小麦转录因子基因TaPHR1参与调控每穗小穗数

利用水分高效基因资源创制新型小麦品种是应对气候变化和人口高速增长的有效途径。MYB(v-mybavian myeloblastosisviral oncogene homolog)是植物中最大的转录因子家族之一,参与调控植物生长发育,生物和非生物胁迫。本研究在TaPHR1-4A和TaPHR1-4B中分别鉴定出19个和15个SNP,基于这些多态性位点开发了分子标记。关联分析表明,Hap-4B-I是小穗数多的优异单倍型。通过创制两个回交导入系群体,进一步证实Hap-4B-I有利于改善小麦穗部性状。TaPHR1的转录表达分析发现Hap-4B-I单倍型幼穗中TaPHR1的表达水平均高于Hap-4B-II单倍型。此外,TaPHR1在水稻中的异源表达导致穗分支变多,也证实TaPHR1参与调控每穗小穗数。小麦育成品种的时空分布分析发现尽管Hap-4B-II在我国现代育成品种中占比最多,但随小麦育种时间的推进,Hap-4B-I的占比在逐渐增多。总之,TaPHR1是小麦每穗小穗数的正调节因子。因此,本研究开发的分子标记可作为小麦标记辅助选择和遗传改良的重要来源。     

大穗小麦多小穗基因的染色体定位

采用中国春单体系列对大穗普通小麦品系“88F2185”的多小穗性状进行了基因定位研究。结果表明，“88F2185”决定多小穗的基因位于其1B、3D和5A染色体上，其中3D染色体的效应最强。“88F2185”1B和3D染色体上的基因表现显性，而5A染色体上的基因表现隐性。此外，“88F2185”4D染色体上还存在减少小穗数目的隐性基因。据前人研究及本试验结果分析认为，“88F2185”5”的1B及4D染色体上具控制小穗数目的新基因。     

小麦细胞分裂素氧化酶基因Tackx3参与穗粒数的形成

细胞分裂素氧化酶基因与禾本科作物的穗粒数密切相关.本文根据已报道的小麦细胞分裂素氧化酶(cytokinin oxidase,CKX)基因EST序列在GenBank中搜索更新的EST序列,组装后设计特异引物在豫麦8679/红芒春31重组自交系群体(recombined inbreed lines,RILs)中鉴定与小麦穗粒数相关的CKX基因.结果表明,Tackx3基因在RILs群体中表现较好的多态性,并与小麦穗粒数相关.具有"A"型Tackx3等位基因的家系其穗粒数大都分布在较低的范围内(穗粒数15～60),平均值为55:而具有"B"型Tackx3等位基因的家系其穗粒数大都分布在较高的范围内(61～95),平均值为65,穗粒数均值T测验达极显著水平,说明Tackx3基因等位变异与小麦穗粒数形成关系密切.     

科学家揭示小麦幼穗发育基因调控特点

正近日,由中国农业科学院作物科学研究所毛龙研究员领衔的作物生物信息与应用创新团队,在小麦幼穗发育基因调控网络解析研究中取得新进展。相关成果于近日在线发表在国际植物学主流杂志《植物生理(Plant Physiology)》上。科研团队利用生物信息手段,通过对小麦幼穗发育早期的转录组分析发现,该过程中小麦基因表达     

小麦转录因子基因TaMYB70的分离和表达分析

为了探究小麦MYB转录因子基因TaMYB70的功能,采用同源克隆方法分离TaMYB70（MK024291）基因cDNA序列,运用生物信息学手段分析该基因序列特征,采用实时荧光定量反转录PCR（qRT-PCR）检测其在不同逆境胁迫下的表达模式。结果表明,分离得到的TaMYB70部分序列长度为1 272bp,包含一个长度为1 008bp的开放阅读框,编码335个氨基酸残基。TaMYB70蛋白含有2个螺旋-转角-螺旋结构的Myb-type HTH DNA结合结构域。TaMYB70氨基酸序列与粗山羊草、二穗短柄草等植物MYB44同源性较高,与拟南芥R2R3-MYB转录因子第22亚族成员属于同一分支。qRT-PCR分析表明,TaMYB70在脱落酸胁迫下表达量升高,在PEG和NaCl胁迫下表达量下降,该转录因子可能参与小麦逆境胁迫应答。     

