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Stoneville, MS, United States

Jiang T.,University of Georgia | Jiang T.,Northeast Forestry University | Zhou B.,University of Georgia | Zhou B.,Northeast Forestry University | And 7 more authors.
Toxins | Year: 2011

This research examined the expression patterns of 94 stress-related genes in seven maize inbred lines with differential expressions of resistance to aflatoxin contamination. The objective was to develop a set of genes/probes associated with resistance to A. flavus and/or aflatoxin contamination. Ninety four genes were selected from previous gene expression studies with abiotic stress to test the differential expression in maize lines, A638, B73, Lo964, Lo1016, Mo17, Mp313E, and Tex6, using real-time RT-PCR. Based on the relative-expression levels, the seven maize inbred lines clustered into two different groups. One group included B73, Lo1016 and Mo17, which had higher levels of aflatoxin contamination and lower levels of overall gene expression. The second group which included Tex6, Mp313E, Lo964 and A638 had lower levels of aflatoxin contamination and higher overall levels of gene expressions. A total of six ''cross-talking'' genes were identified between the two groups, which are highly expressed in the resistant Group 2 but down-regulated in susceptible Group 1. When further subjected to drought stress, Tex6 expressed more genes up-regulated and B73 has fewer genes up-regulated. The transcript patterns and interactions measured in these experiments indicate that the resistant mechanism is an interconnected process involving many gene products and transcriptional regulators, as well as various host interactions with environmental factors, particularly, drought and high temperature. © 2011 by the authors. Source


Kebede H.,Crop Genetics Research Unit | Abbas H.K.,Biological Control of Pests Research Unit | Fisher D.K.,Crop Genetics Research Unit | Bellaloui N.,Crop Genetics Research Unit
Toxins | Year: 2012

Increased aflatoxin contamination in corn by the fungus Aspergillus flavus is associated with frequent periods of drought and heat stress during the reproductive stages of the plants. The objective of this study was to evaluate the relationship between aflatoxin contamination and physiological responses of corn plants under drought and heat stress. The study was conducted in Stoneville, MS, USA under irrigated and non-irrigated conditions. Five commercial hybrids, P31G70, P33F87, P32B34, P31B13 and DKC63-42 and two inbred germplasm lines, PI 639055 and PI 489361, were evaluated. The plants were inoculated with Aspergillus flavus (K-54) at mid-silk stage, and aflatoxin contamination was determined on the kernels at harvest. Several physiological measurements which are indicators of stress response were determined. The results suggested that PI 639055, PI 489361 and hybrid DKC63-42 were more sensitive to drought and high temperature stress in the non-irrigated plots and P31G70 was the most tolerant among all the genotypes. Aflatoxin contamination was the highest in DKC63-42 and PI 489361 but significantly lower in P31G70. However, PI 639055, which is an aflatoxin resistant germplasm, had the lowest aflatoxin contamination, even though it was one of the most stressed genotypes. Possible reasons for these differences are discussed. These results suggested that the physiological responses were associated with the level of aflatoxin contamination in all the genotypes, except PI 639055. These and other physiological responses related to stress may help examine differences among corn genotypes in aflatoxin contamination. © 2012 by the authors; licensee MDPI, Basel, Switzerland. Source


Chen J.,Biological Control of Pests Research Unit | Rashid T.,Alcorn State University | Feng G.,Alcorn State University
PLoS ONE | Year: 2014

Solenopsis invicta and Solenopsis richteri are two very closely related invasive ant species; however, S. invicta is a much more successful invader. Physiological tolerance to abiotic stress has been hypothesized to be important to the success of an invasive species. In this study, we tested the hypothesis that S. invicta is more tolerant to heat and desiccation stress than S. richteri. The data strongly support our hypothesis. S. invicta was found to be significantly less vulnerable than S. richteri to both heat and desiccation stress. Despite S. richteri having significantly higher body water content, S. invicta was less sensitive to desiccation stress due to its significantly lower water loss rate (higher desiccation resistance). After the cuticular lipid was removed, S. invicta still had a significantly lower water loss rate than S. richteri, indicating that cuticular lipids were not the only factors accounting for difference in the desiccation resistance between these two species. Since multiple biological and/or ecological traits can contribute to the invasion success of a particular species, whether the observed difference in tolerance to heat and desiccation stresses is indeed associated with the variation in invasion success between these two species can only be confirmed by further extensive comparative study. Source


