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M.A.L. Smith

Soils, entomology, forestry and horticulture faculty were combined into a single merged Department of Natural Resources and Environmental Sciences (NRES) during a recent College of Agriculture, Consumer, and Environmental Sciences restructuring process at the University of Illinois. The merger initially spawned multiple concerns from faculty, but after an adjustment period, ultimately resulted in enhanced organization, accountability, and collaboration. New, multidisciplinary initiatives within NRES, such as the Illinois Green Industry Survey or development of a highly successful off-campus masters program, attest to the fact that the merger brought new strength and expanded opportunities to our unit.

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M.A.L. Smith

The bright red pigmentation in edible, anthocyanin-rich fruits and vegetables is a definite bonus in terms of market appeal. As a result, breeders have worked consistently to intensify anthocyanin levels or alter composition in crops. The positive links between consumption of crops and food products containing natural anthocyanin pigments, and reduced incidence of cardiovascular and other chronic diseases, have been established anecdotally and more recently validated in research trials including those from our laboratory group. The protective events, most attributed to the potent antioxidant properties of anthocyanin pigments and associated phytochemicals, place anthocyanin-rich crops in the category of “Functional Foods,” yielding health protection unrelated to nutritional value. In vitro bioactivity assays have identified components from these crops capable of blocking the initiation stages of carcinogenesis, while a completely separate class of phytochemicals and sets of assays establish efficacy against the promotion stages of tumorigenesis. Animal models for carcinogen-induced damage to mammary gland and skin DNA subsequently demonstrate the in vivo potency of the same target compounds. Similarly, to establish cardioprotective properties, demonstrations of ability to inhibit platelet aggregation, relax vascular muscle tissue, and reduce total serum cholesterol are demonstrated in a series of in vitro assays, and via animal models and human studies. While activity-directed fractionations seek to identify specific responsible compounds, it is increasingly evident that bioactivity is drastically attenuated once specific compounds are isolated, and the synergistic interaction of associated phytochemicals in horticultural crops is prerequisite to realizing health benefits. These complications have slowed the establishment of effective minimum “dosages,” but all the more strongly promote consumption of the crops.

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M.A.L. Smith and A.A. Obeidy

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M.T. McClelland and M.A.L. Smith

Effects of three variables (vessel type, closure, and explant orientation) on microcutting quality were investigated using five woody species [low shadblow, Amefanchier spicata (Lam.) C. Koch (Syn. A. humilus Wieg.); red maple, Acer rubrun L. `Red Sunset'; border forsythia, Forsythia ×intermedia Zab. `Sunrise'; apple, Malus ×domestica Borkh. `McIntosh'; river birch, Betula nigra L.]. Uniform shoot explants were oriented vertically or horizontally in three vessel types (60-ml glass culture tubes, 200-ml glass baby food jars, and 350-ml polypropylene GA7 vessels) with and without a Parafilm seal. Visual density per explant obtained by image analysis was increased in larger vessel types, and significantly more shoots were produced from horizontally placed explants. Closure treatments influenced microshoot quality, but trends were species specific. Overall, horizontal explant orientation in larger vessels wthout parafilm maximized shoot response for most of the species studied. In vitro rooting of microcuttings was significantly enhanced in larger vessels.

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Rida A. Shibli and M.A.L. Smith

Ohelo (V. pahalae Skottsb.) and bilberry (V. myrtillus L.) shoots were regenerated via direct organogenesis from whole leaves and leaf sections and also from hypocotyl explants of bilberry. Explants preincubated for 1 to 2 weeks in darkness yielded ≈75% regeneration frequencies and the highest number of regenerating shoots/explant on TDZ-supplemented media (0.9 to 2.7 μm). When 2iP or zeatin were substituted as the cytokinin source, frequencies of regeneration and shoot productivity were significantly lower. Explants held under constant illumination (no dark pretreatment) had significantly lower regeneration frequencies in all tested cytokinin-supplemented media. 2,4-D stimulated callus formation, but did not support regeneration from vegetative explants. Cells from callus and suspension cultures did not exhibit regeneration in any of the media that supported organogenesis from leaves. Regenerants were successfully micropropagated, although callus formation caused by zeatin and high 2iP levels interfered with shoot proliferation. Zeatin induced hyperhydricity in shoots from both species, but more severely in ohelo. Ex vitro rooting after treatment with 4.9 μm IBA or 5.4 μm NAA was 95% and 60% successful for bilberry and ohelo, respectively, and plants were readily acclimatized after an interval in a fog chamber. Bilberry microshoots also rooted in vitro in the absence of growth regulator treatment. Chemical names used: 1H-indole-3-butanoic acid (IBA); N-(3-methyl-2-butenyl)-1-H-purine-6-amine (2iP); 6-furfurylaminopurine (kinetin); 1-naphthaleneacetic acid (NAA); thidiazuron=1-phenyl-3-(1,2,3-thiadiazio-5-yl)urea (TDZ); 2,4-dichlorophenoxyacetic acid (2,4-D); 6-(4-hydroxy-3-methylbut-2-enylamino) purine (zeatin).

