The systemic disease of downy mildew (DM) caused by Peronosclerospora maydis Shaw has been an important limiting factor for maize production in Indonesia. Resistance against P. maydis is necessary for developing high yielding cultivars to be released in the country. The molecular marker assisted selection (MAS) program for breeding resistance against P. maydis started in 1999 when Indonesia joined the Asian Maize Biotechnology Network (AMBIONET). A set of inbred lines was phenotypically evaluated in four sites for DM under artificial inoculation using spreader row technique. Several lines showed consistent resistance reaction, including Ki3, P345G/S2B46-2-2-1-2-B-B-B, Nei 9008, AMATL COHS-115-1-2-3-3-1-2-B-B, AMATL COHS-9-1-1-1-1-1-2-3, and Nei 9202. Four of the lines that are highly susceptible were then used to trap the pathogen under natural condition at four hotspot areas. Molecular analysis of the DM by single strand conformational polymorphism (SSCP) using Peronosclerospora genus-specific (PGS) primers did not successfully differentiate DM samples from each location. This result was confirmed with RFLP analysis. A mapping population was developed using two lines: J1-46-2-2-3 f, an elite inbred which developed by InCRI but susceptible to DM as recurrent parent, and AMATL COHS-9-1-1-1-1-1-2-3, a resistant CIMMYT inbred as donor parent. SSR analysis of six inbred lines using 112 primers revealed high level of polymorphism between JI-46-2-2-3f and AMATL COHS-9-1-1-1-1-1-2-3.

English

0501|AGRIS 0501|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Publications Collection