9S-lipoxygenase that can use linoleic acid or linolenic acid as substrates. Plant lipoxygenases may be involved in a number of diverse aspects of plant physiology including growth and development, pest resistance, and senescence or responses to wounding. Catalyzes the hydroperoxidation of lipids containing a cis,cis-1,4-pentadiene structure. Function as regulators of root development by controlling the emergence of lateral roots (PubMed:17369372, PubMed:18949503). 9S-lypoxygenase-derived oxylipins may play an antagonistic role to ethylene signaling in the control of responses involving oxidative stress, lipid peroxidation and plant defense (PubMed:21481031). LOX1-derived oxylipins may be involved in stress signaling from roots to shoots in response to cadmium exposure (PubMed:23314084). 9S-lypoxygenase-derived oxylipins are engaged during infection to control the balance between salicylic acid (SA) and jasmonate (JA) signaling to facilitate infection by the fungal pathogen Fusarium graminearum (PubMed:26075826). 9S-lypoxygenase-derived oxylipins activate brassinosteroid signaling to promote cell wall-based defense and limit pathogen infection (PubMed:26417008). The LOX1-derived compound (9S)-hydroperoxy-(10E,12Z,15Z)-octadecatrienoate protects plant tissues against infection by the bacterial pathogen Pseudomonas syringae pv tomato DC3000 (PubMed:22199234). The LOX1-derived oxylipins are required to trigger stomatal closure in response to both infection by the bacterial pathogen Pseudomonas syringae pv tomato DC3000, and the pathogen-associated molecular pattern (PAMP) flagellin peptide flg22 (PubMed:23526882). Contributes to the oxidation of free fatty acids during seed aging (PubMed:28371855). (9Z,12Z)-octadecadienoate + O2 = (9S)-hydroperoxy-(10E,12Z)-octadecadienoate (9Z,12Z,15Z)-octadecatrienoate + O2 = (9S)-hydroperoxy-(10E,12Z,15Z)-octadecatrienoate Binds 1 Fe cation per subunit. Iron is tightly bound. Lipid metabolism; oxylipin biosynthesis. Monomer. Seedlings, roots, leaves, and flowers (at protein level) (PubMed:12232208, PubMed:17369372, PubMed:7506426, Ref.7). Expressed in guard cells (PubMed:23526882). Transiently expressed during germination, within 1 day after imbibition, especially in the epidermis and the aleurone layer. Later present in the epidermis of the radicle and the adaxial side of the cotyledons. In roots, confined to the pericycle cells and in the lateral root primordia (LRP), and declined at the time of lateral root emergence. Expression is greatly increased in leaves during leaf senescence. By pathogens (e.g. Pseudomonas syringae), wounding, abscisic acid (ABA) and methyl jasmonate (MeJA). Higher levels in light than in dark conditions (PubMed:12232208, PubMed:7506426). Induced by infection with the fungal pathogen Fusarium graminearum (PubMed:26075826). Increment in the number of lateral roots, and moderate increase in the length of the primary root (PubMed:17369372). Enhanced disease resistance to the fungal pathogen Fusarium graminearum (PubMed:26075826). Enhanced susceptibility to the bacterial pathogen Pseudomonas syringae pv tomato DC3000 (PubMed:22199234, PubMed:23526882). The double mutant plants lox1 and lox5 exhibit enhanced susceptibility to the bacterial pathogen Pseudomonas syringae pv tomato DC3000 and the biotrophic powdery mildew pathogen Golovinomyces cichoracearum (PubMed:26417008). Belongs to the lipoxygenase family.