A plant gene up-regulated at rust infection sites.
Expression of the fis1 gene from flax (Linum usitatissimum) is induced by a compatible rust (Melampsora lini) infection. Infection of transgenic plants containing a beta-glucuronidase (GUS) reporter gene under the control of the fis1 promoter showed that induction is highly localized to those leaf mesophyll cells within and immediately surrounding rust infection sites. The level of induction reflects the extent of fungal growth. In a strong resistance reaction, such as the hypersensitive fleck mediated by the L6 resistance gene, there is very little fungal growth and a microscopic level of GUS expression. Partially resistant flax leaves show levels of GUS expression that were intermediate to the level observed in the fully susceptible infection. Sequence and deletion analysis using both transient Agrobacterium tumefaciens expression and stable transformation assays have shown that the rust-inducible fis1 promoter is contained within a 580-bp fragment. Homologs of fis1 were identified in expressed sequence tag databases of a range of plant species including dicots, monocots, and a gymnosperm. Homologous genes isolated from maize (Zea mays; mis1), barley (Hordeum vulgare; bis1), wheat (Triticum aestivum; wis1), and Arabidopsis encode proteins that are highly similar (76%-82%) to the FIS1 protein. The Arabidopsis homologue has been reported to encode a delta1-pyrroline-5-carboxylate dehydrogenase that is involved in the catabolism of proline to glutamate. RNA-blot analysis showed that mis1 in maize and the bis1 homolog in barley are both up-regulated by a compatible infection with the corresponding species-specific rust. The rust-induced genes homologous to fis1 are present in many plants. The promoters of these genes have potential roles for the engineering of synthetic rust resistance genes by targeting transgene expression to the sites of rust infection.
Ayliffe
Michael A
MA
Commonwealth Scientific and Industrial Research Organization, Division of Plant Industry, Box 1600, Canberra, Australian Capital Territory 2601, Australia. michaela@pi.csiro.au
Roberts
James K
JK
Mitchell
Heidi J
HJ
Zhang
Ren
R
Lawrence
Gregory J
GJ
Ellis
Jeffrey G
JG
Pryor
Tony J
TJ
D050842:1-Pyrroline-5-Carboxylate Dehydrogenase; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D019597:Flax / Q000235:genetics* / Q000382:microbiology; D005658:Fungi / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D001467:Hordeum / Q000235:genetics; D008969:Molecular Sequence Data; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011392:Proline / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000235:genetics; D015854:Up-Regulation; D003313:Zea mays / Q000235:genetics
D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D011392:Proline; C095387:FIS1 protein, Linum usitatissimum; D050842:1-Pyrroline-5-Carboxylate Dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D005966:Glucuronidase