BUD2,encoding an S-adenosylmethionine decarboxylase,is required for Arabidopsis growth and development

Polyamines 在在植物，而是他们的准确角色调整各种各样的发展过程被含有并且他们怎么管理这些过程尚待逃犯。我们这里报导浓密的 Arabidopsis 和矮子异种， bud2，哪个从编码 S-adenosylmethionine decarboxylases (SAMDC ) 的小基因家庭的一个成员的完全的删除的结果为在 polyamine 简历的不可缺少的中介的形成必要合成小径。bud2 植物在开花期，根，和叶柄扩大了脉管的系统，并且 polyamines 的改变的动态平衡。bud2 和 samdc1 的双异种，另一个 SAMDC 成员的击倒的异种，是胚胎致命，证明 SAMDC 为植物胚胎开始是必要的。我们的结果建议 polyamines 为更高的植物的正常生长和发展被要求。

A snapshot of the Chinese SOL Project

In 2003, the International Solanaceae Project （SOL） was initiated by an international consortium of ten countries including Korea, China, the United Kingdom, India, the Netherlands, France, Japan, Spain, Italy and the United States. The first major effort of the SOL aimed to produce a DNA sequence map for euchromatin regions of 12 chromosomes of tomato （Solanum lycopersicum） before 2010. Here we present an update on Chinese effort for sequencing the euchromatin region of chromosome 3.

A complete assembly of the rice Nipponbare reference genome

Dear Editor,In 2005,the current commonly used rice reference genome(Oryza sativa ssp.japonica cv.Nipponbare)was initially released by the International Rice Genome Sequencing Project(International Rice Genome Sequencing Project,2005).Thereafter,the reference genome was further updated in 2013 with improved genome assembly(IRGSP-1.0)and gene annotations(MSU7,RAP-DB)(Kawahara et al.,2013;Sakai et al.,2013).In the past 10 years,this reference has been serving as one of the most important genetic resources for subsequent rice functional genomics efforts.As several rice genomes had been assembled into gapless chromosomes with only 2–5 telomeres absent(Li et al.,2021;Song et al.,2021;Zhang et al.,2022),the IRGSP1.0 and its annotations still performed as the most widely used reference.However,limitations of sequencing technology and intricate genomic organization led to an under-representation of complex regions in this reference,leaving a total of 72 major gaps(including 19 telomeres),167 minor gaps,and 779 unknown bases(Kawahara et al.,2013),with an estimated length of3%of the genome unsolved.

Activation of gibberellin 2-oxidase 6 decreases active gibberellin levels and creates a dominant semi-dwarf phenotype in rice (Oryza sativa L.)

Gibberellin （GA） 2-oxidase plays a key role in the GA catabolic pathway through 2β-hydroxylation.In the present study,we isolated a CaMV 35S-enhancer activation tagged mutant,H032.This mutant exhibited a dominant dwarf and GA-deficient phenotype,with a final stature that was less than half of its wild-type counterpart.The endogenous bioactive GAs are markedly decreased in the H032 mutant,and application of bioactive GAs （GA3 or GA4） can reverse the dwarf phenotype.The integrated T-DNA was detected 12.8 kb upstream of the OsGA2ox6 in the H032 genome by TAIL-PCR.An increased level of OsGA2ox6 mRNA was detected at a high level in the H032 mutant,which might be due to the enhancer role of the CaMV 35S promoter.RNAi and ectopic expression analysis of OsGA2ox6 indicated that the dwarf trait and the decreased levels of bioactive GAs in the H032 mutant were a result of the up-regulation of the OsGA2ox6 gene.BLASTP analysis revealed that OsGA2ox6 belongs to the class III of GA 2-oxidases,which is a novel type of GA2ox that uses C20-GAs （GA12 and/or GA53） as the substrates.Interestingly,we found that a GA biosynthesis inhibitor,paclobutrazol,positively regulated the OsGA2ox6 gene.Unlike the over-expression of OsGA2ox1,which led to a high rate of seed abortion,the H032 mutant retained normal flowering and seed production.These results indicate that OsGA2ox6 mainly affects plant stature,and the dominant dwarf trait of the H032 mutant can be used as an efficient dwarf resource in rice breeding.

Rice Functional Genomics Research： Past Decade and Future

Rice （Oryza sativa） is a major staple food crop for more than 3.5 billion people worldwide. Under- standing the regulatory mechanisms of complex agronomic traits in rice is critical for global food security. Rice is also a model plant for genomics research of monocotyledonso Thanks to the rapid development of functional genomic technologies, over 2000 genes controlling important agronomic traits have been cloned, and their molecular biological mechanisms have also been partially char- acterized. Here, we briefly review the advances in rice functional genomics research during the past 10 years, including a summary of functional genomics platforms, genes and molecular regulatory networks that regulate important agronomic traits, and newly developed tools for gene identification. These achievements made in functional genomics research will greatly facilitate the development of green super rice. We also discuss future challenges and prospects of rice functional genomics research.

