水稻矮秆迟抽穗突变体d534的性状及其对赤霉素的敏感性分析

水稻半矮秆突变体在株型改良和高产育种中具有重要价值。前期通过辐射诱变籼稻品种五山丝苗(R534)获得了半矮秆且抽穗期延迟突变体d534,分析了d534的表型、遗传模式和GA3敏感性。大田性状分析发现,和野生型R534相比,d534的抽穗期延迟了7 d,株高下降了29.22 cm,降幅为26.86%。d534的穗及倒1至倒5节都明显缩短,长度分别为野生型的71.27%、68.75%、70.18%、85.17%、77.86%和71.18%,说明d534的目的基因调控穗及茎节的伸长。遗传分析发现,d534的矮化和迟抽穗性状受同一核基因控制,呈隐性遗传。内源GA3含量测定发现,一叶一心期d534茎中GA3含量为0.17 ng·g^(-1),比R534降低了60.47%,表明d534的矮化与内源GA3合成不足有关。用25和50 mg·L^(-1)外源GA3处理一叶一心期幼苗5 d,d534的株高比未处理组(0 mg·L^(-1)GA3)增加了71.76%和74.98%,且超过了未处理组R534的株高,说明外源GA3能回补d534的株高表型;qRT-PCR分析发现,与R534相比,d534茎和叶中OsGA20ox2和OsGA3ox2基因表达水平均显著下调,表明d534内源GA3合成不足可能与OsGA20ox2和OsGA3ox2基因表达水平下调有关。明确了d534是茎节缩短且内源GA3积累不足的矮化突变体,为解析d534半矮秆性状形成的生物学机理奠定了基础。

A 36 Mb terminal deletion of chromosome 2BL is responsible for a wheat semi-dwarf mutation

Reduced plant height is one of the most important traits related to lodging resistance and crop yield. The use of reduced height genes has been one of the main features in breeding modern high-yielding wheat varieties with less lodging. A spontaneous dwarf mutant DD399 was identified in a high yielding, gibberellic acid(GA)-insensitive, lodging-resistant variety Nongda 399(ND399). Significant differences in upper internode lengths between mutant DD399 and wild type ND399 were caused by reduced cell elongation. The plant height of ND399 × DD399 F_(1) hybrids was intermediate between the parents, indicating incomplete dominance or a dose–response effect of a reduced height gene. Plant height showed continuous distribution in the F_(2) population, and segregation distortion was observed among the 2292 F_(2:3) progenies. The reduced height mutation was characterized by Illumina 90 K iSelect SNP genotyping and bulked segregant RNA-Seq(BSR-Seq) analysis of the segregating population. A concentrated cluster of polymorphic SNPs associated with the reduced height phenotype was detected in the distal region of chromosome arm 2 BL. Co-segregation of reduced height phenotype with the clustered markers revealed a 36 Mb terminal deletion of chromosome 2 BL in mutant DD399.

Effect of Dominant Semi-Dwarf Gene on Plant Height and Its Related Traits and Sensitivity to Gibberellic Acid in Rice

Six pairs of tall and dwarf near-isogenic lines derived from a dominant semi-dwarf mutant （Y98149） were selected to study height expression and sensitivity to gibberellic acid （GA3）. The lengths of the 4-5th internode, the 3rd, 2nd, 1st internodes from the top and the panicle length in the six dwarf near isogenic lines were 97.2%, 53.3%, 65.1%, 61.9% and 94.7% of those in the six tall ones, respectively, indicating that the dominant semi-dwarfing gene significantly inhibited the internode elongation. Moreover, Y98149 （mutant type） was more sensitive to GA3 than Y98148 （wild type）, and had a lower GA3 concentration in plant, about 78% of Y98148.

