| 1. |
- Agback, Peter, et al.
(author)
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Root morphology and cluster root formation by seabuckthorn (Hippophae rhamnoides L.) in response to nitrogen, phosphorus and iron deficiency
- 2015
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In: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 397, s. 75-91
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Journal article (peer-reviewed)abstract
- The aims were to investigate effects of availability of nitrogen (N), phosphorus (P) and iron (Fe) on root properties of seabuckthorn (HippophaA << rhamnoides) and to test the hypothesis that seabuckthorn is able to form cluster roots (CRs).Two sources of seabuckthorn were used: the seabuckthorn cultivar BHi10726 originating from a breeding programme based on H.r. ssp mongolica and carried out in rich agricultural field soil in the black earth (chernozem) region of Russia and the seabuckthorn accession named Pk originating in a natural population of H.r. ssp turkestanica in the mountainous region of northern Pakistan. Three cultivation systems giving different water availabilities were used at two levels each of N, P and Fe. Root morphology of seedlings and clones was characterized and metabolite content in extracts of young and old CRs of Pk was analyzed by proton nuclear magnetic resonance spectroscopy.Availability of N affected growth and distribution of biomass between shoot and root, while P and Fe deficiency modified root system architecture towards more lateral roots. Densely positioned rootlets with a determinate type of growth consistent with the definition of CR were observed under low P and low Fe. Pk formed on average 12 CRs per plant, which was 3 to 4-fold higher compared to BHi10726 also when normalized per root length. Malate and glycine were most abundant of the organic acids and amino acids, respectively, and decreased in old CRs.Seabuckthorn has the ability to form cluster roots especially in Pk and under deficiency of P and Fe. The two sources of seabuckthorn with different histories showed distinctly different root system architectures. The high contents of malate and glycine and their decrease in old CRs may reflect roles in CR metabolism.
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| 2. |
- Lundquist, Per-Olof, et al.
(author)
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Root traits of seabuckthorn
- 2016
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In: RPD Abstracts. - 2255-8624 .- 2500-9788. ; 2, s. 87-87
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Conference paper (other academic/artistic)
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| 3. |
- Shah, Syed Rehmat Ullah
(author)
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Molecular Network for Regulation of Ovule Number in Plants
- 2021
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22
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Research review (peer-reviewed)abstract
- In seed-bearing plants, the ovule (“small egg”) is the organ within the gynoecium that develops into a seed after fertilization. The gynoecium located in the inner compartment of the flower turns into a fruit. The number of ovules in the ovary determines the upper limit or the potential of seed number per fruit in plants, greatly affecting the final seed yield. Ovule number is an important adaptive characteristic for plant evolution and an agronomic trait for crop improvement. Therefore, understanding the mechanism and pathways of ovule number regulation becomes a significant research aspect in plant science. This review summarizes the ovule number regulators and their regulatory mechanisms and pathways. Specially, an integrated molecular network for ovule number regulation is constructed, in which phytohormones played a central role, followed by transcription factors, enzymes, other protein and micro-RNA. Of them, AUX, BR and CK are positive regulator of ovule number, whereas GA acts negatively on it. Interestingly, many ovule number regulators have conserved functions across several plant taxa, which should be the targets of genetic improvement via breeding or gene editing. Many ovule number regulators identified to date are involved in the diverse biological process, such as ovule primordia formation, ovule initiation, patterning, and morphogenesis. The relations between ovule number and related characteristics/traits especially of gynoecium/fruit size, ovule fertility, and final seed number, as well as upcoming research questions, are also discussed. In summary, this review provides a general overview of the present finding in ovule number regulation, which represents a more comprehensive and in-depth cognition on it.