ELE restrains empty glumes from developing into lemmas

Although there is evident homology among reproductive organs when comparing Poaceae （grass） and eudicots, the identity of grass specific organs, such as lodicules, palea, lemma, and glumes has been the subject of a vast and largely inconclusive discussion. Here we provide some direct evidence to support the idea that the empty glumes of rice （Oryza sativa） are counterparts of lemmas. We show that the development of empty glumes is regulated by ELE （elongated empty glume）, which belongs to a plant specific novel gene family. Mutations at the ELE locus cause elongated empty glumes, which mimic the lemmas and have the epidermal morphology of lemmas with four or five vascular bundles. As a nuclear-localized gene, ELE is specifically expressed at the empty glumes of immature spikelets, and its ectopic expression causes many floral development defects, including lemma-like palea, extra palea-like structures, elongated lodicules, extra stamens and stigmas. Our result suggests that empty glumes are lemmas of the sterile florets located at the lateral side of the rice spikelet, and ELE acts as a regulator restraining its growth to maintain its small size in wild-type plants.

Characterization and Fine Mapping of the ibf Mutant in Rice

The pigment Is an important character in plant development. In the present study, we characterized and fine mapped one Inhibitor for brown furrows gene （ibf） in rice （Oryza sativa L.）. In the ibf mutant, brown pigments specifically accumulate in the furrows of hulls as seeds mature and reach a maximum level In dry seeds. Genetic analysis showed that the mutant phenotype is controlled by one recessive nuclear gene, which was finally mapped In a 90-kb region on the long arm of chromosome 9. Polymerase chain reaction and Southern blotting analysis revealed that there was a 26 kb deletion in the 90-kb region in the mutant. Since all the open reading frames outside the gap In the delimited region had no detectable difference in DNA sequence with the wild-type, we postulated that the ibf locus should be located in the gap. Through gene annotation and reverse transcription-polymerase chain reaction （RT-PCR） analysis, we selected OsKF1 encoding a kelch repeat-containing F-box family protein as the candidate gene of ibf.

Ten Years of Gene Discovery for Meiotic Event Control in Rice

Meiosis is the crucial process by which sexually propagating eukaryotes give rise to haploid gametes from diploid cells. Several key processes, like homologous chromosomes pairing, synapsis, recombination, and segregation, sequentially take place in meiosis. Although these widely conserved events are under both genetic and epigenetic control, the accurate details of molecular mechanisms are continuing to investigate. Rice is a good model organism for exploring the molecular mechanisms of meiosis in higher plants. So far, 28 rice meiotic genes have been characterized. In this review, we give an overview of the discovery of rice meiotic genes in the last ten years, with a particular focus on their functions in meiosis.

A strategy for generating rice apomixis by gene editing

Apomixis is an asexual reproduction way of plants that can produce clonal offspring through seeds.In this study,we introduced apomixis into rice(Oryza sativa)by mutating OsSPO11-1,OsREC8,OsOSD1,and OsMATL through a CRISPR/Cas9 system.The quadruple mutant showed a transformation from meiosis to mitosis and produced clonal diploid gametes.With mutated Osmatl,which gives rise to haploid induction in plants,the quadruple mutant is expected to be able to be produced apomictic diploid offspring.We named this quadruple mutant as AOP(Apomictic Offspring Producer)for its ability to produce apomictic offspring.

The Role of OsMSH5 in Crossover Formation during Rice Meiosis

MSH5, a meiosis-specific member of the MutS-homolog family, is required for normal level of recombination in budding yeast, mice, Caenorhabditis elegans, and Arabidopsis. Here, we report the identification and characterization of its rice homolog, OsMSH5, and demonstrate its function in rice meiosis. Five independent Osmsh5 mutants exhibited normal vegetative growth and severe sterility. The synaptonemal complex is well installed in Osmsh5, while the chiasma frequency is greatly reduced to approximately 10% of that observed in the wild-type, leading to the homologous non- disjunction and complete sterile phenotype. OsMSH5 is predominantly expressed in panicles. Immunofluorescence studies indicate that OsMSH5 chromosomal localization is limited to the early meiotic prophase I. OsMSH5 can be loaded onto meiotic chromosomes in Oszip4, Osmer3, and hellO. However, those ZMM proteins cannot be localized normally in the absence of OsMSH5. Furthermore, the residual chiasmata were shown to be the least frequent among the zmm mutants, including Osmer3, Oszip4, hellO, and Osmsh5. Taken together, we propose that OsMSH5 functions upstream of OsZIP4, OsMER3, and HEIl0 in class I crossover formation.

