Nitrogen fertilizer rate but not form affects the severity of Fusarium wilt in banana

Nitrogen (N) fertilizers are routinely applied to bananas (Musa spp.) to increase production but may exacerbate plant diseases like Fusarium wilt of banana (FWB), which is the most economically important disease. Here, we characterized the effects of N rate and form on banana plant growth, root proteome, bacterial and fungal diversity in the rhizosphere, the concentration of Fusarium oxysporum f.sp. cubense (Foc) in the soil, and the FWB severity. Banana plants (Musa subgroup ABB) were grown under greenhouse conditions in soil with ammonium or nitrate supplemented at five N rates, and with or without inoculation with Foc. The growth of non-inoculated plants was positively correlated with the N rate. In bananas inoculated with Foc, disease severity increased with the N rate, resulting in the Foc-inoculated plant growth being greatest at intermediate N rates. The abundance of Foc in the soil was weakly related to the treatment conditions and was a poor predictor of disease severity. Fungal diversity was consistently affected by Foc inoculation, while bacterial diversity was associated with changes in soil pH resulting from N addition, in particular ammonium. N rate altered the expression of host metabolic pathways associated with carbon fixation, energy usage, amino acid metabolism, and importantly stress response signaling, irrespective of inoculation or N form. Furthermore, in diseased plants, Pathogenesis-related protein 1, a key endpoint for biotic stress response and the salicylic acid defense response to biotrophic pathogens, was negatively correlated with the rate of ammonium fertilizer but not nitrate. As expected, inoculation with Foc altered the expression of a wide range of processes in the banana plant including those of defense and growth. In summary, our results indicate that the severity of FWB was negatively associated with host defenses, which was influenced by N application (particularly ammonium), and shifts in microbial communities associated with ammonium-induced acidification. Copyright © 2022 Orr, Dennis, Wong, Browne, Cooper, Birt, Lapis-Gaza, Pattison and Nelson

Orion EM-1 Internal Environment Characterization: The Matroshka AstroRad Radiation Experiment

Presentation Outline: Orion Multipurpose Crew Vehicle (MPCV); Radiation Vest for Astronauts - AstroRad; ISS (International Space Station) Matroshka; Matroshka AstroRad Radiation Experiment (MARE) on Exploration Mission 1 (EM-1)

Functional characterization of the PHT1 family transporters of foxtail millet with development of a novel Agrobacterium-mediated transformation procedure

Phosphate is an essential nutrient for plant growth and is acquired from the environment and distributed within the plant in part through the action of phosphate transporters of the PHT1 family. Foxtail millet (Setaria italica) is an orphan crop essential to the food security of many small farmers in Asia and Africa and is a model system for other millets. A novel Agrobacterium-mediated transformation and direct plant regeneration procedure was developed from shoot apex explants and used to downregulate expression of 3 members of the PHT1 phosphate transporter family SiPHT1;2 SiPHT1;3 and SiPHT1;4. Transformants were recovered with close to 10% efficiency. The downregulation of individual transporters was confirmed by RT-PCR. Downregulation of individual transporters significantly reduced the total and inorganic P contents in shoot and root tissues and increased the number of lateral roots and root hairs showing they have non-redundant roles. Downregulation of SiPHT1;2 had the strongest effect on total and inorganic P in shoot and root tissues. Complementation experiments in S. cerevisiae provide evidence for the ability of SiPHT1;1, 1;2, 1;3, 1;7 and 1;8 to function as high affinity Pi transporters. This work will aid development of improved millet varieties for global food security

Sensitivity of jarrah (Eucalyptus marginata) to phosphate, phosphite, and arsenate pulses as influenced by fungal symbiotic associations

Many plant species adapted to P-impoverished soils, including jarrah (Eucalyptus marginata), develop toxicity symptoms when exposed to high doses of phosphate (Pi) and its analogs such as phosphite (Phi) and arsenate (AsV). The present study was undertaken to investigate the effects of fungal symbionts Scutellospora calospora, Scleroderma sp., and Austroboletus occidentalis on the response of jarrah to highly toxic pulses (1.5 mmol kg−1 soil) of Pi, Phi, and AsV. S. calospora formed an arbuscular mycorrhizal (AM) symbiosis while both Scleroderma sp. and A. occidentalis established a non-colonizing symbiosis with jarrah plants. All these interactions significantly improved jarrah growth and Pi uptake under P-limiting conditions. The AM fungal colonization naturally declines in AM-eucalypt symbioses after 2–3 months; however, in the present study, the high Pi pulse inhibited the decline of AM fungal colonization in jarrah. Four weeks after exposure to the Pi pulse, plants inoculated with S. calospora had significantly lower toxicity symptoms compared to non-mycorrhizal (NM) plants, and all fungal treatments induced tolerance against Phi toxicity in jarrah. However, no tolerance was observed for AsV-treated plants even though all inoculated plants had significantly lower shoot As concentrations than the NM plants. The transcript profile of five jarrah high-affinity phosphate transporter (PHT1 family) genes in roots was not altered in response to any of the fungal species tested. Interestingly, plants exposed to high Pi supplies for 1 day did not have reduced transcript levels for any of the five PHT1 genes in roots, and transcript abundance of four PHT1 genes actually increased. It is therefore suggested that jarrah, and perhaps other P-sensitive perennial species, respond positively to Pi available in the soil solution through increasing rather than decreasing the expression of selected PHT1 genes. Furthermore, Scleroderma sp. can be considered as a fungus with dual functional capacity capable of forming both ectomycorrhizal and non-colonizing associations, where both pathways are always accompanied by evident growth and nutritional benefits

