DcPAR1 is Required for Development and Carotenoid Synthesis in the Dark-Grown Carrot Taproot

Light stimulates carotenoid synthesis in plants during photomorphogenesis through the expression of PHYTOENE SYNTHASE (PSY), a key gene in carotenoid biosynthesis. The orange Daucus carota (carrot) synthesizes and accumulates high amounts of carotenoids in the taproot that grows underground. Contrary to other organs, light impairs carrot taproot development and represses the expression of carotenogenic genes such as DcPSY1 and DcPSY2 reducing carotenoid accumulation. By means of an RNA-seq, in previous analysis we observed that carrot PHYTOCHROME RAPIDLY REGULATED 1 (DcPAR1) is more expressed in the underground grown taproot respect to those grown in light. PAR1 is a transcriptional cofactor with a negative role in the shade avoidance syndrome regulation in Arabidopsis thaliana through the dimerization with PHYTOCHROME INTERACTING FACTORs (PIFs), allowing a moderate synthesis of carotenoids. Here we show that overexpressing AtPAR1 in carrot produces an increment of carotenoids in taproots grown underground as well as higher DcPSY1 expression. The high identity of AtPAR1 and DcPAR1 let us to suggest a functional role of DcPAR1 that was verified through the in vivo binding to AtPIF7 and the overexpression in Arabidopsis, where it increments AtPSY expression and carotenoid accumulation together with a photomorphogenic phenotype. Finally, DcPAR1 antisense carrot lines presented a dramatic decrease in carotenoids levels and in the relative expression of key carotenogenic genes as well as impairment in taproot development. These results let us to propose that DcPAR1 is a key factor for secondary root development, plastid differentiation and carotenoid synthesis in carrot taproot grown underground.One-sentence summaryDcPAR1 is a key factor for secondary root development, plastid differentiation and carotenoid synthesis in carrot taproot grown underground.

Nature and Nurture: Genotype-Dependent Differential Responses of Root Architecture to Agar and Soil Environments

Root development is crucial for plant growth and therefore a key factor in plant performance and food production. Arabidopsis thaliana is the most commonly used system to study root system architecture (RSA). Growing plants on agar-based media has always been routine practice, but this approach poorly reflects the natural situation, which fact in recent years has led to a dramatic shift toward studying RSA in soil. Here, we directly compare RSA responses to agar-based medium (plates) and potting soil (rhizotrons) for a set of redundant loss-of-function plethora (plt) CRISPR mutants with variable degrees of secondary root defects. We demonstrate that plt3plt7 and plt3plt5plt7 plants, which produce only a handful of emerged secondary roots, can be distinguished from other genotypes based on both RSA shape and individual traits on plates and rhizotrons. However, in rhizotrons the secondary root density and the total contribution of the side root system to the RSA is increased in these two mutants, effectively rendering their phenotypes less distinct compared to WT. On the other hand, plt3, plt3plt5, and plt5plt7 mutants showed an opposite effect by having reduced secondary root density in rhizotrons. This leads us to believe that plate versus rhizotron responses are genotype dependent, and these differential responses were also observed in unrelated mutants short-root and scarecrow. Our study demonstrates that the type of growth system affects the RSA differently across genotypes, hence the optimal choice of growth conditions to analyze RSA phenotype is not predetermined.

A Study on The Effect Of Defect Location On Stress In Bending Pipe

In this study, the stress that generated when the first or second root of a corrugated pipe is defective is analyzed. The model is analyzed using F.E.M. code. The boundary conditions of deflection or torsion on the opposite side of the defect in the corrugated pipe are changed. The effect of the defect is evaluated using the change of the stress magnitude and the stress concentration factor(K) according to those conditions. As a result of comparing the stress magnitude, K around the flaw at the secondary root is larger than K around the flaw at the first root. Based on the position of the defect, the stress difference in the 1st root increases depending on the boundary condition of bending deflection. However, when the 2nd root is defective, the stress magnitude is similar in both cases regardless of the bending deflection. The magnitude of the stress generated in the corrugated pipe is the highest when the second root is defective. And the stress magnitude is the lowest when there is no defect. In the absence of defects, the stress gradually increases after the stress reaches the minimum value as the amount of deformation increases. However, if there is a defect, stress continues to increase, and when it passes through the plastic zone, the stress gradually increases.

Secondary Root Canal Treatment with Reciproc Blue and K-File: Radiographic and ESEM-EDX Analysis of Dentin and Root Canal Filling Remnants

