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Abstract
Apios americana Medikus, a nitrogen-fixing, viny legume that produces seeds and tubers is being evaluated as a food crop. About 2500 plants obtained from colchicine-treated and nontreated seeds, tubers from wild sites, and plants derived from tissue culture were cultivated on a silt loam soil. Two tuber-derived plants (probable clone) yielded an average of 3.747 kg and another seed-produced plant yielded 2.170 kg of tubers per plant. Plants were also found that produced mostly rhizomatous material without tubers, only fleshy roots, fleshy roots and tubers, and only tubers. More than 400 pods per plant were observed from some plants, although seed abortion greatly reduced seed yield of many otherwise normal-looking pods.
The objective of this study was to investigate the respiratory pathways in the underground storage tissues (tubers, fleshy roots, and rhizomes) of Apios americana Medikus (apios). Freshly sliced tubers of experimental breeding lines expressed variable capacities for alternative respiration, depending on genetic background, although the alternative respiratory pathway was not engaged in any of the apios tissues tested. The capacity of the alternative pathway present upon slicing was consistent with genetic line over the 5 years of the study. Respiration patterns of tubers and fleshy roots were comparable within a genetic line; however, substantial differences were found in the respiration of the nonthickened sections of rhizomes compared with the storage tubers. Total respiration of stored rhizomes was high (up to 2.7 μl O2/g per rein) compared to that of tubers (up to 0.9 μl O2/g per min). Rhizome tissue respiration had a large capacity for alternative respiration (40%-60% of total respiration), while tuber tissue had 0% to 73% alternative respiration, depending on genetic source. Epidermal layers, obtained from tubers that lacked a capacity for alternative respiration after slicing, had alternative respiration rates comparable to those of rhizomes. Furthermore, the alternative pathway could be induced in these tubers through conventional aging techniques. Etiolated shoots and rhizomes growing from these tubers also had an alternative respiration capacity that was half of the total rate. These results demonstrate that, although the capacity for alternative respiration is present in tissues of apios, freshly sliced tubers may or may not exhibit this pathway depending on genetic background. This attribute maybe significant as apios undergoes further domestication.
Abstract
Plantlets have been produced by germination of somatic embryos derived from callus of Hibiscus acetosella Welw. ex. Hiern. Five of the media used were based on Nitsch and Nitsch's Medium H (purchased formulated without IAA or sucrose). To this base were added, per liter: 40 g glucose for NH; 10 g sucrose for NH-1; 40 g sucrose, 1 mg 2,4-dichlorophenoxyacetic acid (2,4-D), and 1 mg 6-furfurylaminopurine (kinetin) for RM-1; 40 g glucose, 250 mg NaH2PO4·H2O, 28 mg FeC6H5O7·nH2O, 100 mg i-inositol, 30 mg adenine, 0.1 mg (2-chloroethyl)trimethylammonium chloride (chlormequat), and 4 mg 2,4-D for SEM-1; and 40 g glucose, 0.1 mg chlormequat, 0.05 mg B-napthoxyacetic acid (NOA), and 10 mg 2-isopentyladenine (2iP) for HC. The B5 medium was Gamborg's B5 without 2,4-D. All media contained 8 g agar and had the pH adjusted to 5.7 prior to autoclaving. Primary explants placed on HC produced adventitious shoots and callus. When callus explants from HC or primary explants of roots were placed on RM-1, a callus containing embryoid-like structures was produced. Torpedo stage embryos were induced by subculturing this callus from RM-1 on SEM-1 and could be proliferated by sequential transfer from SEM-1 to RM-1, then back to SEM-1. When callus containing torpedo-stage embryos was transferred to B5, the embryos germinated and produced rudimentary plantlets with elongated hypocotyls, short roots, and small cotyledons. These developed into plants when transferred to NH-1.
Abstract
Shoot regeneration has been obtained from leaf and/or cotyledon explants of winged bean [Psophocarpus tetragonolobus (L.) D.C.], Hibiscus acetoseiia Welw. ex. Hiern, muskmelon (Cucumis melo L.), and watermelon [Citrullus lanatus (Thunb.) Mat-sum & Nakai] on 2 media designated HC and BR-1.
Shoots were regenerated from callus of Apios americana Medikus (apios, groundnut) using internodal explants from in vitro-germinated seedlings and from sprouted tubers on a modified Murashige and Skoog (MS) basal medium. Shoot regeneration was observed over a range of 2iP and IBA combinations. GA3 increased the number of shoots regenerated per epicotyl explant. The most efficient regeneration (≈90%) was with internodal epicotyl explants on 100 μm 2iP, 0.5 μm IBA, and 1.5 μm GA3. Regenerated shoots were rooted on liquid and solid MS medium with 0.5 μm IBA; however, rooting was more successful on the liquid medium. About 60% of rooted plants were successfully established in pots. Chemical names used: N-(3-methyl2-butenyl)-1 H-purin-6-amine (2iP), 1 H-indole-3-butanoic acid (IBA), gibberellic acid (G A3).
Shoot proliferation from axillary buds of Apios americana Medikus (apios, groundnut) was obtained on a modified Murashige and Skoog (MS) medium supplemented with 2.22 μm BAP, 0.5 μm IBA, and 3.0 μm GA3. Existed shoots rooted on MS basal medium. About 60% of the rooted plants were successfully established in soil. Chemical names used: 1 H-indole-3-butanoic acid (IBA). gibberellic acid (GA3), N6-benzylaminopurine (BAP).