Plant Growth Regulation

Ethylene (ET) plays a critical role in the activation of plant defenses against different biotic stresses through its participation in a complex signaling network that includes jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA). Pathogen attack, wounding, and herbivory trigger asymmetric activation of this defense signaling network, thereby affecting the final balance of interactions between its components and establishing a targeted response to the initial threat. Ethylene’s contribution to the modulation of this defense network relies on the complexity of the regulation of multigene families involved in ET biosynthesis, signal transduction, and crosstalk and enables the plant to fine-tune its response. The function of the members of these multigene families is tightly regulated at transcriptional, post-transcriptional, and post-translational levels. It is generally accepted that ET cooperates with JA in the activation of defenses against necrotrophic pathogens and antagonizes SA-dependent resistance against biotrophic pathogens. However, this is likely an oversimplified view, because cooperative interactions between ET and SA pathways have been reported and ET has been implicated in the activation of defenses against some biotrophic and hemibiotrophic pathogens. Therefore, deciphering ET’s place in this hormonal network is essential to understanding how the cell orchestrates an optimal response to a specific biotic stress.

Caffeic acid (CA), which is ubiquitously present in plants, is a potent phytotoxin affecting plant growth and physiology. The aim of our study was to investigate whether CA-induced inhibition of adventitious root formation (ARF) in mung bean {Vigna radiata (L.) Wilczek [Phaseolus aureus Roxb.]} involves the induction of conventional stress responses. The effect of CA (0–1000 μM) on ARF in mung bean was determined by measuring the generation of reactive oxygen species (ROS) in terms of malondialdehyde and hydrogen peroxide (H2O2) content, root oxidizability and changes in levels of antioxidant enzymes. Our results show that CA significantly enhanced MDA content, indicating severe lipid peroxidation, and increased H2O2 accumulation and root oxidizability in the lower rooted hypocotylar region (LRHR) of mung bean, thereby inducing oxidative stress and cellular damage. In response to CA, there was a significant upregulation in the activities of scavenging enzymes, such as superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, catalase and glutathione reductase, in LRHRs of mung bean. Based on these results, we conclude that CA inhibits ARF in mung bean hypocotyls by inducing ROS-generated oxidative stress and upregulating the activities of antioxidant enzymes.

Information concerning the sugar status of plant cells is of greatimportance during all stages of the plant life cycle. The aim of this work wasto study primary carbohydrate metabolism in hairy roots of red beet. Growth ofhairy roots of red beet in vitro and changes in concentration of major nutrientsand sugar in the media were measured over a growth cycle

Marco António Teixeira Zullo1,*, Ladislav Kohout2 and Mariangela de Burgos Martins de Azevedo1 1Phytochemistry Laboratory, Instituto Agronômico (IAC), PO Box 28, CEP 13001-970 Campinas, SP, Brazil; 2Institute of Organic Chemistry and Biochemistry, Academy of ...

The present review deals with the importance of fruit thinning in peach.The date of treatment, the severity and the criteria underlying the practiceare discussed. Methods of fruit thinning are described, with particularemphasis on the use of chemical treatment as an alternative to handthinning. Strategies for chemical thinning are advanced.

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.

The influence of air vapor pressure deficit (VPD) and plant fruit load on the expansion and water relations of young tomato fruits grown in a glasshouse were evaluated under summer Mediterranean conditions. The contributions of phloem, xylem and transpiration fluxes to the fruit volume increase were estimated at an hourly scale from the growth curves of intact, heat-girdled and detached fruits, measured using displacement transducers. High VPD conditions reduced the xylem influx and increased the fruit transpiration, but hardly affected the phloem influx. Net water accumulation and growth rate were reduced, and a xylem efflux even occurred during the warmest and driest hours of the day. Changes in xylem flux could be explained by variations in the gradient of water potential between stem and fruit, due to changes in stem water potential. Misting reduced air VPD and alleviated the reduction in fruit volume increase through an increase in xylem influx and a decrease in fruit transpiration. Under low fruit load, the competition for assimilates being likely reduced, the phloem flux to fruits increased, similarly to the xylem and transpiration fluxes, without any changes in the fruit water potential. However, different diurnal dynamics among treatments assume variable contributions of turgor and osmotic pressure in F3 and F6 fruits, and hypothetical short-term variations in the water potential gradient between stem and fruit, preventing xylem efflux in F3 fruits.

