Somatic Embryogenesis In Rosa Chinensis CV. ‘Parson’s Pink China’

This study investigated the effects of explant type, plant growth regulator concentration, callis status, medium conversion time, and medium tilt on the growth of rose somatic embryos. The results showed that Rosa chinensis cv. ‘Parson’s Pink China’ leaves could induce normal embryogenic calli but petioles could not. When the 2,4-dichlorophenoxyacetic acid concentration was 3.0 mg/L, the callis induction rate was the highest in the embryo proliferation medium (EP medium) supplemented with 0.5mg/L kinetin, and white and reddish-brown translucent calli were the main type of embryogenic calli induced. As the culture time in EP medium was extended, the relative induction rate for secondary embryos and multicotyledon secondary embryos gradually increased when transferred to embryo maturation medium (EM medium), but the induction rate for somatic embryos decreased. Placing the EM medium at an angle of 45° made the somatic embryos germinate faster and the germination rate was also higher. The germination buds produced by the somatic embryos with two cotyledons showed the fastest germination and greatest survival rates. The results of this experiment will help improve somatic embryo regeneration rates and explore new ways of regeneration, and lays the foundation for further optimization of the somatic embryo genetic transformation system.

Hormonal interactions underlying parthenocarpic fruit formation in horticultural crops

In some horticultural crops, such as Cucurbitaceae, Solanaceae, and Rosaceae species, fruit set and development can occur without the fertilization of ovules, a process known as parthenocarpy. Parthenocarpy is an important agricultural trait that can not only mitigate fruit yield losses caused by environmental stresses but can also induce the development of seedless fruit, which is a desirable trait for consumers. In the present review, the induction of parthenocarpic fruit by the application of hormones such as auxins (2,4 dichlorophenoxyacetic acid; naphthaleneacetic acid), cytokinins (forchlorfenuron; 6-benzylaminopurine), gibberellic acids, and brassinosteroids is first presented. Then, the molecular mechanisms of parthenocarpic fruit formation, mainly related to plant hormones, are presented. Auxins, gibberellic acids, and cytokinins are categorized as primary players in initiating fruit set. Other hormones, such as ethylene, brassinosteroids, and melatonin, also participate in parthenocarpic fruit formation. Additionally, synergistic and antagonistic crosstalk between these hormones is crucial for deciding the fate of fruit set. Finally, we highlight knowledge gaps and suggest future directions of research on parthenocarpic fruit formation in horticultural crops.

Callus induction of mountain papaya endosperm (Vasconcellea pubescens A. DC) with different combination of 2,4-Dichlorophenoxyacetic acid and Kinetin

Endosperm as a result of double fertilization in Angiospermae shows high level chromosomes and polyploidy. It is also considered as dead tissue that unable to be generated to form plantlet. The aim of this research is to determine the effect of kinetin and 2,4-Dichlorophenoxyacetic acid (2,4-D) in induction of callus formation of mountain papaya. This research used A factorial randomized block design with 18 groups, 1 fruit was used for 1 experimental group. Culture using Murashige and Skog (MS) media with combination of three level of kinetin (0, 2, 4 mgL-1) and six level of 2,4-D (0, 1, 2, 3, 4, 5 mgL-1). Maximum endosperm callus induction (0.88%) was achieved from endosperm explant cultured on MS medium fortified with 2.0 mgL-1 Kinetin and 4.0 mgL-1 2,4-D. The fastest day induction (24,66 day) was observed with 5.0 mg L-1 2,4-D. The maximum number of browning (0,10) was induced by 2.0 mgL-1 Kinetin and 5.0 mgL-1 2,4-D. Combination Kinetin and 2,4-D proved could induces callus formation from mountain papaya endosperm.

CHARACTERISATION OF A MEMBER OF THE GENUS CELLULOSIMICROBIUM AS A DEGRADER OF 2,4-DICHLOROPHENOXYACETIC ACID

On the basis of the cultural, morphological, physiological and biochemical features, the taxonomic position of the NPZ-121 strain (isolated from the soil contaminated with chemical waste in Ufa (Russia)) as belonging to the species Cellulosimicrobium funkei was specified. In a batch culture the dynamics of growth of the strain C. funkei NPZ-121 and utilization of 2,4-dichlorophenoxyacetic acid at a concentration of 100 mg/l were described. For 11 days the culture used up to 69% of the substrate from the initial value. The ability of the strain to metabolize 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was revealed previously. Thus, the polysubstrate activity to chlorinated phenoxyacetic acids of the NPZ-121 strain was established.

