Víctor Ferreira

Cytological analysis of hybrids among triticales and trigopiros

We studied three different tricepiros: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F1 was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F 3 individuals. In all F 8 tricepiros (Don Santiago x Don Noé), F 12 tricepiros (Cumé x Horovitz) and F 12 tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids.

Cytological analysis of the Phalaris arundinacea (L.) x Phalaris aquatica (L.) amphidiploids

Abstract The amphidiploid of the hybrid Phalaris arundinacea (L.) x Phalaris aquatica (L.), 2n = 8x = 56 chromosomes, is a high perennial grass with scarce seed production. Using free pollination progeny, we studied the mitosis in root meristems, the meiosis in pollen mother cells, the meiotic index, pollen viability and seed set production. The average of somatic chromosomes was 48,94 ± 2,20, with a range of variation between 41 and 55 chromosomes. In meiosis, the bivalent average was 22,01 ± 2,93, with a wide variation range, frequent univalents and occasional multivalents. Only four cells had 2n = 56; moreover, only one had 28 II. Both cellular divisions allowed to verify high aneuploidy. Asymmetric divisions, laggards and chromosomes bridges were observed in anaphase I. The Meiotic Index varied from 35 to 65% and stainable pollen had very high variation among individuals. Cytological instability, aneuploid gametes and loss of chromosomes contribute to explain the low fertility of the amphidiploid. Polyploid nature and the genome relationships are discussed.

Genetic parameters estimation in quantitative traits of a cross of triticale (x Triticosecale W.)

Abstract Triticale (x Triticosecale Wittmack) is a cereal used in Argentina as a winter seasonal pasture or feeding grain. Efforts made on breeding have led to varieties with potential grain yield similar or greater than with wheat. The aim of this study was to determine the gene effects, heritability, genetic gain, heterosis and inbreeding depression in various quantitative traits of a cross from contrasting lines of triticale using generation means analysis. The thousand kernel weight was adjusted to a model of additive-dominance, while the rest of the traits exhibited significant epistatic effects: additive x additive (i) for hectoliter weight, additive x dominance (j) for number grains per spike and grain yield per plant. Other traits showed a more complex as inheritance additive x additive (i) and additive x dominance (j) interactions effects for spike length or additive x dominance (j) and dominance x dominance (l) interactions effects for number of spikes per plant and number of spikelets per spike. High values of heritability and genetic gain were also detected for grain yield, spikelets per spike, spike per plant and hectoliter weight. All traits except spike per plant had positive relative mid-parent heterosis, but none resulted in positive heterobeltiosis, therefore this cross is not recommended for obtaining hybrids varieties. Selection in early generations by thousand kernel weight and hectoliter weight would be efficient, while the selection in advanced generations where segregation is minimal would be recommended for the remaining traits.