Marit Jørgensen
Senior Research Scientist
Authors
Akhil Reddy Pashapu Sigridur Dalmannsdottir Marit Jørgensen Mallikarjuna Rao Kovi Odd Arne RognliAbstract
Timothy is the most important perennial forage grass species in northern Norway, a region that is predicted to experience variable winter weather conditions due to climate change. Knowledge about how timothy cultivars respond to a changing climate is crucial for safeguarding forage production at higher latitudes. In the current study, we investigated changes in gene expression under freezing and ice encasement stresses and SNP allele frequencies between temporal populations (seed generations) of the two northern-adapted timothy cultivars Engmo and Noreng. In general, there was a decrease in freezing tolerance (defined as LT 50 , the temperature lethal to 50% of the population) and an increase in ice encasement tolerance (defined as LD 50 , the duration lethal to 50% of the population) over time. Comparative transcriptome analyses identified several genes known to be involved in stress responses, such as ethylene-responsive transcription factors, dehydration-responsive element binding transcription factors, reversion to ethylene sensitivity 1, and abscisic acid repressor 1, as differentially expressed between the temporal populations of Noreng under freezing stress. Several loci with large allele frequency changes were observed to be in close proximity to the genes displaying patterns resembling shifts over time in Noreng. Very few gene expression differences between populations of both cultivars under ice encasement stress could be due to weak selection pressure during seed multiplication. There was a gradual decline in genetic diversity in populations of both cultivars over time. The results indicate that phytohormone-mediated transcriptional regulation might be one of the key mechanisms for adaptation to changing winter weather conditions at higher latitudes. These findings underscore the importance of monitoring genetic shifts during seed multiplication to maintain cultivar stability and suggest that the identified stress-responsive genes could serve as valuable targets for breeding climate-resilient forage crops.
Authors
Trygve S. Aamlid Sigridur Dalmannsdottir Kristoffer Herland Hellton Marit Jørgensen Ievina Sturite Carl Gunnar Fossdal Akhil Reddy Pashapu Mallikarjuna Rao Kovi Helga Amdahl Odd Arne RognliAbstract
No abstract has been registered
Abstract
Aims Ethiopian soils are severely degraded and nutrient depleted, calling for effective remediation strategies. Enhancing soil biological activity through the cultivation of perennial forages may improve soil nutrient cycling and ameliorate soils. The aim of this study was to evaluate specific forage species as to their ability to improve soil biological functions. Methods We set up a fully factorial greenhouse experiment with Ethiopian soils from two regions differing in mineralogy, soil type and climate and tested the effect of two grass species Urochloa cv. ‘Cayman’, Megathyrsus maximus (Mombassa), and two legumes, Desmodium intortum (Greenleaf), Stylosanthes guianensis (Ubon) grown in single stands and mixtures on soil chemical and microbial variables. After 12 weeks of unfertilized growth, we measured soil mineral nitrogen (N), respiration, exoenzyme activities, microbial biomass N and phosphorus and the symbiotic performance of legumes. Results Soils from lower altitude Sidama region had 24% higher soil microbial activity than those from higher altitude Amhara. Aboveground N yield and shoot:root ratios were good indicators for stimulating effects on soil microbial functions, with S. guianensis having the strongest effect. Mixtures did not perform better than single stands. Legumes induced a 15% increase in acid phosphatase (AP) and 34% increase in N-enzyme activity which improved P-supply in three of the four soils. Conclusions AP-activity was stimulated by legumes in all soils but the overall ameliorative effect of perennial forage species appeared to be highly soil dependent. Plant effects on soil biological functions are more pronounced in less acidic soils with higher extractable P.
