Genetic dissection of wheat uppermost-internode diameter and its association with agronomic traits in five recombinant inbred line populations at various field environments

Uppermost-internode diameter (UID) is a key morphological trait associated with spike development and yield potential in wheat. Our understanding of its genetic basis remains largely unknown. Here, quantitative trait loci (QTLs) for UID with high-density genetic maps were identified in five wheat recombinant inbred line (RIL) populations. In total, 25 QTLs for UID were detected in five RIL populations, and they were located on chromosomes 1A, 1D (3 QTL), 2B (2), 2D (3), 3B, 3D, 4A, 4B (3), 4D, 5A (5), 5B (2), 6B, and 7D. Of them, five major and stable QTLs (QUid.sau-2CN-1D.1, QUid.sau-2SY-1D, QUid.sau-QZ-2D, QUid.sau-SC-3D, and QUid.sau-AS-4B) were identified from each of the five RIL populations in multiple environments. QUid.sau-2CN-1D.1, QUid.sau-2SY-1D and QUid.sau-SC-3D are novel QTLs. Kompetitive Allele Specific PCR (KASP) markers tightly linked to them were further investigated for developing near-isogenic lines (NILs) carrying the major loci. Furthermore, candidate genes at these intervals harboring major and stable QTLs were predicted, and they were associated with plant development and water transportation in most cases. Comparison of physical locations of the identified QTL on the ‘Chinese Spring’ reference genome showed that several QTLs including two major ones, QUid.sau-2CN-1D.1 and QUid.sau-2SY-1D, are likely allelic confirming their validity and effectiveness. The significant relationships detected between UID and other agronomic traits and a proper UID were discussed. Collectively, our results dissected the underlying genetic basis for UID in wheat and laid a foundation for further fine mapping and map-based cloning of these QTLs.     

小麦幼苗根系性状的QTL分析

 以小麦DH群体（旱选10号×鲁麦14）为材料，在水分胁迫及非胁迫两种条件下考察水培幼苗的单株根数、最大根长、根鲜重、根干重、根茎鲜重比及根茎干重比等根系性状。应用基于混合线性模型的复合区间作图法分析幼苗根系性状的QTL，以及基因与环境的互作。共检测到11个加性效应QTL和15对上位性互作QTL，分布在除5A、4B、2D、6D和7D以外的所有染色体上。其中3个加性效应QTL和2对上位性效应QTL控制根数；3个加性效应QTL和3对上位性效应QTL控制最大根长；2个加性效应QTL和2对上位性效应QTL控制根鲜重；2个加性效应QTL和3对上位性效应QTL影响根干重；2对上位性效应QTL控制根茎鲜重比；1个加性效应QTL和3对上位性效应QTL与根茎干重比有关。同时还分别检测到1个加性效应QTL、3对上位性效应QTL与水分环境的互作效应。对应用分子标记辅助选择幼苗抗旱优良根系性状的可能性进行了讨论。     

水稻苗期生长特性的遗传剖析

 以1个水稻重组自交系为作图群体进行盆栽试验，分别在播种后第14、24、34和44天进行第1、2、3和第4次取样，考察秧苗苗高和干物重以及播种前所用种子的千粒重。结合1张高密度的遗传图谱，对性状进行复合区间作图，分别检测到控制秧苗干物重、苗高和种子千粒重的主效应QTL 6、14和3个。其中，位于3号染色体RM148-RM85区段的QTL qGC-3-3同时影响第4期干物重和第1、3和4期苗高，且其对苗高的效应呈逐期递增的趋势。与qGC-3-3相反，位于5号染色体RM163-RM161区段的QTL qGC-5 同时影响第1～3期的干物重和苗高，但其效应由强趋弱。在第1～4期中，秧苗干物重与苗高的相关系数分别为0.60～.70，为极显著（P<0.01）正相关。秧苗干物重和苗高与种子千粒重的相关性均呈逐期递减的趋势、以至于到后期相关性较弱或不显著。QTL定位结果表明，对种子千粒重效应最大的QTL正是上述5号染色体上的qGC-5，该QTL对这3个相关性状的效应方向均一致，但对秧苗干物重和苗高的效应大小是逐期递减。将本研究中定位到的QTL与已报道的利用同一定位群体所检测到的籽粒产量性状QTL相比较，发现有的QTL（如3号染色体上的QTL qGC-3-1和qGC-3-3）尽管在水稻生育早期的效应较小，但其效应随着生育进程的发展而逐期递增，且加性效应的方向在全生育期一致；有的QTL（如5号染色体上的qGC-5）在水稻生育早期的效应相对较大，但其效应逐期减弱，以至于对生育后期的生长发育和产量性状没有直接影响或影响很小。这些QTL的表达具有较强的时期特异性。     

