Effects of Drought on the Expression of Lipoxygenase Isoforms in Pea Leaves and Roots

In the agricultural field, plant productivity has been threatened by drought stress. Previous research studies have shown some stress responsive genes involve in the jasmonic acid signaling pathway. Lipoxygenase (LOX) was found to be a key enzyme involved in the jasmonic acid biosynthesis pathway. It catalyzes the hyperoxidation of polyunsaturated fatty acid with a cis, cis-1,4 pentadiene structure. Then the products of hyperoxidation reaction are converted to different oxylipins. LOX activity changes with stress but limited research has been done with specific LOX isoforms. The expression of one chickpea LOX isoenzyme was upregulated in simulated drought conditions. The aim of this study was to find out whether three of the pea lipoxygenase isoforms are induced by drought in pea roots and leaves. Sixteen days old pea seedlings with an average of eight-ten leaves were exposed to drought stress for five days. After that, leaves and roots were harvested from five different pea plants and quickly frozen in liquid nitrogen at -80oC. RNAs were purified from stressed (drought) and non-stressed (control) pea (Pisum sativum) roots and leaves using RNeasy mini kit (Qiagen). The total RNA molecules were reverse transcribed using the cDNA (Applied Biosystems). The expression of LOX N2, LOX N3, and Ps7 were determined by qPCR analysis using EF1a as the house keeping gene. It is expected that one or more of these pea LOX isoforms will be induced by the drought treatment