Acid In Cotyledons Research Articles

Maize seedlings produced from dry seeds exposed to liquid nitrogen display altered levels of shikimate pathway compounds

In light of climate change and risks of food insecurity, it is becoming increasingly important to preserve plant germplasm in genebanks. Storage of seeds, particularly via cryopreservation, is one of the most proficient methods for ex situ plant germplasm conservation. Whilst seed cryo-banking can have little, to no, or even beneficial effects on subsequent seedling vigor in some species, it can lead to a number of plant abnormalities (morphological and physiological). This study investigated the effects of maize seed cryopreservation on seedling growth (until 14 d) and levels of selected amino acids produced in the shikimate pathway, a major link between primary and secondary metabolism. Seed cryopreservation reduced FW in recovered seedlings, reduced caffeic acid (2.5-fold decrease), and increased levels of all other shikimate pathway–related compounds assessed: phenylalanine (2.9-fold increase), tyrosine (2.6-fold increase), and shikimic (2.1-fold increase) and protocathecuic (3.1-fold increase) acids in cotyledons. Our results suggest that maize seed cryopreservation results in seedlings that exhibit signs of an ‘overly’ efficient and caffeic acid–deficient shikimate pathway, possibly related to their reduced growth during a highly vulnerable growth stage. However, these metabolic abnormalities manifested most severely in the maternal (cotyledonary), as opposed to vegetative (roots, stems, and leaves), tissues and hence are likely to disappear when the seedlings shed the cotyledons and become completely autotrophic.

Salicylic acid alleviates arsenic and zinc toxicity in the process of reserve mobilization in germinating fenugreek (Trigonella foenum-graecum L.) seeds

To improve plant growth and increase yield and crop quality, the farmer uses many organic or mineral substances. The presence of extensive mineral substances causes high concentrations of heavy metals. Among these heavy metals we can find arsenic (As) and zinc (Zn). The purpose of this study was to evaluate the physiological parameters (the growth, nutrient elements, soluble sugars contents, etc.) and the enzymatic and non-enzymatic antioxidative systems in radicles and cotyledons of Trigonella foenum-graecum L. after treatment with 0, 3 of Na2HAsO4·7H2O and 5 mM of ZnSO4 for 72 h of germination. As and Zn treatment caused a significant reduction of radicle and cotyledon growth, chlorophyll and carotenoid contents, the accumulation of mineral nutrients (K, Ca, and Cu), soluble proteins and free amino acids in cotyledons, as well as the activities of hydrolytic enzymes (amylase and phosphatase). The increasing As and Zn concentration resulted in the stimulation of SOD, CAT, APX, and GR activities. The detrimental effects of As and Zn were reversed after applying 0.2 mM salicylic acid (SA), causing an increase in radicle growth, soluble sugar, protein and free amino acid contents in cotyledons and radicles. Similarly, the activities of hydrolytic enzymes (α- and β-amylase) were enhanced. On the other hand, cell viability declined, even after the addition of SA. These results suggest that SA may improve fenugreek seedling growth by providing protection against the toxic effects of heavy metal stress caused by As and Zn.

FUSCA3 activates triacylglycerol accumulation in Arabidopsis seedlings and tobacco BY2 cells.