In silico curation of QTL-rich clusters and candidate gene identification for plant height of bread wheat

Many genetic loci for wheat plant height(PH) have been reported, and 26 dwarfing genes have been catalogued. To identify major and stable genetic loci for PH, here we thoroughly summarized these functionally or genetic verified dwarfing loci from QTL linkage analysis and genome-wide association study published from 2003 to 2022. A total of 332 QTL, 270 GWAS loci and 83 genes for PH were integrated onto chromosomes according to their locations in the IWGSC RefSeq v2.1 and 65 QTL-rich clusters(QRC) were defined. Candidate genes in each QRC were predicted based on IWGSC Annotation v2.1 and the information on functional validation of homologous genes in other species. A total of 38 candidate genes were predicted for 65 QRC including three GA2ox genes in QRC-4B-IV, QRC-5A-VIII and QRC-6A-II(Rht24) as well as GA 20-oxidase 2(TaSD1-3A) in QRC-3A-IV. These outcomes lay concrete foundations for mapbased cloning of wheat dwarfing genes and application in breeding.

A dominant semi-dwarf mutant in rice

In the winter of 1997, a semi-dwarf mutant was found inthe F6 population of M9056/ R8018 xuan in HainanProvince. In the spring of 1998, the seeds were sown inHefei, Anhui Province and the plant height of the popula-tion was measured at maturity. Results showed that29. 4% of the plants had the same height as the high par-ent had, and 70. 6% remained semi-dwarf. In the winterof 1998, the reciprocal crosses between the remained se-mi-dwarf line and the two wild-type parental lines were

香猪垂体特异性转录因子基因及其相关基因表达水平的半定量分析

采用RT-PCR方法对香猪及对照猪种(上海白猪、大约克夏猪)PIT-1基因和相关基因(GH、PRL和TSH-β基因)的mRNA扩增,并以β-actin为内参照进行基因表达水平的半定量分析。结果表明,香猪PIT-1基因及GH、TSH-β基因的表达水平均显著低于上海白猪和大约克夏猪(P<0.05),香猪与上海白猪、大约克夏猪在PRL基因表达水平上的差异也接近显著水平。研究结果提示,香猪的PIT-1基因可能存在着突变,从而使其PIT-1基因的表达水平降低,减弱了PIT-1蛋白对于GH、PRL及TSH-β基因转录和表达的激活功能,导致香猪生长缓慢和矮小性。

粳稻半矮秆突变体Y98149的矮生性遗传研究

对粳稻半矮秆突变体 Y9814 9矮生性遗传研究的结果表明 :(1)控制半矮秆材料 Y9814 9矮生性表达的基因为一对显性核基因 ;(2 )该显性基因与控制 KL90 8矮生性表达的显性核基因及控制 AKs1- 10 8矮生性表达的隐性核基因sd- 1均非等位 ;(3)分析 F2 群体株高资料后认为 ,在 C0 78遗传背景下 ,可以检出在近等基因系遗传背景下无法检出的另一对显性主基因。文章还对有关问题进行了讨论。

Mapping and breeding value evaluation of a semi-dominant semidwarf gene in upland rice

Plant height is an important trait related to yield potential and plant architecture. A suitable plant height plays a crucial role in improvement of rice yield and lodging resistance. In this study, we found that the traditional upland landrace ＇Kaowenghan＇ （KWH） showed a special semi-dwarf phenotype. To identify the semi-dwarf gene from KWH, we raised BC2F4 semi-dwarf introgression lines （IL） by hybridization of the japonica rice cultivar ＇Dianjingyoul＇ （DJY1） and KWH in a DJY1 background. The plant height of the homozygous semi-dwarf IL （IL-87） was significantly reduced compared with that of DJY1. The phenotype of the F1 progeny of the semi-dwarf IL-87 and DJY1 showed that the semi-dwarf phenotype was semi- dominant. QTL mapping indicated that the semi-dwarf phenotype was controlled by a major QTL qDH1 and was localized between the markers RM6696 and RM12047 on chromosome 1. We also developed near-isogenic lines （NIL） from the BC3F3 population, and found that the yield of homozygous NIL （NIL-2） was not significantly different compared to DJY1. Breeding value evaluation through investigation of the plant height of the progeny of NIL （NIL-2） and cultivars from different genetic background indicate that the novel semi-dwarf gene shows potential as a genetic resource for rice breeding.