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| 4. |
- Shah, Syed Rehmat Ullah
(author)
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Root system of seabuckthorn (Hippophaë rhamnoides L.) : morphology, metabolism and gene expression
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Nutrient availability is one of the limiting factors for plant growth and development, and the nutrients on Earth are unevenly distributed. To overcome this, plants adapt by modifying their morphology and physiology, especially of the root system. Seabuckthorn is a small tree growing in temperate regions of Europe and Asia. It performs symbiotic N₂ fixation and has high adaptability to environmental constraints. This thesis examined factors shaping the root system of seabuckthorn. It was found that seabuckthorn has the ability to produce structures with dense lateral roots called cluster roots (CRs). Different patterns of root system were found at genotype level; Pk, a wild accession of H. rhamnoides ssp. turkestanica originating from unfertile soils, produced more CRs than cultivars BHi10726 and Sunny with a breeding history in fertile soils. Reduced availability of phosphorus (P), nitrogen or iron affected root morphology by increased lateral roots and CR formation, which may explain the competitive and invasive nature of this plant on nutrient-deficient soils. Abundant compounds in CRs found by metabolite analysis using ¹H-NMR spectroscopy were asparagine, glycine and malate, an organic acid involved in mobilization of P from soil. In Pk as compared to cv. Sunny, the concentration of root metabolites was higher. In roots under low P, RNA sequencing revealed transcripts involved in primary root metabolism, P homeostasis and metabolism consistent with a P-deficient response. To assess functions of CRs which have a determinate growth pattern, analysis of metabolites and transcripts could display changes towards a P-deficient metabolism as well as anaerobic metabolism at later developmental stages of CR. As an enzyme central to organic acid metabolism in plants, the gene family encoding phosphoenolpyruvate carboxylase (HrPPC) was characterised. Both plant-type and bacterial-type isoforms were found with tissue-specific expression patterns and with higher expression of HrPPC2 under low P. In vitro studies showed that auxin stimulated formation of lateral roots at low P levels, while high P gave high formation of shoots from roots, another trait of the seabuckthorn root system. This study provides a basis to understand functions and roles of CRs in seabuckthorn as an actinorhizal representative among the three groups of CR-forming plants.
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| 5. |
- Shah, Syed Rehmat Ullah, et al.
(author)
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Shoot organogenesis from roots of seabuckthorn (Hippophaë rhamnoides L.): structure, initiation and effects of phosphorus and auxin
- 2015
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In: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 29, s. 1989-2001
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Journal article (peer-reviewed)abstract
- Shoots from roots formed on seedlings in vitro in the groove of lateral roots as on plants growing in a natural habitat. The finding has ecological and applied relevance.Shoot organogenesis from roots (root suckers, shoots from roots, SfRs) allows vegetative propagation of the small tree seabuckthorn (HippophaA << rhamnoides L.) in addition to sexual propagation and is an important trait associated with the root system. Using an in vitro system, we studied initiation, localization and development of SfRs and interacting roles of phosphorus (P) and indole-3-acetic acid (IAA). After transfer of seedlings to the W4 medium (WPM medium with added IAA, benzyl adenine and giberellic acid), SfRs protruded after 2 weeks from the primary root initially at the groove of lateral roots (LR) as seen by scanning electron microscopy and light microscopy. This is also the location of SfRs on plants growing in natural conditions, which suggests a similar developmental pathway. To localize SfR initiation, staining by the DNA-binding fluorochrome 4',6-diamidino-2-phenylindole in root cross sections revealed a high density of small cells as in meristems in the pericycle area between endodermis and vascular tissue. During 8-10 weeks, SfRs emerged also in other positions on the primary root, concomitantly with senescence of existing LRs and suppression of new LR formation. Since SfR formed in relation to LRs, we hypothesized that P and IAA play a role in SfR formation. Highest production of SfRs occurred in W4 medium after pre-treatment with high P in the presence of IAA while LR production in WPM was stimulated by IAA in low and middle P. SfRs developed in vitro on seedlings originating from three subspecies of H. rhamnoides showing this trait to be common. This experimental system allowed studies of organogenesis of SfRs and LRs in response to plant growth regulators, P and IAA and may be further implemented in basic studies and in applied clonal propagation of seabuckthorn.
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