Triacylglycerol (TAG) is the main storage lipid in plant seeds and the major form of plant oil used for food and, increasingly, for industrial and biofuel applications. Several transcription factors, including FUSCA3 (At3g26790, FUS3), are associated with embryo maturation and oil biosynthesis in seeds. However, the ability of FUS3 to increase TAG biosynthesis in other tissues has not been quantitatively examined. Here, we evaluated the ability of FUS3 to activate TAG accumulation in non-seed tissues. Overexpression of FUS3 driven by an estradiol-inducible promoter increased oil contents in Arabidopsis seedlings up to 6% of dry weight; more than 50-fold over controls. Eicosenoic acid, a characteristic fatty acid of Arabidopsis seed oil, accumulated to over 20% of fatty acids in cotyledons and leaves. These large increases depended on added sucrose, although without sucrose TAG increased three- to four-fold. Inducing the expression of FUS3 in tobacco BY2 cells also increased TAG accumulation, and co-expression of FUS3 and diacylglycerol acyltransferase 1 (DGAT1) further increased TAG levels to 4% of dry weight. BY2 cell growth was not altered by FUS3 expression, although Arabidopsis seedling development was impaired, consistent with the ability of FUS3 to induce embryo characteristics in non-seed tissues. Microarrays of Arabidopsis seedlings revealed that FUS3 overexpression increased the expression of a higher proportion of genes involved in TAG biosynthesis than genes involved in fatty acid biosynthesis or other lipid pathways. Together these results provide additional insights into FUS3 functions in TAG metabolism and suggest complementary strategies for engineering vegetative oil accumulation.

Evaluation of the quality of protein in cotyledons and radicles of selected legumes after germinating as a healthy food

The quality of protein in cotyledons and radicles (shoot) was separately investigated in selected legumes, namely: Pisum sativum (cultivars: Terno, Xantos, Svit, Achat), Glycine max, Lupinus albus (cultivar Amiga), Pisum sativum var. arvense (cultivar Arkta), Faba vulgaris (cultivar Piestansky) after germinating for 48 hours and compared with the respective raw seeds. The highest content of amino acid in cotyledons and radicles were noted in P. sativum (Xantos) and its phenylalanine was the highest increased essential amino acid in radicles 7.4 g/16 g N with respective raw seeds 4.6 g/16 g N. The in vitro protein digestibility of cotyledons and radicles increased significantly (P < 0.05) of all legumes under study. It is ranged from 79.1% to 86.4% in cotyledons, 86.7% to 93.4%. in radicles and 54.1% to 75.0% in respective raw seeds. The quality of proteins in cotyledons and radicles of all legumes was improved significantly after germinating 48 hours.

Effect of Salicylic Acid and Structurally Related Compounds in the Accumulation of Phytoalexins in Cotyledons of Common Bean (Phaseolus vulgaris L.) Cultivars

In the present work, isoflavonoid phytoalexin production in response to the application of salicylic acid in cotyledons of four common bean (Phaseolus vulgaris) cultivars (SA) was evaluated. The time-course and dose-response profiles of the induction process were established by quantifying the isoflavonoids by HPLC. Cotyledons of anthracnose-resistant cultivars induced by SA produced substantially higher phytoalexin contents as compared to the susceptible ones. In addition, maximum levels of phytoalexins (50–100 fold increases) were reached between 96 and 144 h, and when a concentration of SA from 3.62 to 14.50 mM was used. The observations also indicate that there was a relatively good correlation between the phytoalexin contents and the inhibitory effect against C. lindemuthianum; the higher antifungal activity was observed during the first 48 hours for extracts from cotyledons treated with SA at 1.45 and 3.62 mM, and between 96 and 144 h after induction. Finally, compounds structurally related to SA (dihydro-quinazolinones and some imines) showed a strong elicitor effect. Moreover, induced extracts from cotyledons treated with these potential elicitors, besides the properly elicitors, displayed a weak to moderated antifungal activity. These compounds may be considered good candidates for developing of new phytoprotectants. Furthermore, phytoalexin-eliciting substances may contribute for selecting disease resistant cultivars.

