Flowering characteristics and fertility of interploidy progeny from normal and 2n gametes in Dactylis glomerata L.

Abstract

We performed an extensive experiment to compare male fertility, flowering period, seed set and germination rate between triploid and tetraploid cross-progeny of Dactylis glomerata L. originating trom reciprocal diploid (2.\) X tetraploid (4.t) crosses. Four hundred and forty-five triploid and tetraploid individuals, constituting the cross progeny of 2x-Ax reciprocal crosses between diploids from nine distinct subspecies, and tetraploids trom tive subspecies, were tested for male fertility and phenology under homogeneous conditions. X significant negative correlation was observed between the parental genetic distance and the frequency of sterile panicles (Sl^) in 3.\-progeny, suggesting that selection may occur against fertilit\' in triploid progeny from interploid crosses involving closely related subspecies. Genetic distance between the parental subspecies was not significantly correlated with the frequency of fertile panicles {V'Y), non-spreadmg panicles (NT, non-dehiscent anthers with pollen inside), and ST panicles in the Ax progeny, nor with the frequency of ¥T and NT panicles in the 3.\: progeny. .A.mong the 4.v progeny individuals that produced panicles, more than 60",, were fully fertile, but 24",, possessed only sterile panicles. In the triploids, 63 "" of the reproductive plants were male-sterile, but 31 ",, had variable proportions of fertile panicles and 6"o possessed only fertile panicles. Male fertility in the progeny was signiticantly aftected by individual ploidy level, parental diploid subspecies identity, and by the interaction between these 2 factors in the case of the fertile progeny plants. The frequency of vegetative plants was higher in 4.Y progeny than in 3.\-progeny, more particularly when the seed parent was tetraploid. However, when the seed parent was diploid, the frequencies of vegetative plants were similar in 3.v and 4A progeny. Pollen viability was significantly higher in anthers from fertile panicles than in anthers from non-spreadmg panicles; viability of pollen from non-spreading panicles was, in turn, significantly higher than in sterile panicles. Also, seed set was higher in panicles with fertile anthers than in the two other types. However, seeds from plants with fertile, non-spreading and sterile anthers showed no differences m germination rate. Therefore, in Dcictylis glomerata, tetraploid cross progeny arising from 2ri gametes possess higher fertility, on average, than triploid cross progeny involving normal gametes. In addition to lower male fertility (non-spreadmg or atrophied anthers), the triploids also showed signiticantly lower pollen fertility in anthers and lower seed set in open pollinating conditions, probably because disturbance in meiosis, due to odd chromosome associations, also occurs in eggs. Moreover, triploids were observed to reproduce preferentiallv with individuals possessing the same ploidy levels as their seed parent. These results suggest that the production of 4.x-individuals, derived from 2ii gametes m interploid crosses, is likely to be the main ...

Pollen production and spontaneous polyploidization in diploid populations of Anthoxanthum alpinum

“…This overlap was also seen in haploid and diploid pollen from diploid and tetraploid natural populations of A. alpinum (Humbert-Droz & Felber, 1992 and present study). Moreover, some of the LP may not be 2n (Maceira et al, 1993). However, we could hypothesize that a large proportion of LP produced by our plants corresponds roughly to 2n pollen and hence, we could estimate a frequency of 1.3%, 1% and 0.8% of 2n pollen in the Mo97, Mo98 and Vid98 populations respectively.…”

“…Hence LP is often considered to be 2n. However, a relative overlap in size distribution between haploid and diploid pollen may occur (Maceira et al, 1993;Yan et al, 1997). This overlap was also seen in haploid and diploid pollen from diploid and tetraploid natural populations of A. alpinum (Humbert-Droz & Felber, 1992 and present study).…”

Gametes with the somatic chromosome number: mechanisms of their formation and role in the evolution of autopolyploid plants

“…The fertility of the triploids has, however, usually been found to be much lower than that ofthe diploids or the tetraploids, but rarely zero, and often with differences between male and female gametes. Usually male gametes are sterile, while females are partially fertile (De Wet, 1986;Taylor & Wiseman, 1987;Dweikat & Lyrene, 1988;Lumaret, 1988;Hahn et al, 1990;Maceira, 1990;Iwanaga et al, 1991Maceira et al, 1992;Needham & Frickson, 1992;Pringle & Murray, 1992a, 6;Sato et al, 1993). The progeny analysed in 3x-2x and 3x-4x crosses (i.e.…”

Fitness Differences Among Diploids, Tetraploids, and Their Triploid Progeny in Chamerion Angustifolium: Mechanisms of Inviability and Implications for Polyploid Evolution

“…Triploid hybrids have been observed at moderate frequencies in some populations (9%, Husband and Schemske 1998;11%, Burton and Husband 1999). Furthermore, studies have shown that triploids, when backcrossed with diploids (Zohary and Nur 1959;Haunold 1970;Dujardin and Hanna 1988) and tetraploids (Jones and Borill 1962;Taylor and Wiseman 1987;Sato et al 1993), can yield tetraploid progeny. These data suggest triploids may play a vital role in polyploidy dynamics of natural populations.…”