黄淮麦区小麦品种和CIMMYT材料的矮秆基因型及其对株高和胚芽鞘的影响

为促进矮秆基因在小麦品种遗传改良中的应用,以131份黄淮麦区小麦品种和31份CIMMYT（国际玉米小麦改良中心）小麦材料为研究对象,用分子标记检测 Rht-B1a、 Rht-B1b、 Rht-D1a、 Rht-D1b和 Rht8等小麦矮秆基因,并结合赤霉素处理,分析了供试材料所含矮秆基因类型及其对株高和胚芽鞘长度的影响。结果表明,供试材料中,63份含有矮秆基因 Rht-B1b,66份含有矮秆基因 Rht-D1b,105份含有矮秆基因 Rht8,分别占供试材料的38.88%、40.74%和64.81%。黄淮麦区小麦品种大多数含有矮秆基因 Rht-D1b,CIMMYT小麦中大多数含有矮秆基因 Rht-B1b。赤霉素处理结果显示,供试小麦材料中,有52份对赤霉素敏感,占被检测材料的32.09%。该批材料中,矮秆基因 Rht-D1b和 Rht8的降秆效应最大, Rht-B1b和 Rht-D1b的降秆效应分别是14.69%和17.74%,各基因组合的降秆效应表现为 Rht-D1b+ Rht8＞ Rht-D1b＞ Rht-B1b+ Rht8＞ Rht-B1b＞ Rht8。同时含有矮秆基因 Rht-B1b和 Rht-D1b的材料缩短胚芽鞘长度的效应最强,缩短效应为26.20%,缩短胚芽鞘长度的效应表现为 Rht-B1b+ Rht-D1b＞ Rht-B1b+ Rht-D1b + Rht8＞ Rht-D1b＞ Rht-D1b+ Rht8＞ Rht-B1b＞ Rht-B1b+ Rht8＞ Rht8。基于以上结果,矮秆基因 Rht8能够在降低小麦材料株高的同时不影响胚芽鞘长度,因此应重视其在矮化育种中的应用。     

64份小麦种质的赤霉素响应评价及矮秆基因分子鉴定

为深入了解小麦矮秆种质资源的性状表现和遗传组成，研究了64份小麦品种（系）的株高和节间长度对外施赤霉素的响应，并利用分子标记对矮秆基因组成等进行了鉴定。结果表明，不同材料的株高、节间数量和节间长度对赤霉素响应存在差异。节间长对赤霉素的响应集中在倒二节、倒三节和倒四节。供试材料可以通过增加穗长和穗颈长弥补节间数量减少对株高的影响。赤霉素浓度对供试材料株高构成指数影响较小。通过对不同材料株高构成指数分析发现，SH-04和川麦86两份材料具有良好的株高构成比例。分子标记鉴定表明，供试材料中Rht-B1b、Rht-D1b和Rht8的分布频率为31.25%、10.94%和65.63%。矮秆基因的降秆效应表现为Rht-B1b>Rht8、Rht9和Rht13。本研究得出Rht9+Rht13的株高构成指数为0.613，最接近于0.618，含有该基因组合的材料可以在株型育种中加以利用。     

67份美国小麦品种矮秆基因的分子标记检测

为了明确矮秆基因在美国小麦品种中的分布特点并发掘较少利用的矮秆基因,本研究利用8个小麦矮秆基因的特异分子标记对67份美国小麦品种中的矮秆基因进行了检测。结果表明,67份美国小麦品种中,超过80%的品种（56个）含有矮秆基因,其中 Rht-B1b和 Rht8基因频率较高,分别占62.7%和43.3%。仅有5个品种含有 Rht-D1b基因,同时发现3个品种含有 Rht5基因,2个品种含有 Rht12基因,未发现含有 Rht4、 Rht9和 Rht13基因的品种。在含有矮秆基因的品种中,35.8%的品种含有2个或2个以上的矮秆基因。其中有1个品种同时含有3个矮秆基因,有20个品种同时含有 Rht-B1b和 Rht8基因,有3个品种同时含有 Rht-D1b和 Rht8基因,有1个品种同时含有 Rht-D1b和 Rht12基因,其余32个品种各含有1个矮秆基因。本研究未发现同时含有 Rht-B1b、 Rht-D1b、 Rht8以及同时含有 Rht-B1b、 Rht-D1b的品种。     

