Plants respond to abiotic stress through a variety of physiological, biochemical, and transcriptional mechanisms. Many genes exhibit altered levels of expression in response to abiotic stress, which requires concerted action of both
Despite myriad examples of local adaptation, the phenotypes and genetic variants underlying such adaptive differentiation are seldom known. Recent work on freezing tolerance and local adaptation in ecotypes of
We examined the consequences of a naturally occurring loss‐of‐function (
Freezing tolerance was lower in the Italian (11%) compared to the Swedish (72%) ecotype, and all four experimental
We identified 10 genes that are at least partially regulated by
- NSF-PAR ID:
- 10458095
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 107
- Issue:
- 2
- ISSN:
- 0002-9122
- Page Range / eLocation ID:
- p. 250-261
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary cis‐ andtrans‐ regulatory features. In order to study the variability in transcriptome response to abiotic stress,RNA sequencing was performed using 14‐day‐old maize seedlings of inbreds B73, Mo17, Oh43,PH 207 and B37 under control, cold and heat conditions. Large numbers of genes that responded differentially to stress between parental inbred lines were identified.RNA sequencing was also performed on similar tissues of theF 1hybrids produced by crossing B73 and each of the three other inbred lines. By evaluating allele‐specific transcript abundance in theF 1hybrids, we were able to measure the abundance ofcis‐ andtrans‐ regulatory variation between genotypes for both steady‐state and stress‐responsive expression differences. Although examples oftrans‐ regulatory variation were observed,cis‐ regulatory variation was more common for both steady‐state and stress‐responsive expression differences. The genes withcis‐ allelic variation for response to cold or heat stress provided an opportunity to study the basis for regulatory diversity. -
Abstract Questions What are the primary biotic and abiotic factors driving composition and abundance of naturally regenerated tree seedlings across forest landscapes of Maine? Do seedling species richness (
SR ) and density (SD ) decrease with improved growing conditions (climate and soil), but increase with increased diversity of overstorey composition and structure? Does partial harvesting disproportionately favour relative dominance of shade‐intolerant hardwoods (PIHD ) over shade‐tolerant softwoods (PTSD )?Location Forest landscapes across the diverse eco‐regions and forest types of Maine,
USA .Methods This study used
USDA Forest Service Forest Inventory Analysis permanent plots (n = 10 842), measured every 5 yr since 1999. The best models for each response variable (SR ,SD ,PIHD andPTSD ) were developed based onAIC and biological interpretability, while considering 35 potential explanatory variables incorporating climate, soil, site productivity, overstorey structure and composition, and past harvesting.Results Mean annual temperature was the most important abiotic factor, whereas overstorey tree size diversity was the most important biotic factor for
SR andSD . Both mean annual temperature and overstorey tree size diversity had a curvilinear relationship withSR andSD . Average overstorey shade tolerance and percentage tolerant softwood basal area in the overstorey were the top predictor variables ofPIHD andPTSD , respectively. Partial harvesting favouredPIHD but notPTSD .Conclusions This is one of the first studies to comprehensively evaluate a number of factors influencing naturally established tree seedlings at a broad landscape scale in the Northern Forest region of the eastern
USA and Canada. Despite limitations associated with relatively small plot size, large seedling size class and lack of direct measurements of light, water and nutrients, this study documents the influence of these factors amid high variability associated with patterns of natural regeneration. The curvilinear relationship between mean annual temperature withSR andSD supports the argument that species richness and abundance usually have unimodal relationships with productivity indicators, whereas the curvilinear relationship between overstorey tree size diversity andSR andSD suggest that moderate overstorey diversity incorporates multiple species as well as higher seedling individuals. -
Abstract Ecotypic variation in forage nutrient value of a dominant grassland species,
Andropogon gerardii Vitman (big bluestem), was quantified across a longitudinal precipitation gradient of theUS Great Plains. Ecotypic variation ofA. gerardii has been documented across this gradient, but the extent to which forage nutrient value differs among ecotypes is poorly known. Seven indicators of forage nutrient value (neutral detergent fiber [NDF ], acid detergent fiber [ADF ],in‐vitro dry matter digestibility [IVDMD ], crude protein [CP ], crude fat [CF ], ash content) and relative feed value [RFV ] were examined in 12 populations representing four ecotypes corresponding with distinct climate regions: eastern Colorado, central Kansas, eastern Kansas and southern Illinois. Vegetative material ofA. gerardii was collected from each population in July 2010. A greenhouse study tested the effect of watering regime on seedlings of the ecotypes from three of the precipitation regions grown under controlled conditions. Forage nutrient value indicators nitrogen andCP increased, andADF decreased east to west, whileIVDMD decreased across the gradient corresponding with less annual precipitation. The greenhouse experiment showed that sampling before and after water treatment affected forage nutrient value measurements, with the exception ofNDF andCF . Nutrient value was most related to soil moisture and phenology, with smaller differences among ecotypes. Nutrient value of populations from the southern Illinois ecotype changed the least in response to variation in soil moisture. The southern Illinois ecotype will likely maintain forge nutrient value under variable precipitation projected to occur with climate change better than the ecotypes from more westerly parts of the range ofA. gerardii . -
Premise Cold tolerance is an important factor limiting the geographic distribution and growing season for many plant species, yet few studies have examined variation in cold tolerance extensively within and among closely related species and compared that to their geographic distribution.
Methods This study examines cold tolerance within and among species in the genus
Arabidopsis . We assessed cold tolerance by measuring electrolyte leakage from detached leaves in multiple populations of fiveArabidopsis taxa. The temperature at which 50% of cells were lysed was considered the lethal temperature (LT 50).Results We found variability within and among taxa in cold tolerance. There was no significant within‐species relationship between latitude and cold tolerance. However, the northern taxa,
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Premise Light is critical in the ability of plants to accumulate chlorophyll. When exposed to far‐red (
FR ) light and then grown in white light in the absence of sucrose, wild‐type seedlings fail to green in a response known as theFR block of greening (BOG ). This response is controlled by phytochrome A through repression of protochlorophyllide reductase‐encoding (POR ) genes byFR light coupled with irreversible plastid damage. Sigma (SIG ) factors are nuclear‐encoded proteins that contribute to plant greening and plastid development through regulating gene transcription in chloroplasts and impacting retrograde signaling from the plastid to nucleus.SIG s are regulated by phytochromes, and the expression of someSIG factors is reduced in phytochrome mutant lines, includingphyA . Given the association of phyA with theFR BOG and its regulation ofSIG factors, we investigated the potential regulatory role ofSIG factors in theFR BOG response.Methods We examined
FR BOG responses insig mutants, phytochrome‐deficient lines, and mutant lines for several phy‐associated factors. We quantified chlorophyll levels and examined expression of keyBOG ‐associated genes.Results Among six
sig mutants, only thesig6 mutant significantly accumulated chlorophyll afterFR BOG treatment, similar to thephyA mutant.SIG 6 appears to control protochlorophyllide accumulation by contributing to the regulation of tetrapyrrole biosynthesis associated with glutamyl‐tRNA reductase (HEMA 1) function, select phytochrome‐interacting factor genes (PIF4 andPIF6 ), andPENTA1 , which regulatesPORA mRNA translation afterFR exposure.Conclusions Regulation of
SIG6 plays a significant role in plant responses toFR exposure during theBOG response.