Bellaloui N.,Crop Genetics Research Unit | Bruns H.A.,Crop Production Systems Research Unit | Abbas H.K.,Biological Control of Pests Research Unit | Mengistu A.,Crop Genetics Research Unit | And 2 more authors.
Frontiers in Plant Science | Year: 2015

Information on the effects of management practices on soybean seed composition is scarce. Therefore, the objective of this research was to investigate the effects of planting date (PD) and seeding rate (SR) on seed composition (protein, oil, fatty acids, and sugars) and seed minerals (B, P, and Fe) in soybean grown in two row-types (RTs) on the Mississippi Delta region of the Midsouth USA. Two field experiments were conducted in 2009 and 2010 on Sharkey clay and Beulah fine sandy loam soil at Stoneville, MS, USA, under irrigated conditions. Soybean were grown in 102 cm single-rows and 25 cm twin-rows in 102 cm centers at SRs of 20, 30, 40, and 50 seeds m−2. The results showed that in May and June planting, protein, glucose, P, and B concentrations increased with increased SR, but at the highest SRs (40 and 50 seeds m−2), the concentrations remained constant or declined. Palmitic, stearic, and linoleic acid concentrations were the least responsive to SR increases. Early planting resulted in higher oil, oleic acid, sucrose, B, and P on both single and twin-rows. Late planting resulted in higher protein and linolenic acid, but lower oleic acid and oil concentrations. The changes in seed constituents could be due to changes in environmental factors (drought and temperature), and nutrient accumulation in seeds and leaves. The increase of stachyose sugar in 2010 may be due to a drier year and high temperature in 2010 compared to 2009; suggesting the possible role of stachyose as an environmental stress compound. Our research demonstrated that PD, SR, and RT altered some seed constituents, but the level of alteration in each year dependent on environmental factors such as drought and temperature. This information benefits growers and breeders for considering agronomic practices to select for soybean seed nutritional qualities under drought and high heat conditions. © 2015 by FUOC. Source


Zhao L.,Biological Control of Pests Research Unit | Chen J.,Biological Control of Pests Research Unit | Jones W.A.,Biological Control of Pests Research Unit | Oi D.H.,Center for Medical | Drees B.M.,Texas A&M University
Environmental Entomology | Year: 2012

In 2002, a new invasive pest ant in the genus, Nylanderia (formerly Paratrechina), was found in Houston, TX. This invasive ant has been causing significant economic and ecological damage in infested areas. Because of the morphological and behavioral similarities to Nylanderia pubens Forel (Caribbean crazy ant) found in Florida, this ant was named Nylanderia sp. nr. pubens (Rasberry crazy ant). So far, morphometric and phylogenetic analyses have not determined if the two ants are the same or separate species. To determine the relationships between the two populations, a molecular approach was undertaken. Five novel genes with various functions from N. pubens and N. sp. nr. pubens were cloned, sequenced, and identified, including a chemosensory protein (NpCsp), the cyclophilinlike protein (NpClp), the fatty acid binding protein (NpFabp), the ferritin 2-like protein (NpFlp), and an odorant binding protein (NpObp). The cDNA sequences of NpCsp, NpFabp, NpFlp, and NpObp, shared 100% identity between N. sp. nr. pubens and N. pubens. The cDNA of NpClp shared 99% identity, with the only difference at the nucleotide position 358. Comparisons of four partial genomic DNA sequences from Caribbean and Rasberry crazy ants indicated 100% identity for a 710-bp partial genomic DNA sequence of cytochrome oxidase subunit I gene, 99% identity for a 774 bp, and a 452-bp partial genomic DNA sequence of NpFabp and NpObp containing noncoding regions, and 100% identity for a 289 bp partial genomic DNA sequence of NpCsp containing only coding region. This study showed that N. sp. nr. pubens in Texas is the same, or at most an intraspecific variant or ecotype of the species in Florida. © 2012 Entomological Society of America. Source

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