全基因组关联分析(GWAS)鉴定水稻氮素利用效率候选基因

【目的】挖掘水稻氮高效的种质和基因资源,揭示其分子机制和遗传效应,是当前水稻氮素利用效率(NUE)研究的重要内容和目标。【方法】为了鉴定与水稻NUE相关的变异位点和候选基因,我们收集了190份亚洲稻为关联群体,通过质量过滤和群体频率过滤筛选出3,934,195个高质量的单核苷酸多态性(SNPs)位点,在大田条件下设置低氮(N_(1),90kg/hm^(2))和常规氮(N_(2),180kg/hm^(2))水平,成熟期调查水稻剑叶叶宽在低氮和常规氮处理下的表型数据,结合FarmCPU和MLM模型进行全基因组关联分析(GWAS)。【结果】通过植株在不同氮水平下的叶宽表型数据,计算该群体在低氮和常规氮水平下的剑叶宽表型比值Q(N_(1)/N_(2)),Q值呈现正态分布的特征。对Q值进行全基因组关联分析,在12条染色体上共鉴定了100个显著位点,确定了39个候选QTLs,包括已克隆NUE相关基因OsNR1.2和OsNAC42。进一步鉴定了候选基因OsNR1.2和OsNAC42的优异单倍型和潜在的优势单倍型组合,为水稻NUE的改良提供了有价值的资源和信息。【结论】利用GWAS和单倍型分析,揭示了水稻剑叶叶宽在不同氮处理下的遗传基础,鉴定了与NUE相关的候选QTLs和基因,包括OsNR1.2和OsNAC42。通过组合单倍型分析,鉴定了两个基因的优势单倍型组合,为水稻NUE的改良提供了有价值的资源和信息。

Chlorophyllide-a Oxygenase 1(OsCAO1) Over-Expression Affects Rice Photosynthetic Rate and Grain Yield

Leaf color and photosynthesis are important factors for rice growth and development.Hence,improving the photosynthetic rate is an effective approach for increasing rice yield.We isolated a gene,chlorophyllide-a oxygenase 1(OsCAO1),which characterized a rice near-isogenic line named fgl(faded green leaf).

Genome-Wide Association Analysis and Allelic Mining of Grain Shape-Related Traits in Rice

Excavating single nucleotide polymorphisms (SNPs) significantly associated with rice grain shape and predicting candidate genes through genome-wide association study (GWAS) can provide a theoretical basis for discovery and utilization of excellent genetic resources in rice. Based on 16 352 SNPs, 161 natural indica rice varieties with various grain sizes in southern China were used for GWAS of grain shape-related traits, referring to grain length (GL), grain width (GW), 1000-grain weight (TGW), and grain length/width (GLW). Phenotypic statistics showed that coefficient of variation values for these four traits GL, GW, TGW and GLW were 9.92%, 9.09%, 20.20% and 16.38%, respectively. Each trait showed a normal distribution, and there was a certain correlation between these traits. Through general linear model correlation analysis, a total of 38 significant loci were identified, and a range of 100 kb upstream and downstream of the significant loci was identified as the candidate interval. On chromosome 3, GS3 and qGL3 were found to regulate GL. On chromosome 6, TGW6 and GW6a were found to regulate TGW. Also, some QTLs related to grain shape were found on chromosomes 5 and 9. Besides that, using sequenced 3K-germplasm resources, we found that there are 22 overlapped varieties between these two natural populations. Twenty-six SNPs and fourteen haplotypes were identified in five regions of GS3 genes. The detection of multiple candidate genes/QTLs within the candidate interval is beneficial for further excavation of superior rice genetic resources.

Identification of QTLs for Cadmium Tolerance During Seedling Stage and Validation of qCDSL1 in Rice

Cadmium(Cd)is a non-essential toxic metal that is harmful to plants.To investigate the genetic mechanism of Cd tolerance in rice,quantitative trait loci(QTLs)associated with Cd tolerance at the seedling stage were analyzed using a recombinant inbred line(RIL)population derived from a cross between PA64s and 93-11.A total of 36 QTLs associated with shoot length,root length,shoot dry weight,root dry weight and total dry weight were detected in Hangzhou and Lingshui of China.Among them,15 QTLs were identified under the control condition and 15 QTLs were identified under the Cd stress condition,and 6 QTLs for Cd tolerant coefficient were detected on chromosomes 1,3,7 and 9.The qCDSL1.1 and qCDSL1.2 were identified in Hangzhou and Lingshui,respectively,and had overlapping intervals on chromosome 1.To further confirm the effects of qCDSL1.1 and qCDSL1.2,we developed a chromosome segment substitution line(CSSL),CSSLqCDSL1,in 93-11 background harboring qCDSL1.1/qCDSL1.2 from PA64s.Compared to 93-11,CSSLqCDSL1 had increased shoot length under the Cd stress condition.These results pave the way for further isolation of those genes controlling Cd tolerance in rice and marker-assistant selection of rice elite varieties with Cd tolerance.

Cloning and Characterization of Protein Prenyltransferase Alpha Subunit in Rice

Protein prenylation plays a crucial role in plant development and stress response.We report the function of pren yltra nsferase a-sub unit in rice.Protein-protei n in teractions showed that the fam esyl-transferase(OsPFT)/geranylgeranyltransferase-l(OsPGGT l-a)protein interacted together with OsPFT-P and OsPGGT l-p.The a-and p-subunits of OsPFT formed a heterodimer for the transfer of a farnesyl group from famesyl pyrophosphate to the CaaX-box-containing peptide N-dansyl-GCVLS.Furthermore,the tissue expressi on patter ns of the OsPFT and OsPGGT I sub units were similar,and these sub units were localized in the cytoplasm and nucleus.Moreover,OsPFT/OsPGGT/-a-deletion homozygous rice mutants had a lethal phenotype,and the heterozygous mutants exhibited reduced pollen viability.These results indicated that prenylation plays an important role in rice development.

A Method for Effectively Overcoming Tight Functional Linkage Between Genes in Rice by CRISPR/Cas9 System

Anthocyanins are widely distributed in one or more parts of rice(Oryza sativa L.)plants,including seed coat,stigma,apiculus,leaf sheath and leaf blade,and are the main pigments used in rice to achieve different colors(Hou et al,2009;Aizza and Dornelas,2011).In rice,tissue-specific color traits(especially the color of apiculus,namely the lemma and palea of the spikelet)are not only important for rice variety identification but also important for linkage analysis and rice domestication research(Saitoh et al,2004;Fan et al,2007;Lin et al,2019).The apiculus color is controlled by the complementary functions of three pairs of dominant genes,C,A and P.Gene C(chromogen)is a pigment gene,which is the basic gene for producing pigments.Gene A(activator)activates gene C,converting the chromogen into anthocyanins,and gene P(purple)controls the distribution of anthocyanins in various organs(Reddy,1996;Sakamoto et al,2001).