Fine Mapping of qTGW3-1, a QTL for 1000-Grain Weight on Chromosome 3 in Rice

The QTL qTGW3-1 was located on chromosome 3 of rice (Oryza sativa L.) and associated with the 1000-grain weight (TGW) according to the result of our earlier study. With the objective of fine mapping of this locus, we developed a F₂ population consisting of 3 428 plants derived from the cross between TGW-related near isogenic line DL017 (BC₃F₄ generation of GSL156×Nipponbare) and the recurrent parent Nipponbare. Using six microsatellites, this QTL was delimited between RM5477 and RM6417. Markers MM1455 and MM1456 within this region were used for further mapping of this QTL. Finally, qTGW3-1 was fine-mapped into a 89-kb interval between RM5477 and MM1456, which locates in the BAC clone AC107226 harboring five putative candidate genes.     

A major and stable QTL for wheat spikelet number per spike validated in different genetic backgrounds

The spikelet number per spike (SNS) contributes greatly to grain yield in wheat. Identifying various genes that control wheat SNS is vital for yield improvement. This study used a recombinant inbred line population genotyped by the Wheat55K single-nucleotide polymorphism array to identify two major and stably expressed quantitative trait loci (QTLs) for SNS. One of them (QSns.sau-2SY-2D.1) was reported previously, while the other (QSns.sau-2SY-7A) was newly detected and further analyzed in this study. QSns.sau-2SY-7A had a high LOD value ranging from 4.46 to 16.00 and explained 10.21–40.78% of the phenotypic variances. QSns.sau-2SY-7A was flanked by the markers AX-110518554 and AX-110094527 in a 4.75-cM interval on chromosome arm 7AL. The contributions and interactions of both major QTLs were further analyzed and discussed. The effect of QSns.sau-2SY-7A was successfully validated by developing a tightly linked kompetitive allele specific PCR marker in an F_2:3 population and a panel of 101 high-generation breeding wheat lines. Furthermore, several genes including the previously reported WHEAT ORTHOLOG OF APO1 (WAPO1), an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1) related to SNS, were predicted in the interval of QSns.sau-2SY-7A. In summary, these results revealed the genetic basis of the multi-spikelet genotype of wheat line 20828 and will facilitate subsequent fine mapping and breeding utilization of the major QTLs.     

