The inheritance of mitochondrial (mt) DNA and chloroplast (cp) DNA was investigated in intergeneric hybrids from crossing between Cunninghamia lanceolata (Lamb.) Hook. and Cryptomeria fortunei Hooibrenk. The chloroplast trnL trnF region and one intra genic segment of the mitochondrial gene, Cox Ⅲ, were amplified from those of the parents and hybrids by PCR using gene specific primers. Cp and mtDNA polymorphisms of the amplified regions were detected between the parents after restriction digestions. Restriction fragment length polymorphism (RFLP) analysis revealed that all the F 1 individuals possessed Cox Ⅲ restriction fragment patterns (characteristic of the paternal parent Cryptomeria fortunei ) and the trnL trnF region (identical to the maternal parent Cunninghamia lanceolata ) showing that a different mode of inheritance for organelle DNA has occurred in the hybrids. Furthermore, the maternal inheritance of chloroplast DNA is reported here for the first time in coniferophyta.
Fertilization in flowering plants is completed through several recognitionevents, and the first of which is the recognition of pollen by pistil of female reproductivetissue. Self-incompatibility (SI) is an intraspecific reproductive barrier to prevent selfferitilization and widely distributed in flowering plants. In many species, SI shows simplegenetics and is controlled by a single multi-allelic locus, called the S locus. In gametophyticSI (GSI) exemplified by the Solanaceae, Scrophulariaceae and Rosaceae, a class ofribonucleases, called S RNases, have been shown to mediate the stylar expression of SI butnot the pollen expression of SI. The latter appears to be determined by a gene differentfrom those encoding S RNases, often referred to as pollen S gene. The pollen S gene is thecrucial missing part in understanding the biochemical and molecular mechanisms of self andnon-self pollen recognition in flowering plants. Recent genetic analysis of mutationsaffecting the pollen expression of SI has suggested a possible model of how the pollen S geneinteracts with S RNases to achieve self and non-self pollen recognition. Furthermore, wewill present two approaches, S-locus directed transposon tagging and map-based cloning, forcloning the pollen S in Antirrhinum.
