Transformed petunia, tobacco, and tomato plants have been produced by means of a novel leaf disk transformation-regeneration method. Surface-sterilized leaf disks were inoculated with an Agrobacter...

A simple and general method for transferring genes into plants

Physiological and ecological constraints play key roles in the evolution of plant growth patterns, especially in relation to defenses against herbivores. Phenotypic and life history theories are unified within the growth-differentiation balance (GDB) framework, forming an integrated system of theories explaining and predicting patterns of plant defense and competitive interactions in ecological and evolutionary time. Plant activity at the cellular level can be classified as growth (cell division and enlargement) of differentiation (chemical and morphological changes leading to cell maturation and specialization). The GDB hypothesis of plant defense is premised upon a physiological trade-off between growth and differentiation processes. The trade-off between growth and defense exists because secondary metabolism and structural reinforcement are physiologically constrained in dividing and enlarging cells, and because they divert resources from the production of new leaf area. Hence the dilemma of plants: Th...

https://www.jstor.org/stable/pdfplus/2830650.pdf

The dilemma of plants: To grow or defend.

Seeds are a vital component of the world’s diet. Cereal grains alone, which comprise -90% of all cultivated seeds, contribute up to half of the global per capita energy intake. Not surprisingly then, seed biology is one of the most extensively researched areas in plant physiology. Even in relation to the topics reviewed here, a casual perusal of the Agricola database reveals that well over 5000 publications on seed germination and 700 on seed dormancy have appeared in the last decade. Yet we still cannot answer two fundamental questions: how does the embryo emerge from the seed to complete germination, and how is embryo emergence blocked so that seeds can be maintained in the dormant state? Obviously, with such a large literature on the subject, this review is far from comprehensive. Nevertheless, it provides both an overview of the essential processes that are associated with germination and a description of the possible impediments thereto that may result in dormancy. With the seed, the independence of the next generation of plants begins. The seed, containing the embryo as the new plant in miniature, is structurally and physiologically equipped for its role as a dispersa1 unit and is well provided with food reserves to sustain the growing seedling until it establishes itself as a self-sufficient, autotrophic organism. Because the function of a seed is to establish a new plant, it may seem peculiar that dormancy, an intrinsic block to germination, exists. But it may not be advantageous for a seed to germinate freely, even in seemingly favorable conditions. For example, germination of annuals in the spring allows time for vegetative growth and the subsequent production of offspring, whereas germination in similar conditions in the fall could lead to the demise of the vegetative plant during the winter. Thus, dormancy is an adaptive trait that optimizes the distribution of germination over time in a population of seeds. Seed dormancy is generally an undesirable characteristic in agricultural crops, where rapid germination and growth are required. However, some degree of dormancy is advantageous, at least during seed development. This is particularly true for cereal crops because it prevents germination of grains while still on the ear of the parent plant (preharvest sprouting), a phenomenon that results in major losses to the

/pdf/seed-germination-and-dormancy-33s4axu1ho.pdf

Seed Germination and Dormancy.

https://www.bioinf.uni-leipzig.de/Leere/SS10/Praktikum/Eulgen00_WRKY.pdf

The WRKY superfamily of plant transcription factors

Abscisic acid (ABA) regulates numerous developmental processes and adaptive stress responses in plants. Many ABA signaling components have been identified, but their interconnections and a consensus on the structure of the ABA signaling network have eluded researchers. Recently, several advances have led to the identification of ABA receptors and their three-dimensional structures, and an understanding of how key regulatory phosphatase and kinase activities are controlled by ABA. A new model for ABA action has been proposed and validated, in which the soluble PYR/PYL/RCAR receptors function at the apex of a negative regulatory pathway to directly regulate PP2C phosphatases, which in turn directly regulate SnRK2 kinases. This model unifies many previously defined signaling components and highlights the importance of future work focused on defining the direct targets of SnRK2s and PP2Cs, dissecting the mechanisms of hormone interactions (i.e., cross talk) and defining connections between this new negative regulatory pathway and other factors implicated in ABA signaling.

/pdf/abscisic-acid-emergence-of-a-core-signaling-network-1o69szbfnn.pdf

Abscisic Acid: Emergence of a Core Signaling Network

Cell culture and somatic cell genetics of plants , Cell culture and somatic cell genetics of plants , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Cell culture and somatic cell genetics of plants

Herbicide Resistant Fertile Transgenic Wheat Plants Obtained by Microprojectile Bombardment of Regenerable Embryogenic Callus

/pdf/herbicide-resistant-fertile-transgenic-wheat-plants-obtained-500o3jok6o.pdf

Herbicide resistant fertile transgenic wheat plants obtained by microprojectile bombardment of regenerable embryogenic callus

https://www.cell.com/cell/pdf/0092-8674(91)90436-3.pdf

The Viviparous-1 developmental gene of maize encodes a novel transcriptional activator.

Plant tissue culture techniques have become vitally important for pursuing a wide range of fundamental and applied problems in research and development. The techniques encompass a variety of procedures used for specific purposes. The growing of masses of unorganized cells (callus) on agar or in liquid suspension is widely employed in biochemical and growth studies (1-5). The culture of segments of stems, roots, leaves or of callus provides systems to study differentiation, morphogenesis and plant regeneration (6, 7). Shoot apex culture methods leading to plant regeneration have been adopted for plant propagation and production of virusfree stock (8). The culture of anthers and pollen provides new approaches to haploid plant formation (9). Recently the technology has been extended to include the isolation and culture of plant protoplasts which are employed in fusion and somatic cell hybridization (10-13). The development of the various types of tissue culture has been based on empirical approaches, and some of the observations recorded in the literature may not be typical for plant cells. Differences in medium, environment, age, cell origin, and growth rates may explain the behavior of a particular line and need not represent a general characteristic of plant cells in culture. More uniformity in conditions of culture would assist in making data and observations more comparable.

Indra K. Vasil

Papers

Cell culture and somatic cell genetics of plants

Herbicide resistant fertile transgenic wheat plants obtained by microprojectile bombardment of regenerable embryogenic callus

The Viviparous-1 developmental gene of maize encodes a novel transcriptional activator.

Plant tissue culture media.

Developing Cell and Tissue Culture Systems for the Improvement of Cereal and Grass Crops