盐、碱胁迫条件下粳稻Na~+、K~+浓度的QTL分析

【目的】水稻栽培区土壤的盐、碱化日趋严重,植物体内Na+、K+浓度及Na+/K+是植物耐盐、碱性重要指标。在盐、碱胁迫条件下检测水稻苗期地上部和根部的Na+、K+浓度及Na+/K+的QTL位点,为水稻的耐盐、碱性遗传机制及分子标记辅助育种提供理论依据。【方法】以优质高产水稻品种东农425与耐盐、碱水稻品种长白10为亲本构建重组自交系(RIL)为作图群体,利用102对SSR标记构建遗传连锁图谱,该图谱覆盖水稻基因组约1 915.05 c M,标记间平均距离为18.77 c M;在140 mmol·L-1 Na Cl盐胁迫和0.15%Na2CO3碱胁迫处理条件下,对水稻苗期地上部和根部的Na+、K+浓度及Na+/K+等性状进行测定,利用SPSS v19.0对各性状进行相关分析,并采用QTL Ici Mapping v3.3的完备区间作图法(ICIM)进行QTL定位。【结果】盐、碱胁迫条件下,亲本及RIL群体地上部Na+、K+浓度均高于地下部Na+、K+浓度,各性状在RIL群体中基本符合正态分布,表现出典型的数量性状遗传特征,符合QTL定位要求。相关分析结果表明,盐、碱胁迫条件下,地上部Na+与K+及根部Na+与K+均呈极显著正相关,2种胁迫条件下的各性状相关性不显著。盐、碱胁迫条件下共检测到15个与Na+、K+浓度和Na+/K+相关的QTL,2种条件下所检测到的QTL位于不同染色体区域。在盐胁迫下共检测到5个QTL,包括1个与地上部K+浓度相关QTL,位于第8染色体的RM1308—RM281区间内,贡献率为6.83%;3个与根部Na+浓度相关QTL,位于第3和第8染色体上,其中q SRNC3-1贡献率最大,为16.41%;1个与根部K+浓度相关QTL,贡献率为3.52%;未检测到与地上部Na+浓度、Na+/K+及根部Na+/K+相关的QTL。在碱胁迫下共检测到10个QTL,包括1个与地上部Na+浓度相关的QTL,位于第2染色体的RM1347—RM48区间内,贡献率为14.41%;1个与地上部K+浓度相关QTL,位于第2染色体的RM1255—RM213区间内;3个与地上部Na+/K+相关QTL,分别位于第2、7、10染色体上,其中q ASNK2贡献率最大,为7.57%;1个与根部Na+浓度相关QTL,位于第3染色体的RM293—RM232区间内,贡献率为13.71%;2个与根部K+含量相关QTL,分别位于第1染色体的RM5—RM9和第2染色体的RM12865—RM12941区间内;2个与根部Na+/K+相关QTL,分别位于在第3和第4染色体上,其中q ARNK3贡献率较大,为10.48%。通过比较图谱发现,本研究中的大部分QTL与以往不同群体中影响耐盐、碱相关性状的QTL定位在同一或相邻的染色体区域,另外在碱胁迫下所检测到的q ASKC2和q ARKC2在前人研究中未见报道,可能存在新的耐碱性位点。【结论】在盐、碱胁迫条件下,Na+、K+的吸收和运输均是平行而独立的过程,且根部对Na+和K+的吸收与向地上部运输存在不同的遗传机制;盐、碱胁迫条件下,水稻Na+、K+浓度的遗传是相互独立的。     

浮床植物芦苇在长江口水域的生长特性及对氮、磷的固定能力

以芦苇为浮床植物,在长江口青草沙水库下游水域构建人工生态浮床,研究了芦苇的生长特性和氮磷固定能力。结果表明,在实验期间(2013年5-7月),浮床芦苇的平均密度逐月增加,5月份最低为(25.6±2.5)株/m2,7月份最高达到(100.7±15.3)株/m2。相应地,浮床芦苇的平均株高也逐月增加,5月份最低为(2.6±1.4)cm,7月份最高为(55.0±15.5)cm。不同月份间植株密度和植株高度都存在显著性差异(P0.05),芦苇密度与株高高度正相关(R=0.904)。浮床芦苇单位面积鲜重为(0.212±0.045)kg/m2,干重为(0.063±0.013)kg/m2;植株体内的总氮含量为(1.33±0.03)mg/g,总磷含量为(0.27±0.01)mg/g;浮床芦苇单位面积总氮固定量为(83.67±17.01)mg/m2,总磷固定量为(17.33±4.16)mg/m2。     

