The Genetic and Environmental Adaptation of the Associated Liana Species Derris trifoliata Lour. (Leguminosae) in Mangroves

Derris trifoliata Lour. is an indigenous and associated liana species of mangroves in China; however, its rapid dispersal is threatening mangrove survival. To explore and evaluate their persistence in past disturbances and their potential resistance to future climate and environmental changes, 120 D. trifoliata samples were collected from three sites in Guangdong Province, China, and they were used to develop single nucleotide polymorphic markers using specific-locus amplified fragment sequencing technology. A total of 351.59 Mb reads and 97,998 polymorphic specific-locus amplified fragment sequencing tags were identified, including 360,672 single nucleotide polymorphisms. The principal component analysis, phylogenetic tree, and genetic structure all clustered the samples according to their geographic positions. The three populations showed medium genetic diversity levels and high clonal diversity, indicating that sexual propagation played vital roles in the populations’ succession, although clonal growth was intense within the populations. An association analysis revealed that 9 out of 16 markers were correlated with nitrogen, which indicated the positive roles of nitrogen in population formation and maintenance. This study provides an ecological and molecular basis for understanding the outbreaks of D. trifoliata in mangroves. To control the further expansion of D. trifoliata in mangroves, preventive and control measures should be taken against clonal growth and sexual propagation, respectively; obstructing the clonal growth, especially that of the stolon, should be mainly considered at the junctions of D. trifoliata and mangroves.

Distinct Reproductive Strategy of Two Endemic Amazonian Quillworts

We examined the reproductive strategy of two Amazonian quillworts (Isoëtes cangae and Isoëtes serracarajensis), endemic and threatened species of canga ecosystems. Sexual propagation was examined by in vitro fertilization assays, while asexual propagation was examined by tiller emission. Isoëtes cangae is an outcrossing species that reproduces exclusively by spore germination and is able to propagate by self- and cross-fertilization. Isoëtes serracarajensis reproduces asexually by emitting tillers from the plant corm, despite producing male and female sporangia. These distinct reproductive strategies in the different species may be linked to their contrasting habitats. Isoëtes cangae inhabit a permanent oligotrophic lake with mild environmental changes, while I. serracarajensis are found in temporary ponds facing severe seasonal drought, where asexual propagation may represent an adaptive advantage to the short growth period during access to water. We also observed different relationships between plant growth and reproductive traits between the species, despite their common production of sporophytes with high survival rates. Together, these results are of paramount importance for establishing conservation plans for both species considering the advantages of sexual propagation to maintain the genetic diversity of I. cangae and the diligent management required to do the same with asexually propagated I. serracarajensis.

Standardization of time of budding and sweet orange cultivars on Carrizo rootstock

In sexual propagation of citrus long juvenility, genetic impurity and self incompatibility are the major problems. Hence the use of suitable rootstock is a pre-requisite in citrus propagation. Now a days, the cultivation of sweet orange is boosting up among citrus cultivation. Due to this, there is a great need for the evaluation of sweet orange cultivars onto an appropriate rootstock. A research trial was carried out in consideration with ‘Blood Red’, ‘Jaffa’ and ‘Valencia Late’ sweet orange cultivars T-budded on Carrizo rootstock at five different intervals of first week of July, August, September, October and February. The treatments were replicated thrice and statistically arranged in factorial randomized complete block design. As a result of the study significant variations were noticed in the performance of cultivars under study at various budding intervals. Out of the sweet orange cultivars ‘Blood Red’ was the first to initiate sprouting in 28.30 days with healing of bud union in 31.39 days, maximum survival (89.40%), plant height (22.93 cm), number of branches buddling-1 (1.14), leaf total nitrogen (1.89%), phosphorus (0.07%) and potassium (1.26%). Among budding intervals, the plants budded on the first week of September were the first to sprout in 26.46 days achieving maximum (23.04 cm) plant height, branches buddling-1 (1.15) root formation of (5.98 cm3) volume and survival percentage (91.99). Commercially, ‘Blood Red’ sweet orange cultivar budded in the first week of September can be cultivated for superior progeny.

Vegetative propagation and ex-situ conservation of Acantholimon androsaceum and Limonium chersonesum, two promising local endemics of Crete (Greece) available for floricultural and pharmaceutical sustainable exploitation

The continual search for new attractive ornamentals and innovative natural medicinal products is the main focus of floricultural and pharmaceutical industries worldwide. Aiming to introduce two new Cretan endemic species in the commercial trade, Acantholimon androsaceum (Jaub. & Spach) Boiss. and Limonium chersonesum Erben & Brullo (Plumbaginaceae) have been selected in the current study. These were derived from a total of 223 local endemic species and subspecies of Crete, which constitute an exceptional wild treasure of the Mediterranean flora. Prior to any commercialization, efficient massive propagation protocols are required. Although sexual propagation using seeds collected from the wild was unsuccessful for these two taxa, the results of vegetative propagation experiments were satisfactory. Wild plant material was used for cuttings in order to develop a reasonable and homogenous number of stock mother plants for propagation trials. As a result of experiments conducted in the current research, two vegetative propagation protocols were developed, which could be used commercially for the massive production of elite clonal plants of A. androsaceum and L. chersonesum. These protocols provide 71.43% successful rooting for A. androsaceum within 40 days, using 2000 ppm IBA, and 80.95% rooting for L. chersonesum within 30 days, using 1000 ppm IBA. This study is part of a strategy and research methodology aiming at the selection of new, rare and endemic native industrial crops for the ornamental and pharmaceutical sector, exploiting sustainably the rich phytogenetic resources of Crete.

