Plant Growth Regulator

Callus induction from petiole explants has been achieved in Alocasia micholitziana `Green Velvet'. The highest percentage (71%) of explants inducing callus was obtained on MS medium supplemented with 0.5 μM 2,4-D and 0.5 μM kinetin in the dark after 4 months of culture. Shoots were regenerated at the highest frequency of 33.3% under light condition when 0.5 μM BA was added to MS medium with the average of 7.8±2.3 shoots per callus explant. The callus-derived shoots rooted on hormone free MS medium and within 4 weeks the plantlets were ready for acclimatization. The regenerated plants appeared morphologically similar to mother plants.

Fully habituated organogenic and nonorganogenic sugarbeet calluses reacted to application of the synthetic auxin [3-benzo(b) selenienyl] acetic acid by changes in growth and ethylene production. Treatment of fully habituated cells of periwinkle with 2,4-dichlorophenoxyacetic acid led to the decrease of free cytokinin contents (isopentenyl adenine, zeatin riboside, and zeatin) during the late exponential phase of growth. The polyamine contents were also modified and the capacity to biotransform secologanin into ajmalicine was decreased. Treatment of the habituated periwinkle cells with zeatin greatly increased the amount of a polypeptide of 16 kDa; this response was more marked than that displayed by the auxin-dependent line. These data show that hormone-independent calluses and cell suspensions can retain some sensitivity to growth hormones. However, differences of responses were observed between the auxin-dependent lines and the habituated lines.

Egamberdieva D.
Department of Biotechnology, National University of Uzbekistan, Vuzgorodok, Tashkent, 100174, Uzbekistan, e-mail: egamberdieva@yahoo.com

The action of phytohormone producing bacteria and plant growth regulators on germination and seedling growth of wheat under saline conditions were studied. Seed dormancy enforced by salinity (100 mM NaCl) was substantially alleviated and the germination was promoted by gibberelin, auxin, zeatin and ethephon from 54 to 97%. The IAA producing bacterial strains Pseudomonas aureantiaca TSAU22, Pseudomonas extremorientalis TSAU6 and Pseudomonas extremorientalis TSAU20 significantly increased seedling root growth up to 25% in non salinated conditions and up to 52% at 100mM NaCl, compared to control plants. It is concluded that growth regulators considerably alleviated salinity-induced dormancy of wheat seeds. The facts mentioned above make it possible to recommend root colonizing bacteria that produce phytohormone to alleviate salt stress of wheat grown under conditions of soil salinity.

The present study reports a highly efficient and cost effective protocol for high frequency plantlet regeneration from nodal explants of Dioscorea hispida. Nodal vine segments from 40 days old plants of Dioscorea hispida were cultured on Murashige and Skoog's (MS) medium supplemented with different concentration and combination of cytokinin i.e. 6-Benzyl Aminopurine (BAP) and auxin i.e. α-naphthalene acetic acid (NAA)

Murashige and Skoog’s (MS) basal medium with benzylaminopurine (BA), kinetin (KN), zeatin (Z), and thidiazuron (TDZ) were tested for induction of multiple shoots from mature-tree-derived axillary meristems of Pongamia pinnata. Sprouting of buds was 64% on medium devoid of plant growth regulators (PGR). Incorporation of BA, KN, or Z was ineffective in enhancing sprouting frequency or induction of multiple shoots. Sprouting was completely suppressed in the presence of TDZ. Caulogenic buds appeared in nodal meristems of these explants after withdrawal of TDZ. The number of shoot buds was more on explants precultured in higher concentrations. At higher concentrations of this PGR, a swelling developed at the axil. Multiple shoot primordia appeared and differentiated from this swelling after culturing these explants on MS medium for six passages of 2 wk each. Shoots were harvested and cultured on 0.45 μM TDZ for further proliferation. Primary explants after harvesting of shoots were identified as ‘stump’. Reculturing of stumps on 0.45 μM TDZ produced more shoots. This step was followed for six cycles to obtain additional shoots in each cycle. Shoots maintained on 0.45 μM TDZ elongated and rooted (70%) on growth regulator-free medium. Rooted shoots (65%) survived transfer to a sand/soil mixture. This report describes the protocol for micropropagation of P. pinnata using mature-tree-derived nodal meristems. Recycling of mature stock to produce a stream of useable shoots for subculturing and eventual stabilization is of great value and can possibly be generalized as an isolation protocol especially for woody species. Repeated proliferation of caulogenic buds from the same origin may also find application in rescue of endangered germplasm.

