Abstract
In almost all eukaryotes, mitochondrial (mt) and chloroplast (cp) genes are transmitted to progeny mainly from the maternal parent. The most popular explanation for this phenomenon is simple dilution of paternal mt/cpDNA. Recently, this simple view has been challenged by several reports that describe the active digestion of paternal mt/cpDNA in algae, higher plants, true slime mold and Medaka fish. However, little is known about how paternal mt/cpDNAs are preferentially degraded. To address these questions, we have screened for chlamydomonas mutants that inherit cpDNA biparentally. One of the mutants, BiParental (BP) 31, is defective not only in degradation of mt- cpDNA but also in the formation of pellicle and zygospores. qPCR analysis showed that expression of zygote specific genes (ezy1, ezy2, zys3, zsp1) were down-regulated. Interestingly, the expression of mt+ gamete specific gene, gsp1, was also suppressed in BP31. Upon gamete fusion, GSP1 has been shown to interact with GSM1 (mt- gamete specific homeoprotein) to initiate the zygote maturation program. The suppression of gsp1 in BP31 may explain the "never mature" phenotype.
