Ovarian Incompatibility in Tuberose (Polianthes Tuberosa L.) Cultivars and Breeding Lines

Background: Incompatibility occurs frequently in the plant system upon intra- or interspecific crosses resulting in several pollination barriers. The modest understanding on the breeding behaviour and mechanisms governing tuberose (Polianthes tuberosa L.) through this study will direct us to appraise the pollination and post pollination events on self- and cross- incompatibility and seed set behaviour for cross breeding programme.Results: Self-pollination of tuberose cultivars Arka Prajwal, Mexican Single and Arka Sugandhi failed to produce pods upon autogamy and geitonogamy. Pollen-pistil interaction study of incompatible cultivar Arka Prajwal substantiates that pollen tube enters the ovule within 24 hours after pollination. It discharges its contents into the embryo on the 1st day after pollination and polysaccharide granules evident upon fluorescence microscopic study. The pollen tube growth rates of self and controlled pollination were similar; however, sterility was expressed in the ovary. The female gametophytic development in self and cross incompatible cultivar Arka Prajwal showed normal development initially after pollination whereas embryosac degeneration was observed at later stage. Complete degeneration of the integument and nucellar cells was also observed. Conclusions: This study is the first to elucidate the occurrence of pseudo self-incompatibility in tuberose by identifying tuberose cultivars and breeding lines which produce pods upon geitonogamy. A positive pollen-pistil interaction with the degeneration of embryosac, integument and nucellar cell and pod shrinkage, abortion and fall confirms the prevalence of the ‘Ovarian Incompatibility’ or ‘Late-Acting Incompatibility’ in tuberose.

Pollen Competition and Paternal Contribution during Artificially Controlled Pollination of Black Locust (Robinia pseudoacacia L.) without Castration

(1) Background: Considering the serious damage caused by castration and the extremely high outcrossing rate in nature, we hypothesized that artificial controlled pollination of black locust without castration could be conducted for hybridization breeding. (2) Methods: The study conducted controlled pollination on 20 mating combinations of black locust without castration using a single or mixed male parent. Offspring of different developmental stages and the leaves of parents were collected to extract DNA and perform paternity analysis using SSR molecular markers. (3) Results: The contribution rate of each male parent differed according to developmental stage after pollination using different pollens mixed in equal proportions. There were significant correlations between the genetic similarity between each male parent and female parent and contribution rate of each male parent at three different developmental stages after pollination. (4) Conclusions: The composition of offspring pollen donors showed no bias toward selfing or outcrossing when artificially pollinated without castration. Hybrid breeding of black locust by artificially controlled pollination without castration may not be feasible, given that our manual method resulted in a large number of abortive and abnormal offspring. Introduction of honeybees in a limited space to conduct controlled pollination of black locust for hybrid breeding may be feasible.

Antecological features of Rubus odoratus L. during introduction in the North

The article describes the peculiarities of flowering and pollination of an introduced sample of Rubus odoratus in the conditions of the North (Komi Republic). Experiments on controlled pollination have shown that the species is characterized by xenogamy, although there was also idiogamy. The fruits formed through idiogamy had many voids between the drupes, often did not reach maturity, and the seeds were dissimilar. Dichogamy in the form of protandria and partial hercogamy are not an obstacle, but only additional factors that prevent self-pollination. The probable cause of self-sterility is self-incompatibility. R. odoratus has no specific pollination strategy. The main method of pollination of the species is entomophilia, carried out by pollinating insects mainly representatives of three orders: Coleoptera, Diptera and Hymenoptera. R. odoratus is characterized by visual and olfactory attraction.

Passerine birds supporting cross pollination in Erythrina stricta Roxb.

Erythina stricta is an ecologically important tree species in the rainforests of India and its nectar within the flowers contributes to birds’ diet and survival. Reports on the pollination of this species have not been published so far. We therefore explore the reproductive system of this tree species which has great significance to its ecosystem. Birds have an important role in the reproduction of trees through pollination particularly in tropical areas where reproductive success mostly depends on animal pollinator interactions. Study of visitation and nectar feeding behaviour of birds along with breeding system assessment of Erythina stricta. Birds visiting and foraging behaviour was observed during Erythrina stricta flowering season in an indian tropical rainforest. Reproductive system was assessed through controlled pollination experiments. Thirteen bird species were recorded visiting and foraging nectar from the flowers of Erythrina stricta. The maximum numbers of visits recorded were from the Red-vented Bulbul (Pycnonotus cafer, Pycnonotidae). The nectar feeding birds were, either (i) potential pollinator with long bills (e.g. Pycnonotus spp., Chloropsis aurifrons, and Dicrurus spp.) or (ii) nectar robbers with comparatively shorter bills (e.g. Zosterops palpebrosa, Stachyris ruficeps, Macronous gularis, Heterophasia glaciris). Controlled pollination experiments revealed high degree of cross pollination (xenogamy) and self-incompatibility in E. stricta. Birds were more frequent in early mornings and their foraging activity was also observed during evening hours; the frequency however, declined with respect to nectar availability. Long corolla tubes of E. stricta could restrict access to nectar collecting bees.

