Project description:Closely related lineages can possess phenotypic variation important for adaptation and the evolution of new species; a phenomenon that can be more clearly elucidated by studying hybrid generations. We compare variation in gene expression in response to drought for two taxa and advanced-generation hybrids of the Piriqueta cistoides ssp. caroliniana complex that differ in their levels of tolerance to water limitation. Drought treatments lasted 36 days, through four cycles of drought. Gene expression in drought and control treatments was assessed using heterologous hybridization to a Glycine max microarray. There was a predominance of down-regulated genes in response to sustained drought in all morphotypes. This pattern was more pronounced in the hybrids, which can exhibit greater drought tolerance under field and greenhouse conditions than the parental morphotypes. Expression response profiles were more similar between the hybrid and the drought-tolerant parental morphotype than they were between the hybrid and the parental morphotype that occurs in more mesic habitats. Predominant down-regulation of gene expression contrasts with studies of response to short-term drought and with studies of drought-response in annual and non-drought-tolerant model species, and supports the results of a growing number of studies with other drought-tolerant perennial plants under prolonged drought. A total of 18 array hyridizations. Two conditions (drought and control), three morphotypes (caroliniana, viridis, and hybrid), for a total of 6 morphotype/treatment combinations. Three samples of each morphotypes/treatment combination were hybridized twice in dye swap in a loop design.
Project description:Closely related lineages can possess phenotypic variation important for adaptation and the evolution of new species; a phenomenon that can be more clearly elucidated by studying hybrid generations. We compare variation in gene expression in response to drought for two taxa and advanced-generation hybrids of the Piriqueta cistoides ssp. caroliniana complex that differ in their levels of tolerance to water limitation. Drought treatments lasted 36 days, through four cycles of drought. Gene expression in drought and control treatments was assessed using heterologous hybridization to a Glycine max microarray. There was a predominance of down-regulated genes in response to sustained drought in all morphotypes. This pattern was more pronounced in the hybrids, which can exhibit greater drought tolerance under field and greenhouse conditions than the parental morphotypes. Expression response profiles were more similar between the hybrid and the drought-tolerant parental morphotype than they were between the hybrid and the parental morphotype that occurs in more mesic habitats. Predominant down-regulation of gene expression contrasts with studies of response to short-term drought and with studies of drought-response in annual and non-drought-tolerant model species, and supports the results of a growing number of studies with other drought-tolerant perennial plants under prolonged drought.
Project description:Episodic drought stress negatively impacts the health of long-lived trees. Understanding the genetic and molecular mechanisms that underpin response to drought stress is requisite for selecting or enhancing climate change resilience. Here we aim to establish standardized drought stress protocols for transcriptome studies in poplar trees, to determine how hybrid poplars respond to prolonged and uniform exposure to drought; to determine if the responses to moderate and more severe growth-limiting drought stresses were qualitatively or quantitatively different; and, to determine how response to drought changes throughout the day. We established hybrid poplar trees (Populus x ’Okanese’) from unrooted stem cutting with abundant soil moisture for six weeks. We then withheld water to establish three soil water contents reflecting well-watered, moderate, and severe growth-limiting drought conditions. Plants were rewatered as needed for three weeks to maintain the soil water conditions. The mild and severe drought treatments elicited distinct changes in growth and development, photosynthetic rates and global transcriptomic changes. Notably, the time of day of sampling was strongest signal in the transcriptome data and it quantitatively and qualitatively affected drought responsive changes in gene expression. These analyses emphasize the complex nature of drought regulation in long-lived trees.
Project description:Drought represents a major constraint on maize production worldwide. Understanding the genetic basis for natural variation in drought tolerance of maize may facilitate efforts to improve this trait in cultivated germplasm. Here, using a genome-wide association study, we show that a miniature inverted-repeat transposable element (MITE) inserted in the promoter of a NAC gene (ZmNAC111) is significantly associated with natural variation in maize drought tolerance. For maize RNA-seq analysis, pooled tissues from three, eight-day-old maize seedlings were collected from transgenic and wild-type plants, prior to or after 2-hour dehydration, to conduct the RNA-seq analysis.
