterize gibberellins they
• 5:38
  didn't know there were going to be 130 so we could have ended up with 130 different
• 5:43
  names for 130 different gibberellins and so that was good so yeah all other
• 5:48
  hormones they don't have numbers things like auxins they have complicated scientific
• 5:52
  names cytokinins all these so yeah i thought that would be interesting.
• 5:58
  And have a look in your your crop has
• 6:01
  florigen been discovered in your crop i think
• 6:04
  one of the major like you know you're thinking about one
• 6:07
  of the things that could be a major breakthrough is
• 6:12
  if you could synthesize synthetically these g
• 6:16
  these proteins like ft protein and you
• 6:20
  could then apply them to crops to make them
• 6:22
  flower that would be massive because you
• 6:25
  could you could suddenly have plants that were really we
• 6:29
  call recalcitrant to flowering suddenly producing
• 6:33
  loads of flowers and that would be massive for the
• 6:36
  both ornamental and edible crops
• 6:39
  imagine being able to suddenly make
• 6:42
  plants flower at a whim and it
• 6:46
  could it could improve conservation there's certain plants that we
• 6:49
  struggle to get to flower like certain cycads and things
• 6:52
  like that that you know we can't produce seeds from because they don't flower
• 6:54
  imagine if you could suddenly make a bamboo flower some of these bamboos take
• 6:58
  60 years to flower suddenly bang you could you You can make them flower on cue
• 7:02
  and things like growing plants for the Chelsea Flower Show and other prestigious
• 7:08
  flowering events would be much easier. I was going to swear then.
• 7:12
  It'd be a lot easier because you wouldn't need to do things like cold treatment
• 7:15
  under control of the photoperiod. You'd just spray on a bit of FT protein.
• 7:19
  So, you know, it'd take a scientist far more clever than me to synthesize synthetic
• 7:25
  FT protein. But watch this space.
• 7:27
  Some clever sausage might do it. and yeah that's been Hydroponics Daily for today Florigen.