Phylogeny and Character Evolution of the Neotropical Fern Genus Cyclodium (Dryopteridaceae)

Abstract— Cyclodium is a neotropical fern genus with 13 species, most of them distributed in the Amazonian lowlands, particularly in the Guianan region and along the border with the Andes. It belongs to the polybotryoid clade of Dryopteridaceae, being unique within this clade by a combination of characters related to rhizome growth, leaf dimorphism, anastomosing venation, and peltate indusia. Here we present a molecular phylogenetic hypothesis for Cyclodium resulting from Bayesian and maximum likelihood analyses, using molecular sequences of five plastid markers. We also map 12 morphological characters and habit onto the resulting trees. Our results support Cyclodium as monophyletic and sister to Polybotrya. The presence of peltate indusia is the main character distinguishing Cyclodium. Our results also suggest that plesiomorphic conditions in Cyclodium are free venation (vs. anastomosing), creeping rhizomes (vs. erect or decumbent), highly dissected laminae (vs. 1-pinnate), monomorphic sterile and fertile fronds (vs. dimorphic), and pinnatifid apices (vs. conform).

Echinochloa pyramidalis.

E. pyramidalis, a perennial grass, has decidedly invasive characteristics with its vigorous shoot and rhizome growth and abundant seed production. As an aquatic, it also has the potential to be very damaging to sensitive aquatic habitats. Holm et al. (1979) record it as a major weed in its native area in Nigeria, Swaziland, Sudan and Madagascar. In Guyana, after being introduced and cultivated for some years, it was noticed as a weed in sugar cane in 1982 and increased rapidly to become one of the most troublesome weeds in the aquatic system of the Guyana Sugar Corporation (Bishundial et al., 1997). In Mexico, again after introduction as a fodder grass, it has become widely invasive in wetlands, tending to reduce native wetland species (López Rosas et al., 2010). Apart from its competitive growth, Wells et al. (1986) note its tendency to obstruct water flow. For the USA it is highly ranked as a potential invasive weed of the future (Parker et al., 2007) and it has been identified as a species 'not authorized (for introduction) pending pest risk analysis' (NAPPRA) (USDA-APHIS, 2012).

Nitrogen Nutrition Promotes Rhizome Bud Outgrowth via Regulation of Cytokinin Biosynthesis Genes and an Oryza longistaminata Ortholog of FINE CULM 1

Oryza longistaminata, a wild rice, can propagate vegetatively via rhizome formation and, thereby, expand its territory through horizontal growth of branched rhizomes. The structural features of rhizomes are similar to those of aerial stems; however, the physiological roles of the two organs are different. Nitrogen nutrition is presumed to be linked to the vegetative propagation activity of rhizomes, but the regulation of rhizome growth in response to nitrogen nutrition and the underlying biological processes have not been well characterized. In this study, we analyzed rhizome axillary bud growth in response to nitrogen nutrition and examined the involvement of cytokinin-mediated regulation in the promotion of bud outgrowth in O. longistaminata. Our results showed that nitrogen nutrition sufficiency promoted rhizome bud outgrowth to form secondary rhizomes. In early stages of the response to nitrogen application, glutamine accumulated rapidly, two cytokinin biosynthesis genes, isopentenyltransferase, and CYP735A, were up-regulated with accompanying cytokinin accumulation, and expression of an ortholog of FINE CULM1, a negative regulator of axillary bud outgrowth, was severely repressed in rhizomes. These results suggest that, despite differences in physiological roles of these organs, the nitrogen-dependent outgrowth of rhizome axillary buds in O. longistaminata is regulated by a mechanism similar to that of shoot axillary buds in O. sativa. Our findings provide a clue for understanding how branched rhizome growth is regulated to enhance nutrient acquisition strategies.

Physiological Response of Thallasia hemprichii on Antrophogenic Pressure In Pari Island, Seribu Islands, DKI Jakarta

Seagrass ecosystem is one of tropical marine ecosystem and have important function. The function of ecosystem like a feeding and nursery ground for marine biota. Antrophogenic pressure is one of threat for seagrass ecosystem sustainability. This research study about effect antropogenic pressure for seagrass Thallasia hemprichii physiology response in some different location at Great Barrier Pari Island. The physiology response study cover growth, heavy metal bioaccumulation and histology analysis. The result shows that growth of leaf and rhizome Thalassia hemprichii have positif correlation with nutrient consentration in environment. The highest growth of leaf Thalassia hemprichii at 2nd station (4.16 mm.day-1) and the highest growth of rhizome Thalassia hemprichii at 4th station (1.3 mm.day-1). Seagrass can accumulation heavy metal from environment. The highest heavy metal accumulation is Pb. Not correlation between heavy metal consentration in seagrass with heavy metal concentration from environment. Analysis histology result that not damage seagrass tissue in all research station. Keyword : Bioacumulation,Growth,Physiology,Seagrass, Thalassia hemprichiiSeagrass ecosystems is one of the tropical marine ecosystems that have important functions, among others as a feeding and nursery ground for marine life. Anthropogenic stress is one of the threats that may inhibit the survival of seagrass ecosystems. This study examines the effects of anthropogenic pressures on physiological responses of seagrass Thalassia hemprichii at several different locations in Pari Islands. Physiological responses studied were leaves and rhizome growth, bioaccumulation of heavy metals and histological tissue analysis on seagrass. The results showed that the growth response of seagrass has a positive correlation with the nutrients in the environment. Seagrass leaf growth is highest at Station 2 (4.16 mm.day-1) and rhizome growth is highest at Station 4 (1.3 mm.day-1). Seagrass accumulate heavy metals from the environment and accumulation of heavy metals is highest on Pb. There is no correlation between the concentration of heavy metals in the seagrass and environment. The results of histological analysis showed that there was no damage to the tissue of seagrass leaf and rhizome. Keywords : Bio-acumulation, Growth, Physiology, Seagrass, Thalassia hemprichii