Improved plant regeneration in callus cultures of Sorghum bicolor (L.) Moench

Abstract

Sorghum bicolor is a recalcitrant species for tissue culture regeneration and genetic transformation. Browning of explants is one of the factors limiting organ and tissue cultures. To overcome this, callus tissue was initiated from the shoot tips of in vitro germinating seeds (S. bicolor cv. Róna 1), and then cultured on modified MS media (Murashige and Skoog in Physiol Plant 15:473-497, 1962). In the first experiment, we tested callus induction on several media supplemented with casein hydrolysate, polyvinylpyrrolidone, honey, and sucrose. The best callus induction was recorded for the medium with honey and sucrose (80.0%) and for control medium (79.8%). Shoot regeneration was tested on the MS medium with 6-benzylaminopurine (BAP) supplemented with honey and sucrose at a 1:1 ratio (by weight) or with sucrose only. The highest percentage of calluses regenerating shoots was noted for those induced on the medium with sucrose and honey-approx. four times higher when compared to the control. Rooted plantlets were acclimatized with a 92% survival rate. In the second experiment, we analyzed culture responses to various ways of honey application to the induction media: honey (autoclaved or filtered) in presence or absence of sucrose. Supplementation of the medium with fructose, glucose, and maltose at a proportion typical for honey was also investigated. The explant and callus survival rates were similar to those of the honey-sucrose combination in the first experiment. Only presence of both sucrose and honey in the induction medium improved the total regeneration rate to 37.9% over the control (18.8%). Sucrose and honey appear to act synergistically for shoot regeneration in callus cultures of sorghum.

Comparative Analysis of In Vitro Responses and Regeneration between Diverse Bioenergy Sorghum Genotypes

“…Several studies have targeted the genetic control of in vitro responsiveness in a variety of plants. Many have involved QTL identification [34,65,[79][80][81][82][83], and more recently, GWAS [31,36,84]. These studies have identified several genetic loci and candidate genes associated with various aspects of in vitro responsiveness.…”

“…These studies have shown that sorghum in vitro responsiveness displays genotype-dependency [27][28][29], with sorghum considered to be relatively recalcitrant to in vitro manipulation, due to factors like genotype-dependent phenolic production and tissue browning. Efforts to improve this recalcitrance have used different tissue culture media modifications to improve cell survival [28,30,31] and subsequent regeneration, as well as the overexpression of Baby Boom and Wuschel genes to stimulate the embryogenic potential of explant cells and improve regeneration [32]. An understanding of the genetics associated with tissue culture/in vitro responsiveness would facilitate breeding for improved regenerability/transformability, but also provide for a greater understanding of sorghum developmental processes.…”

Induction of Fingerroot (Boesenbergia Pandurata Roxb.) Buds in Various MS Media and Sucrose

“…In addition to the media, carbon sources also play an important role in plant organogenesis in vitro. Exogenous carbon sources added into the media can influence organ differentiation and plant regeneration efficiency in vitro [10].…”

“…The carbon source most often used in tissue culture is sucrose, because it is the most effective carbon source compared to other types of sugars. According to the research of [10] the use of media with sucrose is most effective against plant induction. [11] mention the concentration of sucrose influences the continuity of cell growth, besides that [12] said that sucrose plays an important role in the induction of cells and energy sources.…”

Comparative Analysis of In Vitro Responses and Regeneration Between Diverse Bioenergy Sorghum Genotypes

“…These studies have shown that sorghum in vitro responsiveness displays genotype-dependency (Kaeppler and Pedersen 1997, Liu et al 2015, Omer et al 2018), with sorghum considered to be relatively recalcitrant to in vitro manipulation, due to factors like genotype-dependent phenolic production and tissue browning. Efforts to improve this recalcitrance have used different tissue culture media modifications to improve cell survival (Elkonin et al 1995, Liu et al 2015, Dreger et al 2019) and subsequent regeneration, as well as the overexpression of Baby Boom and Wuschel genes to stimulate the embryogenic potential of explant cells, and improve regeneration (Lowe et al 2016). An understanding of the genetics associated with tissue culture/in vitro responsiveness would facilitate breeding for improved regenerability/transformability, but also provide for a greater understanding of sorghum developmental processes.…”