Mechanism of action of nitrous oxide gas applied as a polyploidizing agent during meiosis in lilies

Abstract

Nitrous oxide gas (N(2)O) can be used to produce polyploid plants, but the mechanism of action is unknown. The actin and microtubule cytoskeleton was observed in N(2)O-treated microsporocytes of Lilium spp 'Asiatic hybrid lilies' using fluorescence microscopy after staining with DAPI, FITC-conjugated tubulin antibody, and phalloidin-conjugated Alexa Fluor 546. Additionally, microsporocytes of L. longiflorum were observed with acetocarmine staining following N(2)O treatment. A typical metaphase I microtubule distribution was observed in control microsporocytes. After treatment with N(2)O for 24 h, microtubules were effectively depolymerized; this prevented chromosomes from moving to the poles, resulting in chromosome retention in the center of N(2)O-treated cells. Cell plate formation took place without delay, however, yielding one daughter cell with a diploid genome and another daughter without chromosomes. In addition, N(2)O treatment often induced micronuclei due to aberrant chromosome separation during cytokinesis. Actin filaments in microsporocytes are insensitive to N(2)O. These findings indicate that N(2)O mediates polyploidization by inhibiting microtubule polymerization, but not actin filament formation, during microsporocyte meiosis.

Cytogenetic studies on meiotic chromosome behaviors in sterile Oriental x Trumpet lily

“…Multiple spindle poles are visible at early prometaphase I. During mid-prometaphase I, the multiple spindle poles become concentrated into two poles, and the typical bipolar meiotic spindle is complete at metaphase I (Suzuki and Tanaka, 1999;Kitamura et al, 2009). Multiple spindles are a meiotic abnormality in which more than one spindle occurs in meiosis.…”

Use of 2n Gametes in Plant Breeding

“…In Lilium, Barba-Gonzalez et al (2006) showed that N 2 O fumigation produced mainly first division restitution (FDR) gametes, indicating a disruption in meiosis I. Furthermore, Kitamura et al (2009) showed in Lilium that microtubules were depolymerised during metaphase I, which prevented chromosomes from moving to the poles. Dewitte et al (2010b) tried to induce 2n pollen by submerging flower buds of Begonia in a trifluralin solution.…”

Induction of 2n pollen formation in Begonia by trifluralin and N2O treatments

“…In Lilium, Barba-Gonzalez et al (2006) showed that N 2 O fumigation produced mainly first division restitution (FDR) gametes, which indicates a disruption of meiosis I. Furthermore, Kitamura et al (2008) showed in Lilium that microtubules were depolymerised during metaphase I, which prevented chromosomes from moving to the poles. However, cell plate formation was not inhibited.…”