Weedy red rice(Oryza sativa;WRR),a close relative of cultivated rice,is a highly competitive weed that commonly infests rice fields and can also naturally interbreed with rice.Useful genes for biotic stress have been ...Weedy red rice(Oryza sativa;WRR),a close relative of cultivated rice,is a highly competitive weed that commonly infests rice fields and can also naturally interbreed with rice.Useful genes for biotic stress have been maintained in WRR and can be explored for breeding.Here we describe genetic and physiological traits of WRR that can be beneficial in preventing major rice diseases.Rice blast,caused by the hemibiotrophic fungal pathogen Magnaporthe oryzae,and sheath blight disease,caused by the necrotrophic pathogen Rhizoctonia solani,are the two most damaging biotic stresses of rice.Many major and minor resistance genes and QTL have been identified in cultivated and wild rice relatives.However,novel QTL were recently found in the two major U.S.biotypes of WRR,blackhull-awned(BH)and strawhullawnless(SH),suggesting that WRR has evolved novel genetic mechanisms to cope with these biotic stresses.Twenty-eight accessions of WRR(PI 653412–PI 653439)from the southern USA were characterized and placed in the National Small Grains Collection,and are available for identification of novel genetic factors to prevent biotic stress.展开更多
Transgene escape from genetically modified (GM) rice into weedy rice via gene flow may cause undesired environmental consequences. Estimating the field performance of crop-weed hybrids will facilitate our understand...Transgene escape from genetically modified (GM) rice into weedy rice via gene flow may cause undesired environmental consequences. Estimating the field performance of crop-weed hybrids will facilitate our understanding of potential introgression of crop genes (including transgenes) into weedy rice populations, allowing for effective biosafety assessment. Comparative studies of three weedy rice strains and their hybrids with two GM rice lines containing different insect- resistance transgenes (CpTI or Bt/CpTI) indicated an enhanced relative performance of the crop-weed hybrids, with taller plants, more tillers, panicles, and spikelets per plant, as well as higher 1000-seed weight, compared with the weedy rice parents, although the hybrids produced less filled seeds per plant than their weedy parents. Seeds from the F1 hybrids had higher germination rates and produced more seedlings than the weedy parents, which correlated positively with 1000-seed weight. The crop-weed hybrids demonstrated a generally enhanced relative performance than their weedy rice parents in our field experiments. These findings indicate that transgenes from GM rice can persist to and introgress into weedy rice populations through recurrent crop-to-weed gene flow with the aid of slightly increased relative fitness in F1 hybrids.展开更多
Red rice Is an Interfertlle, weedy form of cultivated rice (Oryza sativa L.) that competes aggressively with the crop In the southern US, reducing yields and contaminating harvests. No wild Oryza species occur In No...Red rice Is an Interfertlle, weedy form of cultivated rice (Oryza sativa L.) that competes aggressively with the crop In the southern US, reducing yields and contaminating harvests. No wild Oryza species occur In North America and the weed has been proposed to have evolved through multiple mechanisms, Including "de-domestication" of US crop cultlvars, accidental introduction of Asian weeds, and hybridization between US crops and Asian wild/weedy Oryza strains. The phenotype of US red rice ranges from "crop mimics", which share some domestication traits with the crop, to strains closely resembling Asian wild Oryza species. Assessments of genetic diversity have Indicated that many weed strains are closely related to Asian taxa (Including indica and aus rice varieties, which have never been cultivated In the US, and the Asian crop progenitor O. ruflpogon), whereas others show genetic similarity to the tropical Japonica varieties cultivated In the southern US. Herein, we review what Is known about the evolutionary origins and genetic diversity of US red rice and describe an ongoing research project to further characterize the evolutionary genomlcs of this aggressive weed.展开更多
As one of the largest gene families, F-box domain proteins have important roles in regulating various devel- opmental processes and stress responses. In this study, we have investigated a rice F-box domain gene, MAIF1...As one of the largest gene families, F-box domain proteins have important roles in regulating various devel- opmental processes and stress responses. In this study, we have investigated a rice F-box domain gene, MAIF1. The MAIF1 protein is mainly localized in the plasma membrane and nucleus. MAIF1 expression is induced rapidly and strongly by abscisic acid (ABA) and abiotic stresses. MAIF1 expression is also induced in root tips by sucrose, independent of its hy- drolytic hexose products, glucose and fructose, and the plant hormones auxin and cytokinin. Overexpression of MAIF1 reduces rice ABA sensitivity and abiotic stress tolerance and promotes rice root growth. These results suggest that MAIF1 is involved in multiple signaling pathways in regulating root growth. Growth restraint in plants is an acclimatization strategy against abiotic stress, Our results also suggest that MAIF1 plays the negative role in response to abiotic stress possibly by regulating root growth.展开更多
文摘Weedy red rice(Oryza sativa;WRR),a close relative of cultivated rice,is a highly competitive weed that commonly infests rice fields and can also naturally interbreed with rice.Useful genes for biotic stress have been maintained in WRR and can be explored for breeding.Here we describe genetic and physiological traits of WRR that can be beneficial in preventing major rice diseases.Rice blast,caused by the hemibiotrophic fungal pathogen Magnaporthe oryzae,and sheath blight disease,caused by the necrotrophic pathogen Rhizoctonia solani,are the two most damaging biotic stresses of rice.Many major and minor resistance genes and QTL have been identified in cultivated and wild rice relatives.However,novel QTL were recently found in the two major U.S.biotypes of WRR,blackhull-awned(BH)and strawhullawnless(SH),suggesting that WRR has evolved novel genetic mechanisms to cope with these biotic stresses.Twenty-eight accessions of WRR(PI 653412–PI 653439)from the southern USA were characterized and placed in the National Small Grains Collection,and are available for identification of novel genetic factors to prevent biotic stress.
