Int. J. Plant Biol., Volume 6, Issue 1 (September 2015) – 11 articles

Traditional conventions that a protein’s sequence dictates its definitive, tertiary structure, and that this fixed structure provides the protein with the ability to carry out its designated role(s) are still correct but not for all proteins. Research over the past decade discovered that several key proteins possess intrinsically disordered regions (IDRs) that are crucial to their ability to perform specific functions and are observed clustered together within important classes of proteins. In this review, we aim to demonstrate how free energy landscapes, molecular dynamics simulations, and homology modeling are helpful in understanding key conformational dynamics of intrinsically disordered proteins (IDPs). Additionally, we use a list of predicted IDPs found in Arabidopsis to identify chromatin organizers and transcriptional regulators as being highly enriched in IDPs. Furthermore, we focus our attention to specific proteins within these families such as HAC5, EFS, ANAC019, ANAC013, and ANAC046. Future studies are needed to experimentally identify additional IDPs and their binding mechanisms. Full article

Proline is one of amino acid that usually accumulates inside the plant cell when facing drought stress. The accumulation of proline can protect the plant cell from damage during drought. The aim of this research was to determine proline content and yield components of local corn cultivars from Kisar Island, Maluku, Indonesia. The field trial was organized using randomized block design with three replicates. Six local corn cultivars found in Kisar Island (Deep Yellow, Early Maturing Yellow, Red Blood, Rubby Brown Cob, Waxy, and White) were used as plant materials and a recommended tolerance variety (Srikandi) was taken as reference group. Proline content was determined using ninhydrin method. Yield components variables included cob weight (at harvest, after air dry, after oven dried, at 12% of water content), cob water content at harvest, cob length, cob diameter, number of seed row per cob, number of seed per cob, and cob yield at 12% of water content. Data collected was analysed with analysis of variance followed by Duncan multiple range test at the significant level 0.05 using Statistical Analysis System/SAS software version 9.0. The result shows that highest proline content and yield components (except for cob water content) was showed by the Deep Yellow cultivar. The lowest proline content was showed by Rubby Brown Cob cultivar. The lowest corn yield components was showed by Red Blood local cultivar. Deep Yellow cultivar can be proposed as superior drought tolerance variety, and can be recommended for further wide cultivation in Maluku province. Full article

When sperm cells of the plant Lycium barbarum L. (L. barbarum) form in a style they begin to synthesize nuclear DNA (nDNA), which monotonically increases over time. To characterize the dynamics of nDNA accumulation, we present two new dynamical/statistical models. We applied these models to the accumulation of the nDNA content of sperm cells in L. barbarum between 16 to 32 h after pollination in a style. A statistical analysis of experimental data, involving Markov chain Monte Carlo methods, allowed estimation of parameters of the models. We conclude that the model with no variation in the rate of nDNA accumulation adequately summarizes the data. This is the first work where the dynamics of nDNA accumulation has been quantitatively modeled and analyzed. Full article

With the ever growing population and economic needs of Mauritius, the flora of Mauritius has never been in more danger and one group of vascular plants is even more in peril; ferns. Diplazium proliferum is indigenous to the Mascarene region and is considered as a rare species in Mauritius. The need to develop a tested in vitro propagation protocol is a must to protect the biodiversity of Mauritius. This experiment was geared towards the establishment of a proper sterilization technique and the effect of 6-benzylaminopurine (BAP) and light on in vitro culture of this fern. Sterilization with 0.05% Mercuric chloride was effective to eliminate fungal contamination and allow germination of spores. Culture media supplemented with BAP did not significantly increase growth rate of both gametophytes and sporophytes of D. proliferum. Present results suggest efficient sterilization methods to be a crucial stage for successful in vitro regeneration of ferns. The established protocol will be used as an optimized baseline protocol for the propagation of other indigenous ferns. Full article

