After studying this chapter you will be able to understand: Stimuli and a stationary life; signal transduction pathways link signal reception to response; plant hormones help coordinate growth, development, and responses to stimuli; responses to light are critical for plant success; plants respond to a wide variety of stimuli other than light; plants defend themselves against herbivores and pathogens.
Plant response to reduced water availability and other abiotic stress (e.g. metals) have
been analysed through changes in water absorption and transport mechanisms and
also by molecular and genetic approach. A relatively new aspects of fruit nutrition are
presented in order to provide the basis for the improvement of some fruit quality
traits. The involvement of hormones, nutritional and proteomic plant profiles together
with some structure/function of sexual components have also been addressed.
Salinity stress negatively impacts agricultural yield throughout the world affecting production whether it is for subsistence or
economic gain. The plant response to salinity consists of numerous processes that must function in coordination to alleviate both cellular
hyperosmolarity and ion disequilibrium. In addition, crop plants must be capable of satisfactory biomass production in a saline
environment (yield stability).
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Roles of arabidopsis WRKY18, WRKY40 and WRKY60 transcription factors in plant responses to abscisic acid and abiotic stress
MOST OF US are familiar with the observation that house plants placed near a window have branches that grow toward the incoming light. This response, called phototropism, is an example of how plants alter their growth patterns in response to the direction of incident radiation. This response to light is intrinsically different from light trapping by photosynthesis. In photosynthesis, plants harness light and convert it into chemical energy (see Chapters 7 and 8). In contrast, phototropism is an example of the use of light as an environmental signal.
Phototrophic green bacteria, phototrophic purple
bacteria, and heliobacteria are three groups of bacteria that use anoxygenic photosynthesis.
Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls.
Bacteriochlorophyll a and b have maxima wavelength absorption at 775 nm and 790 nm,
respectively in ether. Unlike oxygenic phototrophs, anoxygenic photosynthesis only
functions using a single photosystem. This restricts them to cyclic electron flow only, and
they are therefore unable to produce O2 from the oxidization of H2O.
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The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species.
Does this mean that differences in genetic diversity levels will have predictable
ecological consequences? The answer is no, because only one portion of genetic diversity is
connected to ecological factors, i.e. adaptation. Ecological adaptation is a significant factor
for example, in range expansion of plant species. Plants with different genotypes conferring
the highest levels of fitness are expected to survive and reproduce better, shifting the gene
pool over time towards higher frequencies of the alleles making up the more successful
genotypes (Ward et al., 2008).
Abiotic stresses are serious threats to agriculture and the environment which have been exa‐
cerbated in the current century by global warming and industrialization. According to FAO
statistics, more than 800 million hectares of land throughout the world are currently salt-af‐
fected, including both saline and sodic soils equating to more than 6% of the world’s total
land area. Continuing salinization of arable land is expected to have overwhelming global
impact, resulting in a 30% loss of agricultural land over the next 25 years and up to 50% loss
The same amount of water has been present on our planet for about 4 billion years, since shortly after the Earth was formed. Since then it has cycled through evaporation, condensation, precipitation and surface runoff multiple times. Water scarcity as an abiotic factor ranging from moderate to severe stress levels, accompanied by loss of moisture in the soil, is extremely hard for most organisms to cope with, particularly terrestrial plants and their food-chain dependents.
SURVIVAL ON LAND POSES SOME SERIOUS CHALLENGES to terrestrial plants, foremost of which is the need to acquire and retain water. In response to these environmental pressures, plants evolved roots and leaves. Roots anchor the plant and absorb water and nutrients; leaves absorb light and exchange gases. As plants increased in size, the roots and leaves became increasingly separated from each other in space. Thus, systems evolved for long-distance transport that allowed the shoot and the root to efficiently exchange products of absorption and assimilation.
Physiological and biochemical responses induced by salt stress were studied in laboratory-grown young plants of the mangrove, Bruguiera gymnorrhiza. The growth rates and leaf areas were highest in the culture with 125 mM NaCl. Transpiration rates showed a diel periodicity when the plants were placed in water, but the oscillatory cycles disappeared for plants placed in higher
Plants are sessile organisms and as such must have mechanisms to deal with both abiotic
and biotic stresses to ensure survival. The term “abiotic stress” includes many stresses
caused by environmental conditions such as drought, salinity, UV and extreme
temperatures. Due to global climate change it is predicted that abiotic stresses will increase
in the near future and have substantial impacts on crop yields (Intergovernmental Panel of
Climate Change; http://www.ipcc.ch).
How different levels of
genetic variance affect the rate of evolutionary change within populations has also been
intensively studied. Such changes were originally studied using phenotypic markers:
variation among individual plants in traits, such as leaf shape or flower color (Ward et al.,
2008). Subsequently the detection of genetic variation has become more sensitive, firstly
through the utilization of variation in enzymes (allozymes) and then through PCR-based
marker systems allowing direct examination of DNA sequence variation.
THE FORM AND FUNCTION of multicellular organism would not be possible without efficient communication among cells, tissues, and organs. In higher plants, regulation and coordination of metabolism, growth, and morphogenesis often depend on chemical signals from one part of the plant to another. This idea originated in the nineteenth century with the German botanist Julius von Sachs (1832–1897). Sachs proposed that chemical messengers are responsible for the formation and growth of different plant organs.
The focus of the MA is on ecosystem services (the benefits people
obtain from ecosystems), how changes in ecosystem services have
affected human well-being in the past, and what role these
changes could play in the present as well as in the future. The
MA is an assessment of responses that are available to improve
ecosystem management and can thereby contribute to the various
constituents of human well-being. The specific issues addressed
have been defined through consultation with the MA users.
THE CONVERSION OF SOLAR ENERGY to the chemical energy of organic compounds is a complex process that includes electron transport and photosynthetic carbon metabolism (see Chapters 7 and 8). Earlier discussions of the photochemical and biochemical reactions of photosynthesis should not overshadow the fact that, under natural conditions, the photosynthetic process takes place in intact organisms that are continuously responding to internal and external changes. This chapter addresses some of the photosynthetic responses of the intact leaf to its environment....
DURING THE NINETEENTH CENTURY, when coal gas was used for street illumination, it was observed that trees in the vicinity of streetlamps defoliated more extensively than other trees. Eventually it became apparent that coal gas and air pollutants affect plant growth and development, and ethylene was identified as the active component of coal gas. In 1901, Dimitry Neljubov, a graduate student at the Botanical Institute of St.