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1.
J Fungi (Basel) ; 10(1)2024 Jan 05.
Article in English | MEDLINE | ID: mdl-38248958

ABSTRACT

Xylanases are hydrolytic enzymes that have tremendous applications in different sectors of life, but the high cost of their production has limited their use. One solution to reduce costs and enhance xylanase production is the use of agro-wastes as a substrate in fungal cultures. In this study, olive mill pomace (OMP) and barley bran (BB) were used as carbon sources and possible inducers of xylanase production by three species of Trichoderma (atroviride, harzianum, and longibrachiatum), one major xylanase producer. The experiments were conducted under a solid-state fermentation system (SSF) in flask cultures and a packed-bed bioreactor. Cultures of OMP and BB were optimized by examining different ratios of OMP and BB, varied particle sizes, and inoculum size for the three species of Trichoderma. The ratio of 8:2 OMP and BB yielded the highest xylanase activity, with a particle size of 1 mm at 29 °C and an inoculum size of 1 × 107 spores/mL. Studying the time profile of the process revealed that xylanase activity was highest after seven days of incubation in flask SSF cultures (1.779 U/mL) and after three days in a packed-bed bioreactor (1.828 U/mL). The maximum percentage of OMP degradation recorded was about 15% in the cultures of T. harzianum flask SSF cultures, compared to about 11% in T. longibrachiatum bioreactor cultures. Ammonium sulfate precipitation and dialysis experiments showed that Xylane enzyme activity ranged from 0.274 U/mL in T. harzianum to 0.837 U/mL in T. atroviride when crude extract was used, with the highest activity (0.628 U/mL) at 60% saturation. Xylose was the main sugar released in all purified fractions, with the G-50 and G-75 fractions showing the maximum units of xylanase.

2.
Medicina (Kaunas) ; 59(12)2023 Dec 18.
Article in English | MEDLINE | ID: mdl-38138296

ABSTRACT

Background and Objectives: The acute effects of exercise on the myosin heavy-chain (MHC) isoform mRNA expression and the upstream transcription factors in diabetic and non-diabetic hearts remain unexplored. We aimed to determine the acute effect of a single exercise session on the expression of left ventricular MHC, MHC-α and MHC-ß, and thyroid receptor (TR), TR-α1 and TR-ß, isoform mRNA in diabetic and non-diabetic rats. Materials and Methods: Sprague-Dawley rats were assigned to four groups: non-diabetic control (CS), diabetic exercise (DIEX), sedentary diabetic (DIS), and non-diabetic exercise (CEX). Diabetes was induced via streptozotocin injection (55 mg/kg). DIEX and CEX rats performed an exercise session (60 min at 50 m/min and 0% grade) 6-7 weeks after diabetes induction. Results: MHC-α mRNA was lower in DIS (p = 0.03) and not different in DIEX (p = 0.1) relative to CS. DIS showed higher MHC-ß mRNA than the non-diabetic rats, CS and CEX (p = 0.02 and p = 0.009, respectively). MHC-ß mRNA in DIEX was normalized to non-diabetic levels in CS (p = 0.3). TR-α1 was higher in DIS and not different in DIEX relative to CS and CEX (p = 0.03 and p = 1.0, respectively). In CEX, exercise did not change MHC-α, MHC-ß, and TR-α1 relative to CS (p = 1.0). TR-ß was not different between groups. Conclusion: In conclusion, exercise appears to acutely normalize the myocardial MHC and TR isoform mRNA expression only in the diabetic heart. These responses may induce therapeutic mechanisms other than changing the MHC isoform composition.


Subject(s)
Diabetes Mellitus, Experimental , Diabetic Cardiomyopathies , Rats , Animals , Myosin Heavy Chains/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Diabetic Cardiomyopathies/metabolism , Rats, Sprague-Dawley , Diabetes Mellitus, Experimental/complications , Diabetes Mellitus, Experimental/metabolism , Myocardium/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism
3.
J Med Biochem ; 40(2): 129-137, 2021 Mar 12.
Article in English | MEDLINE | ID: mdl-33776562