Phytotoxicity in Seedlings of Rhizophora mangle (L.) Exposed to 2,4-Dichlorophenoxyacetic Acid under Experimental Conditions

Mangroves are considered one of the most productive ecosystems worldwide, providing multiple environmental goods and services; however, in recent years, there have been modifications and deterioration in the structure and function of these ecosystems, caused by various natural events and anthropic activities, such as the construction of roads, wastewater discharge, unsustainable livestock, and agricultural practices, as well as the impact of chemicals, such as heavy metals, oil spills, and the use of herbicides. In this research, phytotoxic effects on seedlings of Rhizophora mangle were evaluated at an exposure of five dilutions w/v (5%, 10%, 25%, 50%, and 100%) of the commercial presentation of 2,4-dichlorophenoxyacetic acid (2,4-D). Propagules grown in a greenhouse under local tidal regimes were used, so the growth of stem diameter, height, biomass production in root, leaves, and stems, as well as the concentration of chlorophyll a of the exposed seedlings were measured. The comparison of these parameters in seedlings with only seawater presented significant differences (p ≤ 0.05) and inhibitory effects on growth (diameter), the stem concentration of chlorophyll a, and the production of biomass of leaves, stems, and roots. The inhibitory effect of exposure to 2,4-D on chlorophyll production and root biomass is highlighted, with an average decrease of 45% relative to the control. The sensitivity of the Rhizophora mangle seedlings to the applied concentrations of herbicide evidence the inhibitory effects on the morphological variables of biomass production and chlorophyll a production in mangrove leaves.

The Enhanced Effect of Bicarbonate Anion for the Removal of 2,4-Dichlorophenoxyacetic Acid on a Palladium/Nickel-Foam Electrode

Palladium/nickel-foam (Pd/Ni) electrode is used as a typical efficient electrocatalytic electrode for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in surface water and industrial wastewater. Many researches had reported how to enhance the dechlorination efficiency of the Pd/Ni electrode by using less Pd loading. However, there are few reports of choosing a suitable electrolyte solution to improve the efficiency of dechlorination. Efforts were made in this work of the different catholyte influenced the dechlorination efficiency. The results showed the fastest removal efficiency of 2,4-D in 34 mmol/L NaHCO3 than in 34 mmol/L NaCl, 34 mmol/L NaClO4, 17 mmol/L Na2SO4 catholyte, respectively on Pd/Ni electrode with pd loading of 0.202 mg/cm2 at constant potential of -0.55 V (vs saturated calomel electrode). The dechlorination current efficiency (CE) was 20.5% in the 34 mmol/L NaHCO3 catholyte more than three times that in 17 mmol/L Na2SO4 catholyte for that HCO3- was the most likely source of protons for adsorbed active hydrogen (H*) in Pd active centers.

Overcoming Pre-Fertilization Barriers in Intertribal Crosses between Anemone coronaria L. and Ranunculus asiaticus L.

Hybridization in flowering plants depends, in the first place, on the delivery of pollen to a receptive stigma and the subsequent growth of pollen tubes through the style to the ovary, where the sperm nucleus of the pollen grain can ultimately fertilize the egg cell. However, reproductive failure is often observed in distant crosses and is caused by pre- and/or post-zygotic barriers. In this study, the reproductive pre-fertilization barriers of intertribal crosses between Anemone coronaria L. and Ranunculus asiaticus L., both belonging to the Ranunculaceae, were investigated. Despite the incongruity of intertribal crosses between A. coronaria and R. asiaticus having been of low intensity at the stigmatic level, interstylar obstructions of the pollen tube growth occurred, which confirmed the presence of pre-fertilization barriers. We show that these barriers could be partially bypassed by combining pollination with a stigma treatment. More specifically, a significantly higher ratio of the pollen tube length to the total style length and a better seed set were observed when the stigma was treated with the auxin 2,4-dichlorophenoxyacetic acid (2,4-D, 1 mg.mL−1) together with the cytokinin kinetin (KIN, 0.5 mg.mL−1) 24 h after pollination, irrespective of the cross direction. More specifically, the stigma treatments with any form of auxin (combined or not combined with cytokinin) resulted in a full seed set, assuming an apomictic fruit set, because no pollination was needed to obtain these seeds.