Parasitic plant, from inside out: endophytic development in Lathrophytum peckoltii (Balanophoraceae) in host liana roots from tribe Paullineae (Sapindaceae).

BACKGROUND AND AIMS: Balanophoraceae is one of the most bizarre and biologically interesting plant clades. It groups species with peculiar features that offers an opportunity for investigating several aspects of parasite plant development and morphogenesis. We analysed the development and the mature vegetative body of Lathrophytum peckoltii Eichler, focusing on the formation of the host-parasite interface. Additionally, we analysed how this parasitic interaction causes modifications to the anatomy of Paullinia uloptera Radlk and Serjania clematidifolia Cambess host roots. METHODS: Vegetative bodies of the parasite at different developmental stages were collected while infesting the roots of Sapindaceae vines. Non-parasitized host roots were also collected for comparison. Light, epifluorescence, confocal and scanning electron microscopy were used for the analysis. KEY RESULTS: The initial cells of the vegetative axis divide repeatedly, originating a parenchymatous matrix, which occupies the space from the cortex to the vascular cylinder of the host's root. In the peripheral layers of the matrix, located near the xylem of the host's roots, a few cells initiate the process of wall lignification, originating the parasitic bundle. The vascular cambium of the host's root changes the division plane and becomes composed of fusiform initials, forming the vascular bundle. The vegetative axis presents a dermal tissue similar to a phellem, a parenchymatous matrix and a vascular system with different origins. CONCLUSION: The parasite reproduces by endophytic development, in a manner similar to that observed for endoparasites. The strategy of late cell differentiation could aid the parasite in avoiding early detection and triggering of defence responses by the host. This development causes changes to the host root cambial activity, leading to the establishment of direct, vessel to vessel connection between host and parasite. We associate these changes with the cambium modularity and an influx of parasite-derived hormones into the host cambium.

Artisans and dugout canoes reveal pieces of Atlantic Forest history.

Dugout canoes are boats made from a single tree trunk. Even with the modernization of fishing, they are still made and used for artisanal fishing on the coast of southern and southeastern Brazil and in other regions of the world. Various tree species are used to construct these canoes and choosing a species is related to characteristics of the location, available raw materials and purpose of the boat. Our objective was to better understand the variation in dugout canoes in relation to tree species, tree size and fishing use, over time, along a coastal strip of southern and southeastern Brazil within the Atlantic Forest domain. We interviewed 53 artisans and analyzed 358 canoes that ranged from 1 to around 200 years old. Schizolobium parahyba is currently used the most. In the past, species of the family Lauraceae (Nectandra sp. / Ocotea sp.) were frequently used, as well as Cedrela fissilis and Ficus sp. The size of the canoes varied based on time, coastal region, environment where the boat is used (exposed or sheltered) and type of fishing. The average size of recent canoes was smaller than older canoes for more common species (S. parahyba and C. fissilis), reflecting changes in the vegetation of the biome over time, both in the species and size of individuals available. Latitudinal variation can also influence the availability of tree species along the studied regions. An increase in environmental monitoring has contributed to a decline in constructing dugout canoes, resulting in the use of fiberglass canoes and other motorized boats. Although canoe size varied based on region, location and use, today some of the older canoes represent large trees of the past and pieces of Atlantic Forest history.

Unravelling roots of lianas: a case study in Sapindaceae.

Background and Aims Roots are key in the evolution of plants, being in charge of critical functions, such as water and nutrient uptake and anchorage of the plant body. Stems of lianescent Sapindaceae conform to the anatomical patterns typical of climbing plants, having cambial variants in their stems and vessel dimorphism in their wood. The roots of these lianas, however, are largely unexplored, so we do not know whether the plant habit has as strong an impact on their anatomy as on the anatomy of their stems. Our aim was, therefore, to thoroughly explore the anatomy of liana roots, underground organs under selective pressure completely different from that experienced by the stems. Methods We studied mature roots of 14 species belonging to five of the six genera currently recognized in the lianoid tribe Paullinieae (Sapindaceae) using traditional methods for macro- and microscopic analyses, as well as micro-computed tomography (micro-CT) techniques. Key Results Roots were shown to be strongly shaped by the lianescent habit in Paullinieae, exhibiting traits of the lianescent vascular syndrome in terms of both wood and overall anatomy. The only way to distinguish root from stem in secondary growth is by the exarch protoxylem position in the roots, as opposed to the endarch position typical of the stems. The most conspicuous trait of the lianescent vascular syndrome, which is the presence of vessel dimorphism, is evident in all roots, and we hypothesize that it helps to create an efficient, safe pathway for water conduction from this organ towards the stems. Other anatomical features present were parenchyma bands, present in the wood of almost all of the analysed species, except for Thinouia and Urvillea, where parenchyma-like fibre bands alternating with ordinary fibres are present. The majority of the roots showed no cambial variants. However, lobed roots were found in Urvillea rufescens and phloem wedges were observed in Serjania lethalis and Serjania caracasana. Neo-formed peripheral vascular strands and cylinders were common in mature roots of Serjania caracasana, and vascular connections were found uniting the peripheral and central vascular cylinders through phloem wedges, as revealed by anatomical and micro-CT analyses. The vascular connections likely represent another key mechanism to create a network that increases the area of vascular tissue and contributes as an additional conduction pathway within these thick roots. Conclusions Some traits from the lianescent vascular syndrome, such as vessel dimorphism, are present in the roots of lianescent Sapindaceae, while others, such as cambial variants common in the stems, are largely absent.