PHOSPHATIDYLETHANOLAMINE-BINDING PROTEINS: the conductors of dual reproduction in plants with vegetative storage organs

Geophytes, the plants that form vegetative storage organs, are characterized by a dual reproduction system, in which vegetative and sexual propagation are tightly regulated to ensure fitness in harsh climatic conditions. Recent findings highlight the role of the PEBP (PHOSPHATIDYLETHANOLAMINE-BINDING PROTEIN) gene family in geophytes as major players in the molecular cascades underlying both types of reproduction. In this review, we briefly explain the life cycle and reproduction strategies of different geophytes and what is known about the physiological aspects related to these processes. Subsequently, an in-depth overview is provided of the molecular and genetic pathways driving these processes. In the evolution of plants, the PEBP gene family has expanded, followed by neo- and subfunctionalization. Careful characterization revealed that differential expression and differential protein complex formation provide the members of this gene family with unique functions, enabling them to mediate the crosstalk between the two reproductive events in geophytes in response to environmental and endogenous cues. Taking all these studies into account, we propose to regard the PEBPs as conductors of geophyte reproductive development.

Plant propagation.

It is thought that plant propagation, i.e. multiplying plants, preserving their qualities, and tending them, began approx. 10,000 years ago when people began to cultivate plants for food and other products (Hartman et al., 2010). Most basic methods of plant propagation had been discovered before the start of recorded history, and many plant species had already been domesticated (selected and adapted to human use), including cereals and legumes (Hartman et al., 2010). The two main types of plant propagation are sexual and asexual propagation. Sexual propagation usually involves the production of seed, leading to production of progeny with variable characteristics, so it is often used in plant breeding. Asexual propagation leads to clones of the parent plant and is useful when specific characteristics are desired in the new plants. There are many different forms of asexual or vegetative propagation, including cuttings, grafting, division, storage organs and in vitro techniques.

Influence of scarification method on seed germination of the terrestrial orchid Anacamptis laxiflora (Lam.)

A critical step during in vitro sexual propagation of terrestrial orchids is the treatment of the microscopic seeds with a disinfecting solution that kills bacteria and fungi attached to the seeds. This treatment is necessary to prevent infection of the culture vessels. At the same time, the treatment serves to scarify the seeds, a process that disrupts seed dormancy and initiates germination. The literature is inconclusive with respect to the proper combination of disinfecting solution strength and treatment duration. Both factors should be adapted to each species to guarantee minimal infection rate without damaging the embryo. This research aims to compare three disinfection/scarification methods for seeds of Anacamptis laxiflora (Lam.): (i) soaking in 0.5% NaClO, (ii) soaking in 0.5% NaClO, then centrifugation, and (iii) presoaking the seeds in sucrose solution, then soaking in 0.5% NaClO. The seeds were soaked in the disinfecting solution for 5 to 85 min. Following scarification, the seeds were sown in modified Malmgren nutrient medium. Infected and germinated vessels were counted at 41 and 189 d after sowing. We found that the longer the chemical treatment, the lower the infection rate, and the higher the germination rate. There was no significant difference in germination rate between the NaClO and the NaClO-plus-centrifugation method; in fact, the slight savings in disinfection time effected by centrifugation were more than offset by the added complexity of the method. Moreover, we found that centrifugation significantly delays germination. The sucrose presoak-plus-NaClO method was superior to plain NaClO, as the sucrose stimulates the germination of microbial spores on the surface of the seeds, making them easier to kill. Perhaps seeds with thicker testa as well as whole immature capsules could benefit even more from the pretreatment in sucrose solution.

Pre-germinative treatments applied to Chionanthus pubescens and C. virginicus seeds for sexual propagation

ABSTRACT Chionanthus pubescens Kunth and C. virginicus seeds present double dormancy, what represents a problem for their sexual reproduction, given that it prevents them from reaching adequate germination rates. This research aimed to apply pre-germinative treatments to overcome the double dormancy in C. pubescens and C. virginicus seeds, as well as to improve both the germination speed and the amount of obtained seedlings. A completely randomized design was applied, with four treatments for each species (soaking seeds in cold water, soaking seeds in hot water, mechanical scarification and control) and three replications. For C. pubescens, the pre-germinative treatment with the best results was mechanical scarification, with a 39.22 % germinative capacity; while, for C. virginicus, the best treatment was soaking seeds in hot water (49.00 %).

