Cauline Leaf Research Articles

Growth and development of AtMSH7 mutants in Arabidopsis thaliana

DNA mismatch repair (MMR) is a highly conserved biological pathway that improves the fidelity of DNA replication and recombination. MMR is initiated when MutS proteins recognize mismatches and small loops of unpaired nucleotides. Arabidopsis thaliana and other plants encode MutS protein homologs (MSH) conserved among other eukaryotic organisms, but also encode an extra MSH polypeptide (MSH7). In order to better understand the role of MSH7 in vivo, a full set of phenotypic parameters that covered the development of the plant from seed imbibition to flowering and seed maturation was analyzed in A. thaliana harboring two different msh7 alleles. Plants deficient in MSH7 show statistically significant faster germination rates, longer primary roots during the juvenile vegetative phase, and higher cauline leaf and axillary and lateral inflorescence numbers compared with wild type. We also quantified number, length and area of siliques and seed number per silique. Disruption of MSH7 resulted in a higher number of smaller siliques than wild type. There were no differences in seed number per silique between genotypes. These findings suggest that mutant plant growth appears to be caused by an impaired cell cycle checkpoint that allows cell division without adequate DNA repair. This increase in proliferation activity demonstrates a functional and temporal link between DNA repair and cell cycle regulation.

Calathea multispicata (Marantaceae), a new species endemic to Colombia

Calathea multispicata H. Kenn. & M. Serna, endemic to Colombia, is described as new. Currently, it is known only from the Department of Valle de Cauca in premontane (1300–1800 m) pluvial forest habitat. Calathea multispicata is characterized by the presence of only two leaves per shoot, one basal and one cauline and the numerous relatively small, short-pedunculate inflorescences. Each inflorescence has 3–4 bracts, which, after the first terminal one, are borne in the axil of the cauline leaf. Calathea multispicata is most similar in aspect to C. harlingii H. Kenn. Calathea multispicata shares the habit of a single cauline leaf subtending inflorescences above one or more basal leaves with C. harlingii, C. hagbergii H. Kenn, C. andersonii H. Kenn. and C. pluriplicata H. Kenn. but differs from these species in having a single vs. 2–10 basal leaves, more numerous (up to 19 vs. 2–7) inflorescences with fewer bracts (3–4 vs. 5–17) borne in a series in the axil of the cauline leaf.

Quantification of Cauline Leaf Abscission in Response to Plant Pathogens.

Abscission is a process that allows plants to shed unwanted organs. Plants can use abscission as a defense mechanism to shed leaves that are heavily infected with pathogenic bacteria. By shedding infected leaves, plants completely eliminate the bacteria from the plant body, thus preventing further spreading of the disease. A lot is known about how plants limit the growth of pathogenic bacteria in vegetative leaf tissues. Much less is known about how plants defend themselves in non-vegetative developmental stages and how they use organ level responses such as leaf abscission for defense. Organ level defense responses can be effectively studied in the Pseudomonas syringae-triggered leaf abscission system in Arabidopsis. This method article describes detailed procedures for quantitative analysis of cauline leaf abscission including dissecting abscission zones for extraction of RNA and proteins for quantitative gene or protein expression analysis. The method described for molecular analysis of abscission zones could also be used in other cases where tissue is extremely limiting.

Onosma zagrica (Boraginaceae), a new species from Iran

A new species of Onosma sect. Onosma L. (Boraginaceae), O. zagrica Dehshiri, is described and illustrated from the western part of Iran from Khargushan Mountain near the Khorramabad city (Lorestan Province). The new species differs from Onosma kilouyensis Boiss. & Hausskn. in being a smaller plant, 1.4–3 × 0.25–0.7 cm, narrowly elliptic or linear-lanceolate cauline leaf, longer pedicels, yellow or at first cream, then blue corolla, and smaller nutlet. The IUCN threat category of O. zagrica is determined as “CR (Critically Endangered)”.

Antioxidative Properties of Amaranth Cauline Leaf and Suppressive Effect against CT-26 Cell Proliferation of the Sausage Containing the Leaf.