ABSTRACT

BACKGROUND: Intervertebral disc degeneration (IDD) is a musculoskeletal disorder and one of the major causes of low back pain leading to the disability with high economic repercussions worldwide. This study applied the candidategene approach to investigate the potential association of selected polymorphisms with IDD development in a Jordanian population. METHODS: MRI-diagnosed IDD patients (N=155) and asymptomatic individuals as a control group (N=55). Whole blood samples for four variants in three genes (rs1800587 of IL-1α, rs1143634 of IL-1ß and rs2228570 and rs731236 of VDR) were genotyped by PCR-RFLP. RESULTS: There was no significant association between the studied polymorphisms or their allelic frequency and the occurrence of IDD. However, the cohort presented a significant reverse association between rs1143634 C > T of the IL-1ß gene and the occurrence of IDD (p<0.0001). In addition, BMI showed a significant association with the IDD in the study population (p<0.005). The current study was conceptualized based on the candidate-gene approach to investigate the role of inflammatory and metabolic genes, IL and VDR, respectively, in the occurrence of IDD. CONCLUSIONS: While the data presented in this study showed that polymorphisms in these genes were not associated with IDD of the cohort investigated, elevated BMI, as a measure of obesity, is strongly associated with IDD. Investigating potential roles of other structural genes, such as col-IX and aggrecan (ACAN), in IDD and considering a GWAS to elucidate a genomically global look at the basis of IDD development would be of considerable impact on our understanding of IDD.

4.
Physiol Mol Biol Plants ; 26(8): 1599-1608, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32801489

ABSTRACT

Salt stress is a major abiotic stress causing adverse effects on plant growth and development. The aim of this study was to investigate the effect of NaCl stress on growth, stress indicator parameters (lipid peroxidation, chlorophyll content and proline content), yield, and the expression of heat shock proteins genes (Hsp17.8, Hsp26.3, Hsp70 and Hsp101) of five Jordanian durum wheat (Triticum durum) landraces. Plants were irrigated with tap water as control or 200 mM NaCl. Significant differences among the 5 Triticum durum landraces in terms of growth parameters, stress indicator parameters, and expression of heat shock proteins genes were observed. Salt stressed landraces demonstrated decreased growth, increased levels of stress indicator parameters, and upregulation in Hsp17.8, Hsp26.3, Hsp70 and Hsp101 expression. Landraces T11 and M23 showed the highest growth, lowest levels of stress indicator parameters, and high expression of heat shock protein genes under NaCl stress. Whereas, J2 and A8 landraces showed the lowest growth, highest levels of stress indicator parameters and low expression of heat shock protein genes under NaCl stress. In conclusion, NaCl stress caused significant reduction in growth parameters, increased level of lipid peroxidation and proline content and upregulation in heat shock proteins gene expression levels. Growth, stress indicator parameters and gene expression results suggest that T11 and M23 landraces are the most NaCl stress tolerant landraces and could be used to enhance the gene pool in wheat breeding programs.

5.
J Nutr Sci Vitaminol (Tokyo) ; 65(4): 309-317, 2019.
Article in English | MEDLINE | ID: mdl-31474680

ABSTRACT

Vitamin B12, folate, and ferritin are vital for the development of the nervous system, blood formation, and diverse metabolic functions. The aim of the current study is to evaluate the status of vitamin B12, folate and ferritin in the Jordanian population across distinct geographical locations. In this retrospective study, the cohort population included 2,880 Jordanian individuals with an average age of 47 y for males and 34 y for females (January 2014-December 2016). Vitamin B12, folate, and ferritin were measured in the blood samples by immunoassay on an automated instrument. Prevalence of low levels of vitamin B12 among males and females was similar across the four regions (24%). Equivalently high levels of folate were reported in males (24.4%) and females (23.4%). Additionally, 37.4% of males and 20.4% of females showed low levels of ferritin. Pearson's correlations did not show any association between age, vitamin B12, folate, and ferritin levels in both sexes. Univariate odd ratio (OR) and age-adjusted OR in males showed a significant decrease in low vitamin B12 risk in the region of Tafela when compared to Irbid. In conclusion, our results showed a significant difference in vitamin B12 levels between populations according to their geographical locations. Ferritin levels were low in almost a quarter of the Jordanian population with a high prevalence in males and females in Irbid and Maan, respectively. These differences might be associated with the genetic, dietary and lifestyle situation which requires further studies to elucidate the risk factors for vitamin B12 and ferritin deficiency.


