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46 results on '"Baldwin, Timothy C."'

5. Physiological Responses of Hollyhock (Alcea rosea L.) to Drought Stress.

Author

Sadeghi, Arezoo, Karimmojeni, Hassan, Razmjoo, Jamshid, and Baldwin, Timothy C.

Subjects
DROUGHTS, BIOMARKERS, DROUGHT management, PHOTOSYNTHETIC pigments, PLANT breeders, FIELD research
Abstract

Hollyhock (Alcea rosea L.) is an aromatic, ornamental/medicinal plant species for which the selection of drought-tolerant varieties based on physio-chemical traits is desirable. The data presented resulted from a field experiment. This experiment was designed as a split-plot, based on a randomized complete block design, in which the main plots consisted of the three irrigation regimes (30, 60 and 80% permissible discharge moisture available in the soil), and the subplots consisted of nine hollyhock varieties. Photosynthetic pigments, Fv/Fm, proline content and selected antioxidant enzymes were measured throughout the period of induced drought stress. The data obtained illustrate the nature of the physiological response of hollyhock to drought stress. Based on the measured traits the varieties Isfahan 1, Shiraz 1 and Tabriz were shown to display the highest degree of resistance to drought stress. These data suggest that the effect of drought stress is dependent upon the drought level, variety and the trait in question. In this regard, future plant breeders for this species may find it useful to utilize ascorbate peroxidase (APX), catalase (CAT) and guayacol peroxidase (POX) activities as biochemical markers to select for drought-tolerant genotypes. As such, hollyhock can be considered a promising ornamental/medicinal species for cultivation in semi-arid environments. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Biodegradable PBAT/PLA blend with bioactive MCPA-PHBV conjugate suppresses weed growth

Author

Kwiecien, Iwona, Adamus, Grazyna, Jiang, Guozhan, Radecka, Iza, Baldwin, Timothy C., Khan, Habib R., Johnston, Brian, Pennetta, Valentin, Hill, David, Bretz, Inna, Kowalczuk, Marek M., and Publica

Abstract

The herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) conjugated with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was prepared via a melt transesterification route. The resultant bioactive oligomer was then mixed with a blend of polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with different loadings; to manufacture films to be used as a bioactive, biodegradable mulch to deliver the herbicide to target broadleaf weed species. The biological targeting of the MCPA-PHBV conjugate in the mulch film was investigated under glasshouse conditions using faba bean (Vicia faba) as a selective (non-target) model crop species having broadleaf morphology. The presence of the MCPA-PHBV conjugate in the biodegradable PBTA/PLA blend was shown to completely suppress the growth of broadleaf weed species, whilst displaying only a mild effect on the growth of the model crop. The degradation of the mulch film under glasshouse conditions was quite slow. The release of the MCPA-PHBV during this process was detected using NMR, GPC, EDS and DSC analyses, indicating that the majority of the MCPA diffused out after MCPA-PHBV conjugate bond scission. These data provide a strong ""proof of concept"" and show that this biodegradable, bioactive film is a good candidate for future field applications and may be of wide agricultural applicability.

Published
2018

33. Biodegradable PBAT/PLA Blend with Bioactive MCPA-PHBV Conjugate Suppresses Weed Growth

Author

Kwiecien, Iwona, Adamus, Grazyna, Jiang, Guozhan, Radecka, Iza, Baldwin, Timothy C., Khan, Habib R., Johnston, Brian, Pennetta, Valentina, Hill, David, Bretz, Inna, and Kowalczuk, Marek

Abstract

The herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) conjugated with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was prepared via a melt transesterification route. The resultant bioactive oligomer was then mixed with a blend of polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with different loadings to manufacture films to be used as a bioactive, biodegradable mulch to deliver the herbicide to target broadleaf weed species. The biological targeting of the MCPA-PHBV conjugate in the mulch film was investigated under glasshouse conditions using faba bean (Vicia faba) as a selective (nontarget) model crop species having broadleaf morphology. The presence of the MCPA-PHBV conjugate in the biodegradable PBTA/PLA blend was shown to completely suppress the growth of broadleaf weed species while displaying only a mild effect on the growth of the model crop. The degradation of the mulch film under glasshouse conditions was quite slow. The release of the MCPA-PHBV during this process was detected using NMR, GPC, EDS, and DSC analyses, indicating that the majority of the MCPA diffused out after MCPA-PHBV conjugate bond scission. These data provide a strong “proof of concept” and show that this biodegradable, bioactive film is a good candidate for future field applications and may be of wide agricultural applicability.

Published
2024
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44. DEVELOPMENTAL REGULATION OF MANNAN, ARABINOGALACTAN-PROTEIN, AND PECTIC EPITOPES IN PISTILS OF VICIA FABA (FABA BEAN).

