Gene expression analysis of glutamate synthase and alcohol dehydrogenase from corn (Zea mays) exposed to different durations of flooding / Ian Jomari C. Panaga Eureka Teresa M. Ocampo, adviser.

Date

7-2015

Degree

Bachelor of Science in Agricultural Biotechnology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Eureka Teresa M. Ocampo

Abstract

The study was conducted to select flood tolerant half-sib families from 460 half-sib families IPB Var 6. There were 188 half-sib families selected in the initial screening in cups. Half-sib families 255, 203 and 221 were selected for verification of their flood response in a greenhouse tank experiment. The greenhouse experiment showed that the superior flood tolerant lines were half-sib families 255 and 203. The gene expression of glutamate synthase and alcohol dehydrogenase was semi-quantitatively measured in leaves and roots of corn half-sib families 255 and 203 exposed to flooded treatment with periods of 0, 2, 4 days of flooding and 3, and 6 days of draining. RNA samples were extracted from the young leaves and primary roots of the seedlings for each period per treatment. The isolated RNA samples were used to synthesize cDNA with equal concentration and were used in semi-quantitative gene expression analysis using regular PCR. The primers specific for each gene were used in the regular PCR to check the expression in the cDNA samples. The relative expressions of the genes amplified in regular PCR were analyzed in 1.5% agarose gel electrophoresis and the density of the PCR product bands were analyzed using the program ImageJ. The expression of glutamate synthase (gs) and alcohol dehydrogenase (adh) increased in leaves and roots of corn seedlings exposed to prolonged duration of flooding. The expression of alcohol dehydrogenase and glutamate synthase were higher in flooded treatment compared to the control treatment. Glutamate synthase was highly expressed at leaves of flooded treatment sampled at 4 days of flooding and 6 days of draining respectively. In roots, the gs gene was up-regulated in seedlings planted in saturated soil. Glutamate synthase gene was up-regulated at 4 days of flooding with an adjusted density of 1.24. After 3 days of draining, the gs gene was still up-regulated with an adjusted value of 1.67 but lowered significantly at 6 days of draining with an adjusted value of 0.58. Glutamate synthase gene was more expressed in the roots compared to the leaves for both treatments sampled at different durations of flooding. The bands of the gs gene amplified from root samples in the agarose gel were denser in the roots compared to bands produced using the leaf sample. Thus, the glutamate synthase gene was up-regulated in the roots submerged in water under anaerobic condition and in roots recovering from anaerobic stress. The semi-quantitative expression of analysis in alcohol dehydrogenase gene in leaves showed that it was most expressed at 4 days of flooding. Removal of flooding stress down-regulated the adh gene expression in leaves. In roots, the expression of the adh gene was expressed highest at early stage of flooding stress within 2 days of flooding and lowered at the removal of the flooding stress. The expression of the adh gene in the roots were higher compared to the expression in the leaves as seen in the denser bands produced in agarose gel electrophoresis.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2015 A127 /P36

Notes

Major: Crop Biotechnology

status: in process

loc: Cataloging sec.

Document Type

Thesis

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