Subject(s)
Ferritins/blood , Ferritins/deficiency , Folic Acid/blood , Vitamin B 12 Deficiency/epidemiology , Vitamin B 12/blood , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Jordan/epidemiology , Male , Middle Aged , Retrospective Studies , Sex Factors , Young Adult
6.
Environ Monit Assess ; 191(3): 153, 2019 Feb 09.
Article in English | MEDLINE | ID: mdl-30739207

ABSTRACT

The purpose of this study is to examine the impact of treated wastewater irrigation on agricultural soils and vegetables along the upper reach of Zarqa River (Jordan). Multiple samples of reclaimed wastewater, soil pits from farms, and vegetables (spinach, parsley, cabbage cauliflower, radish, and onion) were collected and analyzed for pH, total dissolved solids (TDS), and/or NO3- and NO2- contents. The average levels of NO3- and NO2- in treated wastewater samples varied from 167.2 to 209.9 mg/l for NO3- and from 80.3 to 106.1 µg/l for NO2-. Values of TDS and pH exhibited relatively comparable spatial patterns, with higher values in the downstream channel and lower in the upper reach, adjacent to Al-Samra Wastewater Treatment Plant. The average values of NO3- and NO2- showed broadly decreasing trends down-gradient towards King Talal Dam. In soil pits, a marginal increase of pH values with depth was noted, whereas TDS showed a remarkable decrease in soil profile by ~ 2 to 3 folds. Concurrently, the levels of NO3- and NO2- in all soil pits markedly decreased from top to bottom. In vegetables irrigated with treated wastewater, substantially elevated levels of NO3- were observed, compared with those irrigated with rainwater, with leafy vegetables demonstrating higher levels than the root crops. Spinach exhibited higher capacity for NO3- accumulation (4614.1 mg/kg), while onion showed the lowest content (1722 mg/kg). The highest NO2- level was observed in parsley (1.19 mg/kg), and the lowest concentrations were found in cauliflower (0.25 mg/kg). The markedly high accumulation of NO3- in vegetables is an indicator of pollution activities around Zarqa River and poses potential health risks to humans when they are consumed.


Subject(s)
Agricultural Irrigation/methods , Environmental Monitoring/methods , Nitrites/analysis , Soil/chemistry , Vegetables/chemistry , Wastewater/chemistry , Humans , Jordan , Nitrates/analysis , Rivers/chemistry , Soil Pollutants/analysis
7.
Bot Stud ; 59(1): 18, 2018 Jul 25.
Article in English | MEDLINE | ID: mdl-30046932

ABSTRACT

BACKGROUND: Blepharis constitutes an important part of the vegetation of the Jordanian arid and semi-arid regions, yet whether one or more species of this genus occurs in the Jordanian area is uncertain. We addressed this question by assessing morphological characters and testing Inter-Simple Sequence Repeat (ISSR) markers from three populations of Blepharis: two northern (lower slopes of Kufranjah valley and the Dead Sea region) and one southern (Wadi al Yutm). RESULTS: Shoots from randomly chosen Blepharis plants were harvested from each of the three populations for morphological and molecular analyses. In the northern populations, spikes were lax and bract width was significantly shorter than length of the longest lateral spine compared to the southern population. A multivariate linear discriminant analysis distinguished the northern populations from the southern one by internode length, bract width, longest lateral spine length, and bract width to spine length ratio. The ISSR analysis revealed that 44 markers across eight primers were polymorphic with major allele frequency of 83.6% and an average of 5.5 polymorphic markers per primer. The genetic resemblance among individuals ranged from 0.27 to 0.96. The three Blepharis populations were accordingly clustered into two distinct groups, similar to the analysis of morphological differences and corresponding with the "northern" and "southern" population designations. CONCLUSIONS: Our results strongly indicate the occurrence of two discrete Blepharis species in Jordan and reject the hypothesis that the genus is represented by only one species. We propose that the Blepharis species in Jordan are B. attenutata Napper (represented by the northern populations) and B. ciliaris (L.) B. L. Burtt (represented by the southern population). These findings are important for informing and revising floristic work within the region and an updated key has been included in our findings.