In capitula of the cultivated sunflower (Helianthus annuus L.) achene size and mass commonly decrease from proximal to distal positions. Temporal limitation of resources of the distal achenes over the proximal ones has been the common explanation for this response. Nevertheless, because the capitulum architecture and expansion dynamics also interacts with achene growth and development, also space exert a coupled effect with resources on achene size along the inflorescence radius. In this work we removed young achenes from different capitulum positions [inner sector (IS) and outer sector (OS)] and applied an artificial restriction to the capitulum/achenes radial expansion. Removal of outer achenes significantly increased the final dry mass of the remnant ones between 17.1 to 27.6%. Removal of inner achenes also produced the same effect but in less magnitude, between 9.3 to 17.9% of the outer ones. The removal of outer achenes with the application of an artificial peripheral constraint did not significantly increase the dry mass of the remnant ones (2.7% of the inner and 7.1% of the control). Percentage of empty achenes significantly diminished in the middle sector (MS) in capitula with the outer achenes removed and in capitula with the outer achenes removed plus a peripheral constraint but in the range of 7.1% (MS achenes) and 2.7% (IS achenes). Percentage of empty achenes of the MS did not change when the outer achenes were removed but was significantly lower when the OS was removed and the peripheral constraint was applied. This results suggest that a part of the reduced growth and development of IS and MS achenes is not only controlled by the competition for resources but also is restricted by space and pressure exerted by the neighboring ones. Full article

Olive cultivation in hot arid areas is hindered by the scarcity of irrigation water. The exploitation of saline water has been proposed as a solution to partially cover plant water demands. This paper presents the effects of salinity [0, 60 and 120 mM sodium chloride (NaCl)] on physiological and reproductive functions of cultivars Koroneiki and Amphissis in a closed hydroponic system. Shoot growth was markedly reduced in high salinity dose in Amphissis (−81%) and Koroneiki (−75%). The photosynthetic rate was significantly reduced at 120 mM NaCl for both cultivars, as well as chlorophyll and carotenoids content (43% and 44%, respectively). The Na+ content in all plant parts increased in both salinity doses especially in Amphissis while K concentration decreased for both cultivars. Inflorescences in Amphissis were severely damaged due to salinity. Consequently, pollen sampling and in vitro germination study was only feasible for Koroneiki. Indeed, Koroneiki pollen germination was reduced at 60 mM NaCl (−42%) and at 120 mM NaCl (−88%). Pollen tube length was also reduced by 15% and 28% for the middle and high salinity dose, respectively. The results of the present study indicate that Amphissis is more sensitive in high salinity doses compared to Koroneiki and that reproductive functions are severely affected by salinity. Full article

Dehydrins (DHNs) are a sub-family of the late embryogenesis abundant proteins generally induced during development of desiccation tolerance in seeds and water deficit or salinity stress in plants. Nevertheless, a detailed understanding of the DHNs function is still lacking. In this work we investigated the possible protective role during salt stress of a Dhn from Hordeum vulgare (L.), aba2. The coding sequence of the aba2 gene was constitutively expressed in transgenic lines of Arabidopsis thaliana (L.). During salt stress conditions germination rate, cotyledon expansion and greening were greatly improved in the transgenic lines as compared to the wild type. Between 98 and 100% of the transgenic seeds germinated after two weeks in media containing up to 250 mM NaCl, and 90% after 22 days at 300 mM NaCl. In conditions of 200 mM NaCl 93% of the transgenic cotyledons had greened after two weeks, outperforming the wild type by 45%. Our study provides further evidence that DHNs have an important role in salt stress tolerance. The production of plants constitutively expressing DHNs could be an effective strategy to improve plant breeding programs. Full article

