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Gibberellins: a phytohormonal basis for heterosis in maize (1988)

S. B. Rood ; R. I. Buzzell ; L. N. Mander ; [et al.]

American Association for the Advancement of Science (AAAS)

In: Science. 241(4870): 1216-8. doi: 10.1126/science.241.4870.1216.

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Publication Date: 1988-09-02

Description: Four commercially important maize parental inbreds and their 12 F(1) hybrids were studied to investigate the role of the phytohormone gibberellin (GA) in the regulation of heterosis (hybrid vigor). All hybrids grew faster than any inbred. In contrast, all inbreds showed a greater promotion of shoot growth after the exogenous application of GA(3). Concentrations of endogenous GA(1), the biological effector for shoot growth in maize, and GA(19), a precursor of GA(1), were measured in apical meristematic shoot cylinders for three of the inbreds and their hybrids by gas chromatography-mass spectrometry with selected ion monitoring; deuterated GAs were used as quantitative internal standards. In 34 of 36 comparisons, hybrids contained higher concentrations of endogenous GAs than their parental inbreds. Preferential growth acceleration of the inbreds by exogenous GA(3) indicates that a deficiency of endogenous GA limits the growth of the inbreds and is thus a cause of inbreeding depression. Conversely, the increased endogenous concentration of GA in the hybrids could provide a phytohormonal basis for heterosis for shoot growth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rood, S B -- Buzzell, R I -- Mander, L N -- Pearce, D -- Pharis, R P -- New York, N.Y. -- Science. 1988 Sep 2;241(4870):1216-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17740785" target="_blank"〉PubMed〈/a〉

Print ISSN: 0036-8075

Electronic ISSN: 1095-9203

Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics

Published by American Association for the Advancement of Science (AAAS)

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Branch growth of riparian cottonwoods: a hydrologically sensitive dendrochronological tool (1998)

Willms, Jennifer ; Rood, S. B. ; Willms, Walter ; [et al.]

Springer

Trees 12 (1998), S. 215-223

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ISSN: 0931-1890

Keywords: Key words Branch growth ; Cottonwoods ; Instream flow needs ; Populus ; Riparian ecosystems

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The conservation of riparian (river valley flood plain) forests relies on the provision of instream flows that are sufficient to sustain tree growth. In the present study, annual branch growth increments were investigated as an indicator of environmental favorability for riparian cottonwoods. Trees of three species, Populus angustifolia, P. balsamifera, and P. deltoides, and their natural interspecific hybrids, were studied at five sites along the Oldman and South Saskatchewan rivers in Alberta, Canada. Annual branch growth increments for the interval from 1983 to 1992 were positively correlated with stream flows (r 2 = 0.79 at Lethbridge) and slightly negatively correlated with weather variables that contribute to water demand: evaporation, temperature, wind, and/or sunshine. The combination of January to May stream flow (water supply) and June evaporation (water demand) almost entirely accounted for the branch growth variation across years (r 2 = 0.91 at Lethbridge). Tree ring increments were also investigated but were less closely correlated than branch increments across trees or with stream flow. Branch growth increments thus provide an accurate but short duration (1 or 2 decades) record of environmental favorability for growth. The close correlation between branch growth and stream flow indicates that water is the principal limitation to growth of these riparian cottonwoods and that these trees obtained their water from a source linked to the stream, the riparian water table. Analyses of branch increments should provide a management tool for (i) determining instream flow needs for riparian cottonwoods and (ii) analyzing impacts of stream flow alterations due to river damming or water diversion.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004680050143

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Gibberellin physiology of safflower: endogenous gibberellins and response to gibberellic acid (1993)

Potter, T. I. ; Zanewich, K. P. ; Rood, S. B.

Springer

Plant growth regulation 12 (1993), S. 133-140

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ISSN: 1573-5087

Keywords: gibberellins ; paclobutrazol ; GC-MS ; safflower ; Carthamus tinctorius ; growth ; yield

