Talk:Paclobutrazol

Recent biochem changes

Hello Michael D. Turnbull thank you for reminding me to come in and help here. Glad to work with you. I think we should restore some of these which I gather you thought were primary sources. Specifically Liu et al., 2018, Zhou et al., 2021, Hajihashimi 2021, Jeger 2004 are reviews that I added. (I agree with keeping Kamran because it has Wakjira next to it.) And could you add the page number for However, in normal use, there is no selective pressure on plants to develop resistance to PBZ since it is not lethal to them. in Tanaka? Invasive Spices (talk) 7 April 2022 (UTC)

@Invasive Spices: Before we can proceed, we need to understand why Convolvulus sepium has restored so much of what I removed yesterday, creating duplication of information and adding screeds of poorly cited primary material. The article has become bloated and unencyclopedic. I hope that they will engage with us here to help trim it back to be more informative. As to your query about the page number, there is none, I added the comment about selective pressure as a statement of what is obviously true. I would be happy to delete it if you believe it's too close to WP:OR. Mike Turnbull (talk) 10:03, 8 April 2022 (UTC)

Yes certainly I agree. Convolvus sepium needs to explain these changes. The lack of communication is a problem. Invasive Spices (talk) 8 April 2022 (UTC)

Thanks for notifying them on their Talk Page, Invasive Spices: I was going to do so given that they have continued to edit the article today. Storchy may also like to comment. Mike Turnbull (talk) 16:52, 8 April 2022 (UTC)

There seems to be a consensus here for reverting the re-addition of poorly written, poorly sourced content. As I replied to User:Michael D. Turnbull at my talk page, this looks very much like some students on an assignment, with their instructor not going through the usual procedures outlined at Wikipedia:School and university projects. Storchy (talk) 18:28, 8 April 2022 (UTC)

Storchy, despite your recent noble efforts, the article is still a total mess in ways I don't want to list here as that would just be a waste of our time. My proposal is to revert it to this oid from 7 April and then work forward to tackle some of Invasive Spices' concerns (see sections below). We've heard nothing from Convolvulus sepium since placing pleas on their Talk Page so I would also propose reverting on sight any future edit they make here unless and until they engage with us. Is this OK with you? Mike Turnbull (talk) 12:21, 13 April 2022 (UTC)

Too right it's still a total mess. Revert it with all speed please. Storchy (talk) 12:50, 13 April 2022 (UTC)

 Done. We can now move on. Mike Turnbull (talk) 13:28, 13 April 2022 (UTC)

As for the text we don't need to take it out but I just wanted to be certain about where <ref name="Tanaka"> should be placed. Invasive Spices (talk) 8 April 2022 (UTC)

Tanaka source and a suggested replacement

@Invasive Spices: I've now had time to look at the Tanaka reference (available as ) All it says about PBZ is The loss-of-function gai allele, gai-t6, has wild-type features, but has slightly increased resistance to a GA-biosynthesis inhibitor, paclobutrazol, in vegetative growth (49). The word "slightly" worried me, so I drilled back to the reference 49. That's a much better and highly cited paper (look for "PAC" within it). I think we should recast the "Resistance" section to emphasise how PBZ has been used as a tool to understand the genes involved in GA biosynthesis, rather than focus on any potential loss of PBZ's efficacy when used as described in the "Usage" section. In that respect, PBZ is unlike other pesticides: resistance can be useful! You are the expert on the topic, so maybe you would like to compose something, based on Peng et al. I don't think we should actually be adding to the article any more until Convolvulus sepium joins us: I've added a long plea on their TP today. Meanwhile, I'll continue with other comments to discuss the reviews you wanted to add back, in another section Mike Turnbull (talk) 16:26, 10 April 2022 (UTC)

References

• I have no problem also adding Peng - that is the same Peng I was referring to. I was only being lazy. I thought Tanaka would be enough because Tanaka is an Annual Review and so certainly does establish Peng's notability, while Peng by itself would not. Similar to your edit keeping all the secondaries, Tanaka certainly is an RS.

