Stigma factors regulating self-compatible pollination

Pollination is one of the most important steps during fertilization and sexual reproduction in plants, and numerous cell-cell interaction events occur between the pistil and the pollen grain/tube during this process. The pollen-stigma interaction is a highly selective process which leads to compatible or incompatible pollination. Previous studies in Solanaceae, Papaveraceae, and Brassicaceae provided some important insights into pollen-stigma recognition in self-incompatible systems. In recent years, considerable data have been available regarding pollen-stigma interaction during self-compatible pollination. In this review, we focus on discussing current knowledge on stigma factors that regulate pollen-stigma interaction in self-compatible systems in comparison with self-incompatible systems.     

The Pollen Tube Pathway in Tasmannia insipida (Winteraceae): Homology of the Male Gametophyte Conduction Tissue in Angiosperms

Abstract: The pathway of the pollen tube in Tasmannia insipida (Winteraceae), an archaic angiosperm, is described. Visual observations and measurements of percentage sugar content from stigmatic exudate and the calyptra droplet were made. The droplet that forms on the calyptra of unopened flowers was artificially pollinated, but no pollen tubes appeared to grow through it to the gynoecium of female flowers. Calyptra droplets occur on both female and male (having reduced female structures) flowers of this dioecious plant. It is considered unlikely that a drop pollination mechanism, analogous to that found in some gymnosperms, is at work in T. insipida, and it is proposed that one possible droplet function is as a "reward" to potential pollinators in advance of flower opening. Pollen tubes were observed to grow almost exclusively along epidermal cells. Early thoughts on angiosperm transmission tissue are re-examined and built upon. It is proposed that the male gametophyte conduction tissue in angiosperms is homologous with epidermal tissue, and that pollen tube passage occurred originally solely along the surface of specialized epidermal cells, or possibly for short distances along unspecialized regions covered with exudate derived from these cells. Some earlier attempts to explain transmitting tissue homology and evolution are discussed.     

枸杞新品系NQ-2开花生物学研究

为探讨枸杞新品系NQ-2纯系种植结实率低的原因,采用TTC法、联苯胺—过氧化氢法、花粉—胚珠比、杂交指数和套袋试验等方法,对NQ-2花粉活力、柱头可授性及繁育系统等进行了研究。结果表明:NQ-2单花花期为3~4 d,花后8 h散粉结束,开花当天花粉活力最高,花粉寿命可持续9 d以上;开花前一天柱头已具可授性,开花第1天柱头可授性最强,开花第3天柱头基本失去可授性;枸杞新品系NQ-2平均花粉-胚珠比8615,OC I=4,结合人工授粉实验结果确定其繁育系统为专性异交。自交不亲和是导致NQ-2纯系种植落花落果结实率低的主要原因。     

Transmitting tissue ECM distribution and composition, and pollen germinability in Sarcandra glabra and Chloranthus japonicus (Chloranthaceae)

BACKGROUND: and Aims Free-flowing surface exudates at the stigmatic (wet versus dry stigma) and adaxial epidermis at the site of angiospermy in carpels of Chloranthaceous species have been proposed to comprise a continuous extracellular matrix (ECM) operating in pollen tube transmission to the ovary. The aim of this research was to establish the spatial distribution and histo/immunochemical composition of the ECM involved in pollen tube growth in Sarcandra glabra and Chloranthus japonicus (Chloranthaceae). METHODS: Following confirmation of the pollen tube pathway, the histo/immunochemical make-up of the ECM was determined with histochemistry on fresh tissue to detect cuticle, esterase, proteins, pectins, and lipids and immunolocalization at the level of the TEM on sections from cryofixed/freeze-substituted tissue to detect molecules recognized by antibodies to homogalacturonans (JIM7, 5), arabinogalactan-proteins (JIM13) and cysteine-rich adhesion (SCA). KEY RESULTS: Pollen germinability is low in both species. When grains germinate, they do so on an ECM comprised of an esterase-positive cuticle proper (dry versus wet stigma). Pollen tubes do not track the surface ECM of stigma or adaxial epidermal cells at the site of angiospermy. Instead, tubes grow between stigmatic cells and subsequently along the inner tangential walls of the stigmatic and adaxial carpel cells at the site of angiospermy. Pollen tubes enter the ovary locule at the base of the funiculus. The stigmatic ECM is distinct by virtue of the presence of anti-JIM5 aggregates, lipids, and a protein recognized by anti-SCA. CONCLUSIONS: The Chloranthaceae joins a growing number of basal angiosperm taxa whereby pollen tubes germinate on a dry versus wet stigma to subsequently grow intercellularly en route to the ovary thereby challenging traditional views that the archetype pollen tube pathway was composed of the surface of stigma and adaxial epidermal cells covered with a free-flowing exudate.     

Self-mortification and the stigma of leprosy in northern India

This article examines the biocultural dynamics of social discrimination and physical disfigurement among people with leprosy, or Hansen's disease (HD), in Banaras, northern India. Based on the narratives and observations ofpeople living in colony and street settings, I trace three destructive processes by which the social stigmata of leprosy become physically expressed. First, strategies of concealment further the progression and spread of HD through late detection and undertreatment. Second, the internalization of stigma can lead to bodily dissociation and injury through self-neglect. Finally, some people intentionally seek injuries under conditions of desperate poverty. As a result of such mortification processes, these people came to embody, quite literally, the prejudices that exacerbated their condition in the first place.     

Standardised measures of needs,stigma and informal care in schizophrenia using a bottom-up,cross-cultural approach

Background There is a lack of instruments to measure the needs, stigma and informal care of people with schizophrenia that take account of sociocultural variation and patients'' and formal and informal carers'' opinions and experiences.Aims To develop questionnaires to measure stigma, needs and informal (non-professional) care for people with schizophrenia.Method We undertook the study in seven countries and in English, Spanish and Portuguese. We first held focus group discussions with patients, formal carers (professionals) and informal carers (family and friends) in Spain, the UK, Argentina, Brazil, Chile and Venezuela to elicit the main dimensions of needs, stigma and informal care. We then held nominal group discussions about these dimensions with patients, family members and professionals in Spain, Portugal and the UK, to develop the instruments.Results Three hundred and three people participated in 46 focus groups and results were discussed in three nominal groups, each involving eight participants. Three instruments were developed in this iterative process: needs for care (46 items), stigma (38 items) and informal care (20 items).Conclusions These instruments are based on service users'' and carers'' views and experiences and have cross-cultural validity. They will have application in assessment of outcomes for people with schizophrenia and their families.