We have developed micropropagation systems for 21 species of Mexican cacti using explants from seedlings germinatedin vitro or shoot segments of juvenile 2–3-yr-old greenhouse plants. The species propagated belong to the generaAstrophytum, Cephalocereus, Coryphantha, Echinocactus, Echinocereus, Echinofossulocactus, Ferocactus, Mammillaria, Nyctocereus, andStenocactus. Multiple shoot formation from areoles was achieved in Murashige and Skoog (MS) medium supplemented with either 1 or 2 mg N6-benzyladenine (BA) per 1 (4.44 or 8.87 μM) or BA at 1 or 2 mg/l plus naphthaleneacetic acid at 0.1 or 1 mg/l (0.54 or 5.37 μM). The requirements of growth regulators for optimal shoot proliferation, the velocity of the response, and the number of buds produced by explant were different among the genera and species studied. Rooting of the shoots generatedin vitro was achieved in MS medium supplemented with indoleacetic acid at 0.5–1 mg/l (2.85–5.71 μM) or indolebutyric acid at 0.5–1 mg/l (2.46–4.90 μM). Finally, 70–95% of the rooted plants transferred to potting medium survived.

A successful protocol for high frequency callus induction and plant regeneration from Anthurium andreanum Linden ex André cv. Tropical half-anthers is described. Different variables using Winarto and Teixeira and Murashige and Skoog basal media supplemented with several plant growth regulators [2,4-dichlorophenoxy acetic acid (0.1–1.0 mg/l), α-naphthalene acetic acid (0.01–0.2 mg/l), thidiazuron (0.5–2.0 mg/l), 6-benzylaminopurine (0.5–1.0 mg/l), and kinetin (0.5–1.0 mg/l)] were tested for their ability to induce high frequency callusing in half-anthers, indirect regeneration and rooting of shoots. Basal medium, as well as the combination and concentration of hormones applied, had a significant effect on callus formation, shoot regeneration and adventitious root formation. Winarto and Teixeira-1, an original basal medium containing 0.01 mg/l α-naphthalene acetic acid, 0.5 mg/l thidiazuron and 1.0 mg/l 6-benzylaminopurine was suitable for callus formation while an improved basal medium i.e., New Winarto–Teixeira-3 supplemented with 0.25 mg/l 2,4-dichlorophenoxy acetic acid, 0.02 mg/l α-naphthalene acetic acid, 1.5 mg/l thidiazuron and 0.75 mg/l 6-benzylaminopurine enhanced callus formation. High shoot regeneration and multiplication was also possible on New Winarto–Teixeira-3. Shoots formed a strong adventitious root system on New Winarto–Teixeira-3 containing 0.2 mg/l α-naphthalene acetic acid and 1.0 mg/l kinetin. Plantlets that varied in size and performance were successfully acclimatized and adapted to ex vitro conditions. Cytological analysis of 180 acclimatized-plantlets ex vitro revealed that 34 were haploid (n = 14–18), 15 aneuploid (n = 20–26), 126 diploid (n = 28–34) and 5 triploid (n = 45–57). The potential use of this protocol for developing half-anther culture of other Anthurium species or cultivars is discussed.

