Journal of Plant Growth Regulation

Bacon, Charles; Hinton, Dorothy; Chamberlain, William; Norred, William

doi: 10.1007/BF00210946pmid: N/A

The de novo induction of roots in tomatoes (Lycopersicon esculentum) Mill. cvs. “Earlypak-7,” “Ace,” “Better Boy,” “Roma,” and “Parks' Whopper” by fumonisin B1, a mycotoxin produced by Fusarium moniliforme J. Sheld., was studied. In graded dosages of fumonisin B1, detached stems of the cultivars “Ace,” “Better Boy,” and “Roma” were induced to produce calluses and roots earlier than controls. The cultivar “Ace” was especially responsive to this mycotoxin, and following a single application, callus initiation was observed to occur within a 24–48-h period and roots were produced as early as 72 h with 10 μg/shoot or as late as 96 h with low dosages. The control plants of all cultivars were completely negative for a rooting response during this time. Some cultivars treated with fumonisin B1 showed either no response or developed signs of phytotoxicity. Those cultivars that were stimulated to produce roots did not show signs of phytotoxicity, except at dosages of 0.5 mg/plant and higher. One cultivar did not show any signs of phytotoxicity nor was it induced to root. The ability of fumonisin B1 to affect the accumulation of calcium in other systems, and its structural similarity to sphingosine suggest that the induction of adventitious roots may be a calcium-dependent process.

Dathe, Wilfried; Parry, Andrew; Heald, James; Scott, Ian; Miersch, Otto; Horgan, Roger

doi: 10.1007/BF00210947pmid: N/A

The endogenous levels of abscisic acid (ABA) and jasmonic acid (JA) were analyzed in wheat seedlings grown in water, a system which in the past has been used to test the effects of these plant growth inhibitors. The levels in different plant parts and in the medium were measured by gas chromatography-mass spectrometry-selected ion monitoring, using [2H3]ABA and [2H6]JA as internal standards. In every plant part, JA levels were about 2 orders of magnitude greater than those of ABA. The exudation of JA from roots per seedling was about 14,000-fold greater than that of ABA, although the roots contained only about 170 times more JA than ABA. It is suggested that JA is a possible allelopathic compound.

Suzuki, Yoshihito; Murofushi, Noboru; Zhang, Yun-Hui; Takeuchi, Yasutomo

doi: 10.1007/BF00210948pmid: N/A

Endogenous gibberellins were analyzed from a parasitic plant, clover broomrape (Orobanche minor Smith), and its host, clover (Trifolium repens L.). Members of both the early-13- and the early-non-hydroxylation pathways were identified from both the parasite and the host (GA12, GA24, GA9 GA4, GA44, GA19, GA20, and GA1 from clover broomrape; GA9, GA4, GA44, GA19, GA20, and GA1 from clover). Quantitative analyses showed that GA44 was present at high levels in both host and parasite. The similarity in the gibberellins suggests the possibility that the major gibberellins in clover broomrape are transported from clover. However gibberellins such as GA58, GA38, and notably GA47 which was identified from a plant for the first time were detected only from clover broomrape, suggesting that the parasite may have the ability to produce at least those gibberellins

Jirage, Dayadevi; Ravishankar, G.; Suvarnalatha, G.; Venkataraman, L.

doi: 10.1007/BF00210949pmid: N/A

The profile of free and conjugated polyamines putrescine, spermidine, and spermine was studied at the onset of sprouting and during various stages of vegetative growth in saffron (Crocus sativus L.) corms. Polyamines were extracted from the shoot meristems and estimated by high performance liquid chromatography. Free putrescine was not detected at the onset of sprouting, whereas free spermidine and spermine levels increased rapidly on sprouting and decreased during further stages of corm development. The levels of conjugated polyamines were several times higher than the free forms indicating their possible role in the developmental processes. A comparison of polyamine levels of vegetative and floral corms showed higher titers of free polyamines in vegetative and conjugated polyamines in floral corms.

Šimko, Ivan

doi: 10.1007/BF00210950pmid: N/A

Stems of potato plants (Solanum tuberosum L. cv. Dianella) were immersed in solutions containing water (control), sucrose, glucose, paclobutrazol, and gibberellic acid. The effects of these treatments on the ethylene release, levels of endogenous gibberellins, glucose, sucrose, and starch were correlated with tuberization of nodal cuttings, excised from potato stems. Paclobutrazol and sucrose improved the percent of tuberization and/or increased tuber weight. In contrast, GA3 inhibited tuber formation compared with the control. The level of endogenous free GAs was negatively correlated with percent tuberization. However, the level of conjugated GAs was positively correlated with both percent tuberization and tuber weight. The effect of sucrose on potato tuber induction in relation to the possible role of sucrose in GA-conjugate formation is discussed.

Stotz, Henrik; Hertel, Rainer

doi: 10.1007/BF00210951pmid: N/A

Binding of 1-naphthylacetic acid (1-NAA) was assayed in microsomal membranes from Zea mays coleoptiles and from hypocotyls of Cucurbita pepo. Auxin binding site II was differentiated from site I binding by using phenylacetic acid (PAA) to saturate site I binding capacity. The amount of type-II binding sites, per gram original fresh weight, was 34 pmol with Zea and 6.4 pmol with Cucurbita. When maize membranes were separated by dextran gradient centrifugation, auxin binding site II migrated coincident with tonoplast marker enzymes. The physiologically active auxin 4-chloroindoleacetic acid (4-Cl-IAA) competed very poorly with 1-NAA binding to both site I and site II. This result suggests that sites I and II are not involved in the regulation of growth. When comparing isolated outer epidermis with intact coleoptile of Zea, similar amounts and ratios of site I and site II binding activities were observed.

Martínez, G.; Chaves, A.; Añón, M.

doi: 10.1007/BF00210952pmid: N/A

Effect of GA3 on postharvest ripening in strawberry fruit was evaluated through different biochemical parameters. Strawberry slices at different ripening stages were incubated with GA3. A significant decrease on respiratory activity depending on GA3 concentration was obtained. Also GA3 was applied to whole and deachened fruit at white and green ripening stages. Our results show that GA3 has an inhibitory effect on strawberry fruit ripening, evidenced by a decrease in the respiratory activity and a delay in anthocyanin synthesis and chlorophylls degradation.

Gross, Dieter; Parthier, Benno

doi: 10.1007/BF00210953pmid: N/A

This review includes novel natural products of microbial and plant origin reported to exert plant growth-regulating activities. The well-known “classic” plant hormones are excluded. The substances described with their biological activities are restricted to those that have been isolated from microbial or plant sources later than 1990 or that have been intensively investigated during the last few years, such as jasmonic acid and brassinosteroids.