Evaluation of the potential for somatic embryogenesis in sugar beet (Beta vulgaris L.) breeding lines and improvement of regeneration efficiency

Abstract

A wide range of genotypes suitable for a plant regeneration system is needed when utilizing genetic transformation techniques to develop new crop cultivars. We examined the regeneration efficiencies for somatic embryogenesis in 61 genetically diverse sugar beet (Beta vulgaris L.) breeding lines developed in Japan using a previously reported procedure. Frequencies of embryogenic callus formation from seedling leaf and petiole explants ranged from 0 to 89% and those of somatic embryo formation from the calli ranged from 0 to 99%. There was no clear correlation between the two frequencies, suggesting that different genetic backgrounds are involved in the two formation mechanisms. To evaluate each breeding line's capability for somatic embryogenesis, we proposed a somatic embryogenesis capability index based on four parameters. Based on the values of this index, only 21 breeding lines were suitable materials for regeneration via somatic embryogenesis. These breeding lines include four lines with moderate or better resistance to three major sugar beet diseases in Japan and one line with strong resistance to these diseases, and these lines will be useful materials with superior characteristics for developing transgenic breeding lines. To increase the regeneration efficiencies in the other 40 breeding lines, we examined other types of explants from seedlings and the effects of various plant growth regulators. We found that cotyledon explants generally showed improved callus formation and that using thidiazuron instead of N 6 -benzylaminopurine improved somatic embryo formation in some lines.

Methods for suspension culture, protoplast extraction, and transformation of high‐biomass yielding perennial grass Arundo donax

“…These data suggest that further optimization of the culture media may be necessary for Arundo , as for other bioenergy crops researchers have placed extensive effort in this direction . Also, the ability of plant species to be manipulated in vitro is strongly genotype‐dependent , therefore more effort is needed to screen different accessions and identify genotypes more amenable to in vitro cultivation.…”

Overexpression of the Transcription Factor GROWTH-REGULATING FACTOR5 Improves Transformation of Dicot and Monocot Species

“…On the other hand, several reports have shown that sugar beet breeding lines and cultivars generally exhibit diverse in vitro responses to plant regeneration from friable callus, which illustrates strong genotype dependency of the regeneration in that crop ( Dovzhenko and Koop, 2003 ; Ivic-Haymes and Smigocki, 2005 ; Tomita et al., 2013 ). Importantly, in our analysis AtGRF5 overexpression dramatically improved the recovery of transgenic events in several sugar beet inbred lines, including a genotype that was not amenable for transformation up to date ( Figure 3 ).…”

A robust method for haploid sugar beet in vitro proliferation and hyperhydricity reduction

“…Many published studies report on the effects of various hormonal treatments on the regeneration, proliferation and propagation of different genotypes of sugar beet via diverse tissues (Mezei et al 2006, Mishutkina and Gaponenko 2006, Gürel et al 2011, Tomaszewska-Sowa 2012, Klimek-Chodacka and Baranski 2013, Tomita et al 2013. However, in spite of the evidence for hyperhydricity provided by them (e.g.…”

“…6-benzylaminopurine (BAP) is one of the growth regulators from among the CKs, which has been widely used in sugar beet ovule culture for gynogenesis (reviewed in Aflaki et al 2017). However, the proliferated or regenerated plantlets can be hyperhydric (Tomita et al 2013, Pazuki et al 2017a. A hyperhydric sugar beet subculture on a medium with a new composition or under new conditions takes time and effort to produce a normal plant, which is a costly practice (Tomaszewska-Sowa 2012).…”