Effect of Meiotic Polyploidisation on Selected Morphological and Anatomical Traits in Interspecific Hybrids of Brassica oleracea × B. napus

In Brassica, interspecific hybridisation plays an important role in the formation of allopolyploid cultivars. In this study, the ploidy of F1 and F2 generations resulting from interspecific hybridisation between B. oleracea inbred lines of head cabbage (B. oleracea L. var. capitata) (2n = 18) and kale (B. oleracea L. var. acephala) (2n = 18) with inbred lines of rapeseed (B. napus L.) (2n = 38) was examined by flow cytometry analysis and chromosome observation. Furthermore, the effect of meiotic polyploidisation on selected phenotypic and anatomical traits was assessed. The F1 hybrids of head cabbage × rapeseed (S3) and kale × rapeseed crosses (S20) were allotriploids with 2n = 28 chromosomes, and nuclear DNA amounts of 1.97 (S3) and 1.99 pg (S20). These values were intermediate between B. oleracea and B. napus. In interspecific hybrids of the F2 generation, which were derived after self-pollination of F1 hybrids (FS3, FS20) or by open crosses between F1 generation hybrids (FC320, FC230), the chromosome numbers were similar 2n = 56 or 2n = 55, whereas the genome sizes varied between 3.81 (FS20) and 3.95 pg 2C (FC230). Allohexaploid F2 hybrids had many superior agronomic traits compared to parental B. napus and B. oleracea lines and triploid F1 hybrids. In the generative stage, they were characterised by larger flowers and flower elements, such as anthers and lateral nectaries. F2 hybrids were male and female fertile. The pollen viability of F2 hybrids was comparable to parental genotypes and varied from 75.38% (FS3) to 88.24% (FC320), whereas in triploids of F1 hybrids only 6.76% (S3) and 13.46% (S20) of pollen grains were fertile. Interspecific hybrids of the F2 generation derived by open crosses between plants of the F1 generation (FC320, FC230) had a better ability to set seed than F2 hybrids generated from the self-pollination of F1 hybrids. In the vegetative stage, F2 plants had bigger and thicker leaves, larger stomata, and significantly thicker layers of palisade and spongy mesophyll than triploids of the F1 generation and parental lines of B. oleracea and B. napus. The allohexaploid F2 hybrids analysed in this study can be used as innovative germplasm resources for further breeding new vegetable Brassica crops at the hexaploid level.

Reciprocal intercompatibility between Byrsonima Rich. exKunth species (Malpighiaceae), in an urban ecotonal fragment of Semi-Deciduous Seasonal Forest and Cerrado

Byrsonima species present floral monomorphism and sharing visitor/pollinator guild. These traits suggest the hypothesis evaluation of reciprocal inter-incompatibility between two syntopic Byrsonima species: B. pachyphylla and B. crassifolia. Pollen tube growth with similar behavior was observed in the stigmatic surface, pistil canal, ovary and micropylar channel to both species. In addition, partial self-incompatibility in self-pollination with greater fruiting in autogamy was observed. Cross-pollination and self-pollination coexist, and reciprocal intercompatibility occurs. Prezygotic isolation mechanisms are unlikely by the absence of abnormal pollen tubes, higher fruiting production and absence of hybrids in the study site. Las especies de Byrsonima presentan monomorfismo floral y comparten gremio de visitantes/polinizadores. Estos rasgos sugieren la evaluación de hipótesis de interincompatibilidad recíproca entre dos especies sintópicas de Byrsonima: B. pachyphylla y B. crassifolia. Se observó el crecimiento del tubo polínico con comportamiento similar en la superficie estigmática, canal del pistilo, ovario y canal micropilar de ambas especies. Además, se describió la autoincompatibilidad parcial en la autopolinización con mayor fructificación en la autogamia. La polinización cruzada y la autopolinización coexisten y se produce una intercompatibilidad recíproca. Los mecanismos de aislamiento precigóticos son improbables por la ausencia de tubos polínicos anormales, producción de frutos y ausencia de híbridos en la área de estudio.