矮秆基因在中国不同麦区小麦品种中的分布及其对赤霉病抗性的影响

为研究矮秆基因在中国不同麦区的分布,以及株高和小穗密度与赤霉病抗性的相关性,本研究通过分析3个矮秆基因 Rht1、 Rht2和 Rht8在211份不同麦区小麦自然群体中的分布,并结合其在不同环境下株高、小穗密度以及赤霉病抗性的调查数据,分析矮秆基因 Rht1、 Rht2和 Rht8对赤霉病抗性的影响。结果表明：（1）不同麦区矮秆基因的分布频率差异较大, Rht1主要分布在长江中下游麦区, Rht2和 Rht8主要分布在黄淮麦区;（2）与野生型品种相比,携带 Rht1、 Rht2和 Rht8的小麦品种,株高均显著或极显著降低;（3）携带 Rht2和 Rht8的小麦品种,赤霉病抗性均极显著低于野生型品种,而携带 Rht1的小麦品种,赤霉病抗性则极显著高于野生型品种;（4）携带 Rht2和 Rht8的小麦品种,小穗密度显著大于野生型品种,而携带 Rht1的小麦品种,小穗密度则显著降低。因此,不同矮秆基因对小穗密度性状的遗传差异可能是导致小麦赤霉病抗性和不同麦区矮秆基因选择利用差异的部分原因。     

小麦矮秆基因 Rht-B1b和 Rht-D1b的检测及其验证

为研究矮秆基因 Rht-B1b、 Rht-D1b在小麦品种中的分布及其对株高的影响,以3个小麦群体（中国冬麦区白粒小麦品种、中国小麦历史品种、春小麦育种材料）共321份小麦品种为材料,检测矮秆基因 Rht-B1b和 Rht-D1b的分布频率,并分析比较它们对春小麦育种材料株高的影响。结果表明,在检测的321份材料中,共有193份材料含有 Rht-B1b矮秆基因,分布频率为60.1%,其中,中国冬麦区白粒小麦品种、中国小麦历史品种、春小麦育种材料中含有 Rht-B1b矮秆基因的材料分别有29、77和87份,分布频率分别为 34.5%、72.6%和66.4%;共有135份材料含有 Rht-D1b矮秆基因,分布频率为42.1%,其中,中国冬麦区白粒小麦品种、中国小麦历史品种、春小麦育种材料中含有 Rht-D1b 矮秆基因的材料分别有41、21和73份,分布频率分别为48.8%、19.8%和55.7%;共有78份材料同时含有 Rht-B1b和 Rht-D1b矮秆基因,分布频率为 24.3%,其中,中国冬麦区白粒小麦品种、中国小麦历史品种、春小麦育种材料中同时含有 Rht-B1b和 Rht-D1b矮秆基因的材料分别有15、17和46份,分布频率分别为17.6%、15.9%和35.1%。对已被鉴定株高表型的91份春小麦育种材料进一步分析发现,同时携带 Rht-B1b和 Rht-D1b矮秆基因的材料株高较低。     

普通小麦品种陕农33矮秆突变体的矮化效应分析

为了解普通小麦品种陕农33矮秆突变体的矮化原因,通过农艺性状调查、茎秆细胞学观察、苗期赤霉素（GA）反应试验、内源激素含量测定和矮秆基因检测,分析了陕农33的13个矮秆突变体植株生长发育、茎秆解剖特征及对GA的敏感性。结果表明,与野生型陕农33相比,矮秆突变体的株高都显著下降,株高的下降与节间数无关,主要是由于节间长度的缩短,其中穗下节和第四节间的降秆效应较大。经进一步细胞学观察,突变体变矮是由茎秆细胞长度减少和细胞变小共同引起的,其中细胞长度减少是主因。从苗期植株对GA₃的反应看,13个矮秆突变体属于赤霉素不敏感型或弱敏感型,说明赤霉素转导途径存在问题,即矮秆突变位点可能在赤霉素转导途径上。从内源激素测定结果看,13个矮秆材料中只有1个材料的茎秆GA₃含量较陕农33略降,其余均增加,而CTK含量均减少,10个材料的IAA含量增加,说明这些材料的株高下降与赤霉素等内源激素代谢变化密切相关。通过矮秆基因检测,13个矮秆突变体和陕农33均含有目前应用范围较广的 Rht-D1b基因,只有两个矮化材料含有 Rht-B1b,因而推测矮秆突变体可能还含有其他致矮相关的基因。     