小麦小穗数调控基因WAPO1的单倍型、遗传效应、地理分布及育种利用分析

小麦穗部性状直接与产量相关,是极重要的农艺性状。WAPO1编码F-box蛋白,是水稻小穗数发育相关基因APO1在小麦中的直系同源基因。本研究鉴定了WAPO1的优异单倍型,并对其遗传效应、地理分布和育种利用情况进行了鉴定。通过开发的KASP标记对编码区第140位碱基变异SNP(G/T)进行鉴定,并使用前人报道的启动子InDel标记对WAPO1启动子115bp的插入缺失进行鉴定,在中国地方小麦中进行单倍型鉴定。结果显示,在前人鉴定到的3种单倍型(H1: 140~G+115^deletion, H2:140~T+115^insertion, H3: 140~G+115^insertion)基础上,鉴定到了新的第4种单倍型(H4:140~T+115^deletion)并证明H2和H4为优异单倍型,能显著提高小麦每穗小穗数。将开发的KASP标记对223份世界小麦、144份中国育成小麦和119份四川小麦进行分型,筛选出优异单倍型并对其在育种中的利用和分布进行了鉴定,结果表明优异单倍型在中国和世界范围都被广泛选育。     

病毒复制酶基因Nib8和ERF转录因子W17基因枪法共转化小麦

将对小麦黄花叶病毒表现高抗的复制酶基因Nib8和具有广谱抗病性的ERF基因W17分别构建到单子叶高效组成型表达载体上,采用基因枪共转化法转化到小麦品种扬麦12和扬麦16中,PCR检测共获得Nib8基因的阳性转基因植株42株,W17基因的阳性转基因植株48株,及两个功能基因均为阳性的转基因植株6株。以扬麦12为受体的转化率分别为1.53%(Nib8)、4.87%(W17)和0.42%(Nib8+W17);以扬麦16为受体的转化率分别为2.05%(Nib8)、0.86%(W17)和0.20%(Nib8+W17)。对两个功能基因都呈阳性的6个植株进行Southern blotting分析,进一步证实功能基因已经整合到小麦基因组中。本研究为获得具有综合抗病性的小麦新材料奠定了基础。     

不同年份对小麦穗数穗粒数的影响及其对策

通过多年的小区高产栽培试验和高产攻关，对小麦的穗数、穗粒数进行了研究。结果表明，在相似栽培条件下，有的年份间穗教相差较多，有的年份间穗粒教相差较多。年后幼苗阶段积温，是决定穗数多少的主要因子；小麦返青后5d平均滑动气温首次≥4℃至拔节前的天数，是决定穗粒数多少的主要因素。但只要采取相应的技术措施，不论什么年份，均可获得足够的穗数和较多穗粒数。     

小麦顶小穗的形成特点及其与大穗的关系

小麦植株开始拔节时,幼穗的分化发育出现转折——停育小穗出现,侧小穗数不再增加,顶小穗开始分化,全穗的总小穗数定型。顶小穗的形成过程、形态结构与侧小穗不同。顶小穗出现的早晚,与温、光、营养等条件密切相关。了解小麦顶小穗的形成特点,注意适期早播,正确施肥,科学管理,可以延长小穗分化时间,推迟顶小穗出现,增加小穗数,     

Converting restriction fragment length polymorphism to single‐strand conformation polymorphism markers and its application in the fine mapping of a trichome gene in cotton

