Proceedings of The Global Conference on Ergot of Sorghum

In June 1996, several of us had the opportunity to see sorghum ergot in Brazil and the damage that the disease can do. We saw severe damage in seed production plots and witnessed the pain that seed producers had to go through to deal with this new problem. There was a wide spread scare in the sorghum community in the Americas because of the infamous reputation of the disease in causing damage in seed production fields. As a silver lining, we also observed first hand, the excellent research program that the Brazilians had in place. It became apparent that all of the sorghum researchers, seed producers and regulators of plant pathogens worldwide needed to come together to study and review this disease. There could be no better venue for such a Global Conference than Sete Lagoas, Brazil. Hence this meeting was proposed and with the support and assistance of the Director of Sorghum and Maize Research (CNPMS) of EMBRAPA, this meeting has been arranged. At the time the meeting was proposed, the disease was known only in a few countries but it has spread today to include much of the Americas and Australia. Obviously, we can no longer avoid the disease, we can only learn to live with it and manage it in future growing seasons. It has been my pleasure to work with the research leaders on ergot at EMBRAPA in developing this conference, to receive cooperation from many of the global leaders on ergot to bring their knowledge to the conference and financial support from the American Seed Trade Association, as well as the support and encouragement from Texas A & M University and INTSORMIL in recognizing the importance of our collaboration on combating sorghum ergot. In this conference, we will learn from the experiences of countries where ergot had existed for a long time while examining the ergot situation in newly invaded countries. We have several dedicated papers dealing with the biology of the pathogen, the epidemiology of the disease, and disease management strategies. We will also chart the movement of the disease and plot ideas on how to collaboratively work to lessen the impact of sorghum ergot in the Americas

Evaluación agronómica de diez híbridos de sorgo en la costa sur de Puerto Rico en 1993 y 1994

Annually, Puerto Rico imports close to 220,000 t of feed grain from the United States and other countries at a cost of $16.0 million, for use as livestock and chicken feed. Previous studies have shown that sorghum [Sorghum bicolor (L.) Moench] can be successfully grown in areas of the southern coast of Puerto Rico, all of which means an alternate crop and a way to reduce grain imports. Grain yield potentials of 10 hybrids of sorghum, including seven red and three white-seeded types, were evaluated at Juana Díaz on the south coast of the island.The test was planted 5 May 1993 and 23 May 1994 following a split-plot experimental design with three replications. Three rows were planted per plot. The middle row was used for yield and other agronomic trait evaluations. Mean grain yields of the test were 5,020 kg/ha. Top-yielding Cargilt Ma Cau 90 (6,240 kg/ha) significantly exceeded yields of all other hybrids except DK-65. Mean values of other agronomic characteristics were days to anthesis, 63.9; plant height, 150.4 cm; 100-seed weight, 3.44 g; harvest index, 31$16.0 millones. Se determinó el potencial de rendimiento y comportamiento agronómico de 10 híbridos de sorgo (siete de grano rojo y tres de grano blanco) en la subestación Experimental Agrícola de Fortuna, municipalidad de Juana Díaz. El experimento se sembró el 5 de mayo de 1993 y 23 de mayo de 1994 utilizando un diseño de bloques al azar con parcelas divididas con tres replicaciones. La parcela experimental consistió de tres hileras donde la hilera central se utilizó para obtener datos de rendimiento y de otras características. En promedio los 10 híbridos produjeron 5,020 kg/ha. El híbrido de mayor rendimiento fue el Cargill Ma Cau 90 con una producción de 6,240 kg/ha, significativamente mayor que la de los demás híbridos, excepto DK-65. El híbrido Cargill Appolo fue el de menor rendimiento. Los valores promedio para otros caracteres agronómicos fueron días a mitad de florecida, 63.9 días; altura de la planta, 150.4 cm; peso de 100 semillas, 3.44 g; índice de cosecha, 31%. Además, se encontró una correlación significativa (r = 0.34) entre altura de la planta y rendimiento de grano. El rendimiento demuestra que algunos de estos híbridos tienen potencial para ser sembrados a escala comercial y ayudar a reducir la dependencia de Puerto Rico en la importación de granos para concentrado de animales

Strong succession in arbuscular mycorrhizal fungal communities.

The ecology of fungi lags behind that of plants and animals because most fungi are microscopic and hidden in their substrates. Here, we address the basic ecological process of fungal succession in nature using the microscopic, arbuscular mycorrhizal fungi (AMF) that form essential mutualisms with 70-90% of plants. We find a signal for temporal change in AMF community similarity that is 40-fold stronger than seen in the most recent studies, likely due to weekly samplings of roots, rhizosphere and soil throughout the 17 weeks from seedling to fruit maturity and the use of the fungal DNA barcode to recognize species in a simple, agricultural environment. We demonstrate the patterns of nestedness and turnover and the microbial equivalents of the processes of immigration and extinction, that is, appearance and disappearance. We also provide the first evidence that AMF species co-exist rather than simply co-occur by demonstrating negative, density-dependent population growth for multiple species. Our study shows the advantages of using fungi to test basic ecological hypotheses (e.g., nestedness v. turnover, immigration v. extinction, and coexistence theory) over periods as short as one season

Fungal community assembly in drought-stressed sorghum shows stochasticity, selection, and universal ecological dynamics.