Conditions for induction of androgenesis in coconut cv. Sri Lanka Tall were studied. Anthers collected from inflorescences at four maturity stages were given heat (38°C) or cold (4°C) pretreatments for 1, 3, 6 and 14 days, either prior to or post inoculation. Three different basal media and different anther densities were also tested. Androgenesis was observed only in anthers collected from inflorescences 3 weeks before splitting (WBS) and after a heat pretreatment at 38°C for 6 days. Modified Eeuwens Y3 liquid medium supplemented with 100 μM 2,4-dichlorophenoxyacetic acid (2,4-d), 0.1% activated charcoal and 9% sucrose was effective in inducing an androgenic response. The lowest anther density tested, 10 per petri plate, was found to be the optimal density. When androgenic calli or embryos were subcultured to Y3 medium containing 66 μM 2,4-d, followed by transfer to Y3 medium without plant growth regulators and finally to Y3 medium containing 5 μM 6-benzyladenine (BA) and 0.35 μM gibberellic acid (GA3), plantlets regenerated at a frequency of 7%. Histological study indicated that the calli and embryos originated from the inner tissues of the anthers. Ploidy analysis of calli and embryos showed that they were haploid. This is the first report of successful androgenesis yielding haploid plants from coconut anthers.

An efficient regeneration protocol for zygotic embryos at varying maturity stages was developed for wild banana (Pisang Jajee (AA)). Embryo ontogeny was studied to determine the best maturity stage for embryo rescue, suitable media and culture conditions (light and dark) for germination and regeneration. The conversion of endosperm from transparent fluid into a semi-solid state was followed by visible embryo development, which commenced only after 70% embryo maturity. Zygotic embryos of Pisang Jajee at different maturity levels were excised and cultured on medium fortified with different concentrations of 6-benzyl adenine (BA) and indole acetic acid (IAA). Zygotic embryos produced callus or plantlets 25 days after initiation. The frequency of callus induction was greater in immature embryos irrespective of the media composition and decreased with increasing maturity. Fully matured embryos regenerated directly into plantlets without producing callus. Immature embryos required medium supplemented with plant growth regulators (PGRs) for successful regeneration. Although the culture conditions had no influence, dark conditions favoured callus induction and plant regeneration.

Conventionally sugarcane propagation using bud setts takes a longer time. Consequently variety utilization period is limited because of clonal degeneration. A study was therefore undertaken to speed up the distribution of planting materials by using “stratified rayungan” method. The results of the study revealed that the sprouted buds from the stump with 9–14 and 15–20 bud positions were faster than that of 9–20 bud position. At 3 and 4 months after planting, the total number of shoots from stump with 9–14 and 15–20 bud positions was greater than that of 9–20 bud position. PS 851 variety produced more shoots than PSJT 941, however, the performance of PSJT 941 shoots was better than that of PS 851. The effect of IAA was better than that of root stimulant, while PSJT 941 showed better response to rooting stimulant than PS 851. The period of storage significantly influenced the percentage of fresh seedlings. Viability more than 80 % was found from rayungan seedlings having 4 leaves for PSJT 941 and 5 leaves for PS 851. Application of rooting stimulant was needed to speed up root growth and enhanced viability for the seedlings having 3 or 4 leaves. The distribution of rayungan planting materials to another sugarcane area for 3 days is still feasible.

