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Previous studies have indicated that China is one of the domestication centres of Asian cultivated rice ( Oryza sativa), and common wild rice ( O. rufipogon) is the progenitor of O. sativa. However, the number of domestication times and the geographic origin of Asian cultivated rice in China are still under debate. In this study, 100 accessions of Asian cultivated rice and 111 accessions of common wild rice in China were selected to examine the relationship between O. sativa and O. rufipogon and thereby infer the domestication and evolution of O. sativa in China through sequence analyses of six gene regions, trn C-ycf6 in chloroplast genomes, cox3 in mitochondrial genomes and ITS, Ehd1, Waxy, Hd1 in nuclear genomes. The results indicated that the two subspecies of O. sativa (indica and japonica) were domesticated independently from different populations of O. rufipogon with gene flow occurring later from japonica to indica; Southern China was the genetic diversity centre of O. rufipogon, and the Pearl River basin near the Tropic of Cancer was the domestication centre of O. sativa in China. [ABSTRACT FROM AUTHOR]

A research was conducted on the pollen fertility of rice sterile lines D52S and D38S responsive to photoperiod during the sensitive stage under natural and controlled conditions. Bulk segregant analysis (BSA) and recessive class approach were applied to identify DNA markers that co-segregate with gene conferring male-sterility in D52S mutant rice. The results showed that in day-light higher or equal to 14.00 h, D52S and D38S rice pollen were fertile; however, they were sterile when day-length was less than 14.00 h. They were therefore considered to be short photo-periodic sensitive genic male sterile lines(Short PGMS lines). Under short day-light conditions, the pollen fertility segregation of F populations from crosses between D52S/Shuhui527 and D52S/Gui99showed 3:1 ratio of fertile to sterile plants suggestingthat male sterility in D52S was controlled by one recessive gene. Two markers RM244 and RM216 located on chromosome number 10 co-segregated completely with the rpms locus. The locus was mapped to the interval between SSR markers RM2571 (6.6 cM) and RM244 (4.6 cM). [ABSTRACT FROM AUTHOR]

We used the Affymetrix rice genome array to study the gene expression change in response to low- (T1 treatment), middle- (T2 treatment), and high-osmotic stresses (T3 treatment) in rice root at the transcription level. Our experiment results showed that osmotic stress could induce some genes in rice root with a total of 2,082 genes being regulated transcriptionally by at least one osmotic stress. There was little overlap between the genes responding to the low-, middle-, and high-osmotic stresses. A total of 190 transcripts overlapped among all three osmotic stress treatments with 112 genes being up-regulated and 78 transcripts being down-regulated. A total of 113, 159, and 132 transcription factors (TFs) transcripts were regulated at the transcription level by T1, T2, and T3 treatments, respectively, and the expression of 296 genes encoding TFs was changed in response to at least one osmotic stress treatment. 47, 49, and 32 TFs transcripts overlapped between T1 and T2, T1 and T3, and T2 and T3 treatments, and 20 TFs overlapped among all treatments. [ABSTRACT FROM AUTHOR]

To study the possibility of utilizing genetically engineered Leifsonia xyli subsp. cynodontis ( Lxc) as an endophytic bacterium in rice, we constructed an Escherichia coli–Lxc shuttle vector, pLGUS, containing a β-glucuronidase reporter gene, which was stable both in vitro and in vivo. Lxc grows and expresses the β-glucuronidase reporter gene in all parts of rice, except for seed. A 2-year field study using three rice varieties from China showed that Lxc inoculation did not have a negative effect on the growth and yield of any of these varieties. Therefore, Lxc has the potential to be used as a benign endophyte for the expression of foreign genes in rice. [ABSTRACT FROM AUTHOR]