As the result of intensive research and breeding efforts over the last 20 years, the yield potential and yield quality of cereals have been greatly improved. Nowadays, yield safety has gained more importance because of the forecasted climatic changes. Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. Yield safety can only be improved if future breeding attempts will be based on the valuable new knowledge acquired on the processes determining plant development and its responses to stress. Plant stress responses are very complex. Interactions between plant structure, function and the environment need to be investigated at various phases of plant development at the organismal, cellular as well as molecular levels in order to obtain a full picture. The results achieved so far in this field indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress. Here we attempt to summarize the currently available information on cereal reproduction under drought and heat stress and to give an outlook towards potential strategies to improve yield safety in cereals.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3040.2007.01727.x

The effect of drought and heat stress on reproductive processes in cereals.

Male reproductive processes in flowering plants take place in the stamen (Esau, 1977). This sporophytic organ system contains diploid cells that undergo meiosis and produce haploid male spores, or microspores. Microspores divide mitotically and differentiate into multicellular male gametophytes, or pollen grains, that contain the sperm cells. Figures 1 and 2 show that the stamen consists of two morphologically distinct partsthe anther and the filament. The filament is a tube of vascular tissue that anchors the stamen to the flower and serves as a conduit for water and nutrients. By contrast, the anther contains the reproductive and nonreproductive tissues that are responsible for producing and releasing pollen grains so that pollination and fertilization processes can occur within the flower. Figure 1 shows that anther development can be divided into two general phases. During phase 1, the morphology of the anther is established, cell and tissue differentiation occur, and microspore mother cells undergo meiosis. At the end of phase 1, the anther contains most of its specialized cells and tissues, and tetrads of microspores are present within the pollen sacs (Figure 1). During phase 2, pollen grains differentiate, the anther enlarges and is pushed upward in the flower by filament extension, and tissue degeneration, dehiscence, and pollen grain release occur (Figure 1). The cellular processes that regulate anther cell differentiation, establish anther tissue patterns, and cause the anther to switch from a histospecification program (phase l) to a cell degeneration and dehiscence program (phase 2) are not known. The developmental events leading to anther formation and pollen release are exquisitely timed and choreographed (Koltunow et al., 1990; Scott et al., 1991). Cell differentiation and dehiscence events occur in a precise chronological order that correlates with floral bud size (Koltunow et al., 1990; Scott et al., 1991). This permits the mechanisms responsible for cell-type differentiation, tissue degeneration, and cellspecific gene activation within the anther to be explored with relative Base. During the past few years, there has been an explosive burst of interest in anther biology, both as a system to dissect plant developmental processes at the molecular and genetic levels (Koltunow et al., 1990; Gasser, 1991; McCormick,

Anther development: basic principles and practical applications.

The great taxonomic diversity of the Orchidaceae is often attributed to adaptive radiation for specific pollinators driven by selection for outcrossing. However, when one looks beyond the product to the process, the evidence for selection is less than overwhelming. We explore this problem by discussing relevant aspects of orchid biology and asking which aspects of reproduction explain the intricate pollination mechanisms and diversification of this family. We reaffirm that orchids are primarily pollination limited, the severity of which is affected by resource constraints. Fruit set is higher in temperate than in tropical species, and in species which offer pollinator rewards than those that do not. Reproductive success is skewed towards few individuals in a population and effective population sizes are often small. Population structure, reproductive success and gene flow among populations suggest that in many situations genetic drift may be as important as selection in fostering genetic and morphological variation in this family. Although there is some evidence for a gradualist model of evolutionary change, we believe that the great diversity in this family is largely a consequence of sequential and rapid interplay between drift and natural selection. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84, 1–54.

Variation in sexual reproduction in orchids and its evolutionary consequences: a spasmodic journey to diversification

https://www.agroparistech.fr/IMG/pdf/wilcocket_al.pdf

Pollination failure in plants: why it happens and when it matters.

This paper reviews the literature concerning digestion and nutrient content of pollen. Four topics are addressed in detail: 1) The mechanism of pollen digestion by animals; 2) The efficiency of mechanical and digestive removal of pollen content by various animals; 3) Range and taxonomic distribution of pollen nutrients, and 4) Adaptive hypotheses proposed to associate pollen chemistry with pollinator reward. Studies on the mechanism(s) of pollen digestion remain inconclusive, but suggest that differences in digestibility among pollen types may reflect differences in pollen wall porosity, thickness, and composition. Although hummingbirds reportedly digest pollen very poorly, most animals studied, including those that do not regularly consume pollen, can digest 50–100% of ingested grains. Overlooked and recent research of pollen protein content shows that pollen grains may contain over 60% protein, double the amount cited in some studies of pollen-feeding animals. Adaptive hypotheses that associate pollen starch and pollen caloric content with pollinator reward remain unsubstantiated when critically viewed through the lens of phylogeny.