The effect of thidiazuron (TDZ) on the micropropagation of Camellia sinensis (China hybrid) was compared with that of benzylaminopurine (BAP) using nodal segments from in vitro raised seedlings. Extremely low concentrations of TDZ (1pM–100nM) alone were effective in inducing shoot bud proliferation and maintaining high rates of shoot multiplication on hormone-free media. On the other hand, higher concentrations of BAP

The modern agriculture is based on the intensive technologies of plant cultivation using phytohormones and their synthetic analogues to regulate the genetic program of plant growth and development during ontogenesis, increase their yield and improve theagricultural product quality, as well as increase the plant resistance to adverse environmental factors and pathogens. The very promising approach is the creation of new plant growth regulators based on low molecular weight synthetic heterocyclic compounds, derivatives of pyrazolotriazinones having phytohormone-like growth regulating activity. The main aim of our work was to study the stimulating effect of low molecular weight heterocyclic compounds, derivatives of pyrazolotriazinones synthesized at the Institute of Bioorga-nic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine, on growth and development of barley (Hordeum vulgare L.) cultivar Commandor during the vegetation period. The conducted researchers showed that the chemical compounds, derivatives of pyrazolotriazinones used at the concentration 10-9M exhibited stimulating activity on seed germination and vegetative growth of 21st-day-old barley seedlings; their activity was similar or exceeded the activity of the phytohormones auxins IAA, NAA and Kinetin used at the same concentration 10-9M. The biometric indices of the 21st-day-old barley seedlings grown on the water solution of the chemical heterocyclic compounds, derivatives of pyrazolotriazinones used in the concentration of 10-9M were similar or higher of the biometric indices of the control barley seedlings grown on the distilled water or barley seedlings grown on the water solution of auxins IAA, NAA and Kinetin used at the same concentration 10-9M in average: at the 11-26 % - by the length of seedlings and at the 21-130 % - by the length of the roots. The obtained results showed also that the testedchemical heterocyclic compounds, derivatives of pyrazolotriazinonesused at the concentration 10-9M stimulated the synthesis of photosynthetic pigments in the leaves of 21th-day-old barley seedlings, which, as is known, play a key role in photosynthetic processes and photoprotection in plants, and provide plant productivity. The content of chlorophyll a in the leaves of 21th-day-old seedlings of barley increased in average: at the 7-13 %; the content of chlorophyll b increased in average: at the 5-19 % ; the content of chlorophylls a+b increased in average: 6-15 %; the content of chlorophylls a/b increased in average: 6-10 %;the content of carotenoids increased in average: at the 10-19 %, as compared with similar indices of barley seedlings grown either on the distilled water (control), or water solution of IAA, NAA, and Kinetin, respectively. The obtained results confirmed the possibility of the application in the agricultural practice of derivatives of pyrazolotriazinonesused at the concentration 10-9M to improve the growth and development of barley (Hordeum vulgareL.) cultivar Commandor during the vegetation period.

The hypothesis that physiologically activeconcentrations of salicylic acid (SA) and itsderivatives can confer stress tolerance in plants wasevaluated using bean (Phaseolus vulgaris L.) andtomato (Lycopersicon esculentum L.). Plantsgrown from seeds imbibed in aqueous solutions (0.1--0.5 mM) of salicylic acid or acetyl salicylic acid(ASA) displayed enhanced tolerance to heat, chillingand drought stresses. Seedlings acquired similarstress tolerance when SA or ASA treatments wereapplied as soil drenches. The fact that seedimbibition with SA or ASA confers stress tolerance inplants is more consistent with a signaling role ofthese molecules, leading to the expression oftolerance rather than a direct effect. Induction ofmultiple stress tolerance in plants by exogenousapplication of SA and its derivatives may have asignificant practical application in agriculture,horticulture and forestry.

