plant physiology chapter 19 auxin the growth hormone doc

... 424 Chapter 19 The first plant hormone we will consider is auxin Auxin deserves pride of place in any discussion of plant hormones because it was the first growth hormone to be discovered in plants, ... transported polarly from the growing tip to the elongation zone The Auxin: The Growth Hormone The production of auxin The perception of a unilateral light stimulus 1.8 Shaded side 1.5 Growth in length ... According to the current hypothesis, the gradient in phototropin phosphorylation induces the movement of auxin to the shaded side of the coleoptile (see Web Topic 19. 7) Once the auxin reaches the shaded...

Ngày tải lên: 16/03/2014, 22:20

... interfering with auxin synthesis and/or transport in the leaf FIGURE 22.10 Effect of ethylene on abscis- sion in birch (Betaul pendula) The plant on the left is the wild type; the plant on the right ... the stem) actually accelerates the abscission process These results indicate that it is not the absolute amount of auxin at the abscission zone, but rather the auxin gradient, that controls the ... Ethylene: The Gaseous Hormone FIGURE 22.1 Ethylene biosynthetic pathway and the Yang cycle The amino acid methionine is the precursor of ethylene The rate-limiting step in the pathway is the conversion...

Ngày tải lên: 16/03/2014, 22:20

... used for the synthesis of sugars in the carbon fixation reactions These synthetic processes take place in the stroma of the chloroplasts, the aqueous region that surrounds the thylakoids The thylakoid ... serve as the energy source for all forms of life This chapter deals with the role of light in photosynthesis, the structure of the photosynthetic apparatus, and the processes that begin with the excitation ... now turn to the architecture of the photosynthetic apparatus and the structure of its components The Chloroplast Is the Site of Photosynthesis In photosynthetic eukaryotes, photosynthesis takes...

Ngày tải lên: 20/02/2014, 01:20

... from the dicot Nicotiana tabacum (tobacco) The section was made perpendicular to the main surface of the leaf The pore faces the atmosphere; the bottom faces the substomatal cavity inside the ... the surface of the root and the soil is essential for effective water absorption by the root This contact provides the surface area needed for water uptake and is maximized by the growth of the ... nongrowing part of the root, several millimeters behind the root tip, at about the same time that the first protoxylem elements mature (Esau 195 3) The Casparian strip breaks the continuity of the apoplast...

Ngày tải lên: 20/02/2014, 01:20

... largely determine the size and shape of the primary plant body The total growth of the plant can be thought of as the sum of the local patterns of cell expansion The analysis of the motions of cells ... obtained at the base of the growth zone The final growth velocity is the final, constant slope of the growth trajectory equal to the elongation rate of the organ, as discussed in the previous ... in plants with the scr mutation These scr mutants also lack the cell layer called the starch sheath, a structure that is involved in the growth response to gravity (see Chapter 19) Roots of plants...

Ngày tải lên: 07/03/2014, 21:20

... Thus the cells at the tip of the leaf remain committed to the juvenile program, while the cells at the base of the leaf become committed to the adult program The developmental fates of the two ... flowering donor plant is forced to grow, either directly on the plant (in situ) by decapitation, or by rooting or grafting to the base of the plant The new leaves and flowers produced by the axillary ... and the plants maintain a rosette form After the plants are transferred to long days, the levels of all the gibberellins of the 13-hydroxylated pathway (GA53 → GA44 → GA19 → GA20 → GA1; see Chapter...

Ngày tải lên: 16/03/2014, 22:20

... have been hormones and growth factors When they so, they reenidentified in the cytoplasm of plant cells (Yang et al 199 5), ter the cell cycle at the critical point in early G1 In contrast, plant ... traffic from the ER to the throughout the cytoplasm (Driouich et al 199 4) Golgi, between Golgi compartments, and from the Golgi to The Golgi apparatus plays a key role in the synthesis and the TGN ... germination the lipids in the oleosomes are broken down and converted to sucrose with the help of the glyoxysome The first step in the process is the hydrolysis of the fatty acid chains from the glycerol...

Ngày tải lên: 20/02/2014, 01:20

... of the affinity of the enzyme for the substrate The smaller the value of Km, the tighter the binding fast slow E + S ← → ES   → E + P   where E represents the enzyme, S the substrate, P the ... reaction They this by a combination of raising the ground state ∆G of the substrate and lowering the ∆G of the transition state of the reaction, thereby decreasing the barrier against the reaction ... reflects the change in the internal energy of the system The amount of heat transferred and the sign of the reaction are related to the change in free energy, as set out in Equation 2.3 The energy...

Ngày tải lên: 20/02/2014, 01:20

... from the plant The Components of Water Potential Vary with Growth Conditions and Location within the Plant Just as Yw values depend on the growing conditions and the type of plant, so too, the ... Because the water is open to the atmosphere, the hydrostatic pressure of the water is the same as atmospheric pressure (Yp = MPa) There are no solutes in the water, so Ys = MPa; therefore the water ... plants can take up water only when the plant Yw is less than the soil Yw As the soil becomes drier, the plant similarly becomes less hydrated (attains a lower Yw) If this were not the case, the...

Ngày tải lên: 20/02/2014, 01:20

... divides the root into two regions: the cortex toward the outside and the stele toward the inside The stele contains the vascular elements of the root: the phloem, which transports metabolites from the ... longitudinal section of the apical region of the root The meristematic cells are located near the tip of the root These cells generate the root cap and the upper tissues of the root In the elongation ... differentiate into the tissues of the functional root and in the direction of the root apex to form the root cap The root cap protects the delicate meristematic cells as the root moves through the soil...

