In vitro screening and field evaluation of tissue-culture-regenerated sorghum (Sorghum bicolor (L.) Moench) for soil stress tolerance

Abstract

SummarySorghum hieolor (L.) Moench is generally quite sensitive to salt and acid (high aluminium) soil stresses, but quite tolerant of drought stress. As with any stress phenomenon, intra-specific variability exists within the genus. In vitro cell selection and somaclonal variation offer an alternative to traditional breeding methodology for generating improved breeding lines for hybrid development. A field selection protocol was developed for the three soil stresses and inter-stress evaluations were conducted in an effort to find multiple, stress-tolerant genotypes. The acid soil-drought stress, super-tolerant selections were located by the R7 generation when exposed to a combined aluminium-drought stress field environment and when the regeneration population (number of regenerated lines from one callus source) was maintained at 15,000 plants or higher. A variant frequency of 0.1 to 0.2% for stress tolerance and acceptable agronomic traits among the surviving somaclones, provided an adequate number of phenotypes with desirable agronomic characteristics and a high level of soil stress tolerance. Subsequent research verified that the stress-tolerant regenerants had superior acid soil and drought stress tolerance to that of the donor parents, that their yield capabilities under stress were superior to their parents, and that their stress tolerance attributes were transferred in hybrid combinations. In vitro selection was not effective in increasing the number of field stress survivors. In fact, superior germplasms were developed from non-stressed callus or salt-stressed callus. In vitro selection reduced regeneration frequency and subsequent survival of plants under field stress. In vitro-stressed regenerants should be subjected only to non-stressed environments to maintain sufficient population numbers for field selection and thereafter should be subjected to stress environments during later (R5+) generations. The optimal strategy for the exploitation of somaclonal variation may be through short-term cell culture « 12 months) with no attempt at in vitro selection.

Efficiency of In Vitro Regeneration is Dependent on the Genotype and Size of Explant in Tef [Eragrostis tef (Zucc.) Trotter]

“…Using somaclonal variation, potato cultivar with reduced plant height, and sorghum and rice varieties tolerant to drought were developed [36][37][38].…”

Biotechnology: Genetic improvement of sorghum (Sorghum bicolor (L.) Moench)

“…Somaclones of sorghum have been produced with tolerance to high concentrations of salts like aluminum and manganese (Smith et al, 1983;Bhaskaran et al, 1985;Duncan et al, 1995;Mgema and Clark, 1995) and tolerance to acid soils (Waskom et al, 1990;Duncan et al, 1991bDuncan et al, , 1995Miller et al, 1992;Foy et al, 1993). Smith et al (1982) and Duncan et al (1995) reported droughttolerant somaclonal variants. Pest-resistant somaclones have also been reported (Duncan et al, 1991a;Isenhour et al, 1991).…”

Climate Change and Citrus

“…Genetic improvement by in vitro selection of Satsuma mandarins (Citrus unshiu Marc.) has been made successfully; however, the frequency of somaclonal variation by factors, including genotypes, explant culture length, sources, and environmental composition [116,117]. Cell lines success stories of some salt-tolerant cultivars are C. sinensis cv.…”