Production and characterization of gamma ray-induced rice mutants with broad-spectrum resistance to the bacterial blight pathogen xanthomonas oryzae pv. oryzae

Issue Date

12-2015

Abstract

An initial bulk M₂ population produced through gamma irradiation of mature seeds of rice variety NSIC Rc 144 was subjected to a series of induced mass screening for potentially novel resistance to bacterial blight, one of the most serious diseases of rice. Lines initially found to be highly resistant to race 3 of the pathogeen Xanthomonas oryzae pv. oryzae (Xoo) were further evaluated in the same manner using other Xoo races. Selection and generation advance ultimately led to identification of two highly resistant M₇lines. DNA fingerprinting using 63 genome-wide SSR markers revealed 100% similar banding patterns in the two mutant lines, indicating that these are sister lines whose origin can be traced to a single M₂ plant. DNA fingerprinting also revealed 98% similarly of the mutant lines with NSIC Rc144 indicating that the resistance is due to mutation and not due to genetic admixture or seed impurity. These lines were advanced and further evaluated using 14 isolates representing the 10 races of Xoo found in the Philippines. Two seasons of induced screening revealed an identical reaction pattern in these lines across a wide range of Xoo races. Such patterns is unique compared to known patterns elicited by four other Xoo-resistant isolates, suggesting possible novel resistance. F₂ segregation data on reaction to bacterial blight suggest a single-gene recessive mutation in these lines (p=0.4 for 3.1 test of fitness). These mutants are now being used as resistance donors in the breeding program while further molecular characterization is being pursued

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

40

Issue

3

Page

1-9

Document Type

Article

Frequency

tri-quarterly

Physical Description

tables, pictures, dendrograms

Language

English

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