Mitochondrial DNA Genetic Polymorphism And Expression Of Related Genes In Rice

There were few reports on genetic polymorphism of Oryza sativa L. and wild rice species at the level of mitochondrial genome. Based on sequence alignment of mtDNA in typical indica and typical japonica,16mtDNA polymorphic loci were chosen, and they were also used to detect the genetic polymorphism and phylogenetic relationship of114rice materials from five O. saliva L. subpopulations and four wild species in the AA genome Oryza. The study was aimed at deepen the understanding of rice cytoplasm genetic polymorphism and povide cytoplasmic molecular evidence of phylogenetic relationship in O. sativa.1. mtDNA indica-japonica differentiation and phylogenetic relationship in A A genome OryzaThe results revealed that indica varieties consisted of indica-typt (15/21) and indica-like-type (6/21). Except for one temperate japonica variety was japonica-like-type, the rest fourteen were all japonica-type. The thirteen tropical japonica varieties were all japonica-type. The ans varieties were mainly indica-type (6/14) and japoniea-like-type (5/14), and the rest were indica-like-type (2/14) and japonica-type (1/14). Aromatic varieties were mainly japonica-like-type (8/13), and the rest were japonica-type (3/13) and indica-like-type (2/13). O. rufipogon Griff, varieties were mainly indica-like-type (14/23) and japonica-like-type (8/23), while the rest Laos CWR was indica-type. Two O. nivara, one O. barthii and one O. meridionalis were japonica-like. The mitochondrial indica-japonica differentiation is likely universal in AA genome. Four indica and two tropical japonica varieties were identified as heterotypes and excluded from the analysis of genetic polymorphism and phylogenetic relationship.The genetic similarity analysis revealed that aus was closer to indica in evolutionary, whereas aromatic was closer to temperate japonica and tropical japonica. Aus and aromatic were possibly transitional populations between indica and japonica. O. rufipogon had a closer relationship with indica than japonica. The mtDNA genetic polymorphism of O. saliva was29.6%, and that of wild rice was96.3%. The comparison of mtDNA genetic polymorphism in five O. sativa subpopulations was as follows:aromatic> aus> indica> temperate japonica> tropical japon ica.2. Genetic difference of13rice CMS linesBased on27loci (including SSVs and SNPs) on mtDNA, the13rice CMS lines were classified into eight groups:(Ⅰ) wild abortive CMS, Indonesian Shuitiangu CMS, K-CMS, Gang CMS, D-CMS and dwarf abortive CMS;(Ⅱ) Maxie-CMS;(Ⅲ) Honglian CMS;(Ⅳ) Boro Ⅱ CMS;(Ⅴ) Dianl-CMS;(Ⅵ) Liao-CMS;(Ⅶ) Lead CMS; and (Ⅷ) Chinese wild rice CMS. According to their pollen abortion phenotypes, groups Ⅰ and Ⅱ were classified as sporophytic CMS lines, the cytoplasmic genetic relationships among which were very close. They could have originated from similar, or even the same, cytoplasm donors. Groups Ⅳ-Ⅷ were categorised as gametophytic CMS lines, the cytoplasms of which differed from one another, with some having relatively far genetic relationships. All sporophytic CMS lines were indica-like. Except the Honglian CMS line, which was indica-like, all gametophytic CMS lines were japonica-like.Dianl-CMS was found to harbor the orf79gene, which causes Boro11CMS, whereas Liao-CMS had an orf79structure that does not result in Lead CMS. Therefore, we speculated that orf79is associated with Dianl-CMS but not with Liao-CMS. The atp6-orf79structure related to sterility was also found to experience multiple evolutionary turnovers.3. Expression of genes related to respiration in leaf color mutant with yellowish-green leavesThe expression of eight genes related to respiration of flag leaves in leaf color mutant Biao810S with yellowish-green leaves and its wild-type810S was compared at9and14o’clock on the same day. Compared with wild-type individual, expression levels of6/8and4/8genes in mutant were significantly lower at9and at14 respectively, and those of other genes were not significantly different. At10o’clock, cytochrome c oxidase activity in mutant was about50%of that in wild-type. These results revealed that respiration was weakened because less energy and organics were produced by photoreaction due to loss of chlorophyll. It was likely that Biao810S down-regultated some metabolisms consuming energy and organics, such as respiration, to compensate the loss of energy and organics.We also found that expression levels of6/8and7/8genes related to respiration in wild-type and mutant individuals were significantly higher at14than at9. It was possibly that respiration was enhanced because more energy and organics were produced by photoreaction with the increase of light intensity. It indicated that plants would control expression of many genes at any time in response to environmental and metabolic changes.