Journal ArticleDOI
Primary and secondary chromosome balance in Pyrus.
C. D. Darlington,A. A. Moffett +1 more
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TLDR
The pairing, morphology, and breeding results show that the thirty-four chromosomes in the “diploid”Pyrus are of seven types, of which four are represented four times and three are represented six times, which makes it plausible that the Pyrus group owe their special morphological characters to this reorganisation of the nucleus.Abstract:
1.
The basic chromosome number inPyrus is seventeen. Cultivated varieties are all orthoploid. Aneuploid seedlings are poor and abnormal.
2.
The somatic chromosomes in “diploid”Pyrus have four representatives of a long type, in “triploid,” six.
3.
Multiple association occurs amongst the chromosomes of “diploid”Pyrus giving, in extreme cases, seven groups; four quadrivalents and three sexivalents (Table I).
4.
In “triploid” varieties ofP. Malus associations of four, five, six, seven, eight and nine chromosomes have been observed, although trivalents are usually formed (Table II). This means that antosyndesis takes place within each of the three supposed haploid complements.
5.
Instead of giving a binomial frequency or the elimination of intermediate numbers, natural seedlings of “triploid” apples most frequently have numbers of chromosomes approximately to 2n + 7 (Table III).
6.
Thus the pairing, morphology, and breeding results show, directly or indirectly, that the thirty-four chromosomes in the “diploid”Pyrus are of seven types, of which four are represented four times and three are represented six times. Such forms may be described as trebly hexasomic tetraploids (v. diagram, p. 145).
7.
The number seventeen is therefore a secondary (unbalanced) basic number, and the derived series of polyploids (2n = 34, 51, 68) aresecondary polyploids.
8.
The establishment of a secondary basic number must mean (on the analogy of all experimental observations) a definite evolutionary step. It is therefore plausible that thePyrus group owe their special morphological characters (e.g. the pome type of fruit) to this reorganisation of the nucleus. The work is being continued with this consideration in view.read more
Citations
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Journal ArticleDOI
Aligning male and female linkage maps of apple (Malus pumila Mill.) using multi-allelic markers
Chris Maliepaard,F. H. Alston,G. van Arkel,L.M. Brown,E. Chevreau,Frank Dunemann,Kate Evans,Susan E. Gardiner,Parry Guilford,A.W. van Heusden,J. Janse,François Laurens,James R. Lynn,A.G. Manganaris,A.P.M. den Nijs,N. Periam,Erik H. A. Rikkerink,P. Roche,C. D. Ryder,Silviero Sansavini,H. Schmidt,Stefano Tartarini,J.J. Verhaegh,M. Vrielink-van Ginkel,Graham J.W. King +24 more
TL;DR: The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.
Book ChapterDOI
Genetic Variation in Chromosome Pairing
Ralph Riley,C. N. Law +1 more
TL;DR: This chapter discusses the genetic variation in chromosome pairing, which is known to result from genetic variation as well as from differences in several environmental factors.
Journal ArticleDOI
Systematic and evolutionary implications of rbcL sequence variation in Rosaceae
TL;DR: RbcL-based phylogenies suggest that chromosome numbers are more reliable indicators of some generic alliances than the more commonly used fruit types and that the subfamily Maloideae may have descended from spiraeoid ancestors and the pome is derived from follicular or capsular fruit types.
Journal ArticleDOI
Cytological characteristics associated with the different growth habits in the dicotyledons
TL;DR: A systematic review of the chromosomal characteristics of all dicotyledonous genera sufficiently recorded in the literature to test a definite set of characteristics associated with the different growth habits of these angiosperms.
References
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Journal ArticleDOI
A cytological and genetical study of progenies of triploid tomatoes
TL;DR: Page 2, line 21, after Navaschin for "1926" read "1925," and page 41, line 13, after "type" put semicolon instead of comma.
Journal ArticleDOI
The Assortment of Chromosomes in Triploid Daturas
TL;DR: The present article is the one of a number of proposed papers which will deal with the behavior of the chromnosomes in the different classes, of Datura mutants, the correlation of the chromosomal differences with changes in structural and other characters, and with the ratios in which Mendelian allelomorphs are found in the offspring.