Dormancia física de la semilla de Peltophorum pterocarpum (DC.) Backer ex Heyne: estudio morfoanatómico, germinación y emergencia de la plántula

Peltophorum pterocarpum (DC.) Backer ex Heyne es un árbol cuyo crecimiento rápido y adaptación a condiciones de estrés hídrico permiten su uso como ornamental en ciudades secas y calientes de los trópicos. Sin embargo, la propagación por semillas se dificulta debido a la dureza de la cubierta seminal, siendo necesaria la aplicación de tratamientos pregerminativos. El objetivo fue describir el proceso de germinación, emergencia y analizar las posibles causas morfoanatómicas de la dormancia en las semillas de P. pterocarpum. Para ello se estimaron los tiempos de germinación (T10, T50, T90), se estudió la fase plantular y se realizaron láminas semipermanentes. Las semillas son elípticas, homogéneas y opacas. Se evidenció la presencia del hilo, micrópilo, funículo, rafe y el lente o estrofíolo ubicados hacia el extremo hilar. El embrión es recto y el eje embrional está conformado por la radícula cónica, anfítropa, con dos cotiledones simples, elípticos, carnosos y endosperma escaso. La germinación fue epígea y fanerocotilar, con el primer par de prófilos bipinnados de ocho folíolos. Las características morfoanatómicas de las semillas proporcionan las estrategias para que la especie pueda propagarse a través del tiempo y el espacio debido a la presencia de la dormancia física, la cual se asocia anatómicamente con el tejido esclerenquimático presentado por la presencia de dos capas de células uniformemente engrosadas, lignificadas y compactas, dispuestas en empalizada, junto a una hilera de osteoesclereidas. Para facilitar los procedimientos a seguir por viveristas y productores durante la propagación sexual de la especie, se recomienda evaluar tratamientos pregerminativos. Palabra clave: Peltophorum pterocarpum, semilla, germinación, dormancia, morfoanatomía. Abstract Peltophorum pterocarpum (DC.) Backer ex Heyne is a tree whose rapid growth and adaptation to hydric stress conditions allow its use as an ornamental in hot, dry cities of the tropics. However, the propagation by seeds is difficult due to the hardness of the seminal cover, being necessary the application of pregerminative treatments. The objective was to describe the germination and emergence process and to analyze the possible morphoanatomic causes of dormancy in P. pterocarpum seeds. For this, the germination times (T10, T50, T90) were estimated, the seedling phase was studied and semi-permanent sheets were made. The seeds are elliptical, homogeneous, and opaque. The presence of the thread, micropyle, funiculus, raphe, and the lens or strophiolelocated towards the end of the line was evidenced. The embryo is straight and the embryonic axis is made up of the conical, amphitropic radicle, with two simple, elliptical, fleshy cotyledons and scant endosperm. Germination was epigeal and phanerocotylar, with the first pair of bipinnate prophiles with eight leaflets. The morphoanatomical characteristics of the seeds provide the strategies for the species to spread through time and space due to the presence of physical dormancy, which is anatomically associated with the sclerenchymal tissue presented by the presence of two layers of cells uniformly thickened, lignified and compact, arranged in a palisade, next to a row of osteosclereids. To facilitate the procedures to be followed by nurserymen and producers during the sexual propagation of the species, it is recommended to evaluate pregerminative treatments. Keywords: Peltophorum pterocarpum, seed, germination, dormancy, morphoanatomy.

Evaluation of pre-germination treatments in Carapa guianensis AUBL

Understanding seed germination of native forest species of the Tropical wet forest is essential for ecosystem regeneration and conservation, which have been affected by the exploitation of wood and non-wood forest products. Carapa guianensis Aulb. (Meliaceae) has been exploited due to the high quality of its wood and seeds. Particularly, the latter is a source of a medicinal oil of high value to the pharmaceutical industry. The indiscriminate use of this species has reduced its population size; therefore, scientific knowledge of its sexual propagation in nurseries is vital. This research aimed to evaluate seed germination of C. guianensis under different pre-germination treatments and substrates at the Centro de Investigación El Mira of AGROSAVIA. Pre-germination assays were conducted in a split-plot design with a random distribution of four repetitions. The cumulative germination percentage (CGP) and mean germination time (t50) were calculated and analyzed through an ANOVA, and Tukey’s multiple comparison test using InfoStat V.2016. Significant differences for CGP among treatments (p<0.0001) and interactions (p<0.0096) were found. The highest germination percentage (61%) was achieved in S1+T4; however, the T50 did not show significant differences (p=0.24). This research demonstrates that the highest germination percentage is achieved through a scarification treatment with imbibition in sand substrate under the agroclimatic conditions of Tumaco.