Salinity has been an important historical factor which has influenced the life span of agricultural systems. Around 10% of the total cropped land surface is covered with different types of salt-affected soils and the Asian continent accounts for the largest area affected by the salinity of various intensities. Cyanobacteria are capable of not only surviving, but thriving in conditions which are considered to be inhabitable, tolerating desiccation, high temperature, extreme pH and high salinity, illustrating their capacity to acclimatise to extreme environments. Until recently, the responses of cyanobacteria to salinity stresses were poorly documented as compared to heterotrophic bacteria and phototrophic eukaryotic algae. Cyanobacteria can be used to reclaim alkaline soils and fertility can be improved for subsequent cultivation of cereal crops, sugarcane and horticultural crops. Therefore we present here a review on cyanobacterial reclamation of salt-affected soil. Substantial progress has been made towards better understanding of the physiological mechanisms responsible for salinity tolerance and osmotic adjustment in cyanobacteria. Many researchers throughout the world have worked on probable mechanisms of salt tolerance studies in cyanobacteria. These organisms evolved about 3,000 million years ago and are considered to be the primary colonisers of the inhospitable ecosystems. The physiological aspects for the adaptation of cyanobacteria to high salinities include (a) synthesis and accumulation of osmoprotective compounds, (b) maintenance of low internal concentrations of inorganic ions and (c) expression of a set of salt-stress proteins. Exposure of cyanobacterial cells to different abiotic stresses resulted in rapid expression of several stress-regulated proteins and modifications in protein synthesis programme. The synthesis of organic solutes like disaccharides (sucrose, trehalose and glucosyl glycerol), quaternary amines (glycine betaine) and free amino acids (glutamine) are well-documented. The protection against alkaline environment is provided by the synthesis of specific fatty acids, sucrose- and osmotic-stress-induced proteins. In cyanobacteria, accumulation of internal osmoticum in the form of inorganic ions and prevention of intracellular Na+ accumulation by the curtailment of Na influx and by efficient active efflux mechanisms or metabolic adjustments have been investigated in depth. The Na+ extrusion in cyanobacteria is driven by a Na+/H+ antiporter, which is energised by enhanced activity of cytochrome oxidase. The inhibition of sodium ion influx appears to be a major mechanism for the survival of cyanobacteria against salt stress and synthesis of salt-stress proteins have been found in cyanobacteria. These organisms have been recognised as an important agent in the stabilisation of soil surfaces primarily through the production of extracellular polysaccharides which are prominent agents in the process of aggregate formation and increase in soil fertility. Cyanobacterial application results in the enrichment of soil with fixed nitrogen, soil structure improvement and declining trend of pH, electrical conductivity (EC) and Na+. The extracellular polysaccharides excreted by cyanobacteria have been reported to be responsible for binding of soil particles, thus, leading to the formation of a tough and entangled superficial structure that improves the stability of soil surface and protects it from erosion. The potential impact of these organisms on agriculture through their use as soil conditioners, plant growth regulators and soil health ameliorators has been well-recognised. Besides bringing about an improvement in the yield of rice, cyanobacteria produce direct and indirect beneficial changes in the physical, chemical and biological properties of soil and soil–water interface in the rice fields, which are of agronomic importance. Certain cyanobacteria have been found not only to grow in saline ecosystems but also improve the physico-chemical properties of the soil by enriching them with carbon, nitrogen and available phosphorus. Flushing of field may not be effective for the reclamation of saline soils and the addition of cyanobacterium inoculum along with the addition of gypsum is required before irrigation to ameliorate saline soils. Nitrogen-fixing cyanobacteria can be used as biological input to improve soil texture, conserve moisture, scavenge the toxic sodium cation from the soil complex and improve the properties of soils. Virtually negligible information exists on the genetics of cyanobacterial halotolerance. The presence of combined nitrogen which effectively curtails sodium accumulation and supports extra nitrogen demand for osmoregulation during slat stress confers considerable salt tolerance on cyanobacteria.

The regulatory effect of derivatives of pyrimidine - Methyur and Kamethur, and pyridine - Ivin on the growth and development of winter barley (Hordeum vulgare L.) cultivar Svitozar was investigated in laboratory conditions. It was found that the morphometric parameters of the 6-week-old barley seedlings grown on water solution of Methyur, Kamethur and Ivin used at the concentration 10-8M, exceeded the morphometric parameters of plants grown on distilled water (control). The positive effect of Methyur, Kamethur and Ivin on the increase of the content of key indicators of productivity of barley plants – the photosynthetic pigments and total soluble proteins was found. The obtained results confirmed the possibility of application of pyrimidine and pyridine derivatives as new effective growth regulators of the winter barley (Hordeum vulgare L.) cultivar Svitozar.

The influence of pyrimidine derivatives - sodium and potassium salts of on the growth and development of lettuce (Lactuca sativa L.) plants in hydroponic conditions has been investigated. The morphometric and biochemical parameters of the 24th-day-old and 45th-day-old lettuce plants obtained from seeds treated with sodium and potassium salts of Methyur used at a concentration of 10-8M in water solution were found to be increased on average: leaf biomass - by 6,95 – 32,32 %, length the longest root - by 8,15 – 45,71 %, the biomass of 10 roots - by 8,74 – 56,76 %, the content of chlorophyll a - by 7,8 – 17,4 %, chlorophyll b - by 15,8 – 33 %, the content of chlorophylls a + b - by 10 – 22,3 %, the content of carotenoids - by 16,1 %, the content of total soluble protein - by 12 – 172 %, compared to similar parameters of control plants. The results of the conducted researches testify to the possibility of application of sodium and potassium salts of Methyur for treatment of seeds of lettuce plants when growing in hydroponic condition for increasing the leaf biomass and content of photosynthetic pigments and soluble protein.
Key words: lettuce (Lactuca sativa L.), pyrimidine derivatives, sodium and potassium salts of Methyur, plant growth and development, hydroponic conditions.