Community assembly of crop-associated fungi is thought to be strongly influenced by deterministic selection exerted by the plant host, rather than stochastic processes. Here we use a simple, sorghum system with abundant sampling to show that stochastic forces (drift or stochastic dispersal) act on fungal community assembly in leaves and roots early in host development and when sorghum is drought stressed, conditions when mycobiomes are small. Unexpectedly, we find no signal for stochasticity when drought stress is relieved, likely due to renewed selection by the host. In our experimental system, the host compartment exerts the strongest effects on mycobiome assembly, followed by the timing of plant development and lastly by plant genotype. Using a dissimilarity-overlap approach, we find a universality in the forces of community assembly of the mycobiomes of the different sorghum compartments and in functional guilds of fungi

Transcriptomic analysis of field-droughted sorghum from seedling to maturity reveals biotic and metabolic responses.

Drought is the most important environmental stress limiting crop yields. The C4 cereal sorghum [Sorghum bicolor (L.) Moench] is a critical food, forage, and emerging bioenergy crop that is notably drought-tolerant. We conducted a large-scale field experiment, imposing preflowering and postflowering drought stress on 2 genotypes of sorghum across a tightly resolved time series, from plant emergence to postanthesis, resulting in a dataset of nearly 400 transcriptomes. We observed a fast and global transcriptomic response in leaf and root tissues with clear temporal patterns, including modulation of well-known drought pathways. We also identified genotypic differences in core photosynthesis and reactive oxygen species scavenging pathways, highlighting possible mechanisms of drought tolerance and of the delayed senescence, characteristic of the stay-green phenotype. Finally, we discovered a large-scale depletion in the expression of genes critical to arbuscular mycorrhizal (AM) symbiosis, with a corresponding drop in AM fungal mass in the plants' roots

Regeneration of oral siphon pigment organs in the ascidian Ciona intestinalis

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Developmental Biology 339 (2010): 374-389, doi:10.1016/j.ydbio.2009.12.040.Ascidians have powerful capacities for regeneration but the underlying mechanisms are poorly understood. Here we examine oral siphon regeneration in the solitary ascidian Ciona intestinalis. Following amputation, the oral siphon rapidly reforms oral pigment organs (OPO) at its distal margin prior to slower regeneration of proximal siphon parts. The early stages of oral siphon reformation include cell proliferation and re-growth of the siphon nerves, although the neural complex (adult brain and associated organs) is not required for regeneration. Young animals reform OPO more rapidly after amputation than old animals indicating that regeneration is age dependent. UV irradiation, microcautery, and cultured siphon explant experiments indicate that OPOs are replaced as independent units based on local differentiation of progenitor cells within the siphon, rather than by cell migration from a distant source in the body. The typical pattern of eight OPOs and siphon lobes is restored with fidelity after distal amputation of the oral siphon, but as many as sixteen OPOs and lobes can be reformed following proximal amputation near the siphon base. Thus, the pattern of OPO regeneration is determined by cues positioned along the proximal distal axis of the oral siphon. A model is presented in which columns of siphon tissue along the proximal-distal axis below pre-existing OPO are responsible for reproducing the normal OPO pattern during regeneration. This study reveals previously unknown principles of oral siphon and OPO regeneration that will be important for developing Ciona as a regeneration model in urochordates, which may be the closest living relatives of vertebrates.This research was supported by PhD fellowships from MRT and ARC to HA, Grants-in-Aid from MEXT, Japan, and the NIJ Cooperative Program (2008-B02) to YS, INRA, CNRS, the ANR Grant Choregnet, and the Marine Genomics Center of Excellence to J-SJ, Laura and Arthur Colwin and Frederick Bang Fellowships from the Marine Biological Laboratory, Woods Hole, MA to WRJ., and NSF grant (IBN-0611529) to WRJ

Genome-resolved metagenomics reveals role of iron metabolism in drought-induced rhizosphere microbiome dynamics