The study investigated antioxidative properties and rectal cancer cell inhibition effect of amaranth (Amaranthus cruentus L.) cauline leaves (ACL) to produce the sausage with ACL powder (ACLP). Antioxidative effects of ACLP prepared with different stem lengths (10–45 cm) were evaluated through DPPH, ABTS, reducing power, total phenol, and total flavonoid. Inhibition effect on rectal cancer cells growth was also examined with CT-26 cell. To determine appropriate ACL amounts in sausage formula, response surface methodology was used. The sausages without ACL (control) and the sausage with ACL (ACLP sausage) were the subjected to the examinations of antioxidation, growth inhibition on CT-26, and physicochemical properties (pH and water content). ACLP made from the leaf with 15 cm length stem generally showed the highest antioxidative effect through results of DPPH, ABTS, reducing power, total phenol, and total flavonoid. ACLP also showed inhibition effect on the proliferation of CT-26, depending on concentration of ACLP. The surface response model showed that 4.87 g of ACLP was optimized amount for sausage production. Physicochemical properties between optimized ACLP and control sausages were not significantly different. Higher antioxidative effect of optimized ACLP sausage extract was observed (p<0.05) in antioxidation tests than control sausage extract except for DPPH. Cell viability of CT-26 cells were higher (p<0.05) in ACLP than in control sausage extracts. These results indicate that ACLP has functional effects on antioxidation activity and growth inhibition on CT-26 cell, and thus, it should be useful as a supplement in sausage, which may some effect as ACLP itself.

HDA9 interacts with the promoters of SOC1 and AGL24 involved in flowering time control in Brassica juncea

HDA9 (a RPD3-like histone deacetylase) belongs to the histone deacetylase family which is involved in flowering time control through repression of AGL19 and FT, but it is still elusive that whether and how HDA9 directly interacts with flowering signal integrators of SOC1 and AGL24 in Brassica juncea. In this study, BjuHDA9 (a homologous HDA9) was cloned from B. juncea and ubiquitously expressed in root, stem, cauline leaf, flower bud and opening flower. BjuHDA9 was highly induced by short-day photoperiod. Yeast two-hybrid and pull-down assays demonstrated that BjuHDA9 could not interact with BjuSOC1 and BjuAGL24 proteins. Whereas, BjuHDA9 directly interacted with promoters of BjuSOC1 and BjuAGL24 via yeast one-hybrid and Dual-Glo® Luciferase assays. It suggested that the histone deacetylase BjuHDA9 was probably involved in flowering time control by binding to promoter regions of BjuSOC1 and BjuAGL24. This study will provide valuable information for elucidating the molecular mechanism of BjuHDA9 in regulating flowering time.

CAPSULE, LEAF AND CYATHIAL GLAND MORPHOLOGY OF TURKISH PERENNIAL TAXA OF Euphorbia L. SECTION Pithyusa (Raf.) Lázaro

Macro and micromorphology of cyathial glands, capsules and cauline leaf surfaces of 13 perennial species of Euphorbia L. subg. Esula Pers. sect. Pithyusa (Raf.) Lázaro in Turkey were studied. Cyathial gland structure, based on cyathial gland shapes, colour and appendages was examined from live material by direct field observations and investigations. Cauline leaves and capsule surface features were analysed with scanning electron microscopy (SEM). Capsule sizes, capsule shapes and capsule and cauline leaf surface ornamentations were also studied . The capsule shape was found to vary from subglobose to conical. In most species, cyathial gland colour ranged from greenish-yellow to yellowish-green but some species were distinguished by their reddish or purplish cyathial glands. Although the number of cyathial glands in all species was four, five cyathial glands were determined to exist in some specimens of E. pestalozzae Boiss. Three different cyathial gland shapes ( elliptic, trapezoid-elliptic or elliptic-reniform ) were observed. Capsule surface of more than half of the studied species (7 taxa) is covered with nipple-like projections (papillate-mammillate) and the rest are covered with tiny rounded or hillock-like ornamentation (colliculate). The cauline leaf surface is papillate-mammillate in the majority of the studied species, although, colliculate surface is also observed in two species ( E. seguieriana Necker and E. thessala (Form.) Degen & Dörf.). In conlusion, macro and micromorphological structures of cyathial gland and capsule of Euphorbia sect. Pithyusa taxa appeared to be useful diagnostic characters for species identifications.

Leaf shedding as an anti-bacterial defense in Arabidopsis cauline leaves.