Involvement of aba in flower induction of Pharbitis nil

&lt;p&gt;Flowering of plants is controlled by hormones among which both stimulators and inhibitors are present. The role of abscisic acid (ABA) in flower induction of the short day plant &lt;em&gt;Pharbitis nil&lt;/em&gt; was shown in our experiments through exogenous applications and endogenous level determination of the hormone in cotyledons of seedlings grown under special light conditions.&lt;/p&gt;&lt;p&gt;The application of ABA to cotyledons or shoot apices during the first half of a 24-h long inductive night inhibits flowering. The same compound applied towards the end of or after a 14-h long subinductive night increases the number of flower buds produced by these plants.&lt;/p&gt;&lt;p&gt;Exposing &lt;em&gt;P. nil&lt;/em&gt; seedlings at the beginning of a 24-h long inductive night to far red light (FR) decreases the level of endogenous abscisic acid in cotyledons and leads to flower inhibition. However, a pulse of red light (R) reversing the inhibitory effect of far red light on the flowering of &lt;em&gt;P. nil&lt;/em&gt; increases the ABA content.&lt;/p&gt;&lt;p&gt;The results obtained confirm previous observations that ABA may play a dual and an important role in the regulation of floral bud formation in &lt;em&gt;P. nil&lt;/em&gt;. The flowering occurs when the level of endogenous abscisic acid is low at the beginning and is high toward the end of the inductive night.&lt;/p&gt;

Metabolic profiling of oxylipins in germinating cucumber seedlings--lipoxygenase-dependent degradation of triacylglycerols and biosynthesis of volatile aldehydes.

A particular isoform of lipoxygenase (LOX) localized on lipid bodies was shown by earlier investigations to play a role in initiating the mobilization of triacylglycerols during seed germination. Here, further physiological functions of LOXs within whole cotyledons of cucumber (Cucumis sativus L.) were analyzed by measuring the endogenous amounts of LOX-derived products. The lipid-body LOX-derived esterified (13 S)-hydroperoxy linoleic acid was the dominant metabolite of the LOX pathway in this tissue. It accumulated to about 14 micromol/g fresh weight, which represented about 6% of the total amount of linoleic acid in cotyledons. This LOX product was not only reduced to its hydroxy derivative, leading to degradation by beta-oxidation, but alternatively it was metabolized by fatty acid hydroperoxide lyase leading to formation of hexanal as well. Furthermore, the activities of LOX forms metabolizing linolenic acid were detected by measuring the accumulation of volatile aldehydes and the allene oxide synthase-derived metabolite jasmonic acid. The first evidence is presented for an involvement of a lipid-body LOX form in the production of volatile aldehydes.

Influencia del almacenamiento a temperatura y humedad relativa altas sobre la calidad de garbanzo (C icer arietinum L.) Influence of storage at high temperature and high relative humidity on seed quality of chickpea ( Cicer arietinum L.)

The effect of storage simulating tropical conditions (33-35°C, RH = 75%, 160 days) on seed quality of three chickpea (Cicer arietinum L) varieties for human consumption (Surutato 77, Mocorito 88, and Blanco Sinaloa 92) was studied. Storage induced the hard to cook (HTC) condition in all samples. For all samples, the Hunter L value decreased (p &lt; 0.05) and the total difference in color (AE) increased (p &lt; 0.05) during storage, meaning a loss of color lightness and development of darkening. Accelerated storage caused a significant decrease (p &lt; 0.05) in the water absorption capacity (WAC) and cooking time (CT) of whole seed, cotyledons and seed coat for all samples,; these changes were more pronounced for the Blanco Sinaloa variety. Furthermore, storage produced significant (p &lt; 0.05) decreases in the seed coat tannin content of the three materials; this parameter increased (11 &lt; 0.05) in cotyledons. In all samples, the levels of phytic acid in cotyledons decreased (y &lt; 0.05) with the seed hardness. Hardening of chickpea seeds caused a decrease (y &lt; 0.05) in the in vitro protein digestibility of all varieties. These results allow us to suggest that both cotyledons and seed coat play a significant role in the process of chickpea hardening. Blanco Sinaloa 92 and Mocorito 88 might be classified as varieties with high and low proneness, respectively, to develop the HTC condition.

