Induction of Proline Iminopeptidase by Nitric Oxide May Result in the Proline Accumulation in the Pea Roots.

The nitric oxide (NO) donor sodium nitroprusside upregulated the proline iminopeptidase content in the pea seedling roots. It is assumed that NO activates deprolinization of the proline-rich proteins, as evidenced by an increase in the content of free proline, which is known to protect plants from the abiotic and biotic stressors.

Salicylate-Induced Chitinases in Pea Roots.

Three proteins induced by salicylic acid were revealed in pea roots. These proteins were identified as chitinase isozymes belonging to the glycoside hydrolases family 18. The PsCam050724 transcript encoding at least one of these isoforms was found, allowing us to determine its primary structure, which lacks the signal peptide.

Azelaic Acid-Induced Enzymes of Phenolic Defense in Pea Roots.

The treatment of pea roots with azelaic acid for 72 h led to a change in the content of 28 proteins: the content of 20 proteins decreased, and the content of 8 proteins (including the phenylpropanoid metabolism enzymes, which are involved in the synthesis of phytoalexins) increased.

Proteomic analysis of salicylate-induced proteins of pea (Pisum sativum L.) leaves.

The effect of 50 microM salicylic acid on soluble proteins of pea (Pisum sativum L.) leaves was studied by proteomic analysis. Thirty-two salicylate-induced proteins were found, and 13 of these were identified using MALDI TOF MS. Salicylate-induced increased content was shown for the first time for the family 18 glycoside hydrolase, alpha-amylase, 33 kDa protein of photosystem II, lipid-desaturase-like protein, and glutamine amidotransferase. Increased content of protective proteins of direct antipathogenic action such as chitinase and beta-1,3-glucanases was also noted.

Effect of brassinolide on tyrosine phosphorylation of pea leaf proteins.

Brassinosteroid-induced phosphorylation of tyrosine residues in proteins was studied. Proteins of crude extract of pea leaves were analyzed by one- and two-dimensional electrophoresis followed by Western blotting with monoclonal antibodies PY20 to phosphotyrosine proteins. One- and two-dimensional electrophoresis revealed 7 and 13 tyrosine-phosphorylated proteins, respectively. Brassinolide increased the phosphorylation level of most of these proteins. With inhibitors of tyrosine protein phosphatases, such as phenylarsine oxide and orthovanadate, the level of tyrosine phosphorylation of these proteins increased.

Effect of jasmonic, salicylic, and abscisic acids on [(14)C]leucine incorporation into proteins of pea leaves.

All investigated exogenous phytohormones (jasmonic, salicylic, and abscisic acids) induced the appearance of (14)C-label in a polypeptide with molecular mass 29 kD that was not found in the control; these acids also increased [(14)C]leucine incorporation into a 25-kD polypeptide and decreased such incorporation into a 45-kD polypeptide. This can be considered as a nonspecific response of the plants to the action of these hormones. Salicylic and abscisic (but not jasmonic) acids induced the synthesis of a 19-kD polypeptide, and jasmonate induced the synthesis of a 96-kD polypeptide.

Influence of (9Z)-12-hydroxy-9-dodecenoic acid and methyl jasmonate on plant protein phosphorylation.

The products of the lipoxygenase pathway, methyl jasmonic acid (MeJA) and (9Z)-12-hydroxy-9-dodecenoic acid (HDA), hardly changed the relative level of phosphorylated polypeptides (RLPPs) during 2 h of incubation: 15 and 17 kDa RLPPs were enhanced by HDA, but decreased by MeJA. RLPPs of 73 and 82 kDa were increased by both compounds. MeJA and HDA treatment induced specific and unspecific effects in some RLPPs. It was shown that HDA and MeJA increased protein kinase activity in the presence of 1 microM cAMP.

Enzymatic activity of aphroproteins.

Chitinase and proteinase activities were found in aphroproteins excreted by larvae of the cicada Aphrophora costalis Mats; this accounts for their fungicidal effect. Aphroproteins did not show DNase or RNase activities and did not exhibit properties of proteinase inhibitors. The data suggest that larval foam protects the larva and host plant from entomogenous and phytopathogenic fungi.

Double hydroperoxidation of alpha-linolenic acid by potato tuber lipoxygenase.

The potato tuber lipoxygenase preparations convert alpha-linolenic acid not only to 9(S)-HPOTE, but also to some more polar metabolites. Two of these polar products, I and II, with ultraviolet absorbance maxima at 267 nm were purified by HPLC. It was found that metabolites I and II have, respectively, one and two hydroperoxy groups. Products of NaBH4 reduction of both I and II were identified by their chemical ionization and electron impact mass spectra and by 1H-NMR spectra as 9,16-dihydroxy-10(E), 12(Z), 14(E)-octadecatrienoic acid. The obtained results suggest that compound II is 9.16-dihydroperoxy-10(E), 12(Z), 14(E)-octadecatrienoic acid and product I is a mixture of two positional isomers, 9-hydroxy-16-hydroperoxy-10(E),12(Z),14(E)-octadecatrienoic and 9-hydroperoxy-16-hydroxy-10(E),12(Z),14(E)-octadecatrienoic acids. Lipoxygenase converts efficiently [14C]9-HOTE into product I. Also, both metabolites I and II are the products of double dioxygenation. The second oxygenation at C-16 position as well as the first one at C-9 is controlled by lipoxygenase.