玉米茎秆相关性状多效性QTL检测及相应R程序包编制

利用回归分析、似然比检验、排列检验、参数自助检验和交叉验证等统计分析方法,构建了多系杂交群体多性状QTL定位模型,并编制了配套的R语言程序包,该套模型和R程序包同样适用于两系杂交群体QTL检测和多效性QTL分析。基于本研究的模型和R程序包,以玉米自交系B73和高油突变体Ce03005为亲本产生的216个RIL群体为研究材料,对玉米茎秆相关性状进行多效性QTL检测分析,结果表明:Bin5.03区域内调控最大折断力矩MF和节间直径d的QTL,Bin6.01区域内调控单位体积中性洗涤纤维NDF和节间含水量Wwc的QTL,Bin8.03区域内影响节间干重WD和MF的QTL均为多效性QTL;在5号染色体上,调控d和NDF的QTL与调控MF和NDF的QTL均为连锁的QTL。本研究不仅为玉米茎秆性状的遗传改良提供了参考,也为其他作物遗传育种研究过程中多效性QTL检测提供了软件分析平台。     

Interaction between CO<Subscript>2</Subscript> elevation and nitrogen metabolism in two varieties of Guar (<Emphasis Type="Italic">Cyamopsis tetragonoloba</Emphasis>) plants

The aim of the experimental study is to analyse the consequence of carbon dioxide elevation on activity of nitrate reductase (NR; EC 1.6.6.1), nitrite reductase (NiR; EC 1.7.7.1), glutamate synthetase (GOGAT; EC 1.4.1.13) in leguminous Cyamopsis tetragonoloba leaves. Plants were exposed to different atmospheric carbon dioxide concentrations 300 ppm (ambient) and 490 ppm (an elevated) conditions. A decrease in activity of Nitrate Reductase (NR), Nitrite Reductase (NiR), Glutamate Synthetase (GOGAT) was found in elevated condition when compared to ambient condition. Plant nitrogen on dry weight basis was found to decrease under elevation with no significant change in soil nitrogen. Soil pH was found to change significantly under elevation, thus showing a decline in pH and promoting soil acidiosis. Total plant fresh weight (FW) and total plant dry weight (DW), Leaf area/cm² were found increased in elevated condition. Thus, in Cyamopsis tetragonoloba plant it can be concluded that under carbon dioxide elevation Nitrate reductase, Nitrite reductase and Glutamate synthetase activity is suppressed due to a reduced amount of nitrate translocation and NADH availability for reduction in plant which is correlated with reduction in plant total nitrogen content where as plant growth and biomass is enhanced due to higher carbon fixation.     

利用重组自交系群体检测水稻种子休眠性数量性状位点

利用由 191个家系组成的密阳 2 3/秋光重组自交家系 (recombinantinbredlines,RIL)F10 代群体 ,进行种子休眠性数量性状基因座 (quantitativetraitlocus,QTL)的检测和遗传效应分析。以抽穗后 35d的种子发芽率作为种子休眠性的表型值 ,分析亲本和 191个RIL的休眠性表现。通过WinQTLCart软件分析 ,检测到分别位于第 5和第 8染色体上的 2个水稻种子休眠性QTL ,其中位于第 8染色体上QTL的加性效应为负值 ,表明该休眠性基因位点来源于亲本秋光 ;第 5染色体上QTL的加性效应为正值 ,表明该休眠性减效基因来源于亲本密阳 2 3。     

Comparative mapping of QTLs for H+ secretion of root in maize (Zea mays L.) and cross phosphorus levels on two growth stages

H⁺ is a root secretion that affects P acquisition and P-use efficiency (PUE) under deficient phosphorus in maize. The secretion of H⁺, difference value of H⁺ between deficient and normal phosphorus (DH), and relative H⁺ (RH) as well as the quantitative trait loci (QTLs) associated with these traits were determined for a F_2:3 population derived from the cross of two contrasting maize (Zea mays L.) genotypes, 082 and Ye107. By using composite interval mapping (CIM), a total of 14, 8, and 9 distinct QTLs were identified for H⁺, DH, and RH, respectively. Most loci of QTLs for traits H⁺, DH, and RH had different cross environments. It showed that H⁺ secretion possessed an environment-sensitive and multi-gene nature. The gene × environment interaction was actually reflected by H⁺ secretion. One region for QTL of trait H⁺ was detected at the interval of bnlg2228-bnlg100 (bin 1.08) on chromosome 1. Coincident QTLs in the important genomic region reflected the cross phosphorus levels, different cross growth stages, and two different cross environments. The QTL explained 10% to 14% total phenotypic variance of H⁺. Therefore, the above segment (bnlg2228-bnlg100) (bin 1.08) identified on chromosome 1 may be used in the future for MAS to improve the phosphorus efficiency in maize.     