Recent studies have demonstrated that drought leads to dramatic, highly conserved shifts in the root microbiome. At present, the molecular mechanisms underlying these responses remain largely uncharacterized. Here we employ genome-resolved metagenomics and comparative genomics to demonstrate that carbohydrate and secondary metabolite transport functionalities are overrepresented within drought-enriched taxa. These data also reveal that bacterial iron transport and metabolism functionality is highly correlated with drought enrichment. Using time-series root RNA-Seq data, we demonstrate that iron homeostasis within the root is impacted by drought stress, and that loss of a plant phytosiderophore iron transporter impacts microbial community composition, leading to significant increases in the drought-enriched lineage, Actinobacteria. Finally, we show that exogenous application of iron disrupts the drought-induced enrichment of Actinobacteria, as well as their improvement in host phenotype during drought stress. Collectively, our findings implicate iron metabolism in the root microbiome’s response to drought and may inform efforts to improve plant drought tolerance to increase food security

Autocrine Activation of the MET Receptor Tyrosine Kinase in Acute Myeloid Leukemia

Although the treatment of acute myeloid leukemia (AML) has improved significantly, more than half of all patients develop disease that is refractory to intensive chemotherapy. Functional genomics approaches offer a means to discover specific molecules mediating aberrant growth and survival of cancer cells. Thus, using a loss-of-function RNA interference genomic screen, we identified aberrant expression of the hepatocyte growth factor (HGF) as a critical factor in AML pathogenesis. We found HGF expression leading to autocrine activation of its receptor tyrosine kinase, MET, in nearly half of the AML cell lines and clinical samples studied. Genetic depletion of HGF or MET potently inhibited the growth and survival of HGF-expressing AML cells. However, leukemic cells treated with the specific MET kinase inhibitor crizotinib developed resistance due to compensatory upregulation of HGF expression, leading to restoration of MET signaling. In cases of AML where MET is coactivated with other tyrosine kinases, such as fibroblast growth factor receptor 1 (FGFR1), concomitant inhibition of FGFR1 and MET blocked compensatory HGF upregulation, resulting in sustained logarithmic cell kill both in vitro and in xenograft models in vivo. Our results demonstrate widespread dependence of AML cells on autocrine activation of MET, as well as the importance of compensatory upregulation of HGF expression in maintaining leukemogenic signaling by this receptor. We anticipate that these findings will lead to the design of additional strategies to block adaptive cellular responses that drive compensatory ligand expression as an essential component of the targeted inhibition of oncogenic receptors in human cancers

Proceedings of The Global Conference on Ergot of Sorghum

In June 1996, several of us had the opportunity to see sorghum ergot in Brazil and the damage that the disease can do. We saw severe damage in seed production plots and witnessed the pain that seed producers had to go through to deal with this new problem. There was a wide spread scare in the sorghum community in the Americas because of the infamous reputation of the disease in causing damage in seed production fields. As a silver lining, we also observed first hand, the excellent research program that the Brazilians had in place. It became apparent that all of the sorghum researchers, seed producers and regulators of plant pathogens worldwide needed to come together to study and review this disease. There could be no better venue for such a Global Conference than Sete Lagoas, Brazil. Hence this meeting was proposed and with the support and assistance of the Director of Sorghum and Maize Research (CNPMS) of EMBRAPA, this meeting has been arranged. At the time the meeting was proposed, the disease was known only in a few countries but it has spread today to include much of the Americas and Australia. Obviously, we can no longer avoid the disease, we can only learn to live with it and manage it in future growing seasons. It has been my pleasure to work with the research leaders on ergot at EMBRAPA in developing this conference, to receive cooperation from many of the global leaders on ergot to bring their knowledge to the conference and financial support from the American Seed Trade Association, as well as the support and encouragement from Texas A & M University and INTSORMIL in recognizing the importance of our collaboration on combating sorghum ergot. In this conference, we will learn from the experiences of countries where ergot had existed for a long time while examining the ergot situation in newly invaded countries. We have several dedicated papers dealing with the biology of the pathogen, the epidemiology of the disease, and disease management strategies. We will also chart the movement of the disease and plot ideas on how to collaboratively work to lessen the impact of sorghum ergot in the Americas

THE INFLUENCE OF DRIP IRRIGATION ON COTTON PETIOLE NITRATES AND YIELD

Three cotton (Gossypium hirsutum L.) cultivars were grown under field conditions at Eloy, AZ in 1985 and 1986 to investigate the effects of five drip irrigation treatments on yield, petiole nitrate concentrations, and fruiting characteristics. Irrigation treatments ranged from 59 to 86 cm applied during the growing season. Petiole samples were collected once a week and analyzed for nitrate content. Flower and boll numbers and yield data were recorded throughout both years. Results indicated that irrigation treatments had significant effects on yield with lower amounts of irrigation producing significantly lower lint yields. Significantly lower nitrate concentrations were also observed among the lower irrigation treatments. Irrigation treatments affected flower and boll production with lower irrigation treatments producing fewer flowers and bolls. Irrigation treatments did not significantly influence percent boll set, however, percent boll set was lower in the higher irrigation treatments. The higher irrigation treatments also produced heavier bolls