Identification of QTLs for relative root traits associated with phosphorus efficiency in two culture systems in Brassica napus

Modifications of root system morphology and architecture are considered important strategies of plant tolerance to phosphorus (P) deficiency. However, the effect of culture system on the responses of root traits to P deficiency is not well documented. In this study, the responses of root traits to P deficiency were recorded in a Brassica napus double haploid (DH) population consisting of 182 lines derived from a cross between cultivar ‘Tapidor’ and ‘Ningyou 7’ using an ‘agar’ system and a ‘pouch and wick’ system. Under P deficient conditions, more DH lines had greater total root length, primary root length, total lateral root length, mean lateral root length and less lateral root density in the ‘pouch and wick’ system than the ‘agar’ system. Ten and two quantitative trait loci (QTLs) were detected for the relative root traits in the ‘agar’ system and the ‘pouch and wick’ system, respectively. The QTL for the same trait in the ‘agar’ system did not overlap with that in the ‘pouch and wick’ system. Two and one QTL clusters identified in the ‘agar’ system were located on chromosome A09 (Cluster1 and Cluster2) and C04 (Cluster3), respectively. RLRN_A04b, RSDW_A09a and Cluster1 were found to affect the seed yield and/or yield-related traits in two field trials. Overall, this study demonstrated a significant impact of different culture systems on the responses of root traits to P deficiency and on the detection of QTLs for the relative root traits, and identified three major QTLs that could be employed for marker assisted selection of P efficient cultivars

MATROSHKA ASTRORAD RADIATION EXPERIMENT (MARE) ON THE ORION EM-1 FLIGHT: HOW TO TACKLE THE HAZARD OF RADIATION FOR EXPLORATION MISSIONS

NASA’s Human Research Program has organized and summarized five classifications of hazards for long duration human exploration missions beyond Low Earth Orbit (LEO). These five hazards are 1) radiation, 2) isolation, 3) distance, 4) gravity fields and 5) the hostile/close environment inside the spacecraft. Leaving LEO and traveling in free space will expose the astronauts to a much harsher radiation environment than currently on board the International Space Station (ISS). The relevant radiation risks for these upcoming exploration missions, to the Moon, near Earth Asteroids and in the end to Mars need to be identified and dealt with to enable safe and secure human exploration. Within this context Orion, being NASA´s next generation spacecraft designed for human exploration of the solar systems will be the home of the next generation of astronauts. The upcoming Orion Exploration Mission 1 (EM-1), being an unmanned test flight scheduled for 2020 venturing beyond LEO and into cislunar space offers the unique opportunity to house a variety of secondary research payloads to tackle the problem of radiation and radiation protection. One of these payloads is the Matroshka AstroRad Radiation Experiment (MARE), a science payload proposed by the German Aerospace Center (DLR) and the Israel Space Agency (ISA) and approved by NASA and manifested for flight aboard EM-1 in 2017. MARE will consist of two anthropomorphic female phantoms (torsos), named Helga and Zohar, located inside the Orion cabin at seat positions 3 and 4. Each of the phantoms will be equipped with a variety of active and passive radiation detectors to determine the skin and organ doses during this first flight beyond LEO since almost 50 years. In addition one of the phantoms (Zohar) will be equipped with a novel radiation protection vest (AstroRad) developed in cooperation between StemRad Ltd, Israel and Lockheed Martin. An ergonomic evaluation of AstroRad is planned onboard ISS as early as 2019. With this flight configuration Helga will act as the reference phantom while the protection properties of the AstroRad vest will be tested with Zohar. MARE is designed to provide a comprehensive picture of the radiation environment beyond Earth orbit specific to the Orion vehicle and internal to human body analogs. This data set will inform about expected exposures, enable better planning by validating the operational toolsets used to predict crew radiation exposure risk on future Orion missions, and evaluate a potential countermeasure. MARE leverages the expertise and international collaboration heritage of the ISS Matroshka experiments, and expands it further by adding the mitigation component of the AstroRad shield. MARE represents a demonstration of science research opportunities aboard NASA’s next generation space exploration vehicle. The presentation will provide an overview of the current status of the experiment hardware design, presenting the first data on the special developed new active radiation detectors included in MARE and provide insights in the international team working together to ensure safe human travels for exploration missions

MARE International Payload aboard Orion EM-1: Status Update for 23rd WRMISS

The natural ionizing radiation environment present in space poses risks to human exploration that require mitigation.Spacecraft designed for Exploration beyond Earth orbit (BEO) do not benefit from the Earth’s magnetosphere protection and are subject to stricter radiation design requirements than their low Earth orbit (LEO) counterparts. Orion is NASA’s nextgeneration crewed spacecraft, developed specifically for Exploration missions. [...