NaCl胁迫对黄瓜幼苗生长及抗氧化系统的影响

采用砂培法研究了NaCl对黄瓜幼苗生长及细胞膜抗氧化系统的影响。结果表明,低盐浓度(45～90mmol.L-1)胁迫5 d和3 d对黄瓜幼苗的干重、鲜重、根系活力和盐害指数影响不大。但随NaCl胁迫时间延长,干重、鲜重和根系活力降低,盐害指数增高;高浓度(180 mmol.L-1)明显抑制了黄瓜幼苗生长。NaCl胁迫下,电解质渗透率、SOD活性和MDA含量上升,膜脂过氧化作用加强。     

Genetic analysis seedling vigour under osmotic stress in rice by QTL mapping

Seed vigour is one of the most important parameters for establishing rice seed that affects high yielding production, especially under stress condition in rice (Oryza sativa L.). Improvement of rice yields under abiotic stress through breeding requires a good understanding of genetic factors controlling important traits such as seedling vigour and related traits. To understand the genetic background of the relationships among these traits in indicia rice, we genetically analyzed F2:3 population derived from a cross between Tarommahalli × Khazar, under osmotic stress caused by sorbitol. In this investigation, a simple sequence repeat (SSR) linkage map of 1231.50 cM of rice was constructed by using 74 markers and quantitative trait loci (QTL) analysis was accomplished for eight traits including germination percent, seed germination rate, radicle length, plumule length, coleoptile length, radicle dry matter, plumule dry matter, and coleoptile dry matter. A total of 32 QTLs were identified for the eight traits. Among them, one QTL for percent of germination (qGP-8) was located in RM6208-8264 on chromosome 8 showed large effect (28.99%) on the trait. These results suggest the potential for increase productivity by transferring osmotic stress tolerance gene from Tarommahalli to other rice lines and identification of QTLs with large effects could be considered for use in marker assisted selection (MAS).     

硅铁施用对水稻生长及磷吸收的影响

为探讨硅铁施用对水稻生长和磷吸收的影响,指导合理施肥、提高磷素利用率,利用水培试验研究了不同浓度铁（0、0.5、1、2 mmol·L^-1）预处理下施加不同浓度硅（0、1、4 mmol·L^-1）对水稻生长及磷吸收的影响。结果表明,低浓度的铁预处理对水稻SPAD、株高、根长和地上部干质量无显著影响,而高浓度的铁预处理下,这些指标则显著降低（P<0.05）。中低浓度铁处理下施硅在一定程度上增加了水稻株高、根长和地上部干质量,但未达到显著水平（P>0.05）。铁预处理显著增加了水稻根表铁膜的厚度及根表铁膜中的磷含量（P<0.05）,施硅则显著降低了0.5 mmol·L^-1和1 mmol·L^-1铁预处理的水稻根表铁膜的厚度（P<0.05）。铁预处理对水稻根部的磷含量无显著影响,但显著降低了地上部磷的含量（P<0.05）。施硅对水稻根和地上部的磷含量无显著影响。研究表明,施铁处理显著诱导了根表铁膜的出现,增加了铁膜中的磷含量并且显著降低了地上部的磷含量;施硅在一定程度上缓解了水稻生长中的铁毒害现象,并且能够改变根表铁膜厚度,减少根冠比,从而影响水稻磷的吸收转运。     

