Genotypic Variation for Low Striga Germination Stimulation in Sorghum “<i>Sorghum bicolor</i> (L.) Moench” Landraces from Eritrea

Abstract

Sorghum (Sorghum bicolour (L.) Moench), the second most important staple crop in Sub-Saharan Africa (SSA) after maize, is well adapted to marginal environments of drought stress and high temperatures. But besides drought stress, the obligate root-parasitic flowering plant Striga hermonthica is an equally economically important biotic stress in agro-ecological zones where soils are marginal. Notwithstanding widespread and intense Striga infestation, genetic variations in defence mechanisms against the parasite have been reported. Sorghum variants, producing low levels of chemical stimulants such as sorgolactones that deter the advance of Striga seed germination and are therefore deemed resistant to the parasite, have been also reported in a few studies. But the existence of sorghum genetic variation for this resistance especially among farmers' landraces is yet to be demonstrated. The objective of this study was therefore to determine the levels of Striga germination stimulants in response to each of the 111 collected sorghum landraces and their progenies from Eritrea. The ability of a sorghum genotype to cause germination of a Striga seed as a measure of the amount of the germination stimulant produced was used to assess the resistance of these accessions. The data were recorded as Striga germination percentage by counting the number of germinated Striga seeds. Landraces EG47, EG1261, EG830, EG1076, EG54 and EG746 with 14.68%, 15.32%, 11.85%, 13.05%, 15.74% and 16.5% germination percentages respectively were found to stimulate low levels of Striga germination percentage compared to commercial checks, IS9830, SRN39, Framida, with 22.46%, 22.67%, 23.27% germination respectively. While these variants did not show complete resistance against Striga seed germination, the low level How to cite this paper: Yohannes, T., Ngugi, K., Ariga, E., Abraha, T., Yao, N., Asami, P. and Ahonsi, M. 2471production of stimulant indicated their high level of resistance to Striga. These results implied that these accessions are likely potential sources of resistance against Striga infestation in SSA sorghum breeding programs.

Response of selected sorghum (sorghum bicolor (l.) moench) genotypes to striga hermonthica (del.) benth in western Kenya

“…Higher maximum germination distances together with higher numbers of induced germinated Striga seeds suggest higher amounts of secreted strigolactones in sorghum genotypes, an indication of potential susceptibility of the genotypes to Striga weed. These findings compare well with those of Yohannes et al (2016) who evaluated sorghum genotypes for secretion of low Striga germination stimulant and Reda et al (1994) who screened maize genotypes for low Striga asiatica stimulant production. Yohannes et al (2016) reported reduced secretion of germination stimulant and subsequent Striga resistance in the evaluated landraces compared to the commercial checks while Reda et al (1994) reported a high correlation between maximum germination distance and numbers of induced germinated Striga seeds.…”

“…These findings compare well with those of Yohannes et al (2016) who evaluated sorghum genotypes for secretion of low Striga germination stimulant and Reda et al (1994) who screened maize genotypes for low Striga asiatica stimulant production. Yohannes et al (2016) reported reduced secretion of germination stimulant and subsequent Striga resistance in the evaluated landraces compared to the commercial checks while Reda et al (1994) reported a high correlation between maximum germination distance and numbers of induced germinated Striga seeds. Both Yohannes et al (2016) and Reda et al (1994) (Mohamed et al, 2010).…”

Reaction of New Quality Protein Maize Genotypes toStriga asiatica

“…Lately, the use of genetic defense mechanisms, such as use of resistant or tolerant genotypes, has become a viable and cost‐effective method to reduce maize yield losses caused by Striga (Rodenburg and Bastiaans, 2011; Ransom et al, 2012; Yohannes et al, 2016). Genetic defense to Striga species has been found to exist in cereal crops, such as sorghum and rice ( Oryza sativa L.) (Oswald, 2005; Badu‐Apraku et al, 2013; Samejima et al, 2016).…”

Breeding maize (Zea mays) for Striga resistance: Past, current and prospects in sub‐saharan africa

“…Screen house technique has been used to screen maize genotypes for tolerance / resistance to Striga (Chitagu et al., 2014; Nyakurwa et al., 2018; Yohannes et al., 2016). In screen houses, screening for varietal resistance has been performed using pots and buried seed studies (Eplee & Norris, 1987; Rao, 1985; Sand et al., 1990).…”