A cost effective procedure was devised for efficient plant propagation of Jatropha curcus L. Direct and indirect in vitro
regeneration was witnessed by addition of plant growth regulator (PGR) combinations. Callus cultures were initiated
from CL, CNR, HC and RT explants on MS basal medium added with 2, 4-D, BAP and NAA in individual and
combined applications. Excellent growth of callus was obtained in all explants with supplementation of BAP (2.0
mg/L) along with NAA (2.0 mg/L), 2, 4-D (0.5 mg/L) being operative for callus induction in only HC explants. These
calli were tested for regeneration and shoot and root organogenesis was successfully induced respectively. Hypocotyl
callus generated 4.0 shoots under the influence of 0.5 mg/L IBA and 1.5 mg/L BAP while CL explant generated 3.0
shoots per callus with slight change in concentration of BAP in same PGRs mixture (0.5 mg/L IBA and 1.0 mg/L
BAP). Along callus mediated organogenic route of regeneration, direct organogenesis was achieved as well. In direct
shoot regeneration ten shoots were formed on CNR with 1.5 mg/L BAP and 0.5 mg/L Kin. Incorporation of 0.25 mg/L
IAA to the medium containing1.5 mg/L BAP + 0.5 mg/L Kin enhanced the regeneration percentage of shoots (11 per
CNR explants). Root initiation in micro-shoots was attained on MS medium (half-strength) added with 0.1 mg/L IBA.
The well-grown plantlets were shifted to peat moss substratum and maintained in field conditions after acclimatization.
This regeneration protocol may also support genetic improvement efforts in J. curcas.

SUMMARY Fruit size can be improved either by increasing carbohydrates availability to fruit or by increasing fruit sink strength. Application of synthetic auxins may act in these two ways, depending on the date of treatment. When they are applied during the physiological drop they have a thinning effect, reducing competition for carbohydrates among developing fruitlets; when applied at the onset

Pigeon pea [Cajanus cajan (L.) Millsp.] (Family: Fabaceae) is an important legume crop cultivated across 50 countries in Asia, Africa, and the Americas; and ranks fifth in area among pulses after soybean, common bean, peanut, and chickpea. It is consumed as a major source of protein (21%) to the human population in many developing countries. In India, it is the second important food legume contributing to 80% of the global production. Several biotic and abiotic stresses are posing a big threat to its production and productivity. Attempts to address these problems through conventional breeding methods have met with partial success. This paper reviews the chronological progress made in tissue culture through organogenesis and somatic embryogenesis, including the influence of factors such as genotypes, explant sources, and culture media including the supplementation of plant growth regulators. Comprehensive lists of morphogenetic pathways involved in in vitro regeneration through organogenesis and somatic embryogenesis using different explant tissues of diverse pigeon pea genotypes are presented. Similarly, the establishment of protocols for the production of transgenics via particle bombardment and Agrobacterium-mediated transformation using different explant tissues, Agrobacterium strains, Ti plasmids, and plant selectable markers, as well as their interactions on transformation efficiency have been discussed. Future research thrusts on the use of different promoters and stacking of genes for various biotic and abiotic stresses in pigeon pea are suggested.

Echinacea, better known as purple coneflower, has received a global attention because of its increasing medicinal value. There is enormous potential for the discovery of new medicinal compounds in this species and an immediate need for techniques to facilitate the production of high quality, chemically consistent plant material for drug development and clinical trials. In vitro tissue culture of Echinacea can play a vital role in the development of novel germplasm, rapid multiplication, and genetic modifications for an enhanced phytochemical production. Recent establishment of liquid culture techniques, large-scale bioreactors, and Agrobacterium-mediated transformation are changing the production parameters of the Echinacea species. This review provides an overview of the recent developments in in vitro technologies and challenges that remain in the Echinacea biotechnology.