红麻6个重要产量性状的QTL定位

 【目的】研究红麻重要产量性状的QTL定位,促进红麻分子辅助育种基础科学研究。【方法】以埃及的阿联红麻与福建农林大学育成的高产抗病优质新品种福红992作为亲本进行杂交,自交衍生的162个F2﹕3家系为材料,通过一年两点的随机区组田间试验,测定了红麻株高、茎粗、节数、单株鲜皮重、单株干皮重和种子千粒重6个重要产量性状的数据,采用混合线性模型的复合区间作图法进行了QTL定位及其遗传互作效应分析。【结果】相关分析结果表明,除种子千粒重外,其它性状之间均存在明显的正相关性。在两地共定位了2个株高QTL、2个茎粗QTL、2个节数QTL、1个单株鲜皮重QTL、2个单株干皮重和2个种子千粒重QTL。【结论】在两地检测到11个QTL,主要集中分布在第6、11、14、9、13、17和4连锁群上,这些QTL在连锁群上分布不均匀,具有集中分布的特点。     

典型沙源区水库大气氮干、湿沉降污染特征研究

为研究典型沙源区水库大气氮干、湿沉降污染特征及其对水域氮素污染的贡献,以京蒙沙源区大河口水库库区为研究区,于2014年沿水库岸边布设12个大气氮沉降监测站点,采集干、湿沉降样本,测定干、湿沉降TN质量浓度,计算全年各月大气TN干、湿沉降通量和年入库TN污染负荷量。结果表明,研究区大气干、湿沉降季节差异显着(P<0.05):全年各月TN干沉降通量变化范围为116.31~382.02 kg·km^-2,主要集中在春季4月和秋季10月,最大TN干沉降通量出现在春季风沙最为严重的4月,其值为382.02 kg·km^-2;湿沉降通量变化范围为0.73~195.53 kg·km^-2,主要集中在夏季(6-8月),最大TN湿沉降通量出现在降水量最大的8月,其值为195.53 kg·km^-2.大气氮沉降以干沉降为主,全年月平均TN干沉降通量是湿沉降通量的2.9倍,且TN湿沉降通量与降水量变化呈显着正相关(R²=0.961 3).同入库河流径流TN污染负荷对比,2014年大气TN沉降入库污染负荷量为7.15 t,占同年滦河和吐力根河两条河流入库TN污染负荷的19.91%.     

Effects of UV-B treatment on controlling lignification and quality of bamboo (Phyllostachys prominens) shoots without sheaths during cold storage

For evaluating the effects of UV-B treatment on lignification and quality of bamboo(Phyllostachys prominens) shoots during postharvest, fresh bamboo shoots without sheaths were irradiated with UV-B at a dose of 8.0 kJ m~(–2) and then stored at(6±1)℃ along with 85–90% relative humidity(RH) for 15 d. The results showed that UV-B treatment apparently slowed down the increase rates of flesh firmness, weight loss, and contents of cellulose and lignin. It also decreased the activities of 4-coumarate CoA ligase(4CL), peroxidase(POD), cinnamyl alcohol dehydrogenase(CAD) and phenylalanine ammonialyase(PAL) and the expression of their encoding genes during cold storage. It was suggested that these effects of UV-B treatment on decreases in these enzymatic activities and the expression of encoding genes might collectively regulate lignin synthesis and accumulation in the flesh of bamboo shoots and consequently benefit in maintaining the edible quality of bamboo shoots during cold storage.     

