Panicle Angle is an Important Factor in Tef Lodging Tolerance.

Tef [Eragrostis tef (Zucc.) Trotter] is an important crop in the Horn of Africa, particularly in Ethiopia, where it is a staple food for over 60 million people. However, the productivity of tef remains extremely low in part due to its susceptibility to lodging. Lodging is the displacement of the plant from the upright position, and it is exacerbated by rain, wind and the application of fertilizer. In order to address the issue of global food security, especially in the Horn of Africa, greater insight into the causes of tef lodging is needed. In this study, we combine modeling and biomechanical measurements to compare the properties relating to lodging tolerance in high yielding, improved tef genotypes, and lower yielding natural landraces. Our results indicate that the angle of the panicle contributes to the likelihood of lodging in tef. Varieties with compact panicles and reduced height had increased lodging resistance compared to the other varieties. By comparing different varieties, we found that overall, the landraces of tef lodged less than improved varieties. We constructed a model of stem bending and found that panicle angle was an important determinant of the amount of lodging. The findings from this study provide key information to those involved in tef improvement, especially those interested in lodging tolerance.

Identification of miRNAs linked with the drought response of tef [Eragrostis tef (Zucc.) Trotter].

Tef [Eragrostis tef (Zucc.) Trotter], a staple food crop in the Horn of Africa and particularly in Ethiopia, has several beneficial agronomical and nutritional properties, including waterlogging and drought tolerance. In this study, we performed microRNA profiling of tef using the Illumina HiSeq 2500 platform, analyzing both shoots and roots of two tef genotypes, one drought-tolerant (Tsedey) and one drought-susceptible (Alba). We obtained more than 10 million filtered reads for each of the 24 sequenced small cDNA libraries. Reads mapping to known miRNAs were more abundant in the root than shoot tissues. Thirteen and 35 miRNAs were significantly modulated in response to drought, in Alba and Tsedey roots, respectively. One miRNA was upregulated under drought conditions in both genotypes. In shoots, nine miRNAs were modulated in common between the two genotypes and all showed similar trends of expression. One-hundred and forty-seven new miRNA mature sequences were identified in silico, 22 of these were detected in all relevant samples and seven were differentially regulated when comparing drought with normal watering. Putative targets of the miRNA regulated under drought in root and shoot tissues were predicted. Among the targets were transcription factors such as CCAAT-HAP2, MADS and NAC. Verification with qRT-PCR revealed that five of six potential targets showed a pattern of expression that was consistent with the correspondent miRNA amount measured by RNA-Seq. In general, candidate miRNAs involved in the post-transcriptional regulation of the tef response to drought could be included in next-generation breeding programs.

Waterlogging affects plant morphology and the expression of key genes in tef (Eragrostis tef).

Tef [Eragrostis tef (Zucc.) Trotter], an allotetraploid cereal that is a staple food to over 60 million people in the Horn of Africa, has a high nutritional content and is resistant to many biotic and abiotic stresses such as waterlogging and drought. Three tef genotypes, Alba, Tsedey, and Quncho, were subjected to waterlogging conditions and their growth, physiology, and change in transcript expression were measured with the goal of identifying targets for breeding cultivars with improved waterlogging tolerance. Root and shoot growth and dry weight were observed over 22 days. Stomatal conductance and chlorophyll and carotenoid contents were quantified. Microscopy was used to monitor changes in the stem cross sections. Illumina RNA sequencing was used to obtain the expression profiles of tef under flooding and control conditions and was verified using qPCR. Results indicated differences in growth between the three genotypes. Waterlogged Tsedey plants grew higher and had more root biomass than normally watered Tsedey plants. Quncho and Alba genotypes were more susceptible to the excess moisture stress. The effects of these changes were observed on the plant physiology. Among the three tested tef genotypes, Tsedey formed more aerenchyma than Alba and had accelerated growth under waterlogging. Tsedey and Quncho had constitutive aerenchyma. Genes affecting carbohydrate metabolism, cell growth, response to reactive oxygen species, transport, signaling, and stress responses were found to change under excess moisture stress. In general, these results show the presence of substantial anatomical and physiological differences among tef genotypes when waterlogged during the early growth stage.

Gibberellin Deficiency Confers Both Lodging and Drought Tolerance in Small Cereals.