Elite sd1 alleles in japonica rice and their breeding applications in northeast China

The Green Revolution gene sd1 has been used extensively in modern rice breeding,especially in indica cultivars.However,elite sd1 alleles and related germplasm resources used for japonica rice breeding have not been identified,and extensive efforts are needed for japonica rice breeding to obtain new dwarfing sources.Data from MBKbase-Rice revealed seven sd1 haplotypes in indica and four in japonica rice.Two new sd1 alleles were identified in indica rice.In 295 japonica accessions from northeast Asia,except for the weak functional allele SD1-EQ,sd1-r was the major allele,reducing plant height in comparison with SD1-EQ.Japonica germplasm resources carrying reported sd1 alleles were identified by genotype searching and further verified by literature search,genealogical analysis,and d Caps markers.Pedigrees and geographic distribution showed that sd1-r is an excellent allele widely used in northern China and Tohoku in Japan,and sd1-j is commonly used in east China and Kyushu in Japan.Dongnong-and Xiushui-series cultivars carrying sd1-r and sd1-j,respectively,are essential branches of the backbone parents of Chinese japonica rice,Akihikari and Ce21,with the largest number of descendants and derived generations.In semi-dwarf japonica rice breeding,sd1-d was introgressed into Daohuaxiang 2(DHX2).Dwarf and semi-dwarf lines carrying sd1-d were selected and designated as 1279 and 1280,respectively,after withstanding typhoon-induced strong winds and heavy rains in 2020,and are anticipated to become useful intermediate materials for future genetic research and breeding.This work will facilitate the introduction,parental selection,and marker-assisted breeding,and provide a material basis for the next step in identifying favorable genes that selected together with the sd1 alleles in japonica backbone parents.

Effects of Growth Type,Sowing Date,and Sowing Rate on the Canopy Architecture,Protein Yields,and Oil Yields of Winter Oilseed Rape(Brassica napus L.)

A split-split-plot design was used to evaluate the effects of sowing dates and sowing rates on three winter rape cultivars,including‘PR45D03’,a semi-dwarf hybrid,‘PR46W31’,a traditional hybrid,and‘Californium’,an open-pollinated cultivar.August 25 was the optimal sowing date for maximizing protein and oil yields across all three cultivars.Of the cultivars,the traditional hybrid,‘PR46W31’,produced the highest protein and oil yields on that date.The yields of the semi-dwarf hybrid,‘PR45D03’,were greater than those of the open-pollinated cultivar,‘Californium’,when these were sown later than the optimal date.Protein and oil yields did not differ significantly among different seeding densities.

An orchestrated ethylene-gibberellin signaling cascade contributes to mesocotyl elongation and emergence of rice direct seeding

A mechanized direct seeding of rice with less labor and water usage,has been widely adopted.However,this approach requires varieties that exhibit uniform seedling emergence.Mesocotyl elongation(ME)offers the main drive of fast emergence of rice seedlings from soils;nevertheless,its genetic basis remains unknown.Here,we identify a major rice quantitative trait locus Mesocotyl Elongation1(qME1),an allele of the Green Revolution gene Semi-Dwarf1(SD1),encoding GA20-oxidase for gibberellin(GA)biosynthesis.ME1 expression is strongly induced by soil depth and ethylene.When rice grains are direct-seeded in soils,the ethylene core signaling factor OsEIL1 directly promotes ME1 transcription,accelerating bioactive GA biosynthesis.The GAs further degrade the DELLA protein SLENDER RICE 1(SLR1),alleviating its inhibition of rice PHYTOCHROME-INTERACTING FACTOR-LIKE13(OsPIL13)to activate the downstream expansion gene OsEXPA4 and ultimately promote rice seedling ME and emergence.The ancient traits of long mesocotyl and strong emergence ability in wild rice and landrace were gradually lost in company with the Green Revolution dwarf breeding process,and an elite ME1-R allele(D349H)is found in some modern Geng varieties(long mesocotyl lengths)in northern China,which can be used in the direct seeding and dwarf breeding of Geng varieties.Furthermore,the ectopic and high expression of ME1 driven by mesocotyl-specific promoters resulted in rice plants that could be direct-seeded without obvious plant architecture or yield penalties.Collectively,we reveal the molecular mechanism of rice ME,and provide useful information for breeding new Green Revolution varieties with long mesocotyl suitable for direct-seeding practice.

