Scott Holaday

Texas Tech University

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Dmytro Kornyeyev

Gilead Sciences (United States)

Randy D. Allen

Oklahoma State University

Paul W. Paré

Texas Tech University

Zhehui Mao

Texas Tech University

Mi‐Seong Kim

KoreaBio

Huiming Zhang

Center for Excellence in Molecular Plant Sciences

Jing Wang

Second Affiliated Hospital of Zhejiang University

Chelsea Griffin

Texas Tech University

Juqiang Yan

Texas Tech University

Elizabeth F. Waring

Northeastern State University

Cooperative Institutions

Texas Tech University

Lanzhou University

Lubbock Christian University

National University of Río Cuarto

Central South University

Zhejiang University

University of North Carolina at Chapel Hill

Institute of Molecular Biology and Genetics

Bowdoin College

Gansu Agricultural University

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Overexpression of the Arabidopsis 14-3-3 Protein GF14λ in Cotton Leads to a “Stay-Green” Phenotype and Improves Stress Tolerance under Moderate Drought Conditions

Plant and Cell Physiology (2004)

Juqiang Yan Cixin He Jing Wang Zhehui Mao Scott Holaday

The Arabidopsis gene GF14λ that encodes a 14-3-3 protein was introduced into cotton plants to explore the physiological roles that GF14λ might play in plants. The expression level of GF14λ under the control of the cauliflower mosaic virus 35S promoter varied in transgenic cotton plants, and lines that expressed GF14λ demonstrated a "stay-green" phenotype and improved water-stress tolerance. These lines wilted less and maintained higher photosynthesis than segregated non-transgenic control plants under water-deficit conditions. Stomatal conductance appears to be the major factor for the observed higher photosynthetic rates under water-deficit conditions. The stomatal aperture of transgenic plants might be regulated by GF14λ through some transporters such as H+-ATPase whose activities are controlled by their interaction with 14-3-3 proteins. However, since 14-3-3 proteins interact with numerous proteins in plant cells, many metabolic processes could be affected by the GF14λ overexpression. Whatever the mechanisms, the traits observed in the GF14λ-expressing cotton plants are beneficial to crops under certain water-deficit conditions.

Cauliflower mosaic virus

Stomatal Conductance

Drought Tolerance

10.1093/pcp/pch115

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Soil bacteria augment Arabidopsis photosynthesis by decreasing glucose sensing and abscisic acid levels in planta

The Plant Journal (2008)

Huiming Zhang Xitao Xie Mi‐Seong Kim Dmytro Kornyeyev Scott Holaday

Photosynthesis is regulated by environmental factors as well as endogenous sugar signals. Whereas light-driven sugar biosynthesis is essential for terrestrial organisms, as well as belowground microflora, whether and how soil symbionts regulate photosynthesis has yet to be reported. Here, we show that the plant growth-promoting soil bacterium Bacillus subtilis GB03 augments photosynthetic capacity by increasing photosynthetic efficiency and chlorophyll content in Arabidopsis. Mechanistic studies reveal an elevation of sugar accumulation as well as the suppression of classic glucose signaling responses, including hypocotyl elongation and seed germination, with exposure to GB03. Compared with wild-type plants, two Arabidopsis mutants defective in hexokinase-dependent sugar signaling exhibit increased photosynthetic capacity, which is not further enhanced with GB03 exposure. Overlap in sugar/ABA sensing is observed in GB03-exposed plants, with a reduction of ABA-biosynthetic transcripts as well as downstream metabolite levels in leaves. Moreover, exogenous ABA abrogates GB03-triggered increases in photosynthetic efficiency and chlorophyll content. These results demonstrate that certain rhizobacteria elevate photosynthesis through the modulation of endogenous sugar/ABA signaling, and establish a regulatory role for soil symbionts in plant acquisition of energy.