Plants utilize an innate immune system to protect themselves from disease. While many molecular components of plant innate immunity resemble the innate immunity of animals, plants also have evolved a number of truly unique defense mechanisms, particularly at the physiological level. Plant’s flexible developmental program allows them the unique ability to simply produce new organs as needed, affording them the ability to replace damaged organs. Here we develop a system to study pathogen-triggered leaf abscission in Arabidopsis. Cauline leaves infected with the bacterial pathogen Pseudomonas syringae abscise as part of the defense mechanism. Pseudomonas syringae lacking a functional type III secretion system fail to elicit an abscission response, suggesting that the abscission response is a novel form of immunity triggered by effectors. HAESA/HAESA-like 2, INFLORESCENCE DEFICIENT IN ABSCISSION, and NEVERSHED are all required for pathogen-triggered abscission to occur. Additionally phytoalexin deficient 4, enhanced disease susceptibility 1, salicylic acid induction-deficient 2, and senescence-associated gene 101 plants with mutations in genes necessary for bacterial defense and salicylic acid signaling, and NahG transgenic plants with low levels of salicylic acid fail to abscise cauline leaves normally. Bacteria that physically contact abscission zones trigger a strong abscission response; however, long-distance signals are also sent from distal infected tissue to the abscission zone, alerting the abscission zone of looming danger. We propose a threshold model regulating cauline leaf defense where minor infections are handled by limiting bacterial growth, but when an infection is deemed out of control, cauline leaves are shed. Together with previous results, our findings suggest that salicylic acid may regulate both pathogen- and drought-triggered leaf abscission.

Three new species of Calathea (Marantaceae) endemic to Colombia

Calathea neurophylla H. Kenn., C. barryi H. Kenn., and C. velutinifolia H. Kenn., endemic to Colombia, are described as new. Calathea neurophylla is characterized by the single cauline leaf subtending one or more inflorescences of spirally arranged bracts and the markedly ridged, narrowly elliptic leaf blades (length 6.25–8.46 times width). Calathea barryi is characterized by the single cauline leaf subtending several inflorescences with 25–43 spirally arranged bracts and the very closely spaced lateral veins (ca. 67 per 3 cm). Calathea velutinifolia is distinguished by the 4–15 basal leaves, the densely appressed velvety tomentose adaxial the leaf surface and the 8–10 distichous, white bracts.&#x0D;

Arabidopsis TEMPRANILLO1 transcription factor AtTEM1 negatively regulates drought tolerance

Arabidopsis TEMPRANILLO 1 (AtTEM1) is a member of the RAV transcription factor subfamily and has plant-specific AP2 and B3 domains. This study demonstrated that AtTEM1 is localized in nuclei. Expression of AtTEM1 was discovered to be high in the flower, stem, rosette, and cauline leaf, but low in the silique and root tissue, and was strongly induced by drought and mannitol treatments. Compared with wild-type plants, the 35S::AtTEM1 plants bolted later and produced more rosette leaves before flowering, whereas, the AtTEM1 mutant plants (tem1) bolted earlier but produced an almost equal number of rosette leaves before flowering. Drought tolerance was significantly reduced in the 35S::AtTEM1 transgenic Arabidopsis plants, but was enhanced in the tem1 plants. Under drought and mannitol stresses, the 35S::AtTEM1 transgenic Arabidopsis exhibited increased relative electrical conductivity (REC), increased malondialdehyde (MDA) content, and decreased proline content compared with the wild type, whereas lower REC and MDA content and higher proline content were found in the tem1 plants. These results suggest that AtTEM1 in Arabidopsis functions as a negative regulator in response to drought and mannitol stresses. Therefore, AtTEM1 transcription factor is proposed to be a versatile regulator reacting negatively to both flowering time and drought stress.

Morphology, anatomy and karyology of endangered Turkish endemic Physoptychis haussknechtii Bornm. (Brassicaceae) from Central Anatolia

Abstract In this study, the morphology, anatomy, pollen morphology, leaf and seed micromorphology and karyology of the Turkish endangered endemic Physoptychis haussknechtii were investigated in detail for the first time. The species was studied in terms of detailed morphology. Basal leaves are narrowly spatulate and cauline leaves are linear to oblanceolate; both leaves are covered with flattened stalked five-armed trichomes. Raceme length was found to be up to 6 cm and 9 cm in the flowering and fruiting stages, respectively. Sepals are linear-oblong, rarely elliptic with obtuse to subacute apex. Petals are spatulate with emarginate apex. Some morphological characteristics such as dimensions of cauline leaves and ovary and length of pistil were measured for the first time. In an anatomical study, root, stem, basal leaf and cauline leaf were examined. The anatomical results showed that the plants have secondary growth in roots, primary growth in stems, amphistomatic and equifacial basal and cauline leaves with anisocytic stomata. Pollen grains are radial symmetrical, isopolar and tricolpate. The ratio of polar axis to equatorial diameter is 1.16, and pollen shape is subprolate. Exine sculpturing is reticulate under light microscope and scanning electron microscope. Seeds are obovatesuborbicular, compressed and pale brown. The chromosome number of P. haussknechtii was defined to be 2n=16. The karyotype formula of P. haussknechtii consists of five metacentric chromosome pairs and three submetacentric chromosome pairs.

