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

Abstract

AbstractSorghum has been considered a recalcitrant plant in vitro, and suffers from a lack of regeneration protocols that function broadly and efficiently across a range of genotypes. This study was initiated to identify differential genotype-in vitro protocol responses across a range of bioenergy sorghum bioenergy parental lines, in order to characterize response profiles for use in future genetic studies. Seven bioenergy sorghum genotypes were compared, along with the common grain sorghum genotype Tx430, for their in vitro regeneration responses using two different in vitro protocols, LG and WU. All genotypes displayed some level of response during in vitro culture with both protocols. Distinct genotype-protocol responses were observed, with the WU protocol significantly better for plantlet regeneration. All bioenergy genotypes, with the exception of Chinese Amber, performed as well, if not better than Tx430, with Rio and PI329311 the top regenerating lines. Genotypes displayed protocol-dependent, differential phenolic exudation responses, as indicated by medium browning. During the callus induction phase, genotypes prone to medium browning exhibited a response on WU medium which was either equal or greater than on LG medium, with Pink Kafir and PI329311 the most prone to medium browning. Genotype- and protocol-dependent albino plantlet regeneration was also noted, with three of the bioenergy genotypes showing albino plantlet regeneration. Grassl, Rio and Pink Kafir were susceptible to albino plantlet regeneration, with the response strongly associated with the WU protocol. Pink Kafir displayed the highest albino formation, with close to 25% of regenerating explants forming albino plantlets.