RESTATED LOAN AGREEMENT

This Restated Loan Agreement ("Agreement") is made as of April 16, 1998 between
Dow AgroSciences LLC, a Delaware limited liability company (the "Lender"), and
Mycoyen S.A., an Argentine corporation (the "Borrower") (together, the
"parties").

WHEREAS, Mycogen Corporation has executed an Assignment of Loan dated April 16,
1998, assigning to Lender all of its rights, title and interest to a certain
Revolving Loan Agreement dated January 1, 1997, between Mycogen Corporation,
successor in interest to Agrigenetics, Inc., and Borrower, and

WHEREAS, the parties agree to restate the Revolving Loan Agreement in its
entirety;

NOW, THEREFORE, the parties hereto have agreed and do hereby agree as follows:

1.   THE LOAN

     1.1  The Advance

          From the above date to December 31, 1998, the Lender agrees to make
          from time to time advances to the Borrower ("Advances"), in an
          aggregate amount not exceeding $50,000,000 (fifty million U.S.
          dollars), at any time outstanding ("Commitment"). Advances repaid
          prior to December 31, 1998, may be reborrowed. This Agreement involves
          U.S. dollars only. The term "Termination Date" shall mean December 31,
          1998. Borrower must give notice to Lender by 9:00 a.m. Eastern
          Standard Time on any Business Day if Advances are requested for that
          day.

     1.2  Repayment

          (a)  The unpaid principal amount of each Advance shall be due and
               payable on the last Business Day of the term of each Advance
               (each, a "Maturity Date"). Notwithstanding the foregoing, the
               unpaid principal amount of the Loan shall be due and payable on
               the Termination Date.

          (b)  Interest on the unpaid principal amount of the Loan shall be
               capitalized and added to the unpaid principal amount of the Loan
               on the first Business Day of each month. Notwithstanding the
               foregoing, all accrued and unpaid interest is due and payable on
               the Repayment date.

          (c)  Repayment may be made at any time, provided that the final
               repayment be made on or prior to December 31, 1998. Borrower must
               receive Lender's request for repayment by 9:00 a.m. Eastern


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               Standard Time on an Business Day if repayment is to be made that
               day.

     1.3  Cancellation/Reduction

          As provided under 2, EVENTS OF DEFAULT, Lender may at any time
          permanently reduce the Commitment and the unpaid principal and all
          interest shall be due and payable immediately.

     1.4  Evidence of Debt

          The Lender shall maintain in accordance with its usual practice an
          account or accounts evidencing the indebtedness of the Borrower
          resulting from the Loan and the amounts of principal and interest
          payable and paid from time to time hereunder. In any legal action or
          proceeding in respect of the Agreement, the entries made in such
          account or accounts shall, unless in case of obvious or manifest
          error, be conclusive evidence of the existence and amounts of the
          obligations of the Borrower therein recorded.

     1.5  Interest

          (a)  The Loan shall bear interest from day to day at an interest rate
               per annum

               (i)  From the date of this Agreement until the Maturity Date
                    equal to the lesser of

                    (x)  LIBOR, as defined below, plus 0.375%, or

                    (y)  the maximum rate allowable by law (the "Interest
                         Rate").

               (ii) "LIBOR" means the rate of deposits in U.S. dollars for a
                    period of one month which appears on the Telerate page 3750
                    as of 11:00 a.m., London time, on the date that is two
                    Business days prior to the first day of the Interest Period.
                    Interest accrues on the unpaid principal amount of each
                    Advance from the date of each Advance and is payable in
                    accordance with Section 1.2.

          (b)  The Interest Rate for each Interest Period is calculated by
               Lender prior to each interest Period. Such calculation is
               conclusive and binding absent manifest error.

          (c)  Interest is calculated on the basis of a 360-day year for actual
               days occurring during the Interest Period.


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          (d)  "Interest Period" means the period commencing on the first
               Business Day of each month and ending on the day immediately
               preceding the first Business Day of the succeeding month.

2.   EVENTS OF DEFAULT

     In the event that:

     (A)  The Borrower fails to pay any sum payable hereunder when due; or

     (B)  The Borrower defaults in the due performance and observance of any
          other term of this Agreement and such default is not remedied within
          15 days after notice of such default; or

     (C)  The Borrower goes bankrupt or becomes insolvent or is subject to a
          receivership either voluntary or compulsory; or

     (D)  Any order is made or law, decree, regulation or resolution passed for
          the liquidation, winding up or dissolution of the Borrower; or

     (E)  All or any substantial part of the business or assets of the Borrower
          is expropriated, nationalized, compulsorily acquired or taken into
          public ownership or the Borrower ceases to be able or entitled to
          exercise the rights of control or ownership of the same; or

     (F)  The Borrower ceases to be directly or indirectly controlled by Lender,

     then and in any such event, and at any time thereafter if any such event
     shall then be continuing, the Lender may, by written notice to the Borrower
     declare the Loan immediately due and payable together with all interest
     accrued thereon and all other amounts payable hereunder, including all
     interest accrued on any past due principal, to the extent permitted by law.