8.
Am J Bot ; 105(5): 822-835, 2018 05.
Article in English | MEDLINE | ID: mdl-29791720

ABSTRACT

PREMISE OF THE STUDY: Tetraena simplex is an independently evolved C4 species in the Zygophylloideae (Zygophyllaceae) and a characteristic forb of saline flats in hot and sandy desert habitats. During early ontogeny, the species had a morphological shift from planar cotyledons (dorsiventral symmetry) to terete, succulent leaves (radial symmetry). We tested whether this shift had a corresponding change in internal Kranz anatomy and tissue patterning. METHODS: For a comprehensive characterization of C4 photosynthesis across early ontogeny in T. simplex, structural and ultrastructural anatomical properties and localization patterns, activities, and immunoblotting of key C4 photosynthetic enzymes were compared in mesophyll and bundle sheath tissues in cotyledons and leaves. KEY RESULTS: Cotyledons and leaves possessed different types of Kranz anatomy (atriplicoid type and a "Tetraena" variant of the kochioid type, respectively), reflecting the change in leaf morphology. In bundle sheath cells, key differences in ultrastructural features included increased organelle numbers and chloroplast thylakoid stacking. C4 enzymes had strict tissue-specific localization patterns within bundle sheath and mesophyll cells in both cotyledons and leaves. The decarboxylase NAD-ME maintained the highest activity, increasing from cotyledons to leaves. This classified T. simplex as fully C4 across ontogeny and a strictly NAD-ME biochemical subtype. CONCLUSIONS: Tetraena simplex cotyledons and leaves showed differences in Kranz type, with associated progression in ultrastructural features, and differing activities/expression levels of C4 enzymes. Furthermore, leaves characterized a new "Tetraena" variation of the kochioid Kranz anatomy.


Subject(s)
Carbon Cycle , Carbon/chemistry , Photosynthesis , Zygophyllaceae/anatomy & histology , Zygophyllaceae/metabolism , Carbon/metabolism , Cotyledon/anatomy & histology , Cotyledon/enzymology , Cotyledon/metabolism , Cotyledon/ultrastructure , Plant Leaves/anatomy & histology , Plant Leaves/enzymology , Plant Leaves/metabolism , Plant Leaves/ultrastructure , Zygophyllaceae/enzymology , Zygophyllaceae/ultrastructure
9.
Phytother Res ; 31(12): 1910-1915, 2017 Dec.
Article in English | MEDLINE | ID: mdl-28960541

ABSTRACT

This study addresses the possible protective effects of thymoquinone (TQ) against the development of experimentally-induced benign prostatic hyperplasia (BPH) in Wistar rats. Eighteen adult male rats were divided into three groups; the negative control group (n = 6) received vehicle, and two groups received subcutaneous testosterone injection (3 mg/kg). Animals receiving testosterone were randomized to untreated BPH group (n = 6) and BPH + TQ treated group (n = 6, 50 mg/kg orally for 14 days). Histological changes and the mRNA levels of transforming growth factor-ß1 (TGF-ß1 ) and vascular endothelial growth factor-A (VEGF-A) were analyzed. Additionally, dihydrotestosterone and interleukin-6 (IL-6) serum levels were determined. The presented research shows significant increases in prostate weight/body weight ratio, prostate epithelial thickness, serum IL-6 and dihydrotestosterone levels, and the prostatic expressions of TGF-ß1 and VEGF-A in the untreated BPH rats. Histological examination of the prostate tissues in the BPH rats showed an elevated level of proliferation in the stromal area and glandular epithelia with abundant intraluminal papillary folds. However, a reduction in prostate weight/body weight ratio, epithelial hyperplasia, serum IL-6 levels, and the expressions of TGF-ß1 and VEGF-A were observed in the BPH + TQ treated rats compared with the untreated BPH rats. The findings support TQ as a useful natural treatment for animal BPH model. Copyright © 2017 John Wiley & Sons, Ltd.


Subject(s)
Benzoquinones/therapeutic use , Prostatic Hyperplasia/chemically induced , Testosterone/adverse effects , Animals , Benzoquinones/pharmacology , Disease Models, Animal , Humans , Male , Rats , Rats, Wistar
10.
Ann Bot ; 111(4): 577-89, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23388881