Prior selfing occur in larger flowers in a mixed mating species with delayed selfing

Theory predicts that prior self-pollination (prior selfing) should not evolve in mixed mating species that enable delayed selfing. In this study, we test the hypotheais that prior selfing has evolved under severe pollinator limitation in the mixed mating species Commelina communis which can reproduce via delayed selfing. The hypothesis predicts that prior selfing occurs more frequently in populations with very low pollinator availability and/or in smaller flowers which receive infrequent visitations. We tested the predictions by comparing the degree of prior selfing among ten populations experiencing various levels of pollinator limitation and by examining a relationship between individual flower size and the occurrence of prior selfing. Populations with higher pollinator availability had higher prior selfing rate. Moreover, prior selfing occurs more frequently in larger flowers. These findings were totally opposite patterns of the predictions and the previous findings. We proposed new hypotheses that prior selfing has been maintained by the presence of reproductive interference from the congener and/or propotency in C. communis to explain our unexpected findings. We should verify potential effects of reproductive interference and propotency in future to elucidate the mystery of prior selfing in this mixed mating species with delayed selfing.

Morphometric trait manifestation in inbred lines of monogerm beetroot (Beta vulgaris L.)

Relevance. Inbreeding is the most widespread method of obtaining starting breeding material and plays a central role in heterosis breeding programs of most crops. Beetroot inbred lines possessing economically valuable characteristics require constant maintenance via self-pollination. However, self-pollination leads to depression of a number of traits. Thorough theoretical studies and practical developments are needed to preserve valuable beetroot lines. We aimed to study the root and leaf rosette variability resulting from beetroot self-pollination. We also investigated the inheritance of monogermity in beetroots.Materials and methods. Experimental work was carried out at the All-Russian Research Institute of Vegetable Growing – branch of the Federal State Budgetary Scientific Institution "Federal Scientific Vegetable Center" (FSBSI FSVC), 2011-202], Moscow Region. The object of the study was inbred beetroot lines originated from beetroots of foreign selection. The research data were obtained via field observations and measurements.Results. It has been experimentally shown that the constant signs of self-pollinated beet lines of 1 year of life are the position and height of the leaf rosette. Stabilization and maintenance of separate fertility at a high level is carried out by selection. A negative correlation was noted between the signs of the degree of separateness and the height of the leaf rosette of the plant, the proportion of the neck of the root crop in its diameter, the mass of the root crop and the proportion of the root crop in the biomass of the plant in the offspring of the fourth generation of the inbreeding. The decrease in the productivity of the seed plant occurs at the beginning of the process of creating self-pollinated lines – in the first generation.

Measurement of inbreeding depression in Rhododendron kaempferi: seed production, germination, juvenile survival, and growth

To understand the reproductive ecology of a plant species with both selfing and outcrossing reproductive systems, it is important to know how selfed individuals contribute to the maintenance of a population. Further, examination of the magnitude of inbreeding depression after pollination is essential for accurate measurement of reproductive success. In this study, we investigated the characteristics of viable seeds and seedlings of Rhododendron kaempferi in a region where the bumblebee pollinator Bombus ardens are abundant. In a hand-pollination experiment, the fruit set from self-pollination was 32%, significantly lower than that from outcross-pollination (81%). The number of seeds per fruit from self-pollination was one sixth the number from outcross-pollination. However, the number of seeds per fruit was negatively correlated with the weight per seed. In addition, the germination rate was low when the seed weight was light. Although selfed seeds could germinate, 89% of the seedlings died within a year. The inbreeding depression coefficient 1 year after sowing was very high (0.89). These results indicate that R. kaempferi shows extremely strong selection for outcrossing but maintains a slight selfing potential in a natural population in central Japan.

