2
$\begingroup$

This answer to Is there any particular reason to choose strawberries for DNA extraction? explains that strawberries are octoploid. Wikipedia's Polyploidy and Morus nigra; Description both point out that Morus nigra or black mulberry is tetratetracontaploidic and cite two sources that both point to a third source in Plos One; Zheng et al. (2015) Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny.

There, Table 1 includes KF784875, M. nigra with Chromosome number (Ploidy) of 308(44)*

So far I have not been able to find the author's meaning for the asterisk following the ploidy value, nor any further sourcing for the assertion of tetratetracontaploidy.

I am supposing that somewhere there will be some actual measurement, either using direct optical/floorescence or electron microscopy imaging or some clever molecular biology that established tetratetracontaploidy, but so far I can't find it.

Question: How do we know for sure that Morus nigra (black mulberry) is tetratetracontaploidic?


Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny; Table 1, Plant materials used in this study. click for full size

$\endgroup$
3
  • $\begingroup$ Ref 8 in your linked PLoS article looks relevant; says docosaploid (308), lots of references therein on cytological studies. $\endgroup$
    – bob1
    May 15 at 2:54
  • $\begingroup$ @bob1 Yes, the title sounds promising doesn't it! However, I was disappointed after I read it. Perhaps you can find something there that I missed? jircas.go.jp/en/publication/jarq/18/3/222 Many of the interesting-sounding references in that 1985 paper are in Japanese. When I get to campus this morning I will try to access some of those references and the try to google translate them if they are text (and not images of pages of text). $\endgroup$
    – uhoh
    May 15 at 3:01
  • 1
    $\begingroup$ There's ref 9: Seki H. “Cytological studies on mulberry, Morus. Part I. polyploidy of the mulberry trees, with special reference to spontaneous occurrence of triploid plants.” J. Fac. Textile and Sericulture, Shinsha Uni., Jpn, 20 (1959): 58-60. Can't find the paper yet though $\endgroup$
    – bob1
    May 15 at 3:10

1 Answer 1

4
$\begingroup$

The linked paper in the question has reference 8:

  1. Toyo I (1985) Research of polyploidy and its application in Morus. Japan Agricultural Research Quarterly 18: 222–228. PDF here

This paper mentions a study by Seki in 1959 with the title Cytological studies on mulberry, Morus. Part I. polyploidy of the mulberry trees, with special reference to spontaneous occurrence of triploid plants. I was unable to find this reference in any usable form, but searches for it came across this paper:

  1. Yamanouchi H, Koyama A, Machii H (2017) Nuclear DNA amounts of mulberries (Morus spp.) and related species. Jpn Agric Res Q JARQ 51(4):299–307 PDF here

This paper, along with reference to Seki (though not the one above), contains a couple of further references, one of which is relatively recent:

polyploidy can extend to docosaploidy (2n = 22x = 308) as in M. nigra (Basavaiah et al. 1990, Darlington & La Cour 1947, Seki & Oshigane 1960).

Basavaiah et al is available online (PDF here) and is a cytological study of Morus nigra, which states:

During anaphase II, 154 chromatids were clearly discernible moving to the respective poles (Figs. 9 and 10).

and supplies Figs 9 and 10 (screen shot from paper. See full reference below):

anaphase Morus nigra

Full reference:

  1. Basavaiah et al. (1990) Meiosis in natural decosaploid (22x) Morus nigra L. Cytologia (Tokyo) 55, 505-509.

I managed to dig out the Seki and Oshigane paper via a Japanese website. The references in the various papers to this paper have the journal as J. Fac. Text. Seric. Shinshu Univ., which it turns out has the full name of Journal of the Faculty of Textiles and Sericulture Shinshu University. This lead me to the University's SOAR page and a text search for the article title (Note the name Morus nigra in the last link on the search) led me to the article itself in PDF form. The article is written in Japanese but has an English summary at the end, with the text:

(1)The chromosome number of the somatic cells of Morus nigra is 2n is 308 and 22x as the basic chromosome number of Morus is 14. This confirmed the reports of Thomas,Darlington and La Cour(1942).

  1. Seki, H. & Oshigane, K. (1960) Studies in polyploid mulberry trees. (IV) Cytological and morphological studies on Morus nigra L. J. Fac. Text. Seric. Shinshu Univ. 10, 7-13

To me this means they are basing the number of chromosomes on the genus as a whole rather than a measurement of the chromosomes in the species itself. You can also view the Darlington and La Cour reference from my first quote at Archive.org (1942 edition) which shows a chromosome spread with n=308 in plate IV(top)

  1. Darlington, C. D. & La Cour, L. F. (1942) In: The handling of chromosomes (2nd ed.) p92 & plate IV, George Allen and Unwin, London
$\endgroup$
6
  • 1
    $\begingroup$ For once, the rabbit hole of link to link to link... worked! $\endgroup$
    – bob1
    May 15 at 3:30
  • $\begingroup$ That's such a beautiful series of meiosis micrographs in Basavaiah et al. 1990. There's also an archived copy in case that link breaks at some point down the road. Thank you for your successful rabbit hole exploration! $\endgroup$
    – uhoh
    May 15 at 8:43
  • $\begingroup$ I've just realized this doesn't actually answer the question of n=22 tetratetracontaploidic, looks like it is publications from Janakai Ammal, a widely respected Indian woman cytogeneticist and Seki. I can't access either of the publications online though. $\endgroup$
    – bob1
    May 15 at 9:18
  • 1
    $\begingroup$ @uhoh Yes, confirmation of the actual number of chromosomes, not the copies. The Yamanouchi paper says 2n = 22x=308, so 2n = 14, but confirming that it is actually 14 not 11 or 22 or even 77 (all being factors of 308), unless that number is based on a basal n for the genus. I can see Janakai Ammal working it out through careful analysis, she really was the expert on this at the time. $\endgroup$
    – bob1
    May 15 at 21:17
  • 1
    $\begingroup$ @uhoh updated with some findings. $\endgroup$
    – bob1
    May 16 at 3:13

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .