Arabidopsis cyclin-dependent kinase gene Cdkg;2 is involved in organogenic responses induced in vitro

The Arabidopsis CDKG;2 gene encodes a putative cyclin-dependent Ser/Thr protein kinase of unknown biological function. This gene shows structural similarity to animal and human cyclin-dependent (PITSLRE) kinases. This study used the homozygous knockout cdkg;2 mutant based on T-DNA insertional line SALK_090262 to study the effect of mutation of the CDKG;2 gene on explant response and in vitro plant regeneration. For callus induction and proliferation, hypocotyls and cotyledons of 3-day-old seedlings of cdkg;2 and A. thaliana ecotype Col-0 were cultured on solid MS medium supplemented with 2,4-D (2 mg l-1). Organogenesis was induced after callus transfer on MS + TDZ (0.5 mg l-1). The initiation time of callus and shoot induction differed between the mutant and control cultures. Shoot regeneration after callus transfer on MS + TDZ was delayed in cdkg;2 (31 days versus 7 days in Col-0). Shoots formed on callus derived from Col-0 hypocotyls but not on cotyledon-derived callus; in cdkg;2, shoots developed on both callus types. Mutant shoots did not form roots, regenerants were dwarfed, and inflorescences had small bud-like flowers with a reduced corolla and generative organs. Abnormalities observed during cdkg;2 organogenesis suggest a role of CDKG;2 as a regulator of adventitious root initiation

Was reduced pollen viability in Viola tricolor L. the result of heavy metal pollution or rather the tests applied?

We used different tests to assess the effect of high soil concentrations of heavy metals on pollen viability in plants from metallicolous (MET) and nonmetallicolous (NONMET) populations. The frequency of viable pollen depended on the test applied: MET plants showed no significant reduction of pollen viability by acetocarmine, Alexander, MTT and X-Gal dye testing, but a drastic reduction of pollen viability in MET flowers (MET 56% vs 72% NONMET) by the FDA test. There was no correlation between pollen viability estimated in histochemical tests and pollen germination in vitro or in vivo. We discuss the terminology used to describe pollen viability as determined by histochemical tests

Genotype-dependent mass somatic embryogenesis: a chance to recover extinct populations of Pulsatilla vulgaris Mill.

The paper presents a technique for micropropagation of endangered in Europe and extinct in Poland Pulsatilla vulgaris for ex situ conservation of the genetic resources. Genotype-dependent induction of somatic embryogenesis and rooting was revealed in series of two experiments (I and II) performed under the same experimental conditions. Shoot tips of seedlings were the best explants in both experiments and Murashige and Skoog (MS) medium supplemented with 0.25 or 0.5 mg L− 1 BAP was suitable for induction of somatic embryos (SE) and adventitious shoots. Mass SE was obtained in experiment I after explants transfer on ½ MS (2% sucrose) + 0.45 mg L− 1 B1 and extending culture to 2–3 months without passages. Rooting of adventitious shoots was a critical point. Out of seven rooting media used in experiment I, only two, ½ MS hormone free (2% sucrose) + 0.45 mg L− 1 B1 or MS + 5 mg L− 1 NAA + 3.76 mg L− 1 B2 resulted in altogether 36.4% rooted shoots. In experiment II, somatic embryogenesis, rooting and acclimatization of adventitious shoots failed. Regenerated plantlets and seedlings converted from SE from experiment I were acclimatized to ex vitro conditions. Both genome size, determined by flow cytometry, and genetic diversity analyzed by ISSR markers, confirmed the compatibility of regenerants from experiment I with P. vulgaris initial seedlings and commercial cultivar. Regenerants obtained in experiment II differed genetically from the regenerants of experiment I and cultivar. Propagated in vitro tissues/organs (SE, adventitious shoots) of P. vulgaris could be a source of material for cryopreservation, artificial seed production and/or for acclimatization of regenerated plantlets and could be used for restoration of the extinct populations. Key Message The micropropagation technique via organogenesis and somatic embryogenesis of endangered in Europe pasqueflower was developed as a tool for species recovery. The critical point is that somatic embryogenesis is genotype-dependent, which affects the repeatability of the experiments and also impose

Evaluation of Picker Discomfort and Its Impact on Maintaining Strawberry Picking Quality