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Endogenous gibberellins (GAs) were extracted from safflower (Carthamus tinctorius L.) stems and detected by capillary gas chromatography-mass spectrometry from which GA1, GA3, GA19,, GA20, GA29, and probably, GA44 were detected. The detection of these GAs suggests that the early 13-OH biosynthetic pathway is prevalent in safflower shoots. Deuterated GAs were used as internal standards and GA concentrations were determined in stems harvested at weekly intervals. GA1 and GA19 levels per stem increased but concentrations per gram dry weight decreased over time. GA20 was only detected in young stem tissue. Gibberellic acid (GA3) was also applied in field trials and both GA3 and the GA biosynthetic inhibitor, paclobutrazol, were applied in growth chamber tests. GA3 increased epidermal cell size, internode length, and increased internode cell number causing stem elongation. Conversely, paclobutrazol reduced stem height, internode and cell size, cell number and overall shoot weight. In field tests, GA3 increased total stem weight, but decreased leaf weight, flower bud number and seed yield. Thus, GA3 promoted vegetative growth at the expense of reproductive commitment. These studies collectively indicate a promotory role of GAs in the control of shoot growth in safflower, and are generally consistent with gibberellin studies of related crop plants.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00144594

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Inheritance of tillering and flowering-time in early maturing maize (1981)

Rood, S. B. ; Major, D. J.

Springer

Euphytica 30 (1981), S. 327-334

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ISSN: 1573-5060

Keywords: Zea mays L. ; maize ; tillering ; flowering-time ; diallel

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Summary A diallel cross and F2 populations derived from eight early maturing maize inbreds were used to investigate the inheritance of tillering and flowering-time (anthesis), and the possible relationship between tillering and flowering-time. Incomplete dominance for increased tillering was observed; potence ratios, representing the overall degree of dominance, ranged from 0.26 to 0.52. Dominance for early flowering ranged from incomplete with a potence ratio of 0.55 to overdominance with a potence ratio of 1.40. Broad-sense heritabilities were low for both characters. The genetic component of variation for tillering was due to general combining ability effects; specific combining ability effects were not significant. A significant negative linear relationship between tillering and flowering-time was found. Lack of independent assortment of tillering and flowering-time in F2 populations indicated that the two characters are genetically related.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00033994

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Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes (2016)

Hauer, F. R., Locke, H., Dreitz, V. J., Hebblewhite, M., Lowe, W. H., Muhlfeld, C. C., Nelson, C. R., Proctor, M. F., Rood, S. B.

American Association for the Advancement of Science (AAAS)

In: Science Advances

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Publication Date: 2016-06-25

Description: Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

Electronic ISSN: 2375-2548

Topics: Natural Sciences in General

Published by American Association for the Advancement of Science (AAAS)

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Higher photosynthetic capacity from higher latitude: foliar characteristics and gas exchange of southern, central and northern populations of Populus angustifolia (2015)

Kaluthota, S., Pearce, D. W., Evans, L. M., Letts, M. G., Whitham, T. G., Rood, S. B.

Oxford University Press

In: Tree Physiology

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Publication Date: 2015-09-25

Description: Narrowleaf cottonwood ( Populus angustifolia James) is an obligate riparian poplar that is a foundation species in river valleys along the Rocky Mountains, spanning 16° of latitude from southern Arizona, USA to southern Alberta, Canada. Its current distribution is fragmented, and genetic variation shows regional population structure consistent with the effects of geographic barriers and past climate. It is thus very well-suited for investigating ecophysiological adaptation associated with latitude. In other section Tacamahaca poplar species, genotypes from higher latitudes show evidence of short-season adaptation with foliar traits that contribute to higher photosynthetic capacity. We tested for similar adaptation in three populations of narrowleaf cottonwoods: from Arizona (south), Alberta (north) and Utah, near the centre of the latitudinal distribution. We propagated 20 genotypes from each population in a common garden in Alberta, and measured foliar and physiological traits after 3 years. Leaves of genotypes from the northern population had higher leaf mass per area (LMA), increased nitrogen (N) content and higher carotenoid and chlorophyll content, and these were associated with higher light-saturated net photosynthesis ( A sat ). In leaves of all populations the majority of stomata were abaxial, with the proportion of abaxial stomata highest in the southern population. Stomatal conductance ( g s ) and transpiration rates were higher in the northern population but water-use efficiency ( A sat / g s ) and leaf carbon isotope composition ( 13 C) did not differ across the populations. These results (i) establish links between A sat and g s , N, chlorophyll and LMA among populations within this species, (ii) are consistent with the discrimination of populations from prior investigation of genetic variation and (iii) support the concept of latitudinal adaptation, whereby deciduous trees from higher latitudes display higher photosynthetic capacity, possibly compensating for a shorter and cooler growth season and reduced insolation.

Print ISSN: 0829-318X

Electronic ISSN: 1758-4469

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Published by Oxford University Press

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