Published in:Proceedings of the National Academy of Sciences of the United States of America
Language:
English
ISSN:
0027-8424;
1091-6490
Origination:
Footnote:
Description:
<p>Northern corn leaf blight (NCLB) caused by the hemibiotrophic fungus<italic>Exserohilum turcicum</italic>is an important foliar disease of maize that is mainly controlled by growing resistant maize cultivars. The<italic>Htn1</italic>locus confers quantitative and partial NCLB resistance by delaying the onset of lesion formation.<italic>Htn1</italic>represents an important source of genetic resistance that was originally introduced from a Mexican landrace into modern maize breeding lines in the 1970s. Using a high-resolution map-based cloning approach, we delimited<italic>Htn1</italic>to a 131.7-kb physical interval on chromosome 8 that contained three candidate genes encoding two wall-associated receptor-like kinases (<italic>ZmWAK-RLK1</italic>and<italic>ZmWAK-RLK2</italic>) and one wall-associated receptor-like protein (<italic>ZmWAK-RLP1</italic>). TILLING (targeting induced local lesions in genomes) mutants in<italic>ZmWAK-RLK1</italic>were more susceptible to NCLB than wild-type plants, both in greenhouse experiments and in the field.<italic>ZmWAK-RLK1</italic>contains a nonarginine-aspartate (non-RD) kinase domain, typically found in plant innate immune receptors. Sequence comparison showed that the extracellular domain of ZmWAK-RLK1 is highly diverse between different maize genotypes. Furthermore, an alternative splice variant resulting in a truncated protein was present at higher frequency in the susceptible parents of the mapping populations compared with in the resistant parents. Hence, the quantitative<italic>Htn1</italic>disease resistance in maize is encoded by an unusual innate immune receptor with an extracellular wall-associated kinase domain. These results further highlight the importance of this protein family in resistance to adapted pathogens.</p>