In this paper, the authors present the relationship between the assumptions of ergonomics in the work of a strawberry picker and quality of picked fruit. The body posture that a person adopts while working has a significant impact on their health, working comfort, and productivity, but also on the quality of the fruit that is harvested. This paper identifies three characteristic picker positions during strawberry harvesting. A synchronized surface electromyography (sEMG) instrument together with the Tekscan® surface pressure measurement system allowed for the determination of the influence of working position on changes in the load of the picker’s musculoskeletal system and the surface pressure exerted on the fruit during manual strawberry picking, which are decisive factors for maintaining fruit quality. In addition, compression tests on whole strawberry fruit were carried out as a benchmark to evaluate and compare the maximum forces as well as the destructive pressures on the fruit. From the tests, we found that the most comfortable position of the worker’s body was determined along with the harvesting technique (position during work) that has the least negative effect on the quality of the harvested fruit. Consequently, the level of dynamic load on the worker was determined

Tomato Fruit Quality as Affected by Ergonomic Conditions While Manually Harvested

The harvest phase plays an important role in the whole process of production of tomato fruit. Therefore, it is necessary to ensure a technological process that will not damage biological materials. The harvest phase plays an important role in the whole process. Many growers use special machines for harvesting, but there are fruits and vegetables that should be harvested manually to avoid damaging the surface or parenchyma tissue of the harvested objects. In addition to maintaining the quality of biological materials, work comfort, and ergonomic conditions for pickers should be ensured because inadequate working conditions do not encourage employees to undertake manual work in horticulture. Therefore, there have been shortages of workers on Polish plantations in the past year. Based on manual tomato harvesting, the authors conducted a matched qualitative research study on biological materials and work ergonomics. For this purpose, the Grip System was used to investigate tomato quality by assessing the impact of picking hand pressure (in three different picker’s body positions) on the harvested objects. Simultaneously, for the picker’s ergonomic analysis, a non-invasive surface electromyography method was used to precisely measure changes in muscle motor unit action in the picker’s wrist and lumbar spine while in three characteristic picker’s positions. The tests found that the poorest body position was when the body was deeply inclined and simultaneously twisted. No significant effect was shown of the body position of the tomato picker on the deterioration of the picked fruit quality. However, body positions significantly affect the level of physical load and work comfort

Histology, histochemistry and SEM are useful tools to study regeneration processes in plant tissue culture

Tissue cultures in vitroare used for the multiplication of plants via direct and indirect (via callus) regeneration. This approach is commonly applied in the protection of endangered species by the introduction of regenerated in vitro plantlets to botanical gardens and to the nature (so called ex situ plant conservation). In vitroconditions, especially the supplementation of tissue culture media with plant growth regulators, cause a somaclonal variation, resulting in genetic differences among regenerated plants. To analyze callus structure, including cell shapes and sizes, cell differentiation (e.g. the presence of xylem vessels) and regeneration processes (organogenesis, somatic embryogenesis), the histological, histochemical and SEM techniques are applied. In this study, to obtain regeneration of plants in culture conditions, we have used three Viola species (V. epipsilaLedeb., V. stagnina Kit. and V. uliginosaBesser), indicated to be critically endangered according to Polish Red Book of Plants (Kazmierczakowa & Zarzycki 2001) and two genotypes of a model plant Arabidopsis thaliana(L.) Heynh. (Columbia-0 and an insertional cdkg ;2mutant line). An Arabidopsis homozygous cdkg ;2 knock-out originated from a T 3 generation of T-DNA insertional line SALK_090262 (Alonso et al. 2003) and has been selected from a subsequent T 4 generation based on PCR analysis using primers complementary to flanking positions of full-length cDNA of CDKG;2gene product (a clone isolated by Seki et al. 2002). The aims of the study were: 1) to select the most convenient method to obtain regenerated Violaplants with maternal genotype i.e., via direct organogenesis or somatic embryogenesis; 2) to determine the effect of mutation in CDKG;2 gene on the explant response to in vitroconditions, including callus proliferation and regeneration. In three Viola species organogenesis was induced on MS (Murashige and Skoog) basal medium supplied with thidiazuron (TDZ) in concentrations 0.5 mg ∙l -1 and 1 mg ∙l -1 . Callus proliferated on MS with equal concentrations of cytokinin and auxin (Kin+2,4-D). Histological analysis indicated two pathways of adventitious shoot formation: an indirect one from callus and a direct one from the explants (petiole, leaf fragments). The regeneration of A. thalianahas been found to be genotype dependent. Histological analysis of hypocotyl-derived callus of Columbia-0 genotype regenerated on MS medium supplemented with TDZ showed the meristematic centers forming shoot apices, as well as sporadically embryo-like structures and organs clearly visible on transverse sections. Hypocotyl-derived callus of cdkg ;2 mutant was a heterogeneous tissue, enriched with parenchymatous cells, differentiated xylem elements, large, vacuolized cells at the periphery of callus tissue and groups of small meristematic cells scattered within the callus tissue. The surface of hypocotyl- and cotyledon-derived calluses of Columbia-0 and mutant was covered with membranous structure similar to extracellular matrix (ECM)