| Weedy rice(Oryza sativa f.spontanea)is one of the most common malignant weeds acompany with cultivated rice,which was found growed in rice growing fields all over the world and hurled the development of rice.At present,there is no effective method and selective herbicide to control these weeds,mainly rely on manual extraction.Weedy rice and cultivated rice(Oryza sativa L.)belongs to the same AA genotypes,have the same physiological composition and morphological properties.Although weedy rice and cultivated rice are self pollinating,but they are not exist the reproductive disorders,can exchange their gene.Using weedy rice populations in China,to study drought tolerance and nature aging tolerance ability,it is beneficial to reveal the physiological mechanism of weedy rice in rice field,and also useful for breeding rice varieties with good adaptability and competition.Red pericarp is a major feature of weedy rice to distinguished with cultivated rice.But the red pigment which is proanthocyanidins,appear only in the mature seeds.Therefore,Rc、Rd are mainly gene to control the pericarp color of rice and will contribute to inspection work,and to control the rapid propagation of weedy rice.To analyze and control the correlation between Rc/Rd genotypes of anthocyanin accumulation and drought tolerance and anti-aging of weedy rice,and to provide some theoretical basis for further research on proanthocyanin accumulation and stress resistance.1.Drought tolerance of weedy rice populations during germination period across China.The growth environment of cultivated rice needs a lot of irrigation water,and drought stress can affect the growth of rice plants.Weedy rice populations and the corresponding cultivated rice germplasm in China were selected in 61 areas in China,and planted them in Jiangpu farm in 2013.After harvest,the seeds were added 20%PEG-6000 to simulate drought stress test,and set up the control group.We counted the number of germinated seed every day until the eighth days,and the root length,shoot length and coleoptile length were measured on the eighth day,calculated the drought response index and germination stress tolerance index.The results show that:1)Drought response index of germination rate、germination index、root length、shoot length、coleoptile length and germination stress tolerance index during germination period in weedy rice populations were significant higher than corresponding cultivated rice(P<0.01).The results showed that weedy rice populations have a better drought tolerance than corresponding cuitivated rice.2)The six indexes of weedy rice populations and the corresponding cultivated rice were negatively correlated with latitude(P<0.01).That means,the drought tolerance of weedy rice populations and the corresponding cultivated rice are decreased with increasing latitude.2.Nature aging in seed of weedy rice populations in China.Due to the aging,the yield of rice is affected,resulting in huge economic losses every year.Weedy rice populations and the corresponding cultivated rice germplasm in China were selected in 61 areas in China,and planted them in Jiangpu farm in 2013.The seeds harvested and then storaged,we did the germination experiment at the same time for four year.Make the break dormancy test and not break dormancy test,and test the activity of germinated rice seeds in fourth years.The results showed that:1)The germination rate of weedy rice populations and corresponding cultivated rice in China during the past four years decreased year by year.And the germination rate in third years were declined significantly faster than the second years.2)The germination rate of weedy rice populations in third and fourth years was significantly higher than corresponding cultivated rice(P<0.01).That is,the nature aging harmful of the weedy rice population was better than corresponding cultivated rice.3)the first year of breaking dormancy,increase the germination rate of weedy rice and cultivated rice,but in second year high temperature treatment to breaking dormancy were decreased the seed germination rate,so we konw high temperature to breaking dormancy on aging seeds will inhibited the vigour of seed.3.Rc/Rd genotype controlling pericarp color of weedy rice populations in China.Regulation of Rc and Rd genes on red pericarp of rice.When RcRd is present,it appears red;when Rcrd is present,it appears brown;when rcRd/rcrd is present,it is white.First from the Nanjing Agricultural University Laboratory of weedy rice germplasm resources,we selected 70 regions and a total of 1368 weedy rice samples in China,then removed the shell and statisticed the color of pericarp.We randomly selected 36 weedy rice samples from each of the 24 populations to carry out the full sequencing of the Rc and Rd genes,and then used the InDel markers and CAPS makers,according to the sequence of detection,and the Rc and Rd allele gene were counted.The results show that:1)There existed red(brown)color pericarp phenotype,and also white pericarp phenotype in these 1368 weedy rice samples.2)36 weedy rice samples of DNA gene sequencing results showed that Rc gene exists Rc and rc genotype,Rd gene only in Rd genotype.3)The PAGE gel experiment of 1368 weedy rice samples of weedy rice populations in China showed that there were a total of 9 Rc/Rd genotype.Mainly is RcRd genotype. |
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