I agree that the resistance I describe doesn't necessarily belong in "Resistance", for the reasons you point out. I did it that way because it is literally resistance so that isn't technically incorrect, and because in the future this could be used to predict resistance mutations in other plants. However you are correct that right now Peng is only an investigative tool to dissect hormonology. So I'll rewrite that more accurately down the road, as soon as we get CS figured out. Invasive Spices (talk) 10 April 2022 (UTC)

Steviol and paclobutrazol

Invasive Spices added a sentence in this diff which read: In Stevia spp., Hajihashemi et al., 2013 find that Paclobutrazol inhbits transcription of steviol glycoside synthesis genes. This is believed to reduce steviol content in the final plant product.

References

As part of a later edit I removed that sentence and now have been asked to justify the removal. Although I don't have access to the two full references, I saw from the graphical abstract of Zhou et al. that steviol is biosynthetically derived from ent-kaurene in the endoplasmic reticulum and so inhibition of its production (by "KS" in that diagram) not surprisingly reduces steviol content. That means that PBZ is of no utility in Stevia cultivation and hence I don't think that the Wikipedia article needs to mention this: there are loads of things PBZ can't be used for and this one is not remarkable! Mike Turnbull (talk) 10:54, 13 April 2022 (UTC)

Zhou says:

In addition, other researchers studied the transcription levels of KS, KO, KAH, UGT85C2, UGT74G1, and UGT76G1 by treating stevia plants with polyethylene glycol (PEG), paclobutrazol (PBZ), and gibberellin (GA). The results showed that PEG and PBZ significantly reduced the transcription levels of KO, UGT85C2, and UGT76G1. Among them, the content of Reb A was significantly reduced, which was attributed to its precursor and transcription of UGT76G1 (Hajihashemi et al. 2013).

Hajihashemi 2021 says:

The biosynthesis pathway of steviol glycosides shares some steps with the gibberellins biosynthesis pathway. In /S. rebaudiana/, kaurene synthase (KS), kaurene oxidase (KO), and kaurenoic acid 13-hydroxylase (KAH) enzymes convert copalyl pyrophosphate into the precursor of steviol. Then, several UDP-dependent glucosyltransferases (UGTs) produce different steviol glycoside molecules by glucosylation of steviol precursor (Hajihashemi et al., 2013; Brandle and Telmer, 2007).

and

The gibberellin treatment increased the transcription of /ent-KO/, /ent-KS1/, /ent-KAH/, /UGT76G1/, /UGT85C2/, and /UGT74G1/ genes and subsequently total steviol glycoside levels, whereas paclobutrazol, a gibberellin biosynthesis inhibitor, decreased the gene transcription and steviol glycosides (Hajihashemi et al., 2013; Hajihashemi and Ehsanpour, 2013; Hajihashemi, 2018).

This may be more directly relevant to the synthase than to steviols. I think that the interest Hajihashemi 2013 has attracted justifies some mention somewhere. (Note that I did not include another review Jain et al., 2014, "BIOTECHNOLOGY AND METABOLIC ENGINEERING OF STEVIA REBAUDIANA (BERT.) BERTONI: PERSPECTIVE AND POSSIBILITIES" because I thought that would be hard to defend. Although the journal is... not one I would normally read... this review (Jain) itself has attracted several very good citations, including several Elsevier books.) The bigger picture in Hajihashemi is PBZ's syndrome mimicking a stress syndrome - drought stress. I mentioned only steviols because I know what that is and I find it interesting, while drought stress I know less about. The right outcome may be some text about Hajihashemi in the synthase article and not here. Invasive Spices (talk) 13 April 2022 (UTC)

Yes, agreed that something is worth putting in the synthase article. I only recently added "is inhibited by paclobutrazol." to Ent-kaurene oxidase and that article is in need of expansion. If you can craft a bit for this article too, I certainly won't object. Mike Turnbull (talk) 09:48, 14 April 2022 (UTC)

I have added this to the synthase. Invasive Spices (talk) 16 April 2022 (UTC)

PBZ and lodging of cereals

In the same diff as mentioned in the previous section Invasive Spices added: Peng et al., 2014 produce better lodging tolerance using paclobutrazol. They find that winter wheat undergoes reduction of internode length, thickened internodes, increased lateral growth, increased lignin synthesis enzyme activity and therefore increased lignification with application of this compound. Although this does not reduce lodging it does make lodging less harmful.