A new species of Chrysosplenium (Saxifragaceae) from Zhangjiajie, Hunan, central China

A new species of Chrysosplenium (Saxifragaceae), C. zhangjiajieense, is described and illustrated from Zhangjiajie, Hunan province in China. This new species is similar to C. macrophyllum in having broad basal leaves and compact cymes, but it differs from the latter in that the whole plant of C. zhangjiajieense is densely covered by coarse and long white villus, and the leaf adaxial surface bears thickly wart points. The new species is also similar to C. davidianum, but differs by having white flowers, only one cauline leaf, oblong sepals and the stamen is longer than sepals while C. davidianum possess yellow flower, 2–5 cauline leaves, orbicular sepals and the stamen much shorter than sepals. Base on the field investigation, this new species is accessed to be endangered according to IUCN category and criteria.

Core Mechanisms Regulating Developmentally Timed and Environmentally Triggered Abscission.

Drought-triggered abscission is a strategy used by plants to avoid the full consequences of drought; however, it is poorly understood at the molecular genetic level. Here, we show that Arabidopsis (Arabidopsis thaliana) can be used to elucidate the pathway controlling drought-triggered leaf shedding. We further show that much of the pathway regulating developmentally timed floral organ abscission is conserved in regulating drought-triggered leaf abscission. Gene expression of HAESA (HAE) and INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) is induced in cauline leaf abscission zones when the leaves become wilted in response to limited water and HAE continues to accumulate in the leaf abscission zones through the abscission process. The genes that encode HAE/HAESA-LIKE2, IDA, NEVERSHED, and MAPK KINASE4 and 5 are all necessary for drought-induced leaf abscission. Our findings offer a molecular mechanism explaining drought-triggered leaf abscission. Furthermore, the ability to study leaf abscission in Arabidopsis opens up a new avenue to tease apart mechanisms involved in abscission that have been difficult to separate from flower development as well as for understanding the mechanistic role of water and turgor pressure in abscission.

A new species of Centaurea (Asteraceae) from East Anatolia, Turkey

Centaurea malatyensis Ş. Kültür &amp; M. Bona sp. nova (Asteraceae) is described as new to science from East Anatolia (B6: Malatya: Turkey). It is morphologically similar to C. leptophylla but differs mainly in its stem, basal and cauline leaf shape and size, achene, pappus and phyllary appendages. The geographical distribution of the new species and its relatives is mapped. The ecology and conservation status of the new species is also presented. Micromorphological structures of achenes of C. malatyensis and C. leptophylla are examined by SEM.

Omnidirectional enhancement of photocatalytic hydrogen evolution over hierarchical “cauline leaf” nanoarchitectures

The scrupulous design and integration of multiple active materials into hierarchical nanoarchitectures is essential for the creation of photocatalytic hydrogen evolution reaction (HER) system that can mimic natural photosynthesis. Here we report the design and preparation of a “cauline leaf”-like structure for highly efficient HER, by decorating TiO2 nanofibers with vertical arrays of atomically-thin MoS2 nanosheets and CdS nanocrystals. The unique integrated “cauline leaf” design can promote light trapping and absorption for highly efficient light harvesting and photocarrier generation, and offer unblocked electron transport pathway for rapid charge separation/transport to suppress charge recombination, as well as high surface area and high density of active sites for highly efficient utilization of photo-generated carriers for productive HER. Structural characterizations by transmission electron microscopy show well-integrated nanoarchitectures. Significantly, photocatalytic studies demonstrate rapid HER rates as high as 12.3 or 6.2mmolh−1g−1 under simulated solar light or visible light irradiation, with apparent quantum efficiencies of 70.5% at 365nm or 57.6% at 420nm, and excellent long term stability, representing one of the best reported MoS2 hybrid HER photocatalysts. The study could open new opportunities for the rational design of nanoscale architectures for HER or other application.

Functional Divergence of APETALA1 and FRUITFULL is due to Changes in both Regulation and Coding Sequence.