Plant Physiology

Photosynthetic efficiency

Terrestrial plant

10.1111/j.1365-313x.2008.03593.x

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Citations (326)

The effects of soil nitrogen availability on the allocation of nitrogen to leaf processes for an invasive grass, Phalaris arundinacea , and native Carex species

F1000Research (2014)

Chelsea Griffin Elizabeth F. Waring Scott Holaday

Phalaris arundinacea

Carex

10.7490/f1000research.1096701.1

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Predicting the Extent of Photosystem II Photoinactivation Using Chlorophyll a Fluorescence Parameters Measured during Illumination

Plant and Cell Physiology (2003)

Dmytro Kornyeyev Scott Holaday Barry A. Logan

The temperature dependence of the relationship between the decline in activity of photosystem II (PSII) and a chlorophyll a fluorescence parameter combining the excitation pressure (1–qP) and efficiency of excitation energy capture by open PSII reaction centers in the light-acclimated state (Fv′/Fm′) was investigated in cotton leaves. A formula for the prediction of PSII inactivation is proposed on the basis of the results obtained. By comparison of the predicted and actual levels of PSII photoinactivation, the rate of PSII recovery was estimated from chlorophyll a fluorescence parameters measured during the day for attached cotton leaves exposed to suboptimal morning temperatures in a greenhouse.

10.1093/pcp/pcg129

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Enhancing Cotton Fiber Elongation and Cellulose Synthesis by Manipulating Fructokinase Activity

David Granot Scott Holaday Randy D. Allen

a. Objectives (a) Identification and characterization of the cotton fiber FRKs; (b) Generating transgenic cotton plants overproducing either substrate inhibited tomato FRK or tomato FRK without substrate inhibition; (c) Generating transgenic cotton plants with RNAi suppression of fiber expressed FRKs; (d) Generating Arabidopsis plants that over express FRK1, FRK2, or both genes, as additional means to assess the contribution of FRK to cellulose synthesis and biomass production. b. Background to the topic: Cellulose synthesis and fiber elongation are dependent on sugar metabolism. Previous results suggested that FRKs (fructokinase enzymes that specifically phosphorylate fructose) are major players in sugar metabolism and cellulose synthesis. We therefore hypothesized that increasing fructose phosphorylation may enhance fiber elongation and cellulose synthesis in cotton plants. Accordinlgy, the objectives of this research were: c. Major conclusions and achievements: Two cotton FRKs expressed in fibers, GhFRK2 and GhFRK3, were cloned and characterized. We found that GhFRK2 enzyme is located in the cytosol and GhFRK3 is located within plastids. Both enzymes enable growth on fructose (but not on glucose) of hexose kinase deficient yeast strain, confirming the fructokinase activity of the cloned genes. RNAi constructs with each gene were prepared and sent to the US collaborator to generate cotton plants with RNAi suppression of these genes. To examine the effect of FRKs using Arabidopsis plants we generated transgenic plants expressing either LeFRK1 or LeFRK2 at high level. No visible phenotype has been observed. Yet, plants expressing both genes simultaneously are being created and will be tested. To test our hypothesis that increasing fructose phosphorylation may enhance fiber cellulose synthesis, we generated twenty independent transgenic cotton plant lines overexpressing Lycopersicon (Le) FRK1. Transgene expression was high in leaves and moderate in developing fiber, but enhanced FRK activity in fibers was inconsistent between experiments. Some lines exhibited a 9-11% enhancement of fiber length or strength, but only one line tested had consistent improvement in fiber strength that correlated with elevated FRK activity in the fibers. However, in one experiment, seed cotton mass was improved in all transgenic lines and correlated with enhanced FRK activity in fibers. When greenhouse plants were subjected to severe drought during flowering and boll development, no genotypic differences in fiber quality were noted. Seed cotton mass was improved for two transgenic lines but did not correlate with fiber FRK activity. We conclude that LeFRK1 over-expression in fibers has only a small effect on fiber quality, and any positive effects depend on optimum conditions. The improvement in productivity for greenhouse plants may have been due to better structural development of the water-conducting tissue (xylem) of the stem, since stem diameters were larger for some lines and the activity of FRK in the outer xylem greater than observed for wild-type plants. We are testing this idea and developing other transgenic cotton plants to understand the roles of FRK in fiber and xylem development. We see the potential to develop a cotton plant with improved stem strength and productivity under drought for windy, semi-arid regions where cotton is grown. d. Implications, scientific and agricultural: FRKs are probably bottle neck enzymes for biomass and wood synthesis and their increased expression has the potential to enhance wood and biomass production, not only in cotton plants but also in other feed and energy renewable plants.

Fructokinase

10.32747/2008.7613878.bard

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