47份外引小麦种质中矮秆基因的检测及其降秆效应分析

为有效利用外引小麦种质资源,明确矮秆基因的组成分布和降秆效应,利用8个矮秆基因( Rht-B1b、 Rht-D1b、 Rht4、 Rht5、 Rht8、 Rht9、 Rht12、 Rht13)的特异性分子标记分别对47份外引种质矮秆基因进行分子检测。结果表明,有46份种质含有矮秆基因,其中, Rht-B1b、 Rht4和 Rht12基因的频率最高,均为40.43%,其余依次为 Rht8(31.91%)、 Rht-D1b和 Rht13(均为19.15%)、 Rht5(8.51%)、 Rht9(6.38%)。有10份小麦种质含有单个矮秆基因,占21.28%;有36份小麦种质含有2个及以上矮秆基因,占76.60%,其中有11份含有3个矮秆基因,有2份含有4个矮秆基因。单个矮秆基因降秆效应以 Rht5最强,为31.78%,含有 Rht5的小麦材料平均株高为86.65cm。含有优良矮秆基因 Rht9、 Rht12和 Rht13的小麦材料平均株高分别为101.07 cm、92.87 cm和92.75 cm,其中, Rht9在8个矮秆基因中降秆效应最弱。     

黄淮麦区小麦种质资源矮秆基因分布及其与农艺性状的关系

为了进一步阐明多个矮秆基因的分布及其与小麦农艺性状的关系,运用分子标记对来自我国黄淮麦区的246份小麦种质资源中6个矮秆基因位点(Rht1、Rht2、Rht4、Rht8、Rht9及Rht12)分别进行了检测,同时连续3年调查参试材料株高、穗长、穗下节长、小穗数、旗叶长、旗叶宽、穗粒数、粒长、粒宽和千粒重共10个农艺性状,分析了不同矮秆基因位点对小麦农艺性状的影响。结果表明,6个矮秆基因在黄淮麦区小麦中均具有广泛分布,其中含有Rht1和Rht2基因的小麦品种分布最广。分析矮秆基因位点对小麦农艺性状的影响发现,在Rht1位点,Rht1-B1a和Rht1-B1b两种基因型间的株高没有显著差异;在Rht2位点,拥有Rht2-D1b类型的小麦品种所有年份间的株高和穗下节长较低,但千粒重较高,为相对优良的基因型。排除Rht1和Rht2基因效应后,Rht4、Rht8、Rht9和Rht12位点对黄淮麦区小麦品种不同农艺性状均具有重要影响,其中,Rht4基因位点主要对小麦株高和千粒重具有重要影响,且Rht4-B1b类型为相对优良的基因型;Rht8基因位点主要对小麦穗下节长、穗长和千粒重具有重要影响,且Rht8-D1b类型为相对优良的基因型;Rht9基因位点主要对小麦株高和千粒重具有重要影响,且Rht9-A1a类型为相对优良的基因型;Rht12基因位点主要对小麦千粒重和穗长具有重要影响,且Rht12-A1a类型为相对优良的基因型。进一步分析发现,6个位点中对株高影响最大的是Rht2基因,其次是Rht4基因;有4个位点(Rht1、Rht2、Rht8、Rht12)对千粒重有显著影响,其中Rht2基因的影响最大。分析除Rht1外其他5个位点优良基因型在不同时期小麦品种中的分布发现,从早期历史品种、近期历史品种到现代品种,不同位点优良基因型分布比例总体呈现上升趋势,表明优良矮秆基因型在黄淮麦区小麦品种选育中的利用逐渐增加,尤其是82.9%的现代小麦品种已含有Rht2-D1b类型。     

秋播冬麦区矮秆基因 RhtB1b、 RhtD1b和 Rht8的分布频率及其与产量性状的关系

为给小麦株高和产量的遗传改良提供参考依据，利用 Rht-B1b、 Rht-D1b基因的STS分子标记BF/MR1和BF/WR1、DF1/MR2和DF2/WR2，以及 Rht8基因的微卫星标记Xgwm261，对237份不同生态区秋播小麦材料进行分子标记检测，并分析 Rht-B1b、 Rht-D1b和 Rht8对株高及产量相关性状的影响。结果表明：（1）在分布频率方面， Rht-B1b、 Rht-D1b和 Rht8在秋播冬小麦中的频率较高，其中携带 Rht-B1b、 Rht-D1b和 Rht8的小麦材料分别占比16.5%、47.9%和44.1%；聚合两个矮秆基因（ Rht-D1b+Rht8、 Rht-B1b+Rht8和 Rht-B1b+ Rht-D1b）的小麦材料占比25.4%；聚合三个矮秆基因（Rht-B1b+Rht-D1b+Rht8）的小麦材料占比2.1%；（2）在分布特点方面，不同冬麦区存在一定偏好性：北部冬麦区、黄淮冬麦区、长江中下游冬麦区均以 Rht-D1b、 Rht8和 Rht-D1b+Rht8为主；西南冬麦区以 Rht-B1b、 Rht-D1b和 Rht8为主，西南冬麦区以 Rht-B1b、Rht-D1b和Rht8为主；（3）在降秆效应方面，降秆效果从强到弱依次为（ Rht-B1b+Rht-D1b+Rht8）>（ Rht-D1b+Rht8）> （ Rht-B1b+Rht8）> Rht-D1b> Rht-B1b> Rht8；(4)在产量结构特点方面， 携带 Rht-D1b和 Rht8的材料总体上具有较高的千粒重和单位面积穗数，携带 Rht-B1b的材料具有较高的穗粒数，但矮秆基因本身与产量因子间无显著的遗传相关性。     