The aim of this study was to characterize phyllosphere and carposphere bacterial communities of olive trees subjected for 13 years to two different soil management systems (sustainable and conventional) in a mature olive grove located in Southern Italy. Amplified DNA fragments of the 16S ribosomal RNA eubacterial gene (16S rRNA) of bacteria living on leaf and fruit surface, and in fruit pulp were analyzed by denaturing gradient gel electrophoresis (DGGE). A clone library of 16S rRNA amplicons extracted from the bacteria living in pulp homogenates and a phylogenetic analysis were performed. Generally, the DGGE patterns of the bacteria from both the treatments clustered separately. The medium-term sustainable orchard management resulted in a higher number of bacterial species from olive fruit pulp. Phyllosphere and carposphere communities evaluated by DGGE were affected by the type of the agricultural practices adopted. A better understanding of phyllosphere and carposphere microbiota of cultivated olive plants could be useful for the promotion of plant growth, a better plant protection and a higher crop quality. Full article

This study assessed the effect of petrol and spent lubricating oil on the major growth traits (such as root length, stem length, leaf area, and biomass), and the changes in epidermal layer of leaf and its mitotic index in Guinea Corn (Sorghum bicolor L.) exposed to 0% (control), 5%, 10%, 15% and 20% concentrations of petrol and spent lubricating oil. Each concentration was mixed with 3 kg of soil in a plastic pot and each treatment was carried out in three replicates. Forty days after planting, the leaf areas of guinea corn plant were 95.83 cm², 89.67 cm², 89.47 cm², and 77.80 cm² in control, 5%, 10%, 15%, and 20% respectively of petrol pollutant. The means of stem length were 32.50 ± 0.5 cm, 22.60 ± 0.65 cm, 21.27 ± 0.75 cm, 20.83 ± 0.28 cm and 20.33 ± 0.28 cm in control, 5%, 10%, 15% and 20% respectively. Both leaf area and stem length of treated seedlings reduced with increased concentration of the pollutants. Additionally, reduction in the dry weight of the seedlings increased with increasing concentration of both petrol and spent oil. The micrograph of the internal anatomy of the upper epidermal layers of the leaf revealed broken and scattered epidermal cells and smaller sizes of the stomata, and were increased with the increasing concentration of the treatment. Statistical analysis of the treatment shows that there was a significant reduction (p < 0.05) in the stem length and leaf area of the seedlings. This study revealed that petroleum pollutant adversely affected germination, growth and development of guinea corn but petroleum products like spent oil can provide nutrition necessary for growth and yield of plant at low concentration. Full article

Berberis microphylla G. Forst is a fruit shrub native from Patagonia, considered as a non-timber forest product. In recent years, there has been an increased demand for its fruits, both for fresh and industrialized consumption, being the establishment of commercial orchards in different sites a need to meet this demand. B. microphylla cloned plants have been introduced from Ushuaia, Tierra del Fuego to Buenos Aires province in order to evaluate its phenotypic plasticity and the possibility of fruit production. At the same time, a comparative study on the morphology and anatomy of the mature leaves of B. microphylla grown in two different environmental conditions was carried out. Moreno leaves were significantly larger than Ushuaia leaves in all the morphological parameters registered, while Ushuaia leaves were more circular than Moreno leaves with the highest roundness and elongation indexes. Nevertheless, histological sections showed that Ushuaia leaves have one more layer of palisade cells respect to Moreno leaves. Ushuaia leaves showed higher palisade cells, larger abaxial epidermal cells and thicker cuticles than Moreno leaves. The stomatal density was superior on Moreno leaves. Scanning Electron Microscope of abaxial epidermis showed a surface with numerous ridges of different forms that prevent the layout of epidermal cells on Moreno leaves. Appearance of this surface is glossy and oily. On the contrary, epidermal cells are well recognized on Ushuaia leaves. Stomata of anomocytic type were observed and surface looks waxy. Auto-fluorescence on leaf cross sections were observed on the vascular bundles and partially on the epidermis cells. B. microphylla leaves showed a high phenotypic plasticity between the two sites of cultivation. The changes in the leaf morphology and structure observed in Moreno leaves could indicate that the plants are trying to adjust its morphology to the new culture conditions i.e. higher temperatures and lower irradiance. Full article