Disease resistance. Leaf rust

Lr21

Contributed by Allan Fritz

PCR-based marker for Lr21

The primers based on the RFLP clone KSUD14 were developed by Talbert et al. (5). You can find additional information about this marker in Ref. 4.

D14-L 5'- CGC TTT TAC CGA GAT TGG TC -3'
D14-R 5'- CCA AAG AGC ATC CAT GGT GT -3'

• 100-350 ng template DNA
• 1 pmol each primer
• 1 unit of Taq DNA polymerase
• 1.25 µl 50 mM MgCl₂
• 2.5 µl 10X buffer
• 2 µl 2.5mM dNTPs

• Denature for 5 minutes at 94°C.
• 30 cycles of 94°C for 1 minute, 50° C for 1 minute and 72° C for 2 minutes.
• The last cycle is 72° C for 5 minutes.

Following amplification, the products are digested with Msp I in a 15-µl reaction containing 1.5 µl of 10X buffer and 10 units of enzyme at 37° C for 3 hours and then separated in 2.2% agarose gels at 35 V constant voltage.

The diagnostic fragment is 885-bp in length.

All TA lines except TA1704 carry an Lr21 allele. The 885-bp band (yellow asterisk) is diagnostic for Lr21. TA1704 is susceptible to leaf rust and has a 1.0 kb fragment.

STS marker for Lr21

The electronic lab manual of the wheat genetics resource center at Kansas State University provides the protocol for an STS marker for Lr21.