Changes of aspartate aminotransferase activity, its isoform pattern, and free amino acids content in peanut cotyledons during seed germination

After imbibition of peanut seeds, the concentration of free amino acids in cotyledons increases probably due to hydrolysis of reserve proteins. That increase was accompanied by a stimulation of aspartate aminotransferase (AAT, EC 2.6.1.1) activity especially pronounced between first and sixth day of imbibition. Peanut cotyledons contained several AAT isoforms which could be visualized after polyacrylamide gel electrophoresis (PAGE). Native PAGE of extracts from cotyledons of dry seeds demonstrate three active bands. The intensity of these bands increased reaching a maximum after 6th day of imbibition. An additional band appears transientely on 6th day, but is not visible after 14 days of incubation. A fastest band appears on this latter day. If germination takes place under hypersalinity conditions. the AAT activity severely diminishes and the free amino acid concentration raises. The possibilities of different types of AAT regulation are discussed.

Correlation of Flowering Induced by Low Temperature and Endogenous Levels of Phenylpropanoids in Pharbitis nil: A Study with a Secondary-metabolism Mutant

A spontaneous mutant that formed white flowers was found in Pharbitis nil , ‘Violet’ of which original flower color is of anthocyanin. The endogenous level of chlorogenic acid in cotyledons of the early developmental stage was significantly lower in this secondary-metabolism mutant than that in the wild type. Flowering was induced under long-day conditions when the plants were exposed to low temperature, and the flowering response was greater in the mutant than in the wild type. The levels of t -cinnamic, chlorogenic, and feruroylquinic acids increased when flowering was induced, and they were significantly higher in the mutant than in the wild type. These compounds may play some role in the process of flowering induced by low temperature.

N-acylphosphatidylethanolamine in dry and imbibing cottonseeds. Amounts, molecular species, and enzymatic synthesis.

N-Acylphosphatidylethanolamine (NAPE), an unusual acylated derivative of phosphatidylethanolamine (PE), was recently shown to be synthesized from PE and free fatty acids in cotyledons of cotton (Gossypium hirsutum L.) seedlings (K.D. Chapman, T.S. Moore [1993] Plant Physiol 102: 761-769). Here we report that NAPE is present in dry seeds of cotton and increases with time of imbibition from 2.31 nmol/seed in dry seeds to 4.26 nmol/seed in 4-h-soaked seeds. Total phospholipid/seed also increased such that the relative percentage of NAPE was similar in dry and soaked seeds (2.3 mol% compared to 2.6 mol%, respectively). The major molecular species of NAPE were identified in both dry and soaked seeds by fast atom bombardment mass spectrometry and collisionally activated dissociation tandem mass spectrometry as 16:0/18:2-PE(N-palmitoyl), 16:0/18:2-PE(N-linoleoyl), and 18:2/18:2-PE(N-palmitoyl). The specific activity of NAPE synthase in seed extracts increased with increasing time of imbibition from 35 pmol h-1 mg-1 protein in dry seeds to 129 pmol h-1 mg-1 protein in 4-h-soaked seeds. Collectively, our results indicate that NAPE is present in dry cottonseeds and synthesized during imbibition. The biosynthesis of NAPE provides a mechanism for maintaining membrane integrity during seed rehydration and may indicate that NAPE plays a protective role in intracellular membranes of plant tissues, as has been suggested for intracellular membranes of animal tissues.

Biosynthesis of gamma-linolenic acid in cotyledons and microsomal preparations of the developing seeds of common borage (Borago officinalis).

