Cytogenetics and reproductive behavior of induced and natural tetraploid guayule (Parthenium argentatum Gray)

Abstract

1989. Cytogenetics and reproductive behavior of induced and natural tetraploid guayule (Parthenium argentatum Gray). Genome, 32: 1 100 -1 104. Tetraploid guayule (Parthenium argentatum Gray) plants with 72 chromosomes were obtained by colchicine application to the shoot apices of the diploid (2n = 36) seedlings. Interspecific hybridization of guayule as female with Parthenium rollinsianum Rzedowski (2n = 36) was used to compare the mode of reproduction of the induced tetraploids with that of natural tetraploids. Plants produced from crosses of induced tetraploid guayule and P. rollinsianum were all hybrids. Hybrid plants showed 2n = 54 chromosomes, indicating that the artificially produced tetraploids reproduce sexually. Interspecific crosses between natural tetraploids and P. rollinsianum produced predominantly maternal type progeny. This suggests that the apomictic mode of reproduction in guayule is a consequence of mutations which accumulated in the natural polyploids. Diploid guayule plants showed regular meiosis with an average of 14.86 rod and 3.14 ring bivalents. Induced tetraploids produced 0.25 I, 29.2 1 11, 0.13 111, and 3.24 IV. In comparison, natural tetraploids showed 1.20 I, 30.85 11, 0.06 111, and 2.23 IV. The frequency of multivalents, which was limited in the induced tetraploids, showed further reduction in natural polyploid guayule, which may indicate diploidization in these plants. Percent pollen stainability was 98.5 f 1.03, 83.7 f 12.24, and 89.5 f 3.4 1 for diploids, induced tetraploids, and natural tetraploids, respectively. Both induced and natural tetraploids had larger capitula, achenes, and pollen and thicker leaves than the diploids.Key words: guayule, natural rubber, reproductive behavior, meiosis, polyploid induction. 5HASHEMI, A., ESTILAI, A., et WAINES, J. G. 1989. Cytogenetics and reproductive behavior of induced and natural tetraploid guayule (Partheniurn argentatum Gray). Genome, 32 : 1 100 -1 104. Des plantes tktraploides de guayule (Parthenium argentatum Gray), ayant 72 chromosomes, ont Ct C obtenues par traitement h la colchicine des apex de tiges de plantules diploides (2n = 36). Une hybridation interspkcifique entre la guayule comme parent femelle et le Parthenium rollinsianum Rzedowski (2n = 36) a Ct C utilisCe pour comparer le mode de reproduction des guayules tCtraploides induits et celui des tCtraploides naturels. Les plantes rCsultant du croisement entre le guayule tetraploide induit et le P. rollinsianum se sont toutes av6rCes hybrides. Le nombre chromosomique de ces hybrides a Ct C de 2n = 54, ce qui indique que les guayules tCtraploides produits artificiellement se reproduisent sexuellement. Les croisements interspkcifiques entre les tCtraploides naturels et le P. rollinsianum ont produit une descendance qui Ctait de type maternelle de f a~o n prkdominante. Ceci suggkre que le mode apomictique de reproduction chez les guayule est une conskquence des mutations qui se sont accumulCes chez les polyploides naturels. La mCiose chez les plantes de guayule diploides a Ct C...

Cytogenetics in Plant Breeding

“…A few, rather arbitrary examples are auto hexaploid Phleum pratense (Nordenskiold 1953), possibly an autoallopolyploid; several potato strains; Vaccinium corymbosum, where four enzyme loci showed clear tetrasomic inheritance but no quadrivalents were observed (Krebs and Hancock 1989); the very low quadrivalent frequency in artificial and natural autotetraploids of Parthenium argentatum (Hashemi et al 1989) and the natural tetraploid Heucheria grossulariafolia (Wolf et al 1989); low quadrivalent frequencies in Hyoscyamus species ). A few, rather arbitrary examples are auto hexaploid Phleum pratense (Nordenskiold 1953), possibly an autoallopolyploid; several potato strains; Vaccinium corymbosum, where four enzyme loci showed clear tetrasomic inheritance but no quadrivalents were observed (Krebs and Hancock 1989); the very low quadrivalent frequency in artificial and natural autotetraploids of Parthenium argentatum (Hashemi et al 1989) and the natural tetraploid Heucheria grossulariafolia (Wolf et al 1989); low quadrivalent frequencies in Hyoscyamus species ).…”

“…When it is normally around the middle of the chromosome, little reduction in effective chiasma formation and the resulting metaphase association in ring quadrivalents or ring bivalents is expected. Examples of low quadrivalent frequencies and a majority of open bivalents are the natural and induced autotetraploids of Parthenium argentatum (Hashemi et al 1989) and the natural autotetraploid of Heuchera grossularia[olia (Wolf et al 1989), which shows clear tetrasomic inheritance but low quadrivalent frequencies and a predominance of open bivalents (Table 11.1). In a somatic tomato (Lycopersicon esculentum) hybrid (4x = 48), de Jong (pers.…”

“…6.4), but that they were concentrated in the subterminal euchromatic regions, with occasionally one in each arm, infrequently even more. Meiotic chromosome associations in diploid (A), and natural (B) and induced (C) autotetraploids of Parthenium argentatum, x = 18, about 100 cells each (Hashemi et al 1989), and of the natural (D) autotetraploid (45 cells) of Heuchera grossulariafolia, x = 7, 45 cells (Wolf et al 1989), all tetraploids with low quadrivalent frequencies and high open bivalent frequencies, E expected for Heuchera when quadrivalent pairing = 0.647, one arm association frequency = 1, the other = 0.092 after quadrivalent and bivalent pairing In Table 11.1 the expected configuration frequencies are given for Heuchera, on the basis of an estimated quadrivalent pairing frequency of 0.647, and chiasmate association frequency of one arm = 1 and of the other arm = 0.092. Examples of low quadrivalent frequencies and a majority of open bivalents are the natural and induced autotetraploids of Parthenium argentatum (Hashemi et al 1989) and the natural autotetraploid of Heuchera grossularia[olia (Wolf et al 1989), which shows clear tetrasomic inheritance but low quadrivalent frequencies and a predominance of open bivalents (Table 11.1).…”

“…Another example where apomixis occurred in polyploids without polyploidy being the cause of apomixis is that of Hashemi et al (1989), who compared the natural diplosporous and pseudogamous apomictic autotetraploid (4x = 72) Parthenium argentatum (the rubber-producing guayule) with the artificial autotetraploid (4x = 72) made from the natural diploid Parthenium argentatum (2x = 36). They observed that the artificial tetraploid, after crossing with the highly compatible, related but morphologically distinct, diploid P. rollinsianum (2x = 36), always formed triploid 3x = 54 progeny.…”

Karyotype and Chromosome Morphology of Parthenium argentatum.

“…These include analyses of ploidy (Bergner 1944(Bergner , 1946 and its relation to interspecific hybridization and pollination (Powers and Rollins 1945, Rollins 1945, Hashemi et al 1989, chromosome pairing (Hashemi et al 1986), B-chromosomes (Bergner 1946, Catcheside 1950, apomixis (Bergner 1944, 1946, Gerstal et al 1953, Bashaw 1980) and species and cultivar verification (Rollins 1950, Tysdal et al 1983, Brown and Zaiger 1987. Although meiotic chromosome morphology has been examined (Bergner 1944, 1946, Stebbins and Kodani 1944, Hashemi et al 1989a, data on mitotic chromosome morphology has been scanty, due, in part, to small chromosome size. As a result no karyotype of guayule has been published.…”