References

The article certainly needs to mention use of PBZ against lodging but we need to avoid WP:CITEKILL. There are lots of possible references, since even in 1985 it was known that this was a useful effect. I'm happy with the three current references against the phrase "PBZ can increase grain yields and reduce potential for lodging." but have no objection to adding back Liu 2018 if Invasive spices thinks it adds recency and depth, as well as being open-access. I don't think that the text about Peng 2014 is needed as that's just one of many, many primary sources. Mike Turnbull (talk) 11:46, 13 April 2022 (UTC)

The second and third refs are studies and so I don't know if they belong here at all. (They may be well cited or not. I haven't checked.) Tesfahun is good. As for Peng I mentioned it because I looked around for PBZ research and that was one of/the most highly regarded. I then cited Liu instead of Peng itself to show how it's regarded by a secondary, but really there are 5 more reviews and books besides Liu showing Peng is widely regarded as essential to understanding the PBZ+lignin situation. I think Peng is one of the best studies we could possibly talk about here. If we have bloated text I think we should nonetheless save Peng above all/many others. Invasive Spices (talk) 13 April 2022 (UTC)

Yes, I absolutely agree that Peng 1997 should be our focus. When writing in articles on subjects that are obviously notable (i.e. paclobutrazol itself) I prefer to quote whatever source is most relevant overall (and Peng has been cited over 1000 times) even if it could arguably be "primary" — which it isn't entirely as it includes a good review of earlier studies — and I don't choose one later review to cite back the reference, as once I'm personally convinced of the merit of in this case Peng I don't feel the need to show anyone else that their publication meets WP:GNG, as that's not very relevant. So, go ahead and tweak the text + references we use as you think best. Mike Turnbull (talk) 10:00, 14 April 2022 (UTC)

And I have put Peng back in. Uncertain what would constitute overkill, I have tried a cite bundle. This does include all 6 worthwhile secondary cites of Peng, but is not ugly. Is this good? Although you and I are now satisfied of Peng's importance, these secondaries will settle that question for others in the future. Invasive Spices (talk) 16 April 2022 (UTC)

I forgot to mention that I also checked the #2 and #3 refs for "lodging" and retained them - in fact they were referenced by Tesfahun. That's why Tesfahun was cited with them. I also noticed that they are cited by Desta & Amare 2021 so I added refs to show that. Invasive Spices (talk) 17 April 2022 (UTC)

@Invasive Spices: Thanks for changing the section name to "As research tool" today: I had forgotten to do that. Looking again at the article now that I've installed the script that highlights unreliable sources, I see that the MDPI ones you put into the bundle (currently #24 and here in this Talk Section) are marked as "borderline" (i.e. probably unreliable as they are/were part of Bentham Open). I'm not enough of an expert on these to judge but perhaps you would like to review them — that bundle probably doesn't need them all in any case. Mike Turnbull (talk) 13:38, 2 May 2022 (UTC)

@Michael D. Turnbull: If I understand correctly that tool only marks entire journals. In this case these particular reviews are well regarded by other, definitely reliable reviews. I did try to leave <!---> comments to that effect but on a second read I see they barely explained anything. I hope I have corrected that. (Certainly they should not all be necessary, yes. Hopefully no one in the future would argue against such a strongly supported primary (Peng).) Invasive Spices (talk) 2 May 2022 (UTC)

The issue here is that MDPI is more concerned about churning out as many articles as possible, rather than with ensuring proper review of what they published. They've sacked editors for being too selective about what they publish, and will churn out an insane number of special issues. The International Journal of Molecular Sciences for example, has over 500 special issues per year in 2019. Most of their journal average over 100 special issues per year. These journals are bottom-tier quality, with at best nominal peer-review. Headbomb {t · c · p · b} 00:31, 3 May 2022 (UTC)