Female reproductive development and pollen tube growth in diploid genotypes of Solanum cardiophyllum Lindl.

Abstract

We have characterized female gametophyte (megagametophyte) development and the kinetics of pollen tube growth in self-pollinated diploid genotypes (2n=2x=24) of Solanum cardiophyllum Lindl. that show normal seed formation. In this species megasporogenesis and megagametogenesis give rise to a female gametophyte of the Polygonum type composed of two synergids, an egg cell, a binucleated central cell and three antipodals; however, asynchronous abnormalities resembling mechanisms that prevail during the formation of second division restitution gametes were observed. In self-pollinated pistils at least 1-2% of germinating pollen tubes were able to reach the megagametophyte 60-84 hours after pollination (hap). Although the egg cell acquired a zygote-like morphology 60-84 hap, division of the primary endosperm nucleus was only observed 84 hap. The analysis of genetic variability in full-sib progeny confirmed that seeds are derived from sexual reproduction. These observations suggest that diploid genotypes of S. cardiophyllum can serve as an ideal system to genetically investigate true seed formation in a tuber-bearing Solanum species.

Use of 2n Gametes in Plant Breeding

“…The frequency of 2n egg formation has often been estimated after crosses between 2x x 4x plants. A cross between a diploid seed parent and tetraploid pollen parent will only result in good tetraploid seed when 2n egg cells are present (Conicella et al, 1991;De Haan et al, 1992;Erazzu & Camadro, 2007;Estrada-Luna et al, 2004;Jongedijk, 1987;Lamote et al, 2002;Ortiz & Peloquin, 1991;Veronesi et al, 1986;Van Laere et al, 2009;Werner & Peloquin, 1987). In Triticum-Aegilops hybrids, Zhang et al (2007a used the selfed seedset as a good indication for the formation of 2n gametes.…”

The MIDASIN and NOTCHLESS genes are essential for female gametophyte development in Arabidopsis thaliana

“…Arabidopsis floral organs were cleared with methyl salicylate as described previously (Estrada-Luna et al, 2004). Siliques were dissected longitudinally with hypodermic needles (1 ml insulin syringes).…”

Occurrence of viable unreduced pollen in a Begonia collection

“…Abnormalities results in the formation of triads, dyads or monads, depending on the mechanism of 2n gamete formation. Of these four techniques, only the latter two methods can be used to detect 2n egg formation (Jongedijk 1987;Lamote et al 2002;Estrada-Luna et al 2004).…”