Riyadh Muhaidat

Diversity of Kranz anatomy and biochemistry in C4 eudicots.

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.

Significant involvement of PEP-CK in carbon assimilation of C4 eudicots

BACKGROUND AND AIMSnC4 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.nnnMETHODSnThree 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.nnnKEY RESULTSnLeaves 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.nnnCONCLUSIONSnInvolvement 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.

Inhibitory Effect of Thymoquinone on Testosterone‐Induced Benign Prostatic Hyperplasia in Wistar Rats

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‐β1 (TGF‐β1) 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‐β1 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‐β1 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

Integrating morphological characters, molecular markers, and distribution patterns to assess the identity of Blepharis species from Jordan

BackgroundBlepharis 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).ResultsShoots 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.ConclusionsOur 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.

C4 photosynthesis and transition of Kranz anatomy in cotyledons and leaves of Tetraena simplex

PREMISE OF THE STUDYnTetraena 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.nnnMETHODSnFor 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.nnnKEY RESULTSnCotyledons 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.nnnCONCLUSIONSnTetraena 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.