Thursday, December 30, 2010

Hallucinatory hybrid with branched hairs

Yes, the Asplenium X helii nothosubsp. lainzii is an allotetraploid hybrid really amazing, the ultimate rarity of genetics, a cross that seems impossible. At the same time their parents are also two pteridological  rarities genetically speaking, two fertile autotetraploid: Asplenium petrarchae ssp. petrarchae and Asplenium trichomanes ssp. quadrivalens, with a doubling in their nuclear genome.

Asplenium X helii nothosubsp. lainzii patch on a wall facing west to the deep shadow of several olive and mastic in December. All around you can see several copies of one parent, the Asplenium trichomanes ssp. quadrivalens. Photo taken in a patch of Puig den Ramis Valley of Soller on Mallorca.
This hybrid has been found on the island of Mallorca, Tarragona and the Sierra de Cazorla in Jaen, living in the same habitat with their parents. When grown in a brightly lit place with a clear heliofobia, applying their fronds to the stones in an attempt to avoid strong light. Its fronds are up to 20 inches with the blade lanceolate longer than the petiole.

Fine specimen of Asplenium X helii nothosubsp. lainzii in the way of "Ses Tres Creus" Valley of Soller on Mallorca Island, photographed in February. It grows in a patch wall oriented toward the northwest in the shade of an old locust tree. (Double click on the photo to enlarge)

Another copy of this incredible hybrid on the road "Sa Coma Soller Valley. It grows in a patch wall facing north in the shade of an almond tree.

And here's their complex family tree:

Asplenium petrarchae ssp. bivalens          Asplenium trichomanes ssp. trichomanes
                 ( PP                                                                        ( TT )
                              l                                                                                                                           l
                              l                                                                                                                           l
               ( Apomeiosis )                                                                                        ( Apomeiosis )
                              l                                                                                                                          l                      
                              l                                                                                                                          l
                             V                                                                                                                        V 
A.  petrarchae ssp. petrarchae ----> X <---- A. trichomanes ssp. quadrivalens
              ( PPPP )                                     l                                ( TTTT )
                                                                 ( Hibridación interespecífica ) 
                                              Asplenium X helii nothosubsp. lainzii      .........................
                                                                   ( PPTT )

His grandparents are two normal diploid ferns. At some point in their evolution, perhaps millions of years ago, suffered a mutation in the gene encoding the meiosis, called apomeiosis, which blocked the meiosis in sporangia (reduction of chromosomes in half) and in its place produced a normal mitosis. A consequence of this anomaly spores produced by the mutated sporangia haploid rather than diploid were normal. When germinated giving rise to diploid gametophytes, which produce diploid gametes (oosphere and anterozoides) and after fertilization arose a tetravalent hybrid fern with two identical genomes in the nucleus of cells.

Just so you understand, the case of grandparents autotetraploid is like a human sperm were diploid instead of haploid and carry 46 chromosomes instead of the 23 normal and turn the female egg and carry well beyond the 46 diploid chromosomes the mother. Upon egg fertilization generate a tetraploid with 46 pairs of chromosomes, that is, with 92 chromosomes, all of the father and all of the mother. In human genetics this aberration would not be viable reproductive and egg tetravalent die. In contrast, in the ferns and flowering plants in many of these aberrations are relatively frequent and perfectly feasible, at least in the first generation individuals.

His cousin brother, Asplenium X orellii also allotetraploid, son of Asplenium Asplenium trichomanes majoricum and ssp. quadrivalens, has a phenotype very similar macroscopically, but no hairs or glandular trichomes, while the X Asplenium helii nothosubsp. lainzii is covered with pilosity abundant in the petiole and the proximal third of the blade, inherited from his father Asplenium petrarchae ssp. petrarchae.

Frond of Asplenium X helii nothosubsp. lainzii with a phenotype is exactly half that of their parents. Rachis dark brown almost black, green only in its apical end, it has inherited from his father Asplenium trichomanes ssp. quadrivalens. The pinnae also look through, although they are more like those of its parent petrarchae Asplenium ssp. petrarchae.

Another frond of this remarkable hybrid. In this issue the pinnae are typically of a parent Asplenium petrarchae ssp. petrarchae, but lack of hairs, but the most proximal. (Double click on the photo to enlarge)

To turn one of its fronds see that the sori are rather scarce and have a similar distribution to that of Asplenium petrarchae ssp. petrarchae. Draws much attention to the spine bright and very dark, almost black, heritage Asplenium trichomanes ssp. quadrivalens. (Double click on the photo to enlarge)

Macro image with details of sori on the underside of a frond with indusium and sporangia up and made after the dispersal of spores. (Double click on the photo to enlarge)

However, what more aid to their identification are the trichomes or glandular hairs, more abundant in the proximal third of the blade and petiole and characteristically multicellular, some of them branched. His father Asplenium trichomanes ssp. quadrivalens no glandular hairs and its parent Asplenium petrarchae ssp. petrarchae has an abundant pilosity, but their hairs or trichomes are unicellular, consisting of a single cell and are never branched tubular.

Glandular trichomes multicellular branching characteristic, exclusive of Asplenium X helii nothosubsp. lainzii, used for its unequivocal identification. To view you need a jeweler's loupe or even better a microscope. (Double click on the photo to enlarge)

Another multicellular glandular hair and bushy Asplenium X helii nothosubsp. lainzii.

Unbranched unicellular glandular hair of his father Asplenium petrarchae ssp. petrarchae, much larger than the hairs of their offspring.

Another beautiful glandular trichomes of Asplenium petrarchae ssp. petrarchae. It is characteristic slightly purple coloration. Tell it the bulb end of the trichome excretory.
Asplenium X helii nothosubsp. lainzii, like most interspecific allotetraploid hybrid, is sterile, because their sporangia are unable to produce viable spores at the time of meiosis. The two genomes that coexist in the nucleus of their cells are so different, so incompatible, that can not be matched to generate haploid spores with a genetic endowment compatible with life and die before maturity, being reduced to very sticky black masses broken .

Sporangium of Asplenium X helii nothosubsp. lainzii with aborted spores and decomposed, which could not be dispersed because they are stuck together. (Double click on the photo to enlarge)

Microscopic image property of the spores of sterile hybrids. They look like black dough broken spores and lumpy.

No comments:

Post a Comment