To improve the production of Kappaphycus plantlets in tissue culture, optimum media concentrations of an Ascophyllum nodosum extract (Acadian Marine Plant Extract Powder, AMPEP), plant growth regulators (PGR), pH–temperature combinations, and explant density were determined. Kappaphycus alvarezii var. tambalang purple (PUR), kapilaran brown (KAP), vanguard brown (VAN), adik-adik (AA), tungawan green (TGR), and K. striatum var. sacol green (GS) were used as explants. Based on the shortest period for shoot emergence and the economical use of AMPEP, the optimum enriched media was 3.0 mg L−1 AMPEP and 0.1 mg L−1 AMPEP + PGR 1 mg L−1 each phenylacetic acid (PAA) and zeatin for PUR, 1.0 mg L−1 AMPEP + PGR for KAP and GS, 0.1 mg L−1 AMPEP + PGR for VAN, and 3.0 mg L−1 AMPEP and 0.001 mg L−1 AMPEP + PGR for AA and TGR. Results showed that the addition of PGR to low concentrations of AMPEP hastened shoot formation. pH–temperature combinations for the most rapid shoot formation were determined for the brown (KAP) and purple (PUR) color morphotypes of K. alvarezii var. tambalang and the green morphotype of K. striatum var. sacol (GS) cultured in 1.0 mg L−1 AMPEP + PGR. The brown morphotype produced the most number of shoots at pH 7.7 at 20°C after as little as 20 days. Purple K. alvarezii showed an increased shoot formation at pH 6.7 at 25°C and the green K. striatum morphotype at pH 8.7 at 25°C. The optimum number of explants added to the culture media was also determined for tungawan green (TGR), brown (KAP), and tambalang purple (PUR) varieties of K. alvarezii in 1.0 mg L−1 AMPEP + PGR. The number of explants and the volume of the culture media combination were also tested. The highest average number of shoots formed occurred in two explants:1 mL culture media (2:1) for KAP and PUR (35.00% and 16.67%, respectively) and 1 explant: 2 mL culture media for the TGR (100.00%) with a range of 0.5–3.0 mm shoot length after 40 days in culture. The earliest shoot formation was observed after 21 days for the brown and 9 days for both the green and purple color morphotypes of Kappaphycus, in all densities investigated. This indicated that within the range tested, the density of explants did not have a significant effect on the rate of shoot formation but did influence the average number generated from the culture. The rate of production of new and improved Kappaphycus explants for a commercial nursery stock was improved through the use of AMPEP with optimized culture media pH, temperature, and density conditions.

Adventitious shoot regeneration from leaves of blackberry cultivar Čačanska Bestrna was examined using 30 different combinations of treatment. Young, fully expanded leaves taken from in vitro proliferating shoots were cultured on Murashige and Skoog (MS) medium containing either N 6-benzylaminopurine (BAP) (2.0 mg l−1) or thidiazuron (TDZ) (1.0 and 2.0 mg l−1) alone, or either of them combined with indol-3-butyric acid (IBA), α-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) at different concentrations (0.1, 1.0 and 2.0 mg l−1). Indirect shoot formation was observed in 12 different treatments, though the efficacy varied greatly among types and concentrations of plant growth regulators. TDZ at 1.0 mg l−1, applied either alone or combined with IBA, was significantly more effective than BAP in inducing shoot regeneration. The highest regeneration rate (41.66%) was obtained on medium containing TDZ alone. Cytological, flow cytometry and isozyme analyses were used for screening of genetic stability/instability in regenerants. Cytological study, based on chromosome counts in root tip meristems, and flow cytometry analysis indicated that adventitious shoots of Čačanska Bestrna are tetraploid with 2n = 4x = 28 as well as those derived from axillary buds. However, a study conducted on the peroxidase patterns of the different blackberry regenerating lines showed differences between some lines and control plants (in vivo plants and micropropagated plants). These differences were visible with 3,3′,5,5′-tetramethylbenzidine (TMBZ) as hydrogenous donor for peroxidase detection.