The developing seeds of Borago officinalis (common borage) accumulate a triacylglycerol oil that is relatively rich in the uncommon fatty acid gamma-linolenate (octadec-6,9,12-trienoic acid). Incubation of developing, whole, cotyledons with [14C]oleate and [14C]linoleate showed that the gamma-linolenate was synthesized by the sequential desaturation of oleate----linoleate----gamma-linolenate. Microsomal membrane preparations from the developing cotyledons contained an active delta 6-desaturase enzyme that catalysed the conversion of linoleate into gamma-linolenate. Experiments were designed to manipulate the [14C]linoleate content of the microsomal phosphatidylcholine. The [14C]linoleoyl phosphatidylcholine labelled in situ was converted into gamma-linolenoyl phosphatidylcholine in the presence of NADH. The substrate for the delta 6-desaturase in borage was, therefore, the linoleate in the complex microsomal lipid phosphatidylcholine, rather than, as in animals, the acyl-CoA. This was further confirmed in experiments that compared the specific radioactivity of the gamma-linolenate, in acyl-CoA and phosphatidylcholine, that was synthesized when [14C]linoleoyl-CoA was incubated with microsomal membranes, NADH and non-radioactive gamma-linolenoyl-CoA. The delta 6-desaturase was positionally specific and only utilized the linoleate in position 2 of sn-phosphatidylcholine. Analysis of the positional distribution of fatty acids in the endogenous microsomal sn-phosphatidylcholine showed that, whereas position 1 contained substantial linoleate, only small amounts of gamma-linolenate were present. The results shed further light on the synthesis of C18 polyunsaturated fatty acids in plants and in particular its relationship to the regulation of the acyl quality of the triacylglycerols in oilseeds.

Sulphur amino acids and free amino acids in cotyledons of germinated seedlings ofAlbizzia lebbeck Benth exposed to different light intensities

Metabolism of sulphur amino acids and free amino acids has been studied in the cotyledons during germination ofAlbizzia lebbeck Benth seeds under different light intensities. Seeds ofA. lebbeck contain a large amount of sulphur amino acids which are rapidly utilised during early stages of germination A similarity in the distribution pattern of amino acids in cotyledon samples raised from different seed stocks is noticed. The level of amino acids was higher in the illuminated samples as compared to dark controls. The higher concentration of asparagine, and SAAII during the seedling growth with the increase in light intensities compared to dark-grown seedlings as well as initial seed sample may indicate the involvement of light-triggered reactions in the synthesis of these metabolites.

Low Temperature Effects on Soybean (Glycine max [L.] Merr. cv. Wells) Free Amino Acid Pools during Germination

The free amino acid concentrations in cotyledons and axes of soybean (Glycine max [L.] Merr. cv. Wells) seedlings were determined by automated single column analysis after germination at 10 and 23 C. After 5 days germination at 10 C, glutamate and aspartate were in high concentration in both cotyledons and axes (38 and 24% of total free amino acids recovered, respectively), whereas the concentrations of their amide derivatives, asparagine and glutamine, were low in cotyledons (4.4%) and high in axes (21%). In contrast, after 5 days germination at 23 C, asparagine and glutamine accounted for 22 and 45% of total free amino acids in cotyledons and axes respectively, and aspartate and glutamate concentrations were low. The activities of glutamine synthetase and asparagine synthetase were considerably lower in tissues from the 10 C treatment than those from the 23 C treatment.Aspartate and glutamate concentrations were nearly equal in all but one sample. Both glutamate oxaloacetate transaminase and glutamate dehydrogenase activities were much higher in axis tissues at 23 C as compared to 10 C. Arrhenius plots of axis glutamate oxaloacetate transaminase and glutamate dehydrogenase activities were biphasic and triphasic, respectively, with energies of activation for both increasing with low temperature. Energies of activation were identical for glutamate oxaloacetate transaminase from 10 and 23 C treatments but much higher for glutamate dehydrogenase from 23 C-treated axes. This indicates a difference in enzyme complement for glutamate dehydrogenase with the two treatments.Hydrolysis of free amino acid sample (basic fraction) aliquots showed large quantities of peptides in 23 C-treated axes at 2 days, while few or no peptides were found in the 10 C treatment. Amino acid residues most prevalent in peptides were aspartate, threonine, serine, glutamate, and glycine.