IV INHERITED condition of pollen abortion is frequently found in many A species of plants. In maize 20 genes for male sterility are listed by EMERSON, BEADLE and FRASER (193.5). Male sterile-1 reported by SINGLETON and JONES (1930) is on chromosome 6 closely linked with the Y y endosperm locus. All of the gene steriles described are independent recessives, each capable of bringing about either ...

pollen morphology of some species of the genus malus (rosaceae) was investigatedtaxonomically. all species are characteristic by tricolpate pollens. exine sculpturing is variable but is mostlystriate. however, species may differ in degree of density of ridges and their orientation. the exine patterns inm. trilobata and m. florentina are very similar and were characterized by short and very bran...

Pollen grains are regularly used as markers to determine an insect's movement patterns or host (plant) feeding behavior, yet conventional morphology-based pollen grain analysis (or palynology) encounters a number of important limitations. In the present study, we combine conventional analytical approaches with DNA meta-barcoding to identify pollen grains attached to migrating adults of the turn...

The ice nucleation of bioaerosols (bacteria, pollen, spores, etc.) is a topic of growing interest, since their impact on ice cloud formation and thus on radiative forcing, an important parameter in global climate, is not yet fully understood. Here we show that pollen of different species strongly differ in their ice nucleation behaviour. The average freezing temperatures in laboratory experimen...

The sediment of a core collected about 2 km north of Paquetá Island, Guanabara Bay, was submitted to pollen analysis, in order to recognize the dynamics of the regional vegetation, and the anthropic influence. Radiocarbon dating of a sample next to the bottom of the core indicates an age of 4.210+/-40 14C yrs B.P (calibrated age). It was possible to establish four palynological zones. Starting ...

In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. The image at top left is a transmission electron micrograph of a wild-type microspore from Arabidopsis thaliana, showing the single, central nucleus. The tetraspore (tes) mutant of Arabidopsis fails to undergo cytokinesis at the end of male meiosis and all four...

The breakdown of self-incompatibility, which could result from the accumulation of non-functional S-haplotypes or competitive interaction between two different functional S-haplotypes, has been studied extensively at the molecular level in tetraploid Rosaceae species. In this study, two tetraploid Chinese cherry (Prunus pseudocerasus) cultivars and one diploid sweet cherry (Prunus avium) cultiv...

Cell wall pectins are some of the most complex biopolymers known, and yet their functions remain largely mysterious. The aim of this paper was to deepen the study of the spatial pattern of pectin distribution in the aperture of Oenothera hookeri.velans ster/+ster fertile pollen. We used "in situ" immunocytochemical techniques at electron microscopy, involving monoclonal antibodies JIM5 and JIM7...

Plant genetic transformation has arguably been the core of plant improvement in recent decades. Efforts have been made to develop in planta transformation systems due to the limitations present in the tissue-culture-based methods. Herein, we report an improved in planta transformation system, and provide the evidence of reporter gene expression in pollen tube, embryos and stable transgenicity o...

Pollen allergens of the Poaceae family comprise one of the main causes of pollinosis worldwide. Although most of cereals are included in this family, certain pollination characteristics and aerobiological features differentiate them from common wild grass pollen. Cereal pollen grains cannot be easily characterised as potential sources of aero allergens, because of their pollination mode (most o...