3.   REPRESENTATIONS AND WARRANTIES OF BORROWER, The Borrower represent and
     warrants as follows:

     (A)  The Borrower is a corporation duly organized, validly existing and in
          good standing under the laws of the Republic of Argentina;

     (B)  The execution, delivery and performance by the Borrower of this
          Agreement are within the Borrower's corporate powers, have been duly
          authorized by all necessary corporate action, and do not contravene
          (i) the Borrower's Articles of Formation or By-laws or (ii) any law or
          any judgment or contractual restriction binding on or affecting the
          Borrower;



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     (C) No authorization or approval or other action by, and no notice to or 
         filing with, any governmental authority or regulatory body which has 
         not already been obtained or made is required for the due execution, 
         delivery and performance by the Borrower of this Agreement; and 

     (D) This Agreement is the legal, valid and binding obligation of the 
         Borrower enforceable against Borrower in accordance with its terms.

4.   COVENANTS OF THE BORROWER; REPORTING REQUIREMENTS. So long as the Loan 
     shall remain unpaid, the Borrower will, unless the Lender shall otherwise 
     consent in writing, furnish to the Lender:

     (A) As soon as practicable, in any event within five Business Days after 
         the occurrence of each Event of Default, or each event which with 
         notice or lapse of time or both would become an Event of Default, 
         which is continuing on the date of such statement, a statement of an 
         authorized representative of the Borrower setting forth details of 
         such Event of Default or event and the action which the Borrower 
         proposes to take with respect thereto; and

     (B) Such other information respecting the business, properties or the 
         condition or operations, financial or otherwise, of the Borrower as 
         the Lender may from time to time reasonably request.

5.   COSTS AND EXPENSES

     The Borrower agrees to pay on demand all losses and all costs and 
     expenses, if any, in connection with the enforcement of this Agreement 
     and any instruments or other documents delivered hereunder, including, 
     without limitation, losses, costs and expenses sustained as a result of 
     a default by the Borrower in the performance of its obligations 
     contained in this Agreement or any instrument or document delivered 
     hereunder.
     
6.   ALTERNATIVE DISPUTE RESOLUTION

     The parties shall negotiate in good faith to resolve any dispute arising 
     out of or relating to this Agreement. In the event that the parties fail 
     to resolve a dispute by good faith negotiations, or if either party 
     deems a resolution by such means to be improbable, either party may 
     initiate mediation of the dispute upon written notice to the other 
     party. Such mediation shall be conducted promptly in accordance with the 
     Center for Public Resources Model Procedure for Mediation of Business 
     Disputes. If, within 60 days after notice of mediation, the parties have 
     failed to resolve the dispute by mediation, either party may propose 
     binding arbitration or initiate litigation. If either party requests 
     mediation, it shall occur in Indianapolis, Indiana.


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7.   CHANGE OF CONTROL. After any change of Control (as defined below) of the 
     Borrower, the Lender may, at its option, upon notice to the Borrower 
     declare all principal, interest, and other amounts payable under this 
     Agreement to be immediately due and payable, whereupon the same shall 
     become immediately due and payable.

8.   DEFINITIONS. Capitalized terms as to which such capitalization would not
     be required in accordance with standard rules of grammar shall have the 
     meanings specified below.

     "Affiliate" means, with respect to each party hereto, a party that 
     directly, or indirectly, through one or more intermediaries, controls 
     or is controlled by, or is under common control with, the party 
     specified. The term "control" is defined below. For purposes of this 
     Agreement, Borrower is not an Affiliate of Lender.

     "Business Day" means any day other than a Saturday, Sunday or other day 
     on which banking institutions in Indianapolis, Indiana are required or 
     authorized by law to suspend operations.

     "Control" means the possession, directly or indirectly, of the power to 
     direct or cause the direction of the management and policies of any 
     individual, corporation, partnership, unincorporated association or 
     other entity, whether through the ownership of voting stock, by contract 
     or otherwise. A person who is the owner of 20% or more of a 
     corporation's outstanding voting stock shall be deemed to have Control 
     of such corporation.

9.   MISCELLANEOUS

     The Borrower agrees to take all such steps and actions and to execute 
     and to deliver and/or cause to be delivered all such further documents 
     and instruments as may be necessary in the opinion of the Lender to 
     establish, maintain and protect the rights of the Lender hereunder and 
     generally to carry out the true intent of this Agreement.

10.  ASSIGNMENT

     This Agreement may not be assigned in whole or in part by Borrower 
     without the express written consent of the other party. This Agreement 
     may be assigned by Lender to any Affiliate.

11.  SUCCESSORS

     This Agreement and any instrument or document executed in accordance 
     herewith shall be binding upon and shall inure to the benefit of the 
     parties hereto and their respective successors and assignees.


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12.  GOVERNING LAW

     This Agreement and any instruments or other documents executed in 
     accordance herewith shall be governed by and construed in accordance 
     with the laws of the State of Indiana.

13.  AMENDMENTS, ETC.

     No amendment or waiver of any provision of this Agreement or any 
     instrument delivered hereunder, nor consent to any departure by the 
     Borrower therefrom, shall in any event be effective unless the same 
     shall be in writing and signed by an authorized representative of the 
     Lender.

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly 
executed on the date first written above.

LENDER:                                     BORROWER:

Dow AgroSciences LLC                        Mycoyen S.A.


By: /s/ Sean S. Skinner                     By: [Illegible]
   ----------------------------                ---------------------------

Printed: Sean S. Skinner                    Printed: [Illegible]
        -----------------------                     ----------------------

Title: Treasurer                            Title: Vice President
      -------------------------                   ------------------------

Date: 5/15/98                               Date: 
     --------------------------                  -------------------------
                                                         [Illegible]


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