基金Supported by the Ministry of Science and Technology (2007CB10920206)the National Natural Science Foundation of China (30730066 and30871503)
文摘Transgene escape from genetically modified (GM) rice into weedy rice via gene flow may cause undesired environmental consequences. Estimating the field performance of crop-weed hybrids will facilitate our understanding of potential introgression of crop genes (including transgenes) into weedy rice populations, allowing for effective biosafety assessment. Comparative studies of three weedy rice strains and their hybrids with two GM rice lines containing different insect- resistance transgenes (CpTI or Bt/CpTI) indicated an enhanced relative performance of the crop-weed hybrids, with taller plants, more tillers, panicles, and spikelets per plant, as well as higher 1000-seed weight, compared with the weedy rice parents, although the hybrids produced less filled seeds per plant than their weedy parents. Seeds from the F1 hybrids had higher germination rates and produced more seedlings than the weedy parents, which correlated positively with 1000-seed weight. The crop-weed hybrids demonstrated a generally enhanced relative performance than their weedy rice parents in our field experiments. These findings indicate that transgenes from GM rice can persist to and introgress into weedy rice populations through recurrent crop-to-weed gene flow with the aid of slightly increased relative fitness in F1 hybrids.
基金Supported by the National Science Foundation Plant Genome Research Program (DBI-0638820). Publication of this paper is supported by the National Natural Science Foundation of China (30624808).Acknowledgements The authors thank David R. Gealy of the Dale Bumpers National Rice Research Center for his insightful comments on US red rice natural history and genetic diversity.
文摘Red rice Is an Interfertlle, weedy form of cultivated rice (Oryza sativa L.) that competes aggressively with the crop In the southern US, reducing yields and contaminating harvests. No wild Oryza species occur In North America and the weed has been proposed to have evolved through multiple mechanisms, Including "de-domestication" of US crop cultlvars, accidental introduction of Asian weeds, and hybridization between US crops and Asian wild/weedy Oryza strains. The phenotype of US red rice ranges from "crop mimics", which share some domestication traits with the crop, to strains closely resembling Asian wild Oryza species. Assessments of genetic diversity have Indicated that many weed strains are closely related to Asian taxa (Including indica and aus rice varieties, which have never been cultivated In the US, and the Asian crop progenitor O. ruflpogon), whereas others show genetic similarity to the tropical Japonica varieties cultivated In the southern US. Herein, we review what Is known about the evolutionary origins and genetic diversity of US red rice and describe an ongoing research project to further characterize the evolutionary genomlcs of this aggressive weed.
文摘As one of the largest gene families, F-box domain proteins have important roles in regulating various devel- opmental processes and stress responses. In this study, we have investigated a rice F-box domain gene, MAIF1. The MAIF1 protein is mainly localized in the plasma membrane and nucleus. MAIF1 expression is induced rapidly and strongly by abscisic acid (ABA) and abiotic stresses. MAIF1 expression is also induced in root tips by sucrose, independent of its hy- drolytic hexose products, glucose and fructose, and the plant hormones auxin and cytokinin. Overexpression of MAIF1 reduces rice ABA sensitivity and abiotic stress tolerance and promotes rice root growth. These results suggest that MAIF1 is involved in multiple signaling pathways in regulating root growth. Growth restraint in plants is an acclimatization strategy against abiotic stress, Our results also suggest that MAIF1 plays the negative role in response to abiotic stress possibly by regulating root growth.