Roxana Khoshravesh- PhD
- Affiliate at University of New Mexico
Roxana Khoshravesh
- PhD
- Affiliate at University of New Mexico
About
33
Publications
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Introduction
Current institution
Publications
Publications (33)
Leaf imaging via microscopy has provided critical insights into research on photosynthesis at multiple junctures, from the early understanding of the role of stomata, through elucidating C4 photosynthesis via Kranz anatomy and chloroplast arrangement in single cells, to detailed explorations of diffusion pathways and light utilization gradients wit...
The engineering of C4 photosynthetic activity into the C3 plant rice has the potential to nearly double rice yields. To engineer a two‐cell photosynthetic system in rice, the rice bundle sheath (BS) must be rewired to enhance photosynthetic capacity. Here, we show that BS chloroplast biogenesis is enhanced when the transcriptional activator, Oryza...
C4 photosynthesis evolved over 65 times, with around 24 origins in the eudicot order Caryophyllales. In the Caryophyllales family Nyctaginaceae, the C4 pathway is known in three genera of the tribe Nyctagineae: Allionia, Okenia and Boerhavia. Phylogenetically, Allionia and Boerhavia/Okenia are separated by three genera whose photosynthetic pathway...
The chloroplastic 2-oxaloacetate/malate transporter (OMT1 or DiT1) takes part in the malate valve that protects chloroplasts from excessive redox poise through export of malate and import of oxaloacetate (OAA). Together with the glutamate/malate transporter (DCT1 or DiT2), it connects carbon with nitrogen assimilation, by providing 2-oxoglutarate f...
The chloroplastic oxaloacetate/malate transporter (OMT1 or DiT1) takes part in the malate valve that protects chloroplasts from excessive redox poise through export of malate and import of oxaloacetate (OAA). Together with the glutamate/malate transporter (DCT1 or DiT2), it connects carbon with nitrogen assimilation, by providing α-ketoglutarate fo...
The Australian grass subtribe Neurachninae contains closely related species that use C3, C4, and C2 photosynthesis. To gain insight into the evolution of C4 photosynthesis in grasses, we examined leaf gas exchange, anatomy and ultrastructure, and tissue localization of Gly decarboxylase subunit P (GLDP) in nine Neurachninae species. We identified p...
C4 photosynthesis is a complex trait that boosts productivity in warm environments. Paradoxically, it evolved independently in numerous plant lineages, despite requiring specialised leaf anatomy. The anatomical modifications underlying C4 evolution have previously been evaluated through interspecific comparisons, which capture numerous changes besi...
The evolution of C4 photosynthesis proceeded stepwise with each small step increasing the fitness of the plant. An important precondition for the introduction of a functional C4 cycle is the photosynthetic activation of the C3 bundle sheath by increasing its volume and organelle number. Therefore, to engineer C4 photosynthesis into existing C3 crop...
Imaging of mesophyll cell suspensions prepared from Arabidopsis has been pivotal for forming our current understanding of the molecular control of chloroplast division over the past 25 years. In this chapter, we provide a method for the preparation of leaf cell suspensions that improves upon a previous method by optimizing cellular preservation and...
The C4 photosynthetic pathway accounts for ∼25% of primary productivity on the planet despite being used by only 3% of species. Because C4 plants are higher yielding than C3 plants, efforts are underway to introduce the C4 pathway into the C3 crop rice. This is an ambitious endeavor; however, the C4 pathway evolved from C3 on multiple independent o...
High-resolution images obtained from plant tissues processed for light microscopy, transmission electron microscopy, and immunohistochemistry have provided crucial links between plant subcellular structure and physiology during photorespiration as well as the impact of photorespiration on plant evolution and development. This chapter presents estab...
Photorespiratory glycine shuttling and decarboxylation in bundle sheath (BS) cells exhibited by C2 species is proposed to be the evolutionary bridge to C4 photosynthesis in eudicots. To evaluate this in grasses, we compare anatomy, cellular localization of glycine decarboxylase
(GDC), and photosynthetic physiology of a suspected C2 grass, Homolepis...