Project description:To investigate the expression and methylation patterns of hybrid embryo development in Brassica napus, we performed pattern analysis on different developmental stages of parental and hybrid embryos
Project description:As exposure to episodic drought can impinge significantly on forest health and the establishment of productive tree plantations, there is great interest in understanding the mechanisms of drought response in trees. The ecologically dominant and economically important genus Populus, with its sequenced genome, provides an ideal opportunity to examine transcriptome level changes in trees in response to a drought stimulus. The transcriptome level drought response of two commercially important hybrid Populus clones (P. deltoides · P. nigra, DN34, and P. nigra · P. maximowiczii, NM6) was characterized over a diurnal period using a 4 · 2 · 2 completely randomized factorial ANOVA experimental design (four time points, two genotypes, and two treatment conditions) using Affymetrix Poplar GeneChip microarrays. Notably, the specific genes that exhibited changes in transcript abundance in response to drought differed between the genotypes and/or the time of day that they exhibited their greatest differences. This study emphasizes the fact that it is not possible to draw simple, generalized conclusions about the drought response of the genus Populus on the basis of one species, nor on the basis of results collected at a single time point. The data derived from our studies provide insights into the variety of genetic mechanisms underpinning the Populus drought response, and provide candidates for future experiments aimed at understanding this response across this economically and ecologically important genus.
Project description:As exposure to episodic drought can impinge significantly on forest health and the establishment of productive tree plantations, there is great interest in understanding the mechanisms of drought response in trees. The ecologically dominant and economically important genus Populus, with its sequenced genome, provides an ideal opportunity to examine transcriptome level changes in trees in response to a drought stimulus. The transcriptome level drought response of two commercially important hybrid Populus clones (P. deltoides · P. nigra, DN34, and P. nigra · P. maximowiczii, NM6) was characterized over a diurnal period using a 4 · 2 · 2 completely randomized factorial ANOVA experimental design (four time points, two genotypes, and two treatment conditions) using Affymetrix Poplar GeneChip microarrays. Notably, the specific genes that exhibited changes in transcript abundance in response to drought differed between the genotypes and/or the time of day that they exhibited their greatest differences. This study emphasizes the fact that it is not possible to draw simple, generalized conclusions about the drought response of the genus Populus on the basis of one species, nor on the basis of results collected at a single time point. The data derived from our studies provide insights into the variety of genetic mechanisms underpinning the Populus drought response, and provide candidates for future experiments aimed at understanding this response across this economically and ecologically important genus. 48 arrays total. 2 genotypes (DN34, NM6), 4 time points (midnight, pre-dawn, mid-day, late day), 2 water regimes (well-watered, water-limited). 3 biological replicates per treatment.
Project description:Expression profiling analyses for 5 maize inbreds and 4 hybrids, chosen to represent diversity in genotypes and heterosis responses, revealed a correlation between genetic diversity and transcriptional variation. The majority of differentially expressed genes in each of the different hybrids exhibited additive expression patterns, and ~25% exhibited statistically significant non-additive expression profiles. Among the non-additive profiles, ~80% exhibited hybrid expression levels between the parental levels, ~20% exhibited hybrid expression levels at the parental levels and ~1% exhibited hybrid levels outside the parental range. These findings indicate that the frequencies of additive and non-additive expression patterns are very similar across a range of hybrid lines. Keywords: Genotype comparison series
Project description:To understand the role of Arabidopsis histone deacetylase HDA6 in drought tolerance, we have employed transcriptional profiling of the hda6 mutant and its parental line under drought and control conditions to identify genes differentially expressed in the hda6 mutant under drought and control conditions. Aligent's Whole Arabidopsis Gene Expression Microarray (Agilent-015059, G2519F, V3, 4x44K) was used.