The purpose of our work was to study the stimulating effect of new synthetic plant growth regulator, created on the base of chemical low molecular weight heterocyclic compound, derivative of pyrimidine – the formulation Methyur  (6-methyl-2-mercapto-4-hydroxypyrimidine) on germination of seeds and vegetative growth of maize plants (Zea mays L.) hybrid Palmyra FAO 190. The conducted studies showed the high stimulating activity of Methyur sodium salt (MetNa) and Methyur potassium salt (MetK) used at the concentration 10-7 M on growth and development of maize plants during the vegetation stage. The growth regulating activity of the formulations MetNa and MetK was compared with the activity of the plant hormone auxin IAA (1H-Indol-3-ylacetic acid). The comparative analysis of the biometric indices of 3-week-old maize seedlings (number of sprouted seeds (%), seedling height (cm), total length of roots (mm) and number (pcs) of roots) showed that the biometric indices of maize seedlings grown in water solution of the formulations MetNa and MetK used at the concentration 10-7 M was similar or higher of the biometric indices of 3-week-old maize seedlings grown in the distilled water (control) or grown in water solution of the natural auxin IAA used at the same concentration 10-7 M. In particular, the growth stimulating effect of the formulation MetNa used at the concentration 10-7 M on the biometric indices of maize seedlings was as follows: the total length of plant roots was increased by 47% and 26% compared to the similar indices of control plants and plants grown in water solution of the auxin IAA, used at the same concentration 10-7 M, respectively; the total number of plant roots was increased by 125%  and 37% compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively. The growth stimulating effect of the formulation MetK used at the concentration 10-7 M on the biometric indices of maize seedlings was as follows: the total length of plant roots was increased by 43% and 22% compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively; the total number of plant roots was increased by 117% and 32% compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively.  The total content of photosynthetic pigments chlorophylls a and b, a key indicators of plant productivity, was increased in the leaves of maize seedlings grown in water solution of the formulations MetNa and MetK used at the concentration 10-7 M as follows: by 11.3% and 9.5%, and by 25.7% and 23.7%, compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively. The content of total soluble proteins was also increased in the leaves of maize seedlings grown in water solution of the formulations MetNa and MetK used at the concentration 10-7 M as follows: by 38% and 28%, and by 72% and 59%, compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively. It was also shown the positive effects of the formulations MetNa and MetK used at the concentration 10-7 M on the increase of activity of the catalase enzyme, which plays an important role in plant adaptation to oxidative stress. The activity of catalase was increased in the leaves of maize seedlings grown in water solution of the formulations MetNa and MetK used at the concentration 10-7 M as follows: by 21% and 15%, and 10% and 5%, compared to the similar indices of control plants and plants grown in water solution of the auxin IAA used at the same concentration 10-7 M, respectively. The obtained results confirmed the possibility of application of low molecular weight heterocyclic compounds, derivatives of pyrimidine - Methyur sodium salt (MetNa) and Methyur potassium salt (MetK) as new effective regulators of vegetative growth of maize plants (Zea mays L.) hybrid Palmyra FAO 190.

In our work the comparative analysis of plant growth stimulating activity of low molecular
weight five and six-membered heterocyclic compounds derivatives of [1,3]oxazolo[5,4-
d]pyrimidine and N-sulfonyl substituted of 1,3-oxazole synthesized at the Institute of Bioorganic
Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, and plant hormones
auxins IAA and NAA was conducted. It was found that all tested heterocyclic compounds used at
the concentration 10-9M revealed high auxin-like growth stimulating activity on the flax (Linum
usitatissimum L.) of cultivar Svitanok. The growth parameters of 20th-day-old seedlings of flax
grown on the 10-9M water solutions of heterocyclic compounds were in general higher of the
growth parameters of seedlings grown on the water solution of auxins IAA and NAA used in the
same concentration 10-9M and control seedlings grown on the distilled water as follows: according
with length of seedlings – at the 11-14%, 13-16% and 21-24% as compared with control, IAA, and
NAA, respectively; according with total length of roots – at the 24-80 %, 15-35 %, and 10-68 % as
compared with control, IAA, and NAA, respectively; according with total number of roots – at the
28-79 %, 14-27 %, and 5-12 % as compared with control, IAA, and NAA, respectively (Figure 1).
It was found that growth stimulating activity of these compounds was various depending on
plant species and different substituents in the chemical structure of heterocyclic compounds. The
highest activity revealed the compound 5-(4-ethylphenyl)-2-phenyl[1,3]oxazolo[5,4-d]pyrimidin-
7(6H)-one, which contains 4-ethylphenyl substituent at the 5th position and oxygen at the 7th
position of pyrimidine fragment and compound 2-phenyl-5-(piperidin-1-ylsulfonyl)-1,3-oxazole-4-
carbonitrile, which contains phenyl substituent at the 2th position of oxazole. Possibly, the high
stimulating effect of these compounds may be depended from substituents at the 5th and 7th
positions of pyrimidine fragment in the compounds derivatives of [1,3]oxazolo[5,4-d]pyrimidine
and substituents at the 2th position of oxazole in the compounds derivatives N-sulfonyl substituted
of 1,3-oxazole.
Obtained data confirmed perceptiveness of application of derivatives of [1,3]oxazolo[5,4-
d]pyrimidine and N-sulfonyl substituted of 1,3-oxazole in the agricultural practice for
intensification of growth and development of flax.

The brown planthopper (BPH) is one of the most serious insect pests of rice throughout Asia. In this study, we constructed a linkage map to determine the locus for BPH resistance gene, using an F2 population from a cross between a resistant indica cultivar, ‘Col.5 Thailand’, and a susceptible cultivar ‘02428’. Insect resistance was evaluated using 147 F3 families and the genotype of each F2 plant was inferred from the phenotype of corresponding F3 families. Two QTLs was detected on chromosome 2 (explains 29.4% phenotypic variation) and 6 (46.2% variation explained) associated with resistance to BPH in the mapping population. Comparison of the chromosomal locations and reactions to BPH biotypes indicated that the gene on chromosome 6 is different from at least 18 of the 19 previously identified BPH resistance genes. These two genes have large effects on BPH resistance and may be a useful BPH resistance resource for rice breeding programs.