Photorespiratory limitations on C3 photosynthesis are substantial in warm, low CO2 conditions. To compensate, certain plants evolved mechanisms to actively concentrate CO2 around Rubisco using ATP-supported CO2 pumps such as C4 photosynthesis. Plants can also passively accumulate CO2 without additional ATP expenditure by localizing the release of p...
Oreosalsola, a non-C4 lineage is described as a new genus segregated from Salsola s.l. (Chenopodiaceae). The phylogenetic position and anatomical structure of the new genus in relation to photosynthetic types are discussed. Anabasis firouzii (Chenopodiaceae) and Salvia shahkuhmahalei (Lamiaceae) are described from Golestan National Park (GNP) and G...
The glycine decarboxylase complex (GDC) plays a critical role in the photorespiratory C2 cycle of C3 species by recovering carbon following the oxygenation reaction of ribulose-1,5-bisphosphate carboxylase/oxygenase. Loss
of GDC from mesophyll cells (MC) is considered a key early step in the evolution of C4 photosynthesis. To assess the impact of p...
Premise of research. Plants with C4 photosynthesis are able to produce carbohydrates more efficiently than plants with C3 photosynthesis in warm climates when levels of atmospheric CO2 are reduced. The C4 pathway has evolved multiple times in distantly related lineages, but it is not known whether the same physiological transitions occurred in all...
In this review, we examine how the specialized “Kranz” anatomy of C4 photosynthesis evolved from C3 ancestors. Kranz anatomy refers to the wreath-like structural traits that compartmentalize the biochemistry of C4 photosynthesis and enables the concentration of CO2 around Rubisco. A simplified version of Kranz anatomy is also present in the species...
The evolution of C4 photosynthesis from C3 ancestors eliminates the RuBP carboxylation function in the mesophyll (M) cell chloroplast while activating PEP carboxylation in the cytosol. These changes may lead to fewer chloroplasts and different chloroplast positioning within M cells. To evaluate these possibilities, we compared chloroplast number, s...
Gisekiaceae are a monogeneric family of the core Caryophyllales distributed in arid regions of Africa and Asia. The only widespread species of the genus, Gisekia pharnaceoides, performs C4 photosynthesis based on CO2 compensation point measurements. This study investigates the C4 syndrome and its evolution in Gisekia. The infrageneric relationships...
he circumscription and generic status of Bassia eriantha (≡ Londesia eriantha) and B. eriophora have often been confused in the literature. The reason is their extreme superficial similarity and phenology. In a multidisciplinary approach, we investigated both in the field, by cultivation in the laboratory, and performed anatomical, ultra-structural...
C4 photosynthesis independently evolved >62 times, with the majority of origins within 16 dicot families. One origin occurs
in the poorly studied genus Anticharis Endl. (Scrophulariaceae), which consists of ~10 species from arid regions of Africa and southwest Asia. Here, the photosynthetic
pathway of 10 Anticharis species and one species from each...
Bienertia is a very interesting genus with its unique C4 photosynthesis in a single cell. Recent investigations on the taxonomy of the genus using a multidisciplinary approach revealed the existence a third species of this genus from the margin of Dasht-e Kavir (desert plain) in central Iran, thus adding a fourth terrestrial C4 plant lacking Kranz...
This study aims at proposing a new bioclimatic
zonation for Iran based on the recently developed
Global Bioclimatic Classification System
(GBC) and tries to re-appraise this classification
system by checking the degree of correspondence
between its bioclimatic zones and the
distribution of major phytogeographical
regions, biomes, and a selection of...
C(4) photosynthesis is a series of biochemical and structural modifications to C(3) photosynthesis that has evolved numerous times in flowering plants, despite requiring modification of up to hundreds of genes. To study the origin of C(4) photosynthesis, we reconstructed and dated the phylogeny of Molluginaceae, and identified C(4) taxa in the fami...
ABSTRACT
The pteridophyte account of Flora Iranica (ed. K.H. Rechinger) is still not published. The Caspian forests provide suitable habitats for the growth of many ferns and fern allies in Iran. In semi-arid and mountainous areas of Iran, mesophilous plants are restricted to rock crevices, waterfall proximity, stream banks and lake shores. Based o...
