Screening African rice (Oryza glaberrima) for tolerance to abiotic stresses: I. Fe toxicity

AbstractIron (Fe) toxicity is recognized as one of the most widely spread soil constraints for rice production especially in West Africa. Oryza glaberrima the cultivated rice species that originated from West Africa is well-adapted to its growing ecologies. The aim of this study was to identify the promising O. glaberrima accessions tolerant to Fe toxicity from the 2106 accessions held at the AfricaRice gene bank. The screenings were conducted over a four-year period and involved evaluating the entries under Fe-toxic field conditions in West Africa, selecting good yielding accessions and repeating the testing with newly selected lines. Three accessions (TOG 7206, TOG 6218-B and TOG 7250-A) were higher yielding than O. sativa checks under stress but with similar yields under control conditions. These accessions yielded over 300g/m2 under both Fe toxicity and control conditions. In conclusion, these materials could be used as donors in breeding programs for developing high yielding rice varieties suited to Fe toxicity affected areas in West Africa

Multiple small-effect alleles of Indica origin enhance high iron-associated stress tolerance in rice under field conditions in west Africa

Open Access Journal; Published online: 15 Jan 2021Understanding the genetics of field-based tolerance to high iron-associated (HIA) stress in rice can accelerate the development of new varieties with enhanced yield performance in West African lowland ecosystems. To date, few field-based studies have been undertaken to rigorously evaluate rice yield performance under HIA stress conditions. In this study, two NERICA × O. sativa bi-parental rice populations and one O.sativa diversity panel consisting of 296 rice accessions were evaluated for grain yield and leaf bronzing symptoms over multiple years in four West African HIA stress and control sites. Mapping of these traits identified a large number of QTLs and single nucleotide polymorphisms (SNPs) associated with stress tolerance in the field. Favorable alleles associated with tolerance to high levels of iron in anaerobic rice soils were rare and almost exclusively derived from the indica subpopulation, including the most favorable alleles identified in NERICA varieties. These findings highlight the complex genetic architecture underlying rice response to HIA stress and suggest that a recurrent selection program focusing on an expanded indica genepool could be productively used in combination with genomic selection to increase the efficiency of selection in breeding programs designed to enhance tolerance to this prevalent abiotic stress in West Africa

Screening African rice (Oryza glaberrima) for tolerance to abiotic stresses: I. Fe toxicity.

Iron (Fe) toxicity is recognized as one of the most widely spread soil constraints for rice production especially in West Africa. Oryza glaberrima the cultivated rice species that originated from West Africa is well-adapted to its growing ecologies. The aim of this study was to identify the promising O. glaberrima accessions tolerant to Fe toxicity from the 2106 accessions held at the AfricaRice gene bank. The screenings were conducted over a four-year period and involved evaluating the entries under Fe-toxic field conditions in West Africa, selecting good yielding accessions and repeating the testing with newly selected lines. Three accessions (TOG 7206, TOG 6218-B and TOG 7250-A) were higher yielding than O. sativa checks under stress but with similar yields under control conditions. These accessions yielded over 300 g/m2 under both Fe toxicity and control conditions. In conclusion, these materials could be used as donors in breeding programs for developing high yielding rice varieties suited to Fe toxicity affected areas in West Africa

Multienvironment Quantitative Trait Loci Mapping and Consistency across Environments of Resistance mechanisms to Ferrous Iron Toxicity in Rice

Analysis of 33 varieties of three sorghum (Sorghum spp.) species cultivated in China showed that sudangrass (Sorghum sudanense Stapf) and sorghum–sudangrass hybrid [Sorghum bicolor (L.) Moench × S. sudanense] samples had higher concentrations of phenolic compounds (including total soluble phenol, proanthocyanidin, flavan-4-ols, anthocyanins, and five phenolic acids) than sorghum (S. bicolor) samples. In addition, the phenolic compounds were distributed extensively in the grain morphological fractions (including glumes, spikelets, caryopsis, endosperm, and embryo) of sudangrass and sorghum–sudangrass hybrid samples; however, they were mainly present in the glumes of sorghum except for total soluble phenol. The results indicated that sudangrass and sorghum–sudangrass hybrid samples in this study would be good sources of useful phenolic compounds such as anthocyanin (6.93 mg g−1 and 4.72 mg g−1) and proanthocyanidin (10.37 mg g−1 and 8.16 mg g−1) compared with sorghum samples (2.97 mg g−1 and 0.18 mg g−1 for anthocyanin and proanthocyanidin, respectively). Sudangrass and sorghum–sudangrass hybrid samples had higher antioxidant activities of 2,2¢-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) (230 and 108 μmol trolox equivalents [TE] g−1 for sudangrass; 258.5 and 130.3 μmol TE g−1 for sorghum–sudangrass hybrid) than sorghum samples (202.5 and 39.5 μmol TE g−1 for ABTS and DPPH, respectively). Thus, the sudangrass and sorghum–sudangrass hybrid samples in this study represented better commercial resources for nutritional and pharmaceutical purposes than sorghum samples because of higher antioxidant activities