Tuesday, June 19, 2007 - 9:55 AM
Molecular Analysis of Cytoplasmic Male Sterility and Restoration in Cotton.
Fei Wang1, James McD Stewart2, Mary O'Connell1, and Jinfa Zhang3. (1) New Mexico State University, NMSU Plant & Enivromental Sciences, PO Box 30003 MSC 3Q, Las Cruces, NM 88003, (2) University of Arkansas, 115 Plant Science Building, Fayetteville, AR 72701, (3) Plant and Enivromental Sciences, New Mexico State University, Skeen Hall, P.O. Box 30003 MSC 3Q, Las Cruces, NM 88003
Cytoplasmic male sterility (CMS) is a maternally inherited trait with which CMS plants do not produce viable pollen and can be used to facilitate hybrid seed production. CMS can be obtained from natural populations, crossing, and interspecific cytoplasmic replacement. Previous studies demonstrated that genes associated with CMS are located on the mitochondrial genome involving sequence rearrangement of functional mitochondrial genes or unidentified sequences. Fertility in CMS plants can be recovered by nuclear restorer genes. Most restorer genes cloned so far are members of pentratricopeptide repeated (PPR) protein family. In our study, CMS-D8 and restoration (Rf2) system was used. In a backcross population with 112 plants, segregation of male fertility was 1 fertile: 1 sterile ratio. Three new RAPD markers were identified for Rf2, one of which was converted to a cleaved amplified polymorphism (CAP) marker. In addition, two AFLP markers and one simple sequence repeat (SSR) marker linked to the fertility restorer gene (Rf2) were identified. PPR motif primers were designed based on the conserved PPR motif and used in combination with AFLP primers to test the mapping population and one PPR-AFLP marker was identified. The map with nine flanking markers, including one from a previous study, was constructed. Among 36 primer pairs designed from mtDNA genes of Arabidopsis, three primer pairs including two for cytochrome c biosynthesis gene produced polymorphism among the CMS-D8 line, male fertile maintainer lines with AD1 cytoplasm, and restorer lines. Primers designed for other genes did not produce STS polymorphism among the lines, confirming that mitochondrial genes are conserved in sequence size in cotton species. Based on RFLP analysis of mtDNA, several polymorphic markers including gene for adenosine triphosphatase1 (atp1) were identified between the normal AD1 cytoplasm and CMS cytoplasms. A comparative gene sequencing of atp1, atp6, atp9, coxI, coxII and coxIII were also conducted.