Genome architecture and tetrasomic inheritance of autotetraploid potato

Potato(Solanum tuberosum)is the most consumed non-cereal food crop.Most commercial potato cultivars are autotetraploids with highly heterozygous genomes,severely hampering genetic analyses and improvement.By leveraging the state-of-the-art sequencing technologies and polyploid graph binning,we achieved a chromosome-scale,haplotype-resolved genome assembly of a cultivated potato,Cooperation-88(C88).lntra-haplotype comparative analyses revealed extensive sequence and expression differences in this tetraploid genome.We identified haplotype-specific pericentromeres on chromosomes,suggesting a distinct evolutionary trajectory of potato homologous centromeres.Furthermore,we detected double reduction events that are unevenly distributed on haplotypes in 1021 of 1034 selfing progeny,a feature of autopolyploid inheritance.By distinguishing maternal and paternal haplotype sets in C88,we simulated the origin of heterosis in cultivated tetraploid with a survey of 3110 tetra-allelic loci with deleterious mutations,which were masked in the heterozygous condition bytwo parents.This study provides insights into the genomic architecture of autopolyploids and will guide their breeding.

From Basic Research to Molecular Breeding——Chinese Scientists Play A Central Role in Boosting World Rice Production

On November 18, 2018, the Future Science Prize Awarding Ceremony was held in Beijing. In the area of life science, Professors Jiayang Li, Longping Yuan, and Qifa Zhang shared the prize for their pioneering contributions in producing high-yield, superior-quality rice through systematic study of molecular mechanisms associated with speci?c rice features and application of novel approaches in rice breeding. The Future Science Prize is also touted as ‘‘China’s Nobel Prize", fully af?rming their achievements in rice basic research and breeding.

A near-complete assembly of an Arabidopsis thaliana genome

The genome sequence of Arabidopsis thaliana,a widely adopted model species,has greatly expedited plant molecular biology research.Over 20 years after the first release of the genome sequence(Arabidopsis Genome Initiative,2000),there remains unresolved gap regions that are presumably composed of highly repetitive sequences,such as telomeres,centromeres,5S rDNA clusters,and nucleolar organizerregions(NORs)containing 45S rDNA.

Extensive sequence divergence between the reference genomes of Taraxacum kok-saghyz and Taraxacum mongolicum

Plants belonging to the genus Taraxacum are widespread all over the world,which contain rubber-producing and non-rubberproducing species.However,the genomic basis underlying natural rubber(NR)biosynthesis still needs more investigation.Here,we presented high-quality genome assemblies of rubber-producing T.kok-saghyz TK1151 and non-rubber-producing T.mongolicum TM5.Comparative analyses uncovered a large number of genetic variations,including inversions,translocations,presence/absence variations,as well as considerable protein divergences between the two species.Two gene duplication events were found in these two Taraxacum species,including one common ancestral whole-genome triplication and one subsequent round of gene amplification.In genomes of both TK1151 and TM5,we identified the genes encoding for each step in the NR biosynthesis pathway and found that the SRPP and CPT gene families have experienced a more obvious expansion in TK1151 compared to TM5.This study will have large-ranging implications for the mechanism of NR biosynthesis and genetic improvement of NR-producing crops.

DsMTOPVIB Promotes Meiotic DNA Double-Strand Break Formation in Rice

Dear Editor,Meiotic recombination is initiated by the generation of DNA double-strand breaks （DSBs）, which are catalyzed by the Spo11 protein （de Massy, 2013）. Two key findings point to the role of Spo11 as the initiator of DSB formation in budding yeast： （1） Spo11 is linked to the 5＇ termini of the broken DNA molecules in rad50s mutants, whose meiosis has been blocked at the stage of the cleavaqe reaction （＇Keenev et al., 1997）.

A functional centromere lacking CentO sequences in a newly formed ring chromosome in rice

An awned rice（Oryza sativa） plant carrying a tiny extra chromosome was discovered among the progeny of a telotrisomic line 2nt4L. Fluorescence in situ hybridization（FISH） using chromosome specific BAC clones revealed that this extra chromosome was a ring chromosome derived from part of the long arm of chromosome 4. So the aneuploidy plant was accordingly named as 2nt4L ring. We did not detect any Cent O FISH signals on the ring chromosome, and found only the centromeric probe Centromeric Retrotransposon of Rice（CRR） was co-localized with the centromere-specific histone CENH3 as revealed by sequential FISH after immunodetection. The extra ring chromosome exhibited a unique segregation pattern during meiosis, including no pairing between the ring chromosome and normal chromosome 4during prophase I and pre-separation of sister chromatids at anaphase I.

Microdissection and amplification of the chromosome arm 5S in a rice telo-tetrasomic

The rice aneuploids with telochromosomes are ideal genetic stocks for chromosome arm identification and microdissection. A rice telo-tetrasomic line with two extra short arms of chromosome 5 (5S) was used in the present study. The arms of 5S were microdissected from the prometaphase cells in mitosis and amplified with linker adaptor PCR (LA-PCR). The amplified fragments, ranging from 200-3000 bp, were confirmed to be from the rice chromosome arm 5S by the rice STS and microsatellite markers.