Alanine Conjugate of Indole-3-butyric Acid Improves Rooting of Highbush Blueberries

Auxins and their synthetic analogues are commonly used for rooting of cuttings, but their efficiency depends on experimental set-up and, even more importantly, on species or cultivar, and type of explants investigated. In attempt to improve rooting procedure for highbush blueberries (Vaccinium corymbosum L.), we investigated alanine conjugate of indole-3-butyric acid (IBA-Ala) as potential root-promoting compounds and compared with commonly used auxins indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA). The effect of different concentrations of auxins on the rooting of highbush blueberry stem cuttings (var. Bluecrop, Bluetta, Burlington and Jersey) and in-vitro-derived microcuttings (var. Jersey) was investigated. Auxin treatments significantly promoted rooting of all four varieties in comparison to control. The most efficient rooting promoter in all varieties appeared IBA-Ala (provided up to 83%, and 93% of the rooted cuttings and microcuttings, respectively). Furthermore, IBA-Ala caused a vigorous, well-branched root system that resulted in better acclimatization and survival of plants. Results suggest the application of IBA-Ala may be beneficial for rooting of difficult-to-root varieties of blueberry and related species and their practical application in the nursery industry

Reproductive Development of the Christmas Rose (Helleborus niger L.): The Role of Plant Hormones

Christmas rose (Helleborus niger L.), a native perennial of southeastern Europe, is characterized by an interesting phenomenon in the world of flowering plants: after fertilization perianth becomes green, photosyntheticaly active, and persists during fruit development. Removal of the reproductive organs (anthers and carpels) affects the elongation and vascular anatomy of flower stalk, prevents complete perianth greening, and promotes perianth senescence. Endogenous plant hormones auxins, gibberellins and cytokinins, identified and quantified in floral and fruit tissues, are shown to regulate reproductive development. Dynamics of these signaling molecules are summarized and their potential role in coordination of floral organ development are discussed.(doi: 10.5562/cca1820

Auxin Amidohydrolases – From Structure to Function: Revisited

The control of plant growth and development is a well-coordinated process between exogenous and endogenous signals. Auxins are plant hormones belonging to the endogenous signals, which control a vast array of different processes. While auxins are growth promoting at low concentrations, higher levels are often inhibitory. Therefore, the tight control of auxin concentrations in a given plant tissue is essential. Among several processes that participate in auxin homeostasis, we focused herein on the process of reversible auxin conjugation that considers the synthesis of inactive auxin conjugates, which can be hydrolyzed back to the active form by so called auxin conjugate hydrolases. Although these proteins have been known for quite some time, their role in plants is still not clear, especially since novel hydrolases with different substrate specificities have been isolated. Thus, we have revisited the knowledge about auxin hydrolases, from their structure and biochemistry to the role in plant development and in dealing with unfavorable climate conditions. This work is licensed under a Creative Commons Attribution 4.0 International License

Morfo-fiziološki i hormonski odgovor različitih sorti ozime pšenice na sušni stres u fazi klijanja i klijanaca

