A Mediterranean japonica rice (Oryza sativa) cultivar improvement through anther culture

Abstract

Certified seed producers systematically select and propagate registered varieties year after year in order to maintain their uniformity and the original registered cultivar traits. However, natural mutations, spontaneous breeding between varieties and alien grain contamination can introduce undesirable variability. NRVC 980385 is a temperate japonica rice cultivar (Oryza sativa ssp. japonica) first registered in Spain in 2002. In 2005 certification tests detected a plot differing from the original traits in terms of uniformity and height suggesting the presence of a certain heterozygosis. This material was therefore seen as an opportunity to obtain newly stabilized doubled haploid (DH) lines which could compete in the Spanish short grain seed market. In this study, an in vitro anther culture protocol is defined which also covers the field tests selection to obtain four new, improved and stabilized DH derived lines ready to be registered for commercial proposes. This took just four years from the initial anther collection until new lines were grown in large scale field trials. Consequently, this protocol reduces the time for obtaining field assessed DH lines thereby having considerable advantages over other techniques by both maintaining the original registered cultivars and/or generating new derived varieties.

An improved anther culture procedure for obtaining new commercial Mediterranean temperate <i>japonica</i> rice (<i>Oryza sativa</i>) genotypes

“…Thus, there are efforts worldwide to accelerate the development of new rice varieties either to attain higher yielding rates and/or to obtain higher quality grains (Guimaraes 2009;Khush 2005;Moon et al 2003;Peng et al 2008;Zeng et al 2017). Despite the efforts made, rice breeders' seed suffer recurrent deteriorations due to successive annual cultivation (IRRI 1988;Serrat et al 2014). Programs for ensuring rice breeders' seeds stability are laborious and time-consuming (Briggs and Knowles 1967;Jennings et al 1979;Serrat et al 2014).…”

“…Programs for ensuring rice breeders' seeds stability are laborious and time-consuming (Briggs and Knowles 1967;Jennings et al 1979;Serrat et al 2014). In addition, selecting and stabilizing new rice lines from an F 1 cross is a long process that usually takes about 8 years minimum (Martínez et al 1996;Serrat et al 2014).…”

“…This technique has been used to obtain pure parental lines and to speed up descendant's selection after an artificial cross (Courtois 1993;Mishra and Rao 2016). Over the years, it has been shown that it is much easier to apply this technique on tropical japonica varieties, since they are more responsive at the callus formation and plant regeneration stages than Mediterranean japonica or indica varieties (Chen et al 1986;Herath et al 2007;Hu 1985;Miah et al 1985;Mishra and Rao 2016;Serrat et al 2014;Yan et al 1996). Despite of that, we have previously reported an anther culture technique adaptation for a Mediterranean temperate japonica rice (Oryza sativa) cultivar (NRVC980385) to produce a new commercial cultivar (NRVC20110077; Serrat el al.…”

“…We employed the F 2 generation as characters segregation is maximum and plants will therefore provide high variability when obtaining the double haploid green plants (Guimaraes 2009). Plants were grown in greenhouse conditions at the Experimental Fields Service at the University of Barcelona (Barcelona, Spain) on four litre plastic containers filled with rice substrate as described in Serrat et al (2014).…”

“…The anther culture procedure was performed similar to Serrat et al (2014). The cold-pretreament was modified in order to enhance the anther-derived callus induction stage according to (Chen et al 1986;TrejoTapia et al 2002aTrejoTapia et al , 2002b.…”