Secondary root canal treatment requires the complete removal of filling materials with different chemical-physical properties. A newly developed single-use NiTi instrument (Reciproc Blue, RB) may be more effective in root canal retreatment. The aim of the present study was to evaluate morphology and composition of remnants after retreatment with RB compared to traditional K-File technique, in canals obturated with Thermafil/AH Plus. Twenty-four single-rooted human teeth were shaped with NiTi obturated with AH-Plus/Thermafil and retreated using RB NiTi instruments or manual K-Files. Radiographs were taken to evaluate endodontic space and radiopacity of residual filling-material before/after procedures. After retreatment, samples were longitudinally split and observed by environmental scanning electron microscopy connected to energy dispersive X-Ray spectroscopy (ESEM-EDX) to analyze the debris/remnant position, microchemistry, and dentinal surface morphology. Time for retreatments was recorded and compared using one-way ANOVA (p-value = 0.05). Radiopaque filling residuals were found in both groups. RB system resulted statistically faster than manual K-File in retreatment procedure (p < 0.001). Root canal space radiographic appearance obtained after retreatment with RB was wider than K-File (p < 0.05). ESEM-EDX revealed 4 different morphological dentin area. Area-1: debris-free with typical Ca, P, and N composition of dentin and detected in 70% of the surface. Area-2: presence of deproteinized smear layer free from N and debris in 15% of the surface. Area-3: a thick packed smear layer N-free and with fine debris consisting of trace elements from sealer in 10% of the surface. Area-4: packed with debris and trace elements. No difference was observed between both instruments regarding root canal space appearance and ESEM-EDX analysis. Both systems were able to remove filling material but created a dentine morphology composed of packed debris and filling materials embedded into the smear layer. Dentin surface composition resulted in collagen depleted by irrigation procedures. The reciprocating system required less time to complete retreatment.

Study of interaction Effect of different colour poly wrappers and PBZ concentration on rooting and growth of Guava air layers.

An experiment was conducted during 2017-18 at the Research orchard of Horticulture, college of Agriculture Gwalior to Study of interaction Effect of different colour poly wrappers and PBZ concentration on rooting and growth of Guava air layers. Total 12 treatment were tested under experiment. Result related that maximum length of primary root, length of secondary root, diameters of primary root, diameters of secondary root, fresh weight of root, dry weight of root, rooting %, number of leaves, number of new sprout, length of air layers, and survival percentage of air layers of guava was observed under Red poly wrapper with 500ppm PBZ. Which was significantly higher then other treatment combination follow by Blue poly wrapper with 500ppm PBZ and result of black poly wrappers and the lowest result found in white wrapper with co (No harmon) PBZ.

Conservation of tropical tree biodiversity through macropropagation by shoot cutting of raru (Cotylelobium melanoxylon), a highly utilized dipterocarp in North Sumatra, Indonesia

Susilowati A, Hartini KS, Elfiati D, Rachmat HH, Kusuma YS, Sinaga MZE, Suhartati T. 2020. Macropropagation by shoot cutting of raru (Cotylelobium melanoxylon), a highly utilized dipterocarp in North Sumatra, Indonesia. Biodiversitas 21: 724-730. Cotylelobium melanoxylon (Hook.f.) Pierre, or locally named raru, is one of native tree species from North Sumatra that has many uses for its wood and medicinal purposes for anti-diabetic, anti laxative and blood coagulation. C. melanoxylon has been experiencing short supply due to its limited natural distribution, forest degradation, illegal harvesting for its wood and bark and uncertain fruiting season of the species. Along with these alterations, C. melanoxylon population has been decreasing. The objective of this research was to determine the effectiveness of C. melanoxylon propagation by shoot cutting. Randomized factorial design with 2 factors was employed in this research. The first factor (factor A) was the cutting media (i.e. topsoil only; topsoil and sand with proportion of 1:1 v/v), and the second factor (factor B) was commercial auxin addition (i.e. 1g/100cuttings; without auxin). The observed parameters were survival percentage, rooted percentage, number of primary and secondary root, length of primary and secondary root and root histology. The results showed that the interaction between media and auxin addition did not have any significant effect on all tested parameters. The average survival percentage was 70-90% and rooting percentage was 50-90%. Adventitious root formation on C. melanoxylon cutting was originated from cell differentiation on wounded area near cambium, followed by root primordia formation and root meristem formation. The success of artificial propagation technique for this species will provide basic practice of C. melanoxylon cultivation and may contribute to the effort of ex situ conservation for valuable and threatened tree species.

Application of compost in mixed media improved oil palm nursery’s secondary root structure thereby reducing the fertilizer requirement for growth

Although conventional inorganic fertilizers increased plant growth and productivity, their excessive use leads to wastage, run-offs and environmental pollution. In order to promote nutrient recycling and zero emission strategy in the palm oil industry, compost was produced from oil palm empty fruit bunch (EFB) and palm oil mill effluent (POME) anaerobic sludge. The main objective of this study is to determine the effect of compost in the mixed media on the growth and inorganic fertilizer requirement in the oil palm nursery. 100% soil as media with 100% inorganic fertilizer as control was compared with mixed media containing 50% compost in soil with inorganic fertilizer at 25%, 50%, 75% and 100% compositions and tested for plant growth and root structure. The results showed that the treatments with compost addition improved plant growth, compared to the control with 100% inorganic fertilizer which did not contain compost in the mixed medium. The improved plant growth corresponded directly to the enhanced secondary root structure, which probably resulted in more efficient absorption and uptake of nutrients by the plants. Furthermore, the plant growth and the secondary root structure in the mixed media with 50% inorganic fertilizer composition was not significantly different to the media with 75% and 100% inorganic fertilizer. Therefore it is suggested that the application of 50% compost in the mixed media enhanced the secondary root structure, resulting in reduced inorganic fertilizer requirement in the oil palm main nursery, without affecting the plant growth.