Genetic mapping of a new semi-dwarf gene,sd-t(t),in indica rice and estimating of the physical distance of the mapping region

Application and functional study of dwarf and semi-dwarf genes are of great importance to both crop breeding and molecular biology. A new semi-dwarf gene, sd-t(t), non-allelic to sd-1,had been identified in an indica rice variety, Aitaiyin 2. In this study the gene was genetically mapped by using an F2 population, which consisted of 474 individuals developed from a cross between Aitaiyin 2 and B30. The sd-t(t) gene was located between the RFLP markers R514 and R1408B with a distance of 1.1 cM to R514, and 4.5 cM to R1408B on chromosome 4. A physical contig covering the sd-t(t) mapping region was further constructed by screening a BAC library with R514 and R1408B as probes, and the physical distance between R514 and R1408B was estimated at approximately 147 kb. This result will facilitate map-based cloning of the sd-t(t) gene.

Shaping polyploid wheat for success:Origins,domestication,and the genetic improvement of agronomic traits

Bread wheat(Triticum aestivum L.,AABBDD,2 n=6 x=42),which accounts for most of the cultivated wheat crop worldwide,is a typical allohexaploid with a genome derived from three diploid wild ancestors.Bread wheat arose and evolved via two sequential allopolyploidization events and was further polished through multiple steps of domestication.Today,cultivated allohexaploid bread wheat has numerous advantageous traits,including adaptive plasticity,favorable yield traits,and extended end-use quality,which have enabled its cultivation well beyond the ranges of its tetraploid and diploid progenitors to become a global staple food crop.In the past decade,rapid advances in wheat genomic research have considerably accelerated our understanding of the bases for the shaping of complex agronomic traits in this polyploid crop.Here,we summarize recent advances in characterizing major genetic factors underlying the origin,evolution,and improvement of polyploid wheats.We end with a brief discussion of the future prospects for the design of gene cloning strategies and modern wheat breeding.

Investigation of CRISPR/Cas9-induced SD1 rice mutants highlights the importance of molecular characterization in plant molecular breeding

Although Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)/CRISPR-associated 9(Cas9)system has been widely used for basic research in model plants,its application for applied breeding in crops has faced strong regulatory obstacles,due mainly to a poor understanding of the authentic output of this system,particularly in higher generations.In this study,different from any previous studies,we investigated in detail the molecular characteristics and production performance of CRISPR/Cas9-generated SD1(semi-dwarf 1)mutants from T2 to T4 generations,of which the selection of T1 and T2 was done only by visual phenotyping for semidwarf plants.Our data revealed not only on-and off-target mutations with small or lager indels but also exogenous elements in T2 plants.All indel mutants passed stably to T3 or T4 without additional modifications independent on the presence of Cas9,while some lines displayed unexpected hereditary patterns of Cas9 or some exogenous elements.In addition,effects of various SD1 alleles on rice height and yield differed depending on genetic backgrounds.Taken together,our data showed that the CRISPR/Cas9 system is effective in producing homozygous mutants for functional analysis,but it may be not as precise as expected in rice,and that early and accurate molecular characterization and screening must be carried out for generations before transitioning of the CRISPR/Cas9 system from laboratory to field.