Role of aldehyde dehydrogenase in submergence ...

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regulate the enzyme activity of ALDH2 in tolerant and sensitive varieties and in normal and submerged conditions. Future research. • Which ALDH genes are the ...
Role of aldehyde dehydrogenase in submergence tolerance during germination in rice Berta Miro, Frederikson Entila, Abdelbagi M. Ismail Crop and Environmental Sciences Division, International Rice Research Institute, College , Los Banos, Philippines

Introduction

The roles of ALDH2a and ALDH2b in tolerance of submergence during germination

In soil conditions

Various traits seem to be associated with tolerance of flooding during germination in rice (AG, anaerobic germiantion); including:

AEROBIC – day 6

•Coleoptile elongation •High ethylene concentration

SUBMERGED – day 6 ALDH2a

Samples were collected every day between days 0 to 10.

ALDH2b

•High ROS amounts and CAT activity and lower peroxidase activity •Amylase activity •High alcoholic fermentation rates

Schematic of western blot and zymogram techniques

Results Metabolism under reduced oxygen conditions (submergence)

Aim To understand the mechanisms of tolerance of flooding during germination, particularly those related to the ethanol fermentation and their molecular characteristics.

Aldehyde dehydrogenase (ALDH) activity in native PAGE

IR42 DAS

•Two ALDH show activity in tolerant Khao Hlan On and only one in IR42

•These ALDH are common in both aerobic and submerged conditions during seed germination

Materials and Methods Varieties studied: TOLERANT SENSITIVE Khao Hlan On IR42 Mha Zhan (Red) FR13A Khaiyan

ALDH2b does not change between tolerant and sensitive varieties.

Conclusions

Aerobic conditions Khao Hlan On

In anaerobic conditions, the pI of ALDH2a decreases in tolerant varieties only.

•Changes in post-translational modifications may differentially regulate the enzyme activity of ALDH2 in tolerant and sensitive varieties and in normal and submerged conditions

Submerged conditions DAS

Future research Growth conditions and sampling:

• Which ALDH genes are the ones showing in-gel activity and what is the role of ALDH2 in submergence are still being investigated

In 0.1% agar conditions

Zymograms for ALDH using acetaldehyde as a substrate and NAD+ as a cofactor

Acknowledgements We’d like to thank Prof. Mikio Nakazono for providing the primary antibody against ALDH2.