Gene duplications are prevalent in plants, and functional divergence subsequent to duplication may be linked with the occurrence of novel phenotypes in plant evolution. Here, we examine the functional divergence of Arabidopsis thaliana APETALA1 (AP1) and FRUITFULL (FUL), which arose via a duplication correlated with the origin of the core eudicots. Both AP1 and FUL play a role in floral meristem identity, but AP1 is required for the formation of sepals and petals whereas FUL is involved in cauline leaf and fruit development. AP1 and FUL are expressed in mutually exclusive domains but also differ in sequence, with unique conserved motifs in the C-terminal domains of the proteins that suggest functional differentiation. To determine whether the functional divergence of AP1 and FUL is due to changes in regulation or changes in coding sequence, we performed promoter swap experiments, in which FUL was expressed in the AP1 domain in the ap1 mutant and vice versa. Our results show that FUL can partially substitute for AP1, and AP1 can partially substitute for FUL; thus, the functional divergence between AP1 and FUL is due to changes in both regulation and coding sequence. We also mutated AP1 and FUL conserved motifs to determine if they are required for protein function and tested the ability of these mutated proteins to interact in yeast with known partners. We found that these motifs appear to play at best a minor role in protein function and dimerization capability, despite being strongly conserved. Our results suggest that the functional differentiation of these two paralogous key transcriptional regulators involves both differences in regulation and in sequence; however, sequence changes in the form of unique conserved motifs do not explain the differences observed.

Non-inductive conditions expose the cryptic bract of flower phytomeres in Arabidopsis thaliana

The aerial plant architecture is built by phytomeres which are metameric units, each composed of a stem segment (internode) and a leaf with axillary meristem (node). In Arabidopsis thaliana, fully developed flower phytomeres lack the leaf even if they temporarily exhibit a cryptic bract (CB) during early development. Recently, we demonstrated that the CB becomes more prominent under non-inductive short-day conditions. However, a full outgrowth as cauline leaf is prevented by Polycomb-group (Pc-G) proteins which silence the MADS gene FLOWERING LOCUS C (FLC) encoding a repressor of FLOWERING LOCUS T (FT). Also the loss of SHORT VEGETATIVE PHASE (SVP) supresses ectopic leaves at the base of Pc-G deficient pedicels. Here we present new expression data of flowering genes LEAFY (LFY) and TWIN SISTER OF FT (TSF) and the re-analysis of morphological changes in Pc-G deficient plants suggesting that the specifications of CB and floral meristem (FM) are separated in time.

Pterolepis haplostemona (Melastomataceae): a new serpentine endemic from Goiás, Brazil

Pterolepis haplostemona from ultramafic outcrops in Goiás, Brazil is described, illustrated, and compared with presumed relatives, all of which are also endemic to Brazil. It is distinguished by its annual habit, simple hypanthial trichomes and intercalycine emergences, haplostemonous flowers, rostrate antesepalous stamens, short pedoconnective, linear-lanceolate cauline leaf blades, calyx lobes tipped with a rigid unbranched trichome, and 3-4-locular ovary. This species and Microlicia macedoi appear to be the only known Melastomataceae that are endemic to serpentine substrates in Brazil. A conservation assessment based on IUCN criteria is also provided.

The Morphotaxonomy and Distribution of the Genus Sargassum C Agardh (Fucales Phaeophyta) from Kampani Coastal Areas

Three species of Sargassum belonging to the Sargassum subgenus Sargassum (Fucales, Phaeophyta) collected from the Kampani coastal areas- Thabawseik and southern Kampani from October 2012 to March 2013, had been identified as Sargassum swartzii (Turner) C. Agardh and S. cervicorne Greville under the section Binderiana and S. plagiophyllum C. Agardh (with or without stolons) under the section Polycystae based on a detailed account of morphologies of vegetative and reproductive structures of the plants. Sargassum plagiophyllum C. Agardh (with or without stolons) is the most common species occurring in the two study areas. The growth patterns in the development of furcate cauline leaf, dwarfs of main branch as well as different orders of branches, leaves, vesicles and receptacles of Sargassum swartzii (Turner) C. Agardh and S. cervicorne Greville under Sargassum section Binderiana was recorded. In addition, S. cervicorne Greville was firstly reported from Kampani coastal areas. Moreover, the simple cauline leaf, dwarfs of main branch or stolons as well as different orders of branches, leaves, vesicles and receptacles of S. plagiophyllum C. Agardh (with or without stolons) under Sargassum section Polycystae belonging to the S. subgenus Sargassum from Kampani coastal areas was also recorded.

Chrysosplenium arunachalense (Saxifragaceae), a new species from India

Summary. Chrysosplenium arunachalense Bhaumik from Arunachal Pradesh, India is described and illustrated. This species forms a small colony as the flowering stem bears new plantlets at the axils of cauline leaves and the colony spreads gradually. It differs from other species of subgen. Gamosplenium Maxim. emend. J. T. Pan in plants glabrous throughout, leaf blade oblong to elliptic-oblong with cordate base and the cauline leaf axil bears new plantlets. The type locality is covered with snow for 3 – 5 months each year.