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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #59848
Title: ISOZYME, PROTEIN, AND RAPD MARKERS WITHIN A HALF-SIB FAMILY OF BUFFELGRASS SEGREGATING FOR APOSPORY

Author
item Gustine, David
item Sherwood, Robert
item GOUNARIS, YANNIS - UNIV OF THESSALIA, GREECE
item HUFF, DAVID - PENN STATE UNIVERSITY

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Asexual reproduction (apomixis) is found in many grass species, including buffelgrass (Pennisetum ciliare). Within a few years apomixis will be used by plant breeders to make stable, highly productive plant hybrids. The introduction of the apomixis gene into important food crops such as corn, wheat, and rice would greatly accelerate the improvement of these crops for rthe US and the world. Because a single gene is responsible for this usefu trait, we undertook research to identify and clone the gene in order to introduce it into plants by genetic engineering. Experiments to map this gene in the DNA of buffelgrass were done with several molecular techniques: variability of enzymes, randomly selected proteins, and molecular markers called RAPDs (randomly amplified polymorphic DNA). The results showed that it is now possible to identify RAPD markers that are physically on the same chromosome and near the gene. As these markers become available, they will lbe used to map the location of the gene on the buffelgrass chromosome. Th results are a critical step in isolating the gene so that plant breeders can use it to ensure sufficient grain crops for growing world populations.

Technical Abstract: Isolation of the genes controlling apomixis would be useful to plant breeders for fixing hybrid vigor. A single gene codes for apospory, a form of apomixis, in buffelgrass (Pennisetum ciliare), but to clone it, tightly linked markers must be found. This study was undertaken to assess the feasibility of using isozyme, protein, and RAPD (Random Polymorphic Amplified DNA) markers to detect apospory-linked sequences within a segregating half-sib population. Five sexual and three aposporous progeny of open-pollinated, highly sexual plant B-2s, and highly aposporous Higgins were studied. Floret and leaf proteins separated by starch gel electrophoresis and stained for 12 enzyme activities did not display isozyme polymorphism. Two dimensional polyacrylamide gel electrophoretic separation of steady state proteins of pistils at meiotic and post-meiotic stages revealed about 12% polymorphism within 308 spots, but none of the spots cosegregated with reproductive mode. Genomic DNA was screened for RAPD markers using 111 10-mer random primers and PCR (Polymerase Chain Reaction). Of 569 markers identified, 87% were polymorphic; one marker cosegregated exclusively with all sexual lines, but none cosegregated solely with all aposporous lines. AMOVA (Analysis of MOlecular VAriance) examination of the B-2s parent and eight progeny (Higgins excluded) showed that the aposporous and sexual groups were not significantly different based on 404 RAPD markers. While no RAPD markers were tightly linked with apospory, the data indicated that additional screening of new primers will allow identification of markers for the gene in a half-sib family.