Pollen nutritional content and digestibility for animals

In the present research we investigated the anti-proliferative activity of Salvia menthifolia Ten. (formerly Salvia menthaefolia), Lamiaceae, on a glioblastoma cell line, since up to date poor therapeutic results have been reported for treatment of malignant glioblastoma. Methanol extracts from different anatomical parts of S. menthifolia were tested on DBTRG-05MG cell line by MTT assay. The most active primary stems extract was also evaluated for apoptosis induction. Results confirmed the anti-tumor property of all the organs and demonstrated that the primary stems extract induced apoptosis after 4 h with the highest values of DNA fragmentation after 6 to 24 h. Some extracts were also HPLC analyzed for polyphenols, althought activities could be due also to other constituents and to synergistic interactions. Rosmarinic acid, caffeic acid, luteolin-7-O-glucosyde and quercitrin were found in all the extracts. The good performance revealed for S. menthifolia towards this extremely aggressive human glioblastoma cell line confirms that the genus Salvia is a natural source of anti-tumor agents though there are great differences among the various species.

/pdf/anti-tumor-activity-of-the-methanolic-extracts-of-salvia-54a9pztjux.pdf

Anti-tumor activity of the methanolic extracts of Salvia menthifolia

Types of pollen dispersal units in Monocots

Introduction The aims of this study were to evaluate whether the antihypertensive effect of garlic could to be associated to interactions with adrenergic and dopaminergic receptors involved in regulating blood pressure and to compare these data with those obtained from wild Allium species.Methods The aqueous extracts of bulbs or leaves of Allium sativum L. (garlic), Allium neapolitanum Cyr., Allium subhirsutum L., and Allium roseum L. were tested for their in vitro affinity for the adrenergic (α1, α2, β1 and β2) and dopaminergic (D1 and D2) receptors by radioligand binding assays.Results Interesting results were shown by bulbs extracts of A. neapolitanum and A. subhirsutum with higher affinities for the β2 receptors and by bulbs extract of A. roseum for D2 receptors.Conclusions The known antihypertensive activity of Allium sativum cannot be correlated with binding to receptors involved in blood pressure regulation. However, aqueous extracts of the wild-type species of Allium show much higher affin...

Cardiovascular receptor binding affinity of aqueous extracts from Allium species

« Harmomegathy »: a still open problem not yet well-known. - Wodehouse used the term « Harmomegathy » to indicate the form and volume change in pollen grains, due to water loss or assumption. Roundish and tricolporate grains in the anther become oval and decrease in volume during the dehydration preceeding anthesis. Viceversa during rehydration on the stigma they undergo the opposite process. Pollen water content at an thesis varies from species to species and it usually ranges between 10 and 20%; nevertheless in some families as Zingiberaceae and Araceae it is higher. Anther and pollen dehydrations are affected by environmental factors, such as humidity of air and temperature, before the anthesis and when pollen is suspended in air. Besides, to avoid the further loss of water during pollen flow, an oily layer derived from tapetum degeneration is deposited outside the pollen grains. During dehydration and rehydration pollen grains undergo a stress due to shape and volume changes expecially in the...

« Harmomegathy »: Un problema aperto e misconosciuto

NIR reflectance spectroscopy was applied to the identification of plant drugs. It was possible to satisfactorily distinguish ginseng, Silybwn marianum and grape seeds, directly analysing the product in its finished form. It was possible to identify Silybum samples grown in different areas. Ginseng samples containing starch were identified and old and young roots were distinguishable. Semiquantitative assay of ginsenoside content was possible.

Gian Gabriele Franchi

Papers

Anti-tumor activity of the methanolic extracts of Salvia menthifolia

Types of pollen dispersal units in Monocots

Cardiovascular receptor binding affinity of aqueous extracts from Allium species

« Harmomegathy »: Un problema aperto e misconosciuto

Application of NIR Reflectance Spectroscopy to the Identification of Drugs Derived from Plants