Author

Wen Chen, Stoddard, Fred L., and Baldwin, Timothy C.

Subjects
FAVA bean, FORAGE plants, PLANT cell walls, POLLEN tube, EPITOPES, CELL membranes, IMMUNOGLOBULINS, ELECTRON microscopes, POLYSACCHARIDES
Abstract

Cell walls of the stigma and style are important zones for cell-cell recognition, nutrition, guidance, and protection of the pollen tube along the transmitting tract. The objective of this study was to investigate the modulation of selected cell wall epitopes during pistil development in the crop species Vicia faba L. (faba bean). An immunocytochemical investigation of pistil development was performed using a panel of four anti- cell wall/plasma membrane antibodies at both light and electron microscope levels during the 4 days leading up to anthesis. The selected antibodies recognized mannan-containing polysaccharides (antimannan antisera), β-1,4-galactan (LM5), α-1,5-ʟ-arabinan (LM6), and arabinogalactan/arabinogalactan-protein (AG/AGP) epitopes, with GlcpUA-β-1,→3-ᴅ-Gal pUA-α-1,→2-ʟ-Rha trisaccharide motifs (JIM13). Mannan accumulation was shown to be associated with the formation and maturation of sclerenchyma cells and xylem elements. The β-1,4-galactan and α-1,5-ʟ-arabinan epitopes were highly expressed in the walls of parenchyma and epidermis in a developmentally regulated manner. AG/AGP epitopes were particularly abundant in the stigma and cells lining the stylar canal, together with the α-1,5-ʟ-arabinan epitope recognized by LM6. These data suggest an association of AGs/AGPs with pollen tube growth, of mannan with strengthening and stiffening the pistil, and of b-1,4-galactan and α-1,5-ʟ-arabinan components with tissue flexibility within the pistil. [ABSTRACT FROM AUTHOR]

Published
2006
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46. An investigation of the biology and chemistry of the Chinese medicinal plant, Amorphophallus konjac

Author

Yee, Melinda Chua Fui and Baldwin, Timothy C.

Subjects
584.64, Amorphophallus konjac, konjac glucomannan, corm, morphogenesis, ethanol extraction, 3,5-dinitrosalicylic acid, gel permeation chromatography, zero shear viscosity, mannan epitopes, developmental regulation
Abstract

Konjac glucomannan (KGM), the main biologically active constituent of konjac flour extracted from corms of Amorphophallus konjac (konjac), can be used to prepare functional foods and may also have potential as a pharmaceutical product to combat obesity. The current study employed three experimental approaches to study the biology and chemistry of konjac, namely (1) glasshouse experiments to study the morphogenesis, growth and productivity of konjac plants, (2) a histological and immunocytochemical investigation of the localisation and developmental regulation of the deposition and metabolism of KGM in developing corm tissues, and (3) a comparative study of methodologies for the extraction and analysis of KGM. The current data demonstrated a morphological and functional separation between the ventral and dorsal regions of corms. The ventral region appeared to function as a source during the initial period of shoot development, while the dorsal region appeared to operate as a sink after the development of mature canopy. Once the corm reached maturity, both an inflorescence and a leaf were produced within a single season. It has also been demonstrated that the age of the ‘mother’ corm is an important factor affecting the quality of offsets produced. An anti-mannan antiserum detected a temporally regulated pattern of mannan epitope production within glucomannan idioblasts in developing corm tissues, with increased expression as the corm approached maturity/dormancy. The current observations also suggest that the mobilization of KGM initiates at the periphery of the corm and proceeds inwards towards the centre of the corm. Compositional analysis showed that the purified konjac flour (PKF) produced using a modified extraction procedure contained 92% glucomannan, with a weight average molecular weight (Mw), polydispersity index (PDI) and degree of acetylation (DA) of 9.5 ± 0.6 x 105 gmol-1, 1.2 and 2.8 wt. %. These data, plus Fourier-transform infrared spectral (FTIR) and zero shear viscosity analyses of the extract (PKF) were all consistent with the literature. Comparison of three existing methodologies for the quantitative analysis of the KGM content, namely 3,5-dinitrosalicylic acid (3,5-DNS), phenol-sulphuric acid and enzymatic colorimetric assays; indicated that the 3,5-DNS colorimetric assay was the most reproducible and accurate method, with a linear correlation coefficient of 0.997 and recoveries between 97% and 103% across three spiking levels of starch. In summary, this study has provided a better understanding of aspects of the biology and cultivation of A. konjac and has also produced methodologies which can be used as the basis for an improved good laboratory practice (GLP) for the commercial extraction and analysis of this multifunctional natural polymer.

Published
2011

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