A new blast resistance gene identified in the Indian native rice cultivar Aus373 through allelism and linkage tests

Blast, caused by Pyricularia grisea , is a major constraint on rice production. To widen genetic diversity for disease resistance, the Indian native rice cultivar Aus373 was screened by F₂ segregation analyses to investigate the genetic basis of its high resistance. Aus373 was crossed with a series of Japanese differential cultivars (JDCs) and the Chinese susceptible cultivar Lijiangxintuanheigu (LTH). The resistance ratios of subsequent F₂ progenies were used to determine the number of blast-resistance loci present as well as allelic relationships with known loci. Resistance of Aus373 was governed by dominant alleles at two loci, one at the Pi-k locus and the second apparently at a new locus linked to an isozyme gene Amp-1 with a recombination fraction of 37.9 ± 3.0% on chromosome 2. This putative new locus and allele were designated Pi16 (t).