Pollen management and controlled pollination in Eucalyptus urophylla

The genus Eucalyptus has shown great potential for the establishment of commercial forest plantations, it is one of the most widely planted worldwide, it is planted in different regions of the planet, which indicates its ability to adapt to various environmental conditions. Eucalyptus urophylla is a species of this genus that adapts to tropical and subtropical regions, in suitable sites it can achieve high growth rates. It is one of the species with the most research in breeding programs in the world, mainly due to its capacity to hybridize naturally, since it generates populations with high genetic diversity, coupled with its ability to reproduce asexually. In Mexico, the breeding programs for Eucalyptus urophylla are in the initial phase, although plantations are already managed under clonal silviculture, controlled crossing are just beginning, so pollen management and crossing techniques are the most important activities in these programs. Since there is currently no information about the management of pollen for Eucalyptus urophylla in Mexico, the aim of this paper is to show a methodology based on the information documented in other parts of the world and the recent experience acquired in the collection and management of pollen, as well as the controlled pollination techniques recently employed in the breeding programs of Eucalyptus urophylla in southeastern Mexico.

Transgenic poplar gene flow monitoring in China.

Poplar is cultivated widely for pulpwood, firewood, and timber. Transgenic poplar may be part of a solution for wood demand in China. Because transgene escape is an important part of ecological security evaluation of transgenic plants, in this chapter we discuss a real transgenic poplar case study. In this case study, mature transgenic male Populus nigra plants harbored a Bacillus thuringiensis toxin gene (i.e. Bt poplar). A plantation of these plants served as a testbed for a relevant example for gene flow monitoring in China. Furthermore, we discuss environmental risk assessment (ERA) of these transgenic plants. While transgenes can drift to related species through natural and controlled pollination, the probability of transgene drift appears to be very low in the field. The resultantBt poplar seeds occurred at a frequency from about 0.15% at 0 m to about 0.02% at 500 m away from the Bt poplar. The Bt poplar progeny seeds had decreased germination within 3 weeks in the field (from 68% to 0%), compared with the 48% germination rate after 3 weeks at 4°C. The survival rate of seedlings in the field was 0% without any treatments, but increased to 1.7% under four combined treatments (clean and trim, watering, weeding, and cover with plastic to retain moisture) after being seeded in the field for 8 weeks. Hybrid offspring appeared to possess segregated traits following artificially controlled pollination. While hybrids of transgenic poplar and non-transgenic poplar can be excellent germplasm, gene flow should be monitored. Transgene expression in grafted scion and rootstock of transgenic poplar is reviewed. The transgenic poplar studied appears to be safe; no ecological or environmental harm has been observed in China.

High gene flow maintains wide-range species cohesion in a Neotropical epiphyte (Tillandsia aeranthos, Bromeliaceae)

Studies of patterns of genetic diversity, genetic structure and ecological data across geographical ranges of species allow us to test hypotheses about the evolutionary responses of organisms to fluctuations in habitat connectivity and availability. Here we present a study aiming to assess genetic diversity, population structure and breeding system across the geographical distribution of a subtropical epiphyte, Tillandsia aeranthos (Bromeliaceae), endemic to the Plata River basin (Pampa biome). Seven nuclear microsatellite markers were genotyped in 203 individuals from 13 localities across Brazil and Argentina and 14 plastid regions were sequenced for a subset of the individuals. Additionally, we performed controlled pollination experiments to discuss correlations between breeding system, genetic diversity and structure in the species. Nuclear diversity levels were high (HE = 0.806, HO = 0.745, allelic richness = 5.860) with no haplotype differentiation detected (c. 9 kpb sequenced). Bayesian assignment analysis, supported by principal coordinate analysis and analysis of molecular variance, show low genetic structure across the studied area (FST = 0.031, P < 0.001). Controlled pollination experiments indicated complete self-incompatibility in all localities analysed. Our results show effective gene flow maintaining low genetic structure between localities for T. aeranthos across an extensive area in the Pampa.

Flower orientation in Gloriosa superba (Colchicaceae) promotes cross-pollination via butterfly wings

Background and Aims Complex modifications of angiosperm flowers often function for precise pollen placement on pollinators and to promote cross-pollination. We explore the functional significance of the unusually elaborate morphology of Gloriosa superba flowers, which are divided into one hermaphrodite meranthium and five male meranthia (functional pollination units of a single flower). Methods We used controlled pollination experiments, floral measurements, pollen load analyses and visitor observations in four populations of G. superba in South Africa to determine the breeding system, mechanism of pollination and role of flower in the promotion of cross-pollination. Key Results We established that G. superba is self-compatible, but reliant on pollinators for seed production. Butterflies, in particular the pierid Eronia cleodora, were the primary pollinators (>90 % of visitors). Butterflies brush against the anthers and stigma during nectar feeding and pollen is carried on their ventral wing surfaces. Butterfly scales were positively correlated with the number of pollen grains on stigmas. We demonstrate that the styles were orientated towards clearings in the vegetation and we confirm that the highest proportion of initial visits was to hermaphrodite meranthia pointing towards clearings. Conclusions The flower morphology of G. superba results in effective pollen transfer on the wings of butterfly visitors. The style-bearing hermaphrodite meranthium of the flowers orientates towards open spaces in the vegetation, thus increasing the probability that butterflies land first on the hermaphrodite meranthium. This novel aspect of flower orientation is interpreted as a mechanism that promotes cross-pollination.