滴灌模式下矮秆基因对小麦部分农艺性状的效应

为探明滴灌模式下矮秆基因对小麦农艺性状的影响,对不同麦区的271份小麦品种(系)所含的矮秆基因Rht-B1b、Rht-D1b和Rht8进行检测,并对其在滴灌栽培模式下的株高、穗长、小穗数、穗粒数和单株产量进行分析。结果表明,参试的271份小麦品种(系)中有177份含矮秆基因Rht-D1b,占65.31%;110份含Rht-B1b,占40.59%;58份含有Rht8,占21.40%;27份材料不含有所检测的3个矮秆基因。34.68%的品种(系)含有2个或3个矮秆基因。根据所含矮秆基因的类型可将271份材料分为8类。3个矮秆基因都能显著降低滴灌栽培模式下小麦的株高,其中Rht-B1b还显著降低了穗长、小穗数和单株产量,对穗粒数的影响不显著;Rht8对穗长、小穗数、穗粒数和单株产量均产生了负效应,但影响不显著;Rht-D1b对株高的影响最大,并对穗长、穗粒数和单株产量具有正效应,在育种中应加强利用。     

The Rht13 dwarfing gene reduces peduncle length and plant height to increase grain number and yield of wheat

The green-revolution Rht-B1b and Rht-D1b dwarfing alleles are usually associated with increased wheat yields but are linked to reduced early growth and poor emergence if sowing conditions are unfavourable. Other dwarfing genes are available but not used in commercial breeding. The Rht13 bread wheat donor, Magnif M1, produces uniquely short peduncle and penultimate internodes to reduce plant height. A set of near-isogenic (NILs) and recombinant inbred (RILs) lines varying for height were developed from the cross of Magnif M1 and the Rht8c-containing Chuan-mai 18, and evaluated for a range of agronomic characteristics across favourable environments. Reductions in plant height were associated with increased grain number (r² = 0.35**) and harvest index (r² = 0.62**) in the NILs. Reduced-height RILs containing the Rht13-linked, Xgwm577_M microsatellite marker were significantly shorter, produced greater biomass, yield and harvest index, and increased spike and grain number than lines without the marker. Approximately 74 and 7% of the total phenotypic variance in plant height was accounted for by allelic differences in Xgwm577 and Rht8 loci, respectively. The peduncle and penultimate peduncle internodes of Rht13-containing lines were proportionately shorter than Rht8c-containing sibs and lines containing the Rht-B1b dwarfing allele. The unique height-reducing phenotype, increased grain number and yield associated with Rht13 indicate considerable potential for use of this dwarfing allele for improving wheat performance.     

Genotypic increases in coleoptile length improves stand establishment,vigour and grain yield of deep-sown wheat

