Time course changes were observed in petiole and stem anatomy and cellulase enzyme patterns in bean (Phaseolus vulgaris L.) explants when 10' or 102 M indoleacetic acid in lanolin paste was applied to acropetal cut surfaces in the presence or absence of ethylene. Auxin (102 M) in the presence of ethylene stimulated rapid ordered cell division and dedifferentiation, with ensuing lateral root formation. Auxin (10-5 M) Lewis and Varner (13). Seedlings 10-to 11-days-old were debladed, the laminar pulvinus and cotyledons were removed, 1 This work was supported by National Science Foundation Grant GB 17850. and the remaining plant was cut off 4 to 5 cm below the cotyledonary node. The intact primary axis with the first leaf node petioles were then placed in cups of water and treated as follows: explants had either 10'2 M or 10' M indoleacetic acid in lanolin paste or pure lanolin paste applied to the acropetal cut petiolar surfaces (Fig. 1). In selected experiments the explants were exposed to 15 u1/I ethylene (Matheson Co.) for the final 20 to 24 hr of IAA treatment. At the termination of treatment periods, the lanolin paste was removed from the control explants or explants treated with auxin or ethylene or both, and the 5 mm area below the treated surface was taken for anatomical study or cellulase extraction (Fig. 1).In experiments where ethylene was used as the sole treatment, the main stem was severed immediately below the basipetal end of the nodal pulvinus of the first leaf axis (Fig. 1). Lanolin paste was then applied to the cut surface of the stem before exposure to 5 ,ul/l ethylene in air-tight chambers. This modification was necessary to circumvent the premature cessation of experiments using petiole tissue due to the abscission of the petiole at the nodal axis after 36 to 48 hr treatment.Cellulase Extraction and Purification. Cellulase was extracted by grinding the excised 5-mm segments for 1 min in a VirTis homogenizer with 0.2 M phosphate buffer, pH 6.1, 1.0 M NaCl, and 3% insoluble polyvinylpyrrolidone. The homogenate was passed through a 50 , mesh nylon cloth. The pellet was resuspended in the above buffer less the polyvinylpyrrolidone, ground for 1 min, and filtered again. The filtered extracts were pooled and centrifuged at 10,000g for 15 min; the resultant supematant solution was centrifuged at 100,OOOg for 1 hr. The final supernatant solution was then dialyzed against two changes of 1 % glycine, pH 6.1, for 2 hr each.The solution was then subjected to isoelectric focusing according to the procedure of Hagland (6) to separate acidic pl (isoelectric point) and basic pl cellulase. Samples were focused for 18 to 24 hr at 300 v.Determination of Ethylene Generated by Explants. Petioles prepared as described were removed from the explants, treated at their acropetal cut surface with either pure lanolin, or lanolin with 10' to 10'2 M IAA. The treated petioles were supported by agar in the bottom of a 50-ml flask which was then sealed with a serum cap. Ethylene measurements were determined on 1-...

Boron is required for fiber growth and development in cotton ovules cultured in vitro. Incorporation of I''Clglucose by such fiber from supplied UDP-j''Clglucose into the hot alkali-insoluble fraction is rapid and lnear for about 30 minutes. Incorporation of I''Clglucose from such substrate by fibers grown in boron-deficient ovule cultures is much less than in the case with fibers from ovules cultured with boron in the medium. Total products (alkali-soluble plus alkali-insoluble fractions) were also greater in fibers from ovules cultured with boron. The fraction insoluble in acetic-nitric reagent was a small part of the total glucans; however, in the boron-sufficient fibers, there was significantly more of this fraction than in fibers from boron-deficient ovule cultures. The hot water-soluble glucose polymers from the labeled fibers had a significant fraction of the total I''Ciglucose incorporated from UDP-1'4Clglucose. Both f8-1,4-and 8-1,3-water-soluble polymers were formed in the boron-sufricient fibers, whereas the same water-soluble fraction from the boron-deficient fibers was predominantly 8-1,3-polymers. The incorporation of 114CIglucose from GDP-1'4Clglucose by the fibers attached to the ovules was insignificant. One of boron's possible roles in higher plant growth and development is that of regulating metabolic processes that result in the build-up of specific products, including UDP-glucose, glucose-1-P, or 6-P-gluconate (13-15, 22, 23, 34). If boron does play such a regulatory role, it would have some influence on cell wall metabolism including the biosynthesis of cellulose and pectin compounds. Torssell (44) proposed that the "complexes between boric acid and carbohydrates control the deposition of oriented cellulose micells and the accompanying stiffening of the cell wall." Spurr (39) observed that boron deficiency in celery plants did alter plant cell walls, and concluded that boron apparently affects the rate and process of carbohydrate condensation into wall materials. Odhnoff (26) also proposed that boron's influence on bean root cell elongation was probably related to the deposition of new cellulose microfibrils. Whittington (50) suggested that cessation of cell division in boron-deficient field bean radicles was related to abnormalities in cell wall formation which, in turn, prevented the cell wall from becoming organized for mitosis. Later work in the same laboratory (36) revealed that 1[4Ciglucose was incorporated into pectic substances of boron-deficient field bean radicles at a higher level than in boron-sufficient radicles. The authors proposed that boron's role in plant growth is as a bonding agent between cell wall polysaccharides. Wilson (51) also observed that boron deficiency affected cell walls of tobacco pith parenchyma grown in tissue culture by doubling the amount of cell wall fraction with no apparent change of the cellulose: pectic substance ratio as compared to control grown tissue. Boron enhanced the incorporation of myo-[3H]inositol into L-arabinosyl units from pectin of pea...

The effects of ozone on the fine structure of palisade parenchyma cells were of two phases. The first phase involved changes in the chloroplast stroma which consisted of either a granulation and an increase in electron density or a formation of ordered arrays of granules and fibrils. In the second phase, there was a general disruption of the cellular membranes and organelles and the cellular contents aggregated in the center of the cells. The characteristic components of this aggregate were remains of the chloroplast membrane system and numerous ordered arrays of granules and fibrils. These changes were identical with those previously observed in cells damaged by peroxyacetyl nitrate and were probably related to the oxidation properties of both molecules. In some cells there was a disruption of the organization of the grana within the chloroplasts.

Photochemically produced oxidants in the atmosphere cause injury to plants primarily through inhibition of basic metabolic processes. Plants vary in their response to the oxidants and this variation must be dependent in part on the variation in metabolic activity with age or environmental conditions for growth, to a large degree not understood. Data are presented in this paper to show: (1) The changes in permeability of leaf tissue to exogenous substrate and in catabolic utilization of this substrate after exposure of plants to ozone but before visible symptoms appear; (2) The change in leaf carbohydrates as a result of exposure to ozone; (3) The protective effect of red light (700 ran) during exposure of bean plants to peroxyacetyl nitrate (PAN); (4) The correlation of sulfhydryl (SH) content in bean leaf tissue with age of plants and light regime; and (5) Effect of light regime and age of plants on incorporation of C 14 from C U-PAN by bean leaf tissue.

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