A well‐characterized and systematically organized collection of genetic markers is crucial in the study of any crop species. It is the basis of map‐based gene cloning and crop improvements through marker‐assisted selections. Single‐strand conformation polymorphism (SSCP) has been a robust way of discovering new polymorphisms in marker development without the requirement of sequencing. Here, we report the first approach of applying SSCP marker discovery methods in the genetic map construction and gene mapping of cotton species. A total of 80 restriction fragment length polymorphism (RFLP) markers were selected from a region on published cotton genetic maps around the T1 gene related to cotton trichome. Among the 80 RFLPs, 28 showed polymorphisms through SSCP, showing a polymorphic rate of approximately 35%, which is much higher than that of simple sequence repeat (SSR) markers in the same region (7.8%). By integrating these newly generated SSCP markers, a detailed genetic map was reconstructed around this region using an F₂ population derived from a cross between Gossypium arboreum and G. herboceum. The reconstructed region comprises 22 SSCP markers, eight SSR markers and the T1 gene, spanning 21.6 cM. The marker order of the new map agrees well with published reference RFLP maps. The above results suggest that SSCP method can be applied very efficiently and reliably to the marker development of cotton genomes. It will prove to be even more valuable and robust after the public release of cotton whole‐genome sequences.     

Genome‐wide association mapping and candidate gene analysis for saturated fatty acid content in soybean seed

Saturated fatty acids (FA), an important component of soybean oil, plays a crucial role in the nutritional value of soybean oil through different concentration and relative proportions. In this study, an association population of 185 diverse soybean accessions was used to identify quantitative trait nucleotide (QTN) and scan candidate genes via genome‐wide association analysis (GWAS), which was based on high throughout single‐nucleotide polymorphisms (SNPs) developed via the Specific Locus Amplified Fragment Sequencing (SLAF‐seq) approach. A total of 33,149 SNPs were identified with minor allele frequencies (MAF) >4%, which covered 97% of the soybean whole genome. For the two saturated FA concentration, including palmitic acid (PA) and stearic acid (SA), up to 65 SNPs were verified via GWAS. Among them, 35 and 16 SNPs loci were the novel loci for PA and SA, respectively. There were other six loci for PA and eight loci for SA overlapped or located in the linked genomic regions reported by the previous study. Furthermore, many loci were repeated in more than two environments, and four pair of pleiotropic loci (PA‐3‐2 and SA‐3‐2, PA‐11‐2 and SA‐11‐1, PA‐12‐2 and SA‐12‐1, and PA‐17‐1 and SA‐17‐2) had similar genomic regions, which might control both PA and SA simultaneously. A total of 49 genes, which could participate in lipid biosynthesis pathway or hormone metabolism, were identified as the potential candidate genes associated with saturated FA. The identified loci with beneficial alleles and the candidate genes would be valuable for studying the molecular mechanisms of saturated FA and further for improving nutritional value of soybean oil.     

小麦粒重相关基因TaCYP78A5功能标记开发及验证

为了开发小麦粒重相关基因TaCYP78A5 (Triticum aestivum Cytochrome P450 78A5)的功能标记,挖掘与千粒重性状相关的优异等位变异,本研究通过对30份不同品种小麦TaCYP78A5启动子区测序及比对鉴定,并根据SNP位点差异开发TaCYP78A5-2A启动子区功能标记CAPS-5Ap。结果表明,在30份不同小麦品种中TaCYP78A5-2A启动子区域出现5个SNP位点差异,可将30份不同品种小麦分为TaCYP78A5-2Ap-HapI和TaCYP78A5-2Ap-HapII两种单倍型;以323份现代育成小麦品种验证发现,TaCYP78A5-2Ap-HapI的分布频率为17.96%,TaCYP78A5-2Ap-HapII的分布频率为82.04%,表明CAPS-5Ap标记可用于小麦TaCYP78A5-2A启动子序列2种单倍型的鉴定。此外,关联分析发现, CAPS-5Ap标记与粒重相关,且TaCYP78A5-2Ap-HapII是提高千粒重的优异单倍型。研究结果为小麦分子标记辅助选择和性状改良提供理论依据。