Hypocotyl

Seeds. Seeds are produced in pods, usually containing three almost spherical-to-oval seeds weighing 0.1—0.2 g. Commercial varieties have a yellow seed coat plus two cotyledons, plumule, and hypocotyl-radicle axis. The cotyledons contain primarily protein and Hpid bodies (see Fig. 1). Cottonseed. 

Cosio C. Vuillemin L. De Meyer M. Kevers C. Penel C. Dunand C. (2009) An anionic class III peroxidases from zuccini may regulate hypocotyl elongation through its auxin oxidase activity / / Planta. V. 229. P. 823-836. 

Dunand C. de Meyer M. Crevecoeur M. Penel C. (2003) Expression of a peroxidases gene in zucchini in relation with hypocotyl growth. / / Plant Physiology and Biochemistry. V. 41. P. 805-811. 

Meyer, R.F. Boyer, J.S. (1972). Sensitivity of cell division and cell elongation to low water potentials in soybean hypocotyls. Planta, 1 8,77-87. 

Fig. 2. Time course of accumulation of HSP mRNA. One jUg of poly(A) RNA isolated from soybean hypocotyls after different times of incubation at 42.5 °C (hs) or at additional times after transfer back to 28 °C after 4 h at the elevated temperature (recovery), were electrophoresed in formaldehyde agarose gels. Blots of these gels were hybridised with a mixture of four cDNAs encoding small soybean HSPs ranging from 15 to 23 kDa. From Schoffl Key (1982).

Bean hypocotyls (Phaseolus vulgaris) incision woimding of hypocotyls oxidative cross-linking of cell wall proteins [176]... 

BolweU, G.P. and Northcote, D.H. (1981) Control of hemiccllulose and pectin synthesis during differentiation of vascular tissue in bean (Phaseolus vulgaris) caUus and in bean hypocotyl. Planta, 152 225-233. 

As illustrated in Fig. 3, in both poplar stems and mung bean hypocotyls, basic isoforms became prevalent in mature, resting cells whereas in young, growing cells, neutral isoforms were predominant. 

Table 7. Cation concentrations in cell-wall fluid centrifiiged from Vigna hypocotyls...

Figure 13. Ion distribution in transverse section of flax hypocotyl. SIMS microscopy.

A), distribution of calcium ( Ca) and (B), potassium ( K) in the mature zone of flax hypocotyl constituted of cells which had stopped their elongation. (C), distribution of calcium in young flax hypocotyl constituted of elongating cells. (D), small areas of calcium accumulation in the aisles of the intercellular spaces. 

In the epidermis, one observes an accumulation of calcium in the tricellular junction (arrow head) and in the tangential wall (open arrow). In young flax hypocotyl, the calcium-signal intensities were lower than in mature flax hypocotyl (conq)are A and C). 

The most conspicuous concentrations of calciiun in the cell-walls of the flax hypocotyl were in the epidermal and subepidermal layers, especially at the tricellular junctions (figure 13 D), where these were filled with pectic polymers [67], Open tricellular jimctions with intercellular spaces had smaller areas of calcium accumulation where the walls of each pair of cells diverged. These sites were occupied by relatively linear pectic polymers with a low degree of esterification, which could be visualised with gold-kbeUed endopolygalacturonase [68] and were extractable by chelation of calcium with CDTA. Similar pectic polymers are located in the corresponding sites in other plant tissue, as established by susceptibility to polygalacturonase... 

B. Northern blot analysis of total RNA extracted from hypocotyls of P. vulgaris and hybridised to a radioactive pg/p-specific probe. 

Flax seeds were placed for germination on moist paper for three days at 22°C and in the dark then, the plantlets were transferred under continuous white light on a liquid culture medium, as previously described [6], Suspension-cultured cells of flax were obtained from hypocotyl-derived calli as described by Schaumann et al. [4] and cultured on a medium described by Murashige and Skoog [7] containing kinetin (0.75 mg 1 ) and 2-4 D (0.2 mg 1 ). 

PMT activity measured without any exogeneous substrate fi om flax seedling microsomes was generally higher at pH 5 than at pH 7 (table 1) which was not the case in the suspension-cultured cells (see fig. 1). The activity was the most important in the cotyledons and particularly low at pH 7 in the hypocotyls. Whatever the pH, the activity increased over the culture duration. 

Cotyl cotyledons and developing up stem and leaves. Hyp Hypocotyl... 

Figure 2 show that the specific activity fi om the cotyledons (mean value 38,200 and 13,900 dpm mg protein at pH 5.5 and 7 repectively) was also larger than from hypocotyls (21,300 and 7,500) or roots (18,600 and 10,500). Whatever the pH, two peaks occured in the cotyledons (days 3 and 9) while the specific activity was slightly increasing in the roots, during the culture. In the hypocotyls, the activity was rather constant at pH 5.5 and presented two peaks at neutral pH. In all cases, the specific activity was larger than that of suspension-cultured cells which had been estimated in the range of 250 and 2500 dpm mg" protein. 

Figure 2 Specific activity of pectin methyltransferases fi om microsomes of flax seedlings. A cotyledons B hypocotyls C roots. The activity was measured at pH 5.5 ( ) and 7 (o)...

PGIP, purified fi om P.vulgaris hypocotyls [11], was immobilized to the sensor ch via amine coupling. A continuous flow of HBS buffer (5 pl/min) was mantained over the sensor surface. The carboxylated dextran matrix of the sensor surface was first activated by a 6-min injection of a mixture of N-hydroxy-succinimide and N-ethyl-N - (3-diethylaminopropyl) carbodiimide, followed by a 7-min injection of PGIP (lOng/pl in 10 mM acetate, pH 5.0). Hie immobilization procedure was con leted by a 7-min injection of 1 M ethanolamine hydrochloride to block the remaining ester groups. 

Ros Barcelo, A. Pomar, F. Oxidation of cinnamyl alcohols and aldehydes by a basic peroxidase from lignifying Zinnia elegans hypocotyls. Phytochemistry 2001, 57, 1105-1113. 

Biological Assay. Individual compounds, I-XVI, were tested for germination inhibition, and radicle and hypocotyl length alteration. 

Anthocyanins are Che most easily assayed and commonly studied derivatives of aromatic amino acids (Figure 1). Glyphosate drastically reduces accumulation of anthocyanin flavonoids in treated tissues (6, 19) (Figure 3). Levels of rutin and procyanidin, both flavonoids, are reduced in glyphosate-treated buckwheat hypocotyls (6). Glyphosate would presumably similarly affect levels of flavonoids and flavonoid derivatives that are known to be allelochemicals. 

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