ABSTRACT

BACKGROUND AND AIMS: C4 eudicot species are classified into biochemical sub-types of C4 photosynthesis based on the principal decarboxylating enzyme. Two sub-types are known, NADP-malic enzyme (ME) and NAD-ME; however, evidence for the occurrence or involvement of the third sub-type (phosphoenolpyruvate carboxykinase; PEP-CK) is emerging. In this study, the presence and activity of PEP-CK in C4 eudicot species of Trianthema and Zaleya (Sesuvioideae, Aizoaceae) is clarified through analysis of key anatomical features and C4 photosynthetic enzymes. METHODS: Three C4 species (T. portulacastrum, T. sheilae and Z. pentandra) were examined with light and transmission electron microscopy for leaf structural properties. Activities and immunolocalizations of C4 enzymes were measured for biochemical characteristics. KEY RESULTS: Leaves of each species possess atriplicoid-type Kranz anatomy, but differ in ultrastructural features. Bundle sheath organelles are centripetal in T. portulacastrum and Z. pentandra, and centrifugal in T. sheilae. Bundle sheath chloroplasts in T. portulacastrum are almost agranal, whereas mesophyll counterparts have grana. Both T. sheilae and Z. pentandra are similar, where bundle sheath chloroplasts contain well-developed grana while mesophyll chloroplasts are grana deficient. Cell wall thickness is significantly greater in T. sheilae than in the other species. Biochemically, T. portulacastrum is NADP-ME, while T. sheilae and Z. pentandra are NAD-ME. Both T. portulacastrum and Z. pentandra exhibit considerable PEP-CK activity, and immunolocalization studies show dense and specific compartmentation of PEP-CK in these species, consistent with high PEP-CK enzyme activity. CONCLUSIONS: Involvement of PEP-CK in C4 NADP-ME T. portulacastrum and NAD-ME Z. petandra occurs irrespective of biochemical sub-type, or the position of bundle sheath chloroplasts. Ultrastructural traits, including numbers of bundle sheath peroxisomes and mesophyll chloroplasts, and degree of grana development in bundle sheath chloroplasts, coincide more directly with PEP-CK recruitment. Discovery of high PEP-CK activity in C4 Sesuvioideae species offers a unique opportunity for evaluating PEP-CK expression and suggests the possibility that PEP-CK recruitment may exist elsewhere in C4 eudicots.


Subject(s)
Aizoaceae/metabolism , Carbon/metabolism , Phosphoenolpyruvate Carboxykinase (ATP)/metabolism , Chloroplasts/metabolism , Chloroplasts/ultrastructure , Light , Malate Dehydrogenase/metabolism , Photosynthesis , Plant Leaves/anatomy & histology , Plant Leaves/metabolism , Plant Leaves/ultrastructure , Thylakoids/metabolism , Thylakoids/ultrastructure
11.
Plant Cell Environ ; 34(10): 1723-36, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21631534

ABSTRACT

Photosynthetic pathway characteristics were studied in nine species of Heliotropium (sensu lato, including Euploca), using assessments of leaf anatomy and ultrastructure, activities of PEP carboxylase and C4 acid decarboxylases, and immunolocalization of ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) and the P-subunit of glycine decarboxylase (GDC). Heliotropium europaeum, Heliotropium calcicola and Heliotropium tenellum are C3 plants, while Heliotropium texanum and Heliotropium polyphyllum are C4 species. Heliotropium procumbens and Heliotropium karwinskyi are functionally C3, but exhibit 'proto-Kranz' anatomy where bundle sheath (BS) cells are enlarged and mitochondria primarily occur along the centripetal (inner) wall of the BS cells; GDC is present throughout the leaf. Heliotropium convolvulaceum and Heliotropium greggii are C3--C4 intermediates, with Kranz-like enlargement of the BS cells, localization of mitochondria along the inner BS wall and a loss of GDC in the mesophyll (M) tissue. These C3--C4 species of Heliotropium probably shuttle photorespiratory glycine from the M to the BS tissue for decarboxylation. Heliotropium represents an important new model for studying C4 evolution. Where existing models such as Flaveria emphasize diversification of C3--C4 intermediates, Heliotropium has numerous C3 species expressing proto-Kranz traits that could represent a critical initial phase in the evolutionary origin of C4 photosynthesis.


Subject(s)
Flaveria/anatomy & histology , Flaveria/enzymology , Heliotropium/anatomy & histology , Heliotropium/enzymology , Plant Leaves/enzymology , Plant Proteins/metabolism , Biological Evolution , Carbon Isotopes/analysis , Flaveria/metabolism , Glycine Dehydrogenase (Decarboxylating)/metabolism , Heliotropium/metabolism , Malate Dehydrogenase/metabolism , Phosphoenolpyruvate Carboxylase/metabolism , Photosynthesis , Plant Leaves/anatomy & histology , Plant Leaves/metabolism , Ribulose-Bisphosphate Carboxylase/metabolism
12.
Plant J ; 51(5): 886-96, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17692080

