Planternes biologi

Trees, shrubs, vines, and grasses in my garden are pictured with flower arrangements, both Japanese and American, created from these plants to inspire gardeners and flower arrangers alike.

Oxygen (O ) appeared in significant amounts in the Earth's atmosphere over 2. 2 2 billion years ago, largely due to the evolution of photosynthesis by cyanobacteria (Halliwell 2006). The O molecule is a free radical, as it has two impaired electrons 2 that have the same spin quantum number. This spin restriction makes O prefer to 2 accept its electrons one at a time, leading to the generation of the so-called reactive oxygen species (ROS). The chemical nature of these species dictates that they can create damage in cells. This has contributed to the creation of the "e;oxidative stress"e; concept; in this view, ROS are unavoidable toxic products of O metabolism and 2 aerobic organisms have evolved antioxidant defences to protect against this tox- ity (Halliwell 1981; Fridovich 1998). Indeed, even in present-day plants, which are full of antioxidants, much of the protein synthetic activity of chloroplasts is used to replace oxidatively damaged D1 and other proteins (Halliwell 2006). Yet, the use of the "e;oxidative stress"e; term implies that ROS exert their effects through indiscriminate widespread inactivation of cellular functions. In this context, ROS must not be able to react with lipids, proteins or nucleic acids in order to avoid any damage to vital cellular components. However, genetic evidence has suggested that, in planta, purely physicoche- cal damage may be more limited than previously thought (Foyer and Noctor 2005).

Today, at the beginning of the third millenium, just three cereal grains - wheat, rice and maize - dominate the world's food supply, accounting for some 75 % of all grains produced. This food "e;oligoculture"e; poses some risks for the future of humankind. The risk of catastrophic food crop failure through insect pests or fungal diseases is ever greater as genetic diversity is reduced. The introduction of genetically modified cereals may exacerbate this situation, as different speeies will share the same genes conferring resistance to pests. The intensive cultivation practices needed to produce the required high yields of these highly developed cereals, the so-called Green Revolution, is leading to environmental degradation through denudation of the soil and pollution of the environment due to pestieide and fertilizer runoff. In addition, the undoubted benefits brought about for many by the Green Revolution, with its use of intensive agricultural practises, cannot be shared by all. Such cultivation practises are often inappropriate in the developing world where farmers simply do not have the income to purchase the required agricultural machinery, inorganic fertilizers and pestieides. Also, the environmental con- ditions in much of the developing world, characterised by frequent droughts interspersed with short periods of very high rainfall, are espeeially dam- aging to the large areas of unprotected soil which result from mechanised agriculture. Reliance on so few different grains for our nutrition also appears to be detri- mental to our long-term health.

Plant reproductive biology has undergone a revolution during the past five years, with the cloning, sequencing and localization of the genes important in reproduction. These advantages in plant molecular biology have led to exciting applications in plant biotechnology, including the genetic engineering of male sterility and other reproductive processes. This book presents an interesting and contemporary account of these new developments from the scientists in whose laboratories they have been made. The chapters focus on two areas: the molecular biology of self-incompatibility, which is the system of self-recognition controlled by the S-gene and related genes; and the cellular and molecular biology of pollen development and genetic dissection of male sterility. Some chapters feature Arabidopsis, with its unique genetic system. Reproduction is vital for seed production in crop plants, and this book presents new approaches to manipulate plant breeding systems for the 21st century.

Rice (Oryza sativa) is one of the most important staple food crops in the world. Breeding efforts to improve the agronomical quality of rice have been conducted, and studies on rice from the viewpoint of basic biological interest have also been carried out. In 1991, a book entitled Rice (edited by Dr. Bajaj) was published as the 14th volume in the series Biotechnology in Agriculture and Forestry (BAF), detailing rice research activities at that time, and focusing mainly on cell and tissue culture and genetic variability. Studies on rice have fundamentally advanced since then, whose outcomes are mentioned below. This is a good reason to compile a new volume on rice. The situation regarding rice research has markedly changed in the last 16 years. First, the genomic sequences of rice were completely determined by the International Rice Genome Sequencing Project in 2004. Since the genome sequence of Arabidopsis thaliana had been determined in 2000, rice became the second species in the seed plants to have its genome well understood. Second, the technology to transform rice by the Agrobacterium-mediated method was developed and is now established. In classical phytopathology, Poaceae (including rice) has not been considered as a host for Agrobacterium. This transformation method is relatively easy and reproducible as compared to conventional transformation methods using protoplasts, and is now widely used in rice research.

The beginnings of human civili zation can be traced back to the time , ne- ly 12 ,000 years ago , when th e early humans gradually ch anged from a life of hunting and gathering food , to producing food. This beginning of pri- tive agriculture ensured a dependable supply of food , and fostered the living together of people in groups and the development of s o c i e ty. During th is time, plant s e e ds were recognized a s a valuable s o ur c e of food and nutrition , and began to be used for growing plants for food. Ever s i n c e , plant seeds have played an important role in the development of the human civilization . Even today, s e e ds of a few crop s p e c i e s , s uc h as the cereals and legume s, are the primary s o u r c e of most human food , and the predominant commodity in international agriculture. Owing to their great importance as food for human s and in international trade , seeds have been a favorite object of s t u d y by developmental biologists and physiologi sts , nutritionist s and chem i sts . A wealth of useful information i s available on th e biology of seed s .

In an era where climate change, natural catastrophes and land degradation are major issues, the conservation of soil and vegetation in mountainous or sloping regions has become an international priority. How to avoid substrate mass movementthroughlandslidesanderosionusingsustainableandecologicallysoundtechniquesisrapidlybecominga scienti?c domain where knowledge from many different ?elds is required. These proceedings bring together papers from geotechnical and civil engineers, biologists, ecologists and foresters, who discuss current problems in slope stabilityresearch,andhowtoaddressthoseproblemsusinggroundbio-andeco-engineeringtechniques.Aselection of papers were previously published in Special Editions of Plant and Soil (2005), volume 278, 1-179, and in the Journal of Geotechnical and Geological Engineering (2006), volume 24, 427-498. Ground bioengineering methods integrate civil engineering techniques with natural materials to obtain fast, effective and economic methods of protecting, restoring and maintaining the environment whereas eco-engineering has been de?ned as a long-term ecological strategy to manage a site with regard to natural or man-made hazards. Studies on slope instability, erosion, soil hydrology, mountain ecology, land use and restoration and how to mitigate theseproblemsusingvegetationarepresentedbybothscientistsandpractitioners.Papersencompassmanyaspectsof this multidisciplinary subject, including the mechanisms and modelling of root reinforcement and the development of decision support systems, areas where signi?cant advances have been made in recent years.