Ngày tải lên: 20/02/2014, 01:20

... enter the stele, because of the presence of the Casparian strip The apoplast forms a continuous phase from the root surface through the cortex At the boundary between the vascular cylinder (the ... charge across the membrane Therefore, the H+/K+-ATPase is an electroneutral pump In the plasma membranes of plants, fungi, and bacteria, as well as in plant tonoplasts and other plant and animal ... gene encodes an isoform of the enzyme (Sussman 199 4) The isoforms are tissue specific, and they are preferentially expressed in the root, the seed, the phloem, and so on The functional specificity...

Ngày tải lên: 20/02/2014, 01:20

... called the induction period, and the rate of photosynthesis increases with time in the first few minutes after the onset of illumination The 150 Chapter increase in the rate of photosynthesis ... sucrose synthesis in the cytosol or diverted to starch synthesis within the chloroplast The regulation of this aspect of photosynthetic carbon metabolism will be discussed further when the syntheses ... cycle FIGURE 8.11 The C4 photosynthetic pathway The hydrolysis of two ATP drives the cycle in the direction of the arrows, thus pumping CO2 from the atmosphere to the Calvin cycle of the chloroplasts...

Ngày tải lên: 07/03/2014, 20:20

... photosynconsideration of the geometry of the part of the plant that thesis At the same time, the structural and functional propreceives the light: Is the plant organ flat or cylindrical? erties of the leaf make ... rise The wavy 1500 Year 2000 196 0 197 0 198 0 199 0 2000 Year nature of the trace is caused by change in atmospheric CO2 concentrations associated with the growth of agricultural crops Each year the ... of the leaf, does photosynthesis occur uni- formly within the leaf tissues, or is there a gradient in photosynthesis across the leaf? The photosynthetic properties of a leaf are determined by the...

Ngày tải lên: 07/03/2014, 20:20

... to the acyl carrier protein, the fatty acid chain is referred to as acyl-ACP The first committed step in the pathway (i.e., the first step unique to the synthesis of fatty acids) is the synthesis ... examine the enzyme that uses the energy of the proton gradient to synthesize ATP: the FoF1-ATP synthase After examining the various stages in the production of ATP, we will summarize the energy ... form the channel through which protons cross the inner membrane The passage of protons through the channel is coupled to the catalytic cycle of the F1 component of the ATP synthase, allowing the...

Ngày tải lên: 07/03/2014, 20:20

... other nod genes The first stage in the formation of the symbiotic relationship between the nitrogen-fixing bacteria and their host is migration of the bacteria toward the roots of the host plant ... signals, the induction of a specialized developmental program within the plant, the uptake of the bacteria by the plant, and the development of nodules, unique organs that house the bacteria within plant ... betaines, secreted by the roots These attractants activate the rhizobial NodD protein, which then induces transcription of the other nod genes (Phillips and Kapulnik 199 5) The promoter region of...

Ngày tải lên: 07/03/2014, 20:20

... to the plants themselves and the metabolic cost of producing them was not excessive, they gave the plants that possessed them greater reproductive fitness than undefended plants had Thus the ... competition In the remainder of this chapter we will discuss the major types of plant secondary metabolites, their biosynthesis, and what is known about their functions in the plant, particularly their ... radiation, or in reducing the growth of nearby competing plants Phenylalanine Is an Intermediate in the Biosynthesis of Most Plant Phenolics Plant phenolics are biosynthesized by several different...

Ngày tải lên: 07/03/2014, 20:20

... activates the output domain and brings about the cellular response (After Parkinson 199 3.) the regulation of gene expression by the phytohormone, auxin, may be mediated in part by the activation of the ... ions out of the cell and into the lumen of the ER, respectively In plant cells, most of the calcium of the cell accumulates in the vacuole The proton electrochemical gradient across the vacuolar ... platelet-derived growth factor (PDGF), and several other protein growth factors Since the transmembrane domain that separates the hormone- binding site on the outer surface of the membrane from the catalytic...

Ngày tải lên: 07/03/2014, 21:20

... oat seedlings, red light can stimulate the growth of the coleoptile and inhibit the growth of the mesocotyl (the elongated axis between the coleoptile and the root) at such low fluences Arabidopsis ... vary the farred content, it was found that for so-called sun plants (plants that normally grow in an open-field habitat), the higher the far-red content (i.e., the lower the Pfr:Ptotal ratio), the ... Despite the great similarity in their structures, each of these phytochromes performs distinct roles in the life of the plant In this section we will discuss the current state of our knowledge of the...

Ngày tải lên: 07/03/2014, 21:20

... from the top The arrows indicate the direction of phototropic curvature The diagrams illustrate how the direction of growth varies with the location and the intensity of the light source, but growth ... to the physiologically inactive form in the absence of blue light (Iino et al 198 5) The rate of the response to a blue-light pulse would thus depend on the time course of the reversion of the ... and the subsequent isolation of the relevant gene Cloning of the gene led to the identification and characterization of the protein encoded by the gene In the case of stomatal guard cells, the...

Ngày tải lên: 16/03/2014, 22:20

... 20 .19) In the absence of auxin the reverse occurs Thus the apical bud promotes growth not only through the direct biosynthesis of auxin, but also through the auxin- induced biosynthesis of GA1 (Figure ... induction and tuber yield of potato plants Plant J 22: 247–256 Davies, P J (199 5) The plant hormones: Their nature, occurrence, and functions In Plant Hormones: Physiology, Biochemistry and Molecular ... to the plant, and produces the same effect on the biosynthetic gene transcription Conversely, a mutation that lowers the level of active gibberellin, such as GA1, in the plant stimulates the...

Ngày tải lên: 16/03/2014, 22:20