小麦单位面积穗数和粒长主效QTL紧密连锁KASP标记的开发及其效应评价

【目的】小麦单位面积穗数和籽粒粒长是小麦产量相关的重要农艺性状,对其进行遗传改良有利于提高小麦的产量。通过对前期QTL定位鉴定到的提高单位面积穗数的主效QTL位点QSn.sau-2D.2和提高籽粒粒长的主效QTL位点QKl.sau-3D.2开发相应的KASP分子标记,并在川农18和T1208构建的RILs群体中进行验证及评价,为更好地利用这两个QTL以及分子标记辅助育种奠定基础。【方法】利用前期在川农18和T1208构建的高代自交群体中鉴定到的控制小麦单位面积穗数主效QTL位点QSn.sau-2D.2和控制籽粒粒长主效QTL位点QKl.sau-3D.2,结合在这两个QTL区间内的55K SNP分子标记序列,开发设计KASP分子标记,并在亲本间筛选具有多态性的KASP分子标记。将筛选到的KASP分子标记在川农18×T1208的RILs群体中分别进行基因分型和鉴定相应表型性状的高低,并分析这两个主效QTL对于其他农艺性状的影响。【结果】KASP-AX-111151907和KASP-AX-109962767在亲本中具有多态性,KASP-AX-111151907和KASP-AX-109962767在群体中的验证表明这两个分子标记分别与QSn.sau-2D.2和QKl.sau-3D.2连锁。KASP-AX-111151907和KASP-AX-10996276能将群体材料的基因型分为2类,按照表型划分,在3年试验中,KASP-AX-111151907对多穗材料的平均选择率均达到72.58%,对少穗材料的平均选择率达到71.68%;KASP-AX-10996276对长粒材料的平均选择率达到69.86%,对短粒基因型的平均选择率可达61.52%,表明这两个标记的可靠性。基于KASP分子标记的基因分型结果表明,这两个QTL对于株高、千粒重、粒长、粒宽、粒径比、单位面积穗数、穗粒重均具有显著性影响。在川农17×川农11的RILs群体中进行验证也表明这两个分子标记对相应性状的选择具有一定的作用。【结论】针对单位面积穗数主效QTL位点QSn.sau-2D.2和籽粒粒长主效QTL位点QKl.sau-3D.2分别开发了1对与之连锁的KASP分子标记,可用于相应性状的选择,与KASP标记连锁的QTL分别能显著提高单位面积穗数和籽粒粒长。QSn.sau-2D.2对株高、千粒重、粒长、粒宽、粒径比、穗粒重是负向影响,QKl.sau-3D.2对株高、千粒重、粒宽、粒径比和穗粒重是正向影响,但对单位面积穗数是负向影响,这两个QTL及开发的KASP标记可应用于小麦高产育种中。     

In vitro micro propagation of “sand pear” Pyrus pyrifolia (Burm. f.) Nakai

This study was undertaken to standardize protocols for in vitro explant establishment, shoot multiplication and in vitro rooting for Pyrus pyrifolia, growing in the Kashmir valley. The explant used was nodal cuttings of 2–3cm size with one or two axillary buds. The highest explant establishment (over 90%) was observed during spring while the lowest (60%) explant establishment frequency was observed during winter season. The shoots sprouted from the axillary buds were excised and subcultured on MS basal medium. The highest shoot multiplication rate (130 shoots from a single nodal cutting) was obtained on MS medium supplemented with BAP 2.2 mg·L^?1 and kinetin 1 mg·L^?1 after four weeks. The shoots were inoculated for rooting in root induction medium of half strength MS salts supplemented with plant growth regulators like IBA, IAA, NAA, and 2, 4-D. However, the best rooting response (8.50 roots per shoot) was obtained in combination of hormones (IBA + NAA) 0.25 mg·L^?1 each. The rooted micro shoots were acclimatized under decreasing humidity regime (95% RH to 75% RH over a period of 5±1 weeks). The highest ex vitro plantlet survival percentage (56.50%) of Pyrus pyrifolia was observed on sand + soil (1:1 v/v).     

Genetic study and molecular breeding for high phosphorus use efficiency in maize

Phosphorus is the second most important macronutrient after nitrogen and it has many vital functions in the life of plants. Most soils have a low available P content, which has become a key limiting factor for increasing crop production. Also, low P use efficiency (PUE) of crops in conjunction with excessive application of P fertilizers has resulted in serious environmental problems. Thus, dissecting the genetic architecture of crop PUE, mining related quantitative trait loci (QTL) and using molecular breeding methods to improve high PUE germplasm are of great significance and serve as an efficient approach for the development of sustainable agriculture. In this review, molecular and phenotypic characteristics of maize inbred lines with high PUE, related QTL and genes as well as low-P responses are summarized. Based on this, a breeding strategy applying genomic selection as the core, and integrating the existing genetic information and molecular breeding techniques is proposed for breeding high PUE maize inbred lines and hybrids.