Reverse genetics is a powerful tool for functional genomics study. Chemical mutagenesis efficiently generates phenotypic variations in otherwise homogeneous genetic backgrounds, enabling linking biological function with a gene of interest. Using ethyl methanesulfonate (EMS), we mutagenized the fresh pollen from maize B73 inbred and obtained a large number of mutants. Exome capture-Based SNP Discovery (EBSD) was used to identify all mutated loci. A website, called Maize EMS induced Mutant Database (MEMD), is constructed to allow scientists to search for and order the mutant seeds of interest for non-profit research. We will keep updating all the information related to the mutants.

To better use the maize EMS resource, please read 'About MEMD' in the Help menu carefully.

Seed Ordering Procedure:

1. Send an email with detailed information of the mutant lines of your interest as attached Excel file to For convienence, you just need to download and fill in the following blank Excel file.

Blank Mutant Infor Table

2. We will check the seed status and give a response in a week.

3. If the seeds are available, we will inform you to sign a Material Transfer Agreement (MTA), which can be downloaded from the website. If not, we will reproduce the seeds within half a year. MTA should be signed by the PI in your group and the head of your institution.

4. We provide 20 M3-generation seeds for each mutant of a single gene.

5. Because we have not got any national funding during the construction of our maize mutant library and we need lots of money to maintain the library, a handling fee of US $300 or 2000 RMB per mutation is charged.

Note: Please be kindly advised that we are NOT responsible for ensuring a 100% accuracy of a mutation of your interest.

Seed Distribution Procedure:

We will distribute mutant seeds two times every year, at November 20 and April 20. Mutant seeds ordered by users before May 1 or from May 1 to December 1 will be sowed, and then young leaves will be sent to the users for DNA extraction to verify these desired mutations. Positive individuals will be self-pollinated and the corresponding seeds will be supplied to the users at November 20 or April 20 last year, respectively.


Please note that we have updated the mutant IDs of 1942 lines to make them consistant with those in maizeGDB, which will be avaiable soon. (2017-12-06)

Sequencing of an additional 360 mutants was completed, and a total of 1942 EMS mutants were avaiable. (2017-11-27)

A total of 496 mutans were newly sequenced and their variations can be searched now. (2017-10-09)

Notice: We have updated our mutantID with a new naming system, i.e., "ems" + five digits or letters. (2017-05-15)

MEMD Update: A total of 1086 mutants were avaiable now after another 770 mutants were sequenced. (2016-08-05)

Due to power fault, MEMD will be unavailable from 16:00 pm, May 29 until 8:30 am, June 1. (2016-05-28)

MEMD Update: Searching Mutants by chromosome range was added. (2016-05-16)

MEMD v1.0 is online and provides mutant resources.(2016-04-18)