Abstract
Shoot tips from ‘Marechal Foch’ and ‘Cascade’ were pretreated in 6-benzylamino purine (BA) solution at 0, 1.33 × 10−3, 2.22 × 10−3, or 3.94 × 10−3 m and cultured in media containing naphthaleneacetic acid (NAA) at 0, 2.9 × 10−6 or 5.7 × 10−6 m. Higher concentrations of either BA or NAA reduced the effectiveness of the other in increasing dry weight of shoot tips. Shoots obtained were pretreated in indolebutyric acid (IBA) at 0, 1.48 × 10−3, 2.46 × 10−3, or 3.94 × 10−3 m and then placed in water, half-strength, or full-strength Murashige and Skoog medium (MS). Rooting of both cultivars was improved by IBA pretreatment with maximum rooting at concentrations of 2.46 × 10−3 or 3.94 × 10−3 IBA and usually in half-strength MS.
Abstract
The effects of foliarly applied Cytex (an aqueous seaweed extract) and kinetin on the tuberization process of potato plants were investigated under field conditions. Tuber number was not influenced by foliar applications of Cytex or kinetin, but total yield of ‘Kennebec’ was increased when Cytex (15 ml/liter) was applied during the initial stages of tuberization. This yield advantage was due to an increase in the number of defective tubers. Since sunburn was the dominant defect, improved yields might be possible through the use of Cytex coupled with modified cultural practices. Neither Cytex nor kinetin had any effect on total yield of ‘Russet Burbank’.
Abstract
A whole-tree foliar application of BA at a concentration of 1000 ppm increased lateral bud density on douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] but not on Colorado blue spruce (Picea pungens Englm.) when treated ≈6 weeks after budbreak. A single BA application made at the same time, but only to the terminal leader, was not effective in increasing overall lateral bud density on either the terminal or lateral branches of either species. Lammas shoots formed on all trees that received whole-tree applications of BA. Bud formation on lammas shoots appeared normal for douglas-fir but uncharacteristic for Colorado blue spruce. Chemical names used: N- (phenylmethyl)-lH-purin-6-amine (BA).
Abstract
Picea pungens Englm. trees were treated with a single foliar spray of solutions containing 0, 100, 250, 500, and 1000 mM BA at 4 different times as follows during the growing season: 1) dormant trees, 2) at bud break, 3) during stem elongation, 4) summer hardwood, and 5) summer hardwood combined with a pruning. Treatments of 1000 mM at the time of bud break and to pruned summer hardwood trees resulted in an increase in bud number but not a corresponding increase in branch number the following year.
Somatic embryos were regenerated from protoplasts isolated from embryogenic callus on young leaf explants from mature coffee trees. Embryos were regenerated on modified Murashige and Skoog medium supplemented with 5 μm BA. Somatic embryos developed into intact plants. Mannitol at 0.5 m was adequate as an osmoticum for isolating protoplasts, but subsequent culture required 0.3 m mannitol. A culture system in which osmolality was decreased gradually accelerated formation of colonies and somatic embryogenesis. Chemical name used: N-(phenylmethyl)-1H-purine-6-amine (BA).
A late-storage root-forming mutant (`KM95-A68') of sweetpotato [Ipomoea batatas (L.) Poir.] was characterized to clarify the genetic and physiological mechanisms of storage root formation. This mutant originated from a somaclonal mutation of `Kokei No. 14'. Storage roots of `KM95-A68' are rare and, when formed, develop 2 or 3 weeks later than those of `Kokei No. 14' from which it originated. Morphological characteristics of the canopy and leaf photosynthetic rates of `KM95-A68' were similar to those of `Kokei No. 14'. No apparent differences were observed in the anatomy of root cross sections of `KM95-A68' and `Kokei No. 14'. An apparent increase in the root zeatin riboside (ZR) levels were observed in `Kokei No. 14' at storage root formation. Root ZR levels differed between `Kokei No. 14' and `KM95-A68'. The onset of increase in root ZR levels was delayed by 2 or 3 weeks in `KM95-A68' in comparison to `Kokei No. 14'. Maximum root ZR levels in `Kokei No. 14' were 2.2 times higher in comparison to `KM95-A68'. This appeared to be a factor in delayed storage root formation of `KM95-A68'. Results of reciprocal grafts of `KM95-A68' and `Kokei No. 14' indicated that the late storage root-forming characteristic of `KM95-A68' is a characteristic that arises from the root itself.
A Lycopersicon esculentum Mill. (tomato) cDNA clone with high similarity to a Nicotiana plumbaginifolia Viv. (tobacco) cytochrome P450 gene was isolated using 5' and 3' rapid amplification of cDNA ends (RACE). The isolated cDNA (GenBank Accession No. AF249329) has an open reading frame of 1494 base pairs (bp) and encodes a protein of 498 amino acids with 75% identity to the N. plumbaginifolia cytochrome P450 (CYP72A2) and 45% to a Catharanthus roseus G. Don (Madagaskar periwinkle) CYP72A1 protein sequence. By Southern-blot analysis, one or two highly homologous genes were detected in the L. esculentum genome. Expression of the cloned P450 gene was regulated by circadian rhythm and enhanced by wounding. Leaf transcripts were detected in the light but not dark. Highest transcript levels were observed 3 hours after mechanical wounding. No increase in expression was seen in response to applications of zeatin as with the N. plumbaginifolia gene. Of the tissues analyzed, shoot tips and young leaves and fruit had the highest detectable transcript levels. Attempts to transform more than 1400 cotyledon explants of L. esculentum with sense or antisense CYP72A2 gene constructs produced no transgenic plants.
Abstract
Applications of 6-benzylamino purine (BA) alone or together with gibberellic acid (GA4+7) increased lateral-shoot development in 1- to 3-year-old apple trees (Malus domestica Borkh.). Cultivars differed in response based in part on their habit of growth. Supplementary surfactant made BA alone as effective in shoot-growth induction as BA + GA4+7 with or without surfactant. Induced shoots achieved lengths of up to 40 cm, and the pattern of shoot-length distribution generally was similar to that of untreated trees. Follow-up pruning was required in direct proportion to increases in lateral-shoot formation. In a 1981 timing study, trees ceased to be responsive to exogenous BA in mid-June. Application of BA or BA + GA4+7 at various times during the preceding 3 weeks induced a constant number of lateral shoots from growing points established the previous season. Increased numbers of lateral shoots originating from newly formed buds were produced with later applications within the 3-week responsive period.
CuCO3 at 100 g·liter-1 in a paint carrier applied to interior container surfaces effectively prevented root deformation in container-grown Malus domestica Borkh. and Fraxinus pennsylvanica Marsh. seedlings. CuCO3 treatments nearly doubled the number of white unsuberized root tips in both species. CuCO3 treatment increased some measures of root and shoot growth before and after transplanting to larger untreated containers. Root pruning at transplanting tended to reduce root and shoot fresh and dry matter accumulation in F. pennsylvanica seedlings and shoot extension in M. domestica seedlings. In some cases, root pruning of M. domestics at transplanting from CuCO3-treated containers increased root growth compared to unpruned CuCO3-treated and untreated seedlings. Changes in growth induced by CuCO3 and root pruning were not related to changes in trans -zeatin riboside-like activity in the xylem sap of-apple.