The relationship between induction of embryogenesis and chromosome doubling in microspore cultures

Abstract

The objective of this paper is to review the relationship between induction of microspore embryogenesis and chromosome doubling. It has been augmented with relative data on chromosome doubling by nuclear fusion. Some of the treatments used for induction of embryogenesis may also lead to doubling of the chromosome number, either through nuclear fusion or endomitosis. High frequencies of spontaneous chromosome doubling in cereal species appear to be induced by treatments that block cell wall formation during the first cell divisions, resulting in coenocytic cells in which the nuclei are able to fuse. The use of mannitol as a pretreatment for induction of embryogenesis in barley, wheat, and maize microspore cultures provides examples of nuclear fusion. The use of antimicrotubule agents for embryo induction via treatments during the first few hours of microspore culture has also resulted in high frequencies of chromosome doubling. Factors such as the doubling agent concentration, temperature during treatment, and duration of treatment may be critical for individual species. Actin filament as well as microtubule assembly studies related to new cell wall formation provide further evidence at the molecular level for the relationship between microspore embryogenesis and chromosome doubling.

Enhanced induction of microspore embryogenesis after n-butanol treatment in wheat (Triticum aestivum L.) anther culture

“…Nuclear fusion has been proposed to be the main mechanism of spontaneous doubling in barley (González-Melendi et al 2005;Kasha et al 2001) and maize (Testillano et al 2004) microspore embryogenesis. High frequencies of spontaneous doubling in cereals appear to be induced by treatments that block cell wall formation during the first cell divisions (Shim et al 2006). Complete cytokinesis after n-butanol treatment or a likely role of cortical MTs in nuclear fusion could interfere with this process.…”

Effects of n-butanol on barley microspore embryogenesis

“…Therefore the inductive effect of n-butanol on microspore embryogenesis is lower with a cold treatment than with mannitol. It is known that n-butanol disrupts cortical and interphase microtubules (Dhonukshe et al 2003, Gardiner et al 2003Hirase et al 2006) and that mannitol could also act as an antimicrotubule agent (Shim et al 2006). Our results indicated that mannitol and n-butanol could have an additive effect on microspore microtubule (MT) disruption.…”

Effect of D Genome on Wheat Anther Culture Response After Cold and Mannitol Pretreatment

“…Sugar starvation by placing anthers on a medium with mannitol as the carbohydrate source is one of the most commonly used stress pre-treatments (Caredda et al, 2000;Kasha et al, 2001; Cistué et Soriano et al, 2007;Castillo et al, 2015). This pre-treatment has resulted in consistently high chromosome doubling rates in barley (Kasha et al, 2001;Shim et al, 2006) and wheat (Hu and Kasha, 1997). In addition, Cistué et al (2006) reported that pre-treating the anthers in 0.7 M mannitol for five days improved green plant regeneration in durum wheat.…”