Tef [Eragrostis tef (Zucc.) Trotter] and finger millet [Eleusine coracana Gaertn] are staple cereal crops in Africa and Asia with several desirable agronomic and nutritional properties. Tef is becoming a life-style crop as it is gluten-free while finger millet has a low glycemic index which makes it an ideal food for diabetic patients. However, both tef and finger millet have extremely low grain yields mainly due to moisture scarcity and susceptibility of the plants to lodging. In this study, the effects of gibberellic acid (GA) inhibitors particularly paclobutrazol (PBZ) on diverse physiological and yield-related parameters were investigated and compared to GA mutants in rice (Oryza sativa L.). The application of PBZ to tef and finger millet significantly reduced the plant height and increased lodging tolerance. Remarkably, PBZ also enhanced the tolerance of both tef and finger millet to moisture deficit. Under moisture scarcity, tef plants treated with PBZ did not exhibit drought-related symptoms and their stomatal conductance was unaltered, leading to higher shoot biomass and grain yield. Semi-dwarf rice mutants altered in GA biosynthesis, were also shown to have improved tolerance to dehydration. The combination of traits (drought tolerance, lodging tolerance and increased yield) that we found in plants with altered GA pathway is of importance to breeders who would otherwise rely on extensive crossing to introgress each trait individually. The key role played by PBZ in the tolerance to both lodging and drought calls for further studies using mutants in the GA biosynthesis pathway in order to obtain candidate lines which can be incorporated into crop-breeding programs to create lodging tolerant and climate-smart crops.

Genetic diversity in tef [Eragrostis tef (Zucc.) Trotter].

Tef [Eragrostis tef (Zucc.) Trotter] is a cereal crop resilient to adverse climatic and soil conditions, and possessing desirable storage properties. Although tef provides high quality food and grows under marginal conditions unsuitable for other cereals, it is considered to be an orphan crop because it has benefited little from genetic improvement. Hence, unlike other cereals such as maize and wheat, the productivity of tef is extremely low. In spite of the low productivity, tef is widely cultivated by over six million small-scale farmers in Ethiopia where it is annually grown on more than three million hectares of land, accounting for over 30% of the total cereal acreage. Tef, a tetraploid with 40 chromosomes (2n = 4x = 40), belongs to the family Poaceae and, together with finger millet (Eleusine coracana Gaerth.), to the subfamily Chloridoideae. It was originated and domesticated in Ethiopia. There are about 350 Eragrostis species of which E. tef is the only species cultivated for human consumption. At the present time, the gene bank in Ethiopia holds over five thousand tef accessions collected from geographical regions diverse in terms of climate and elevation. These germplasm accessions appear to have huge variability with regard to key agronomic and nutritional traits. In order to properly utilize the variability in developing new tef cultivars, various techniques have been implemented to catalog the extent and unravel the patterns of genetic diversity. In this review, we show some recent initiatives investigating the diversity of tef using genomics, transcriptomics and proteomics and discuss the prospect of these efforts in providing molecular resources that can aid modern tef breeding.

Genome and transcriptome sequencing identifies breeding targets in the orphan crop tef (Eragrostis tef).

BACKGROUND: Tef (Eragrostis tef), an indigenous cereal critical to food security in the Horn of Africa, is rich in minerals and protein, resistant to many biotic and abiotic stresses and safe for diabetics as well as sufferers of immune reactions to wheat gluten. We present the genome of tef, the first species in the grass subfamily Chloridoideae and the first allotetraploid assembled de novo. We sequenced the tef genome for marker-assisted breeding, to shed light on the molecular mechanisms conferring tef's desirable nutritional and agronomic properties, and to make its genome publicly available as a community resource. RESULTS: The draft genome contains 672 Mbp representing 87% of the genome size estimated from flow cytometry. We also sequenced two transcriptomes, one from a normalized RNA library and another from unnormalized RNASeq data. The normalized RNA library revealed around 38000 transcripts that were then annotated by the SwissProt group. The CoGe comparative genomics platform was used to compare the tef genome to other genomes, notably sorghum. Scaffolds comprising approximately half of the genome size were ordered by syntenic alignment to sorghum producing tef pseudo-chromosomes, which were sorted into A and B genomes as well as compared to the genetic map of tef. The draft genome was used to identify novel SSR markers, investigate target genes for abiotic stress resistance studies, and understand the evolution of the prolamin family of proteins that are responsible for the immune response to gluten. CONCLUSIONS: It is highly plausible that breeding targets previously identified in other cereal crops will also be valuable breeding targets in tef. The draft genome and transcriptome will be of great use for identifying these targets for genetic improvement of this orphan crop that is vital for feeding 50 million people in the Horn of Africa.