Drought stress can have a significant influence on the reduction of wheat (Triticum aestivum L.) growth and development. This study investigated morpho-physiological, abscisic (ABA) and salicylic (SA) acids\u27 responses of six winter wheat varieties (Rujana, Silvija, Fifi, Bubnjar, Anđelka and Pepeljuga) during the germination and seedling stage. Plants were exposed to 10 and 20% polyethylene glycol (PEG) solution for seven days. Certain morphophysiological changes were observed under stress condition in comparison to controls, such as a reduction of germination energy (GE), shoot length, relative water content (RWC), increase of root growth, depending on varieties and stress intensity. ABA was increased in all cultivars confirming stress status of the plants. SA showed a tendency to decrease depending on the concentration of PEG and was positively correlated with shoot length and shoot dry weight. In the varieties Rujana, Anđelka, Fifi and Bubnjar a less significant decrease in germination energy was recorded, compared to Pepeljuga and Silvija.Sušni stres može značajno utjecati na smanjenje rasta i razvoja pšenice. U ovom radu istraživan je morfo-fiziološki odgovor, te odgovor abscizinske (ABA) i salicilne (SA) kiseline šest sorti ozime pšenice (Rujana, Silvija, Fifi, Bubnjar, Anđelka i Pepeljuga) tijekom klijanja i faze klijanaca. Biljke su izložene 10 i 20% otopini polietilen glikola (PEG) tijekom sedam dana. Od morfo-fizioloških parametara zabilježeno je značajno smanjenje energije klijanja, smanjenje duljine izdanka, smanjenje relativnog sadržaja vode, pojačani rast korijena ovisno o stupnju stresa u odnosu na kontrolne uvjete i sorti pšenice. Koncentracija ABA je povećana u svim sortama što potvrđuje prisutnost stresa u biljkama. SA je pokazala tendenciju smanjenja ovisno o koncentraciji PEG-a i bila je u pozitivnoj korelaciji s duljinom izdanka i suhom masom izdanka. Kod sorti Pepeljuga i Silvija zabilježeno je značajno smanjenje energije klijanja u odnosu na sorte Rujana, Anđelka, Fifi i Bubnjar

Salinity Stress as an Elicitor for Phytochemicals and Minerals Accumulation in Selected Leafy Vegetables of Brassicaceae

The potential role of NaCl (50–200 mM) as an eustressor for the accumulation of health promoting phytochemicals and maintaining the homeostasis of macro- and micro-elements in three, hydroponically grown Brassica leafy vegetables (Chinese cabbage, white cabbage, and kale) was investigated. Considering K+/Na+ ratio and proline contents as reliable stress markers, we confirmed more prominent stress status in Chinese cabbage followed by white cabbage and kale. Low to moderate salinity treatments (50 and 100 mM NaCl) caused an increase in most of the phenolic compounds in the analyzed Brassica leafy vegetables. Total glucosinolates were elicited by NaCl in a dose dependent manner. Salt treatment caused an increase in total chlorophylls but did not significantly affect carotenoid content. Furthermore, low to moderate treatments did not significantly disturb homeostasis of macro- and micro-elements, particularly in white cabbage and kale where the K level did not decrease significantly and Ca was even increased in white cabbage. We may conclude that salinity may elicit phytochemical accumulation in selecting vegetables grown on saline soils without undesirable disturbance in macro- and micro- elements homeostasis depending on salt concentration and species/varieties. This information may be of great importance in the selection of crops grown on saline soils

Structure/activity corrrelations for auxins

Structure-activity correlations for the endogenous phytohonnone, indole- -3-acetic acid (1AA), and its ring-alkylated and -halogenated derivatives are based on geometric and electronic molecular characteristics, and the resulting physical and chemical attributes. Plant growth-regulating properties are discussed with particular emphasis on molecular (bio)conformation and on substituent effects and their influence on properties such as lipophilicity

Beneficial Microbes and Molecules for Mitigation of Soil Salinity in Brassica Species: A Review

Salt stress results from excessive salt accumulation in the soil can lead to a reduction in plant growth and yield. Due to climate change, in the future climatic pressures, changed precipitation cycles and increased temperature will increase the pressures on agriculture, including increasing severity of salt stress. Brassica species contains oilseed and vegetable crops with great economic importance. Advances in understanding the mechanisms of salt stress in Brassica plants have enabled the development of approaches to better induce plant defense mechanisms at the time of their occurrence through the use of beneficial microorganisms or molecules. Both endophytic and rhizospheric microbes contribute to the mitigation of abiotic stresses in Brassica plants by promoting the growth of their host under stress conditions. In this review we summarized so far reported microorganisms with beneficial effects on Brassica plants and their mode of action. Another approach in mitigating the harmful effect of soil salinity may involve the application of different molecules that are involved in the stress response of Brassica plants. We reviewed and summarized their potential mode of action, methods of application and pointed out further research directions