Inter-simple sequence repeats as genetic markers and mapping genes for grain milling quality in maize
Abstract
High-throughput DNA markers, such as inter-simple sequence repeats (ISSRs), are more efficient than RFLPs. ISSRs result from PCR amplification of inter-microsatellite sequences and target multiple loci in the genome. We investigated the usefulness of ISSRs in applied maize (Zea mays L.) breeding. Our specific objectives were to (i) assess the genetic diversity among popcorn and dent corn inbreds with ISSRs, (ii) map ISSR markers relative to RFLP markers using the University of Missouri-Columbia immortalized F$\sb2$ population, (iii) use ISSRs in marker-assisted backcrossing of earliness from dent corn inbred A662 into popcorn inbreds HP86-19 and HP72-11, and (iv) identify RFLP, SSR and ISSR markers associated with grain milling quality in dent corn. Among 19 popcorn and 8 dent corn inbreds, ISSRs yielded an average of 54 bands/primer/inbred, and revealed 73% polymorphism among popcorn and 87% polymorphism among dent corn inbreds. Principal component and cluster analyses classified the dent and popcorn inbreds into their respective heterotic groups. Among 54 immortalized F$\sb2$ lines, ISSR amplification generated 239 markers which were mapped to all arms of the 10 chromosomes of maize with an average marker interval of 2.2 cM. In a ((HP86-19 X A662) X HP86-19) BC$\sb1$ population, we identified a BC$\sb1$ line with $>$92% recurrent parent (RP) background that was used to generate advanced backcross generations. ISSR marker analysis of BC$\sb2$ and BC$\sb3$ generations resulted in a line, with 99.6% RP background, that flowers $\ge$10 days earlier than the RP. In a (B73 X HS99-423) F$\sb2$ population, 70 RFLP, 20 SSR, and 124 ISSR markers were used to map QTL for grain milling quality. The F$\sb{2:3}$ progenies were grown at West Lafayette, IN, and Slater, IA, in 1994. Seventy five QTL were identified, 65 of which were specific to one environment. Different QTL were involved in wet milling and in kernel composition, indicating that the grain composition alone does not predict the milling performance. QTL associated with wet milling qualities were different from those involved in kernel density and seed weight. Our results indicate that maize hybrids with enhanced milling quality can be obtained with the use of DNA markers.
Degree
Ph.D.
Advisors
Bernardo, Purdue University.
Subject Area
Agronomy|Genetics
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