The recent innovation strategy used in the modern agricultural biotechnology is an elaboration of new effective and ecologically safe plant growth regulating substances on the base of synthetic low molecular weight five and six-membered heterocyclic compounds derivatives of pyridine, pyrimidine, pyrazole, oxazole, and isoflavones as an effective substitutes of phytohormones and traditional plant growth regulators to develop agricultural crops with genetically improved commercially important traits such as accelerated growth and development, increased plant productivity and improved quality of production, and enhanced plant tolerance to abiotic stress factors such as drought, salinity, heat, chilling, osmotic stress, soil pollution by anthropogenic factors, and to biotic stress factors such as pathogens and pests [1]. Maize (Zea mays L.) is ancient cereal crop traditionally used as source for dietary food and pharmaceutical industry due to high content of nutrients such as lipids, proteins, carbohydrates, vitamins, dietary fiber and biological active compounds in the seed and seed oil, and as raw material for the biofuel industry and animal feed [2]. Our work was aimed to study of plant growth regulating activity of new synthetic low molecular weight heterocyclic compounds phosphorylated derivatives of oxazole and pyrimidine with perspective their application as a new effective substitutes of phytohormones for improving of cultivation of maize (Zea mays L.) hybrid Palmyra FAO 190. The conducted in the laboratory conditions researches showed high growth stimulating auxin-like effect of tested chemical compounds on germination of seeds, growth and development of maize seedlings during the vegetation. The comparative statistical analysis showed that the biometric indexes of 14th-day-old seedlings of maize grown on the water solution of heterocyclic compounds used at concentration 10-9M were higher than the biometric indexes of 21st-day-old seedlings of maize grown either on the distilled water (control) or on the water solution of auxins IAA and NAA used at the same concentration 10-9M in average: at the 23 % - by total length of seedlings, 5-37 % - by total length of roots, and at the 7-87 % - by total number of roots. The positive effect of some from tested chemical heterocyclic compounds on increase of synthesis of photosynthetic pigments in the leaves of 14th-day-old seedlings of maize was also found: the content of chlorophyll a was increased in average at the 5-10 %; the content of chlorophyll b was increased in average at the 10-74 %; the content of chlorophylls a+b was increased in average at the 5-11 %. The practical application in the agricultural biotechnology of synthetic low molecular weight heterocyclic compounds phosphorylated derivatives of oxazole and pyrimidine as new effective substitutes of phytohormones for improving of growth and development of maize (Zea mays L.) hybrid Palmyra FAO 190 was proposed.
1. V. Tsygankova, Y. Andrusevich, O. Shtompel, O. Myroljubov, A. Hurenko, R. Solomyanny, G. Mrug, M. Frasinyuk, O. Shablykin, V. Brovarets. Study of Auxin, Cytokinin and Gibberellin-like Activity of Heterocyclic Compounds Derivatives of Pyrimidine, Pyridine, Pyrazole and Isoflavones. European Journal of Biotechnology and Bioscience, 2016, 4(12): 29-44.
2. Shah T.R., Prasad K., Kumar P. Maize-A potential source of human nutrition and health: A review. Cogent Food & Agriculture. 2016, 2: 1166995.

The cytokinin-like activity of chemical low molecular weight heterocyclic
compounds, derivatives of oxazolopyrimidine and oxazole was studied. The specific bioassay on cytokinin-like activity conducted on the cotyledons isolated from seeds of muscat pumpkin (Cucurbita moschata Duch. et Poir.) cultivar Gilea showed the high
cytokinin-like stimulating effect of the chemical heterocyclic compounds, derivatives of oxazolopyrimidine and oxazole used at the concentrations 10-9M on the growth of biomass of 16th-day-old cotyledons isolated from seeds of muscat pumpkin (Cucurbita
moschata Duch. et Poir.) cultivar Gilea, which was similar or higher of the effect of plant hormone cytokinin Kinetin used at the same concentrations 10-9M. The obtained results confirmed the inducing cytokinin-like effect of synthetic heterocyclic compounds on plant cell elongation, division, and differentiation that are the basic
processes of plant growth. The practical application of chemical low molecular weight heterocyclic compounds, derivatives of oxazolopyrimidine and oxazole as a new effective plant growth regulating substances was proposed.
Keywords: cytokinin-like activity, Kinetin, oxazolopyrimidine, oxazole, Cucurbita moschata Duch. et Poir.

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.