ABSTRACT

C(4) photosynthesis involves alterations to leaf development, cell biology and biochemistry. Different lineages of C(4) plants use varying mechanisms to generate the C(4) pathway. Although the biochemistry of C(4) photosynthesis was described around 20 years ago, the phylogenetic distance between Arabidopsis and the traditional C(4) models has not facilitated the transfer of knowledge from Arabidopsis research to understanding C(4) systems. We show that Cleome, a genus closely related to Arabidopsis, contains species spanning a developmental progression from C(3) to C(4) photosynthesis. The majority of species we assessed are C(3) plants but have increased venation in leaves. Three C(3) species have both increased venation and enlarged bundle sheath cells, and there is also a tendency to accumulate proteins and transcripts needed for C(4) photosynthesis. Cleome gynandra shows all the characteristics needed for efficient C(4) photosynthesis, including alterations to leaf biochemistry, cell biology and development, and belongs to the NAD-dependent malic enzyme subtype. Combined with its phylogenetic proximity to Arabidopsis, the developmental progression from C(3) to C(4) photosynthesis within the genus provides a potentially excellent new model to increase our understanding of C(4) photosynthesis, and provide insights into its evolution.


Subject(s)
Cleome/physiology , Evolution, Molecular , Photosynthesis/physiology , Plant Leaves/growth & development , Cleome/growth & development , Cleome/ultrastructure , Plant Leaves/ultrastructure , Species Specificity
13.
Am J Bot ; 94(3): 362-81, 2007 Mar.
Article in English | MEDLINE | ID: mdl-21636407

ABSTRACT

C(4) photosynthesis and Kranz anatomy occur in 16 eudicot families, a striking example of convergent evolution. Biochemical subtyping for 13 previously undiagnosed C(4) eudicot species indicated that 10 were NADP-malic enzyme (ME) and three were NAD-ME. A total of 33 C(4) species, encompassing four Kranz anatomical types (atriplicoid, kochioid, salsoloid, and suaedioid), and 21 closely related C(3) species were included in a quantitative anatomical study in which we found that, unlike similar studies in grasses and sedges, anatomical type had no predictive value for the biochemical subtype. In a multivariate canonical discriminant analysis, C(4) species were distinguished from C(3) species by the mesophyll to bundle sheath ratio and exposure of the bundle sheath surface to intercellular space. Discrimination between NADP-ME and NAD-ME was not significant, although in a Mantel test grouping by biochemical subtype was significant, while grouping by family was not. This comprehensive survey of C(4) anatomy and biochemistry unequivocally demonstrated that atriplicoid anatomy and NADP-ME biochemistry predominate in many evolutionary lineages. In addition to a main decarboxylating enzyme, high activity of a second decarboxylating enzyme was often observed. Notably, PEP-carboxykinase activity was significant in a number of species, demonstrating that this enzyme could also serve as a secondary pathway for C(4) metabolism in eudicots.

14.
Funct Plant Biol ; 34(2): 118-129, 2007 Mar.
Article in English | MEDLINE | ID: mdl-32689338

ABSTRACT

Flaveria (Asteraceae) is one of the few genera known to contain both C3 and C4 species, in addition to numerous biochemically-intermediate species. C3-C4 and C4-like intermediate photosynthesis have arisen more than once in different phylogenetic clades of Flaveria. Here, we characterise for the first time the photosynthetic pathway of the recently described species Flaveria kochiana B.L. Turner. We examined leaf anatomy, activity and localisation of key photosynthetic enzymes, and gas exchange characteristics and compared these trait values with those from related C4 and C4-like Flaveria species. F. kochiana has Kranz anatomy that is typical of other C4 Flaveria species. As in the other C4 lineages within the Flaveria genus, the primary decarboxylating enzyme is NADP-malic enzyme. Immunolocalisation of the major C4 cycle enzymes, PEP carboxylase and pyruvate, orthophosphate dikinase, were restricted to the mesophyll, while Rubisco was largely localised to the bundle sheath. Gas exchange analysis demonstrated that F. kochiana operates a fully functional C4 pathway with little sensitivity to ambient oxygen levels. The CO2 compensation point (2.2 µbar) was typical for C4 species, and the O2-response of the CO2 compensation point was the same as the C4 species F. trinervia. Notably, F. vaginata (B.L. Robinson & Greenman), a putative C4-like species that is the nearest relative of F. kochiana, had an identical response of the CO2 compensation point to O2. Furthermore, F. vaginata, exhibited a carbon isotope ratio (-15.4‰) similar to C4 species including F. australasica Hooker, F. trinervia Spreng. C. Mohr and the newly characterised F. kochiana. F. vaginata could be considered a C4 species, but additional studies are necessary to confirm this hypothesis. In addition, our results show that F. kochiana uses an efficient C4 cycle, with the highest initial slope of the A/Ci curve of any C4 Flaveria species.

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