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Ahmed A. Obeidy and M.A.L. Smith

Micrografting is au effective technique for elimination of viruses, early diagnosis of grafting incompatibilities, rejuvenation of mature tissue, and bypassing the juvenile phase in fruit trees. Current micrografting procedures are difficult, impractical, expensive, and generally result in an inefficient rate of successful graft production. To alleviate some of these limitations, a unique apparatus was designed to splice the in vitro-derived scion and rootstock together during the micrografting process. The dual-layer device was constructed with an outer layer of aluminum foil, with flexibility to facilitate manipulation during the grafting of micro-scale plants. A delicate, absorbent inner layer of paper toweling cushions the plant tissue. It also may be treated with hormones and other compounds. After healing, it is easy to remove the grafting apparatus from the grafted plant without damaging the tissues. This apparatus may be used to unite a scion and a rootstock with different stem diameters. Shoot-tip cultures of `McIntosh' and M.7 apple and `North Star' sour cherry, and in vitro seedlings of lemon, orange, and grapefruit were used as a source of in vitro scions and rootstocks. Successful graft unions were developed, and the grafted plants were transplanted into the greenhouse environment.

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Ahmed A. Obeidy and M.A.L. Smith

The regenerative capacity of mature pecan [Carya illinoinensis (Wangenh.) K. Koch] embryonic tissues was demonstrated after pretreating mature nuts to eliminate associated endogenous contaminants. Cultured cotyledon segments were induced to form adventitious roots in a medium with 50 μm NAA. A regeneration medium with 20 μm BA and 5 μm IBA stimulated prolific axillary shoot production from the embryonic axis without causing cotyledon abscission. Cotyledon retention was essential for shoot initiation and long-term development. Eighty-five percent of the shoots emerging from embryonic axes formed at the cotyledonary nodes. Thirty percent of the microshoots rooted on an auxin-free medium after preculture in a medium with 20 μm IBA. TDZ (25 μm) stimulated callus production from the cotyledonary nodes and radicles. Adventitious buds emerged on the callus surface and internally in callus. Chemical names used: a -naphthaleneacetic acid (NAA); 6-benzylaminopurine (BA); indole-3-butyric acid (IBA); N-phenyl-N'-1,2,3-thidiazol-5-ylurea (TDZ).

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Ahmed A. Obeidy and M.A.L. Smith

Micrografting is an effective technique for elimination of viruses, early diagnosis of grafting incompatibilities, rejuvenation of mature tissue, and bypassing the juvenile phase in fruit trees. Current micrografting procedures are difficult, impractical, expensive, and generally result in an inefficient rate of successful graft production. In order to alleviate some of these limitations, a unique apparatus was designed to splice the in vitro-derived scion and rootstock together during the micrografting process. The dual-layer device was constructed with a pliant outer layer to facilitate manipulation during the grafting of micro-scale plants, and a delicate, absorbent inner layer to cushion the plant tissue and retain hormones and other compounds. These chemicals are slowly released at the grafting zone to alleviate oxidation and enhance callus formation at the cut surface of scion and rootstock. After healing, it is easy to remove the grafting apparatus from the grafted plant without damaging the tissues. This apparatus may be used to unite a scion and a rootstock with different stem diameters. Shoot-tip cultures of `McIntosh' and `M-7' apple and `North Star' sweet cherry, and in vitro seedlings of lemon, orange and grapefruit were used as a source of in vitro scions and rootstocks. Successful graft unions were developed, and the grafted plants were transplanted into the greenhouse environment Micrografted plants were sectioned to determine the anatomical characteristics of the graft union.

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M.A.L. Smith and R.B. Rogers

The game-show format, used recurrently in an undergraduate-level, introductory plant propagation course, fostered a friendly, competitive incentive for students to master facts and concepts critical to understanding processes in plant physiology. Because student teams, rather than individuals, served as the contestants in each game, and because game points were never translated into grade points, participants and observers learned from and enjoyed the exercises without anxiety. Propagation-specific clues and questions were prepared for “Wheel of Fortune,” “Win, Lose, or Draw,” and other games. These were followed up at the end of each semester with several play-off rounds of a plant propagation variant of “Jeopardy!”, which served as an excellent means of course synthesis and review of key concepts. The format allowed for liberal use of humor as an effective pedagogical tool and resulted in the hands-on contributions of former students in construction of new game quizzes and puzzles for subsequent semesters.

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Ahmed Obeidy and M. A. L. Smith

Endophytic fungi associated with mature pecan nuts (cultivars `Smart', `Desirable' and `Owens') prevented successful, contaminant-free. in vitro culture of embryo explants, even after rigorous surface disinfestation of the nuts and careful aseptic shelling. Disinfestation with sodium hypochlorite after removing the shells was also unsuccessful, because even dilute concentrations which were ineffective against the fungal contaminants destroyed embryo viability. An alternative disinfestation technique is required to establish in vitro cultures from mature pecan explants. Explanting media with low water availability were developed to capitalize on the relatively stringent requirement of most fungal contaminants for free water. The explanting media were supplemented with 0.9-1.5% agar. Other media components were selectively included or omitted to test their influence on water activity and fungal growth. After four weeks of culture, the incidence of contamination was reduced to 30% or less on modified explanting media, compared to 100% loss to contamination on control medium (0.5% agar). The brief initial culture period effectively eliminated fungal contamination from cultures by plasmolyzing fungal hyphae or denaturing fungal protein, without effecting pecan embryo viability. Cultures remained contaminant-free after transfer to control medium. Axillary and adventitious bud development from disinfested embryo axes was subsequently induced in a medium with 18 μM BAP and 5 μM IBA, and regeneration from cotyledon explants was accomplished in a medium with 50 μM NAA. This disinfestation technique allows mature pecan embryo explants to be used in biotechnology.