Breeding of perennial forage crops for disease resistance

The creation of the initial breeding material of forage crops, promising in terms of disease resistance, is a difficult task that requires the solution of many related issues. Such studies should be carried out on artificial field infectious backgrounds. In FSC “VIK named after V.R. Williams” such backgrounds were created on the basis of data of long-term phytosanitary monitoring to identify the main diseases of forage crops. Techniques for creating field backgrounds and methods for laboratory assessment of resistance have been developed, which make it possible to reduce the number of samples evaluated against backgrounds, due to the rejection of susceptible to the disease. When evaluating 20 collection samples of meadow clover and awnless rump, 10 samples with increased disease resistance were identified. As a result of further breeding study of this material by methods of selection, self-pollination, cloning, promising biotypes in terms of disease resistance were obtained. On the basis of these biotypes, polycross populations of meadow clover and awnless rump were created. An assessment of the stability of these populations against artificial infectious backgrounds was carried out. In terms of resistance to fusarium, the polycross population of meadow clover exceeded the standard variety VIC 77 by 24%. The population of awnless rump exceeded the standard Fakelny cultivar by 21% on average over 2 years. A breeding program has been developed to create the initial material for meadow clover and awnless rump with increased disease resistance.

PHENOLOGY, REPRODUCTIVE BIOLOGY AND SPATIAL DISTRIBUTION OF Chresta scapigera (LESS.) Gardner (ASTERACEAE)

Chrestas capigera (Less.) Gardner is an important medicinal herb which, however, has been poorly studied for its biology and ecology. This study aimed to investigate its phenology, floral biology, reproductive biology (self-pollination tests), spatial distribution and correlations between phenophases and climatic data in two sites (Cerrado stricto sensu and Campo rupestre) in southern Minas Gerais, Brazil. From August of 2012 to August of 2013, we monitored phenophase occurrence for 70 individuals: emission of new leaves, flowering, production of immature fruits, and mature fruits. Floral anthesis occurred during daytime and remained all day until fruit formation. Peak leaf emergence was observed in April, correlating with minimum monthly temperature and mean monthly precipitation. Flowering and green fruit peaked in May and June, respectively, and correlated negatively with all climatic variables. Mature fruits peaked in June, but did not correlate significantly with any of the climatic variables. However, no difference was found between the two sites regarding the timing of phenophases. The spatial distribution pattern of individuals within sites was random. The self-pollination tests showed that the individuals pollinated and fertilized themselves. Our findings allow us to conclude that the phenology of C. scapigera has pronounced phenological seasonality with reproductive peak activities in the drier and colder season, which is congruent with the self-pollination and anemochoric dispersion strategy.

Corolla Abscission Triggered by Nectar Robbers Positively Affects Reproduction by Enhancing Self-Pollination in Symphytum officinale (Boraginaceae)

Nectar robbers, which affect plant fitness (directly or indirectly) in different degrees and in different ways, potentially constitute a significant part of mutualistic relationships. While the negative effects of nectar robbing on plant reproductive success have been widely reported, the positive effects remain unknown. The target of our study was to evaluate the effects of nectar robbers on the reproductive success of Symphytum officinale (Boraginaceae). We observed the behavior, species and times of visitors in the field, and we assessed the effect of nectar robbers on corolla abscission rate and time. To test the fitness of corolla abscission, we detected the changes in stigma receptivity, pollen viability, pollen amount and appendage opening size along with the time of flower blossom. The flowering dynamics and floral structure were observed to reveal the mechanism of self-pollination. Finally, pollen deposition seed set rate and fruit set rate were determined to estimate the effect of nectar robbers on reproduction success. We observed 14 species of visitors and 2539 visits in 50 h of observation; 91.7% of them were nectar robbers. The pressure and nectar removal of nectar robbers significantly promoted corolla abscission during a period when pollen grains are viable and the stigma is receptive. In addition, corolla abscission significantly increased the pollen deposition and seed setting rate. Our results demonstrate that nectar robbing contributes to enhancing seed production and positively and indirectly impacts the reproductive success of S. officinale. This mechanism involved the movement of anthers and indirect participation by nectar robbers, which was rarely investigated. Considering the multiple consequences of nectar robbing, understanding the impact of nectar robbers on plant reproduction is essential to comprehend the evolutionary importance of relationships between plants and their visitors.

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.