Timely sowing is critical for achieving high grain yields in winter cereals. However, inadequate seed-zone moisture for germination commonly delays sowing to reduce biomass and subsequent yield in semi-arid environments. Sowing deep to reach soil moisture is often avoided by growers of Rht-B1b and Rht-D1b semi-dwarf wheat as these wheat show poor emergence when sown deep. Their reduced cell elongation associated with insensitivity to endogenous gibberellins, results in shorter coleoptiles and smaller early leaf area. Alternative dwarfing genes responsive to endogenous gibberellins (e.g. Rht8) are available for use in wheat breeding. These reduce plant height without affecting coleoptile length and offer potential to select longer coleoptile wheat for deep sowing. Nine semidwarf (Rht8, Rht-B1b, and Rht-D1b) and seven tall (rht) wheat genotypes were sown at depths of 50, 80 and 110 mm at three locations in 2 or 3 years. Coleoptile lengths measured in a growth cabinet at four temperatures (11, 15, 19 and 23 °C) were strongly correlated with coleoptile length (r_p = 0.77–0.79^**) and plant number (r_p = 0.49^*–0.79^**) in deep-sown plots in the field. Furthermore, differences in coleoptile length were genetically correlated with greater numbers of emerged seedlings (r_g = 0.97^**), shallower crown depth (−0.58^**), greater seedling leaf area (0.59^**) and seedling biomass (0.44^*). Wheat containing the Rht-B1b or Rht-D1b dwarfing genes produced significantly (P < 0.01) shorter coleoptiles (97 mm) than both Rht8 (118 mm) and tall (117 mm) wheat. In turn, compared with emergence from 50 mm depth, the Rht-B1b and Rht-D1b wheat produced significantly fewer seedlings at 110 mm sowing depth (−62%) than either Rht8 (−41%) or tall (−37%) wheat. Effects of deep sowing early in the season were maintained with reductions in spike number and biomass at both anthesis and maturity. Kernel number was also reduced with deep sowing leading to reductions in grain yield. Over all entries, genotypic increases in plant number were associated with increases in fertile spike (r_g = 0.61^**) and kernel number (0.21^*), total biomass (0.26^*) and grain yield (0.28^*). Reduction in spike number and grain yield with deep sowing was smallest for the Rht8 (−18 and −10%) and rht (−15 and −7%) wheat, and largest for the Rht-B1b/D1b (−39 and −16%) wheat. Plant height and coleoptile length were independent among Rht8 and tall wheat genotypes. This study demonstrates the importance of good seedling emergence in achieving high wheat yields, and the potential use of alternative dwarfing genes such as Rht8 in development of long coleoptile, reduced height wheat suitable for deep sowing.     

Coleoptile length variation of near-isogenic Rht lines of modern CIMMYT bread and durum wheats

A set of 10 bread wheat (Triticum aestivum L.) and six durum wheat (T. turgidum L.) genotypes near-isogenic for either the Rht1 or Rht2 dwarfing genes were analyzed for plant height, kernel weight, coleoptile length and grain yield. Coleoptile length was measured at three different temperatures and plant height, kernel weight and grain yield determined in six different environments. Durum wheat, regardless of stature, produced longer coleoptiles than bread wheat at higher temperature. Within the non-Rht isolines, plant height and coleoptile length were independent characters. The tall durum wheats tended to be taller than their bread wheat counterparts, indicating an absence of minor genes for reduced height. However, a number of bread wheat cultivars showed relatively small height increases following removal of the Rht gene and substantially greater increases in coleoptile length. Coleoptile length was more highly correlated (r²=0.53, P<0.01) with seed weight among the non-Rht isolines compared to cultivars containing either Rht1 or Rht2. Grain yield and plant height were positively correlated among the semi-dwarf Rht isolines in 5 of 6 environments. No equivalent relationship existed among the non-Rht materials. Grain yield (standard sowing depth 3 cm) and coleoptile length were generally not significantly correlated within each isogenic grouping.

Plant breeders should be able to select short statured, non-Rht1 or non-Rht2 hexaploid bread wheat with better emergence characteristics. The non-Rht genotypes developed from the bread wheat cultivars Seri 82 and Culiacan 89 were identified as meeting these criteria. Wheats such as these could offer significant advantages to farmers in environments where deep sowing into stored soil moisture is practiced.     

四川小麦主要矮秆基因的分子鉴定

为系统研究四川小麦品种主要矮秆基因的组成,应用Rht-B1b和Rht-D1b基因的STS标记及Rht8基因的连锁SSR标记,对262个小麦品种(系)进行了检测。结果表明,四川小麦品种(系)具有Rht8基因连锁标记的频率为54.6%,Rht-D1b基因的频率为37.4%,Rht-B1b基因的频率为15.3%。与前人的研究比较发现,四川小麦Rht8连锁标记的频率高于全国平均值,而Rht-B1b和Rht-D1b的频率都低于全国平均值。这3种矮秆基因一共构成了8种组合类型。为分析不同基因组合对株高的影响,对连续种植3年的125份材料进行了测定。这些材料中,不含3种基因的类型占12.8%,仅含有Rht8的类型最多(33.6%),其次为仅含有Rht-D1b基因的类型(20%);同时含有Rht8基因和Rht-D1b基因的类型占17.6%;含有Rht-B1b基因的组合类型所占比例较少(都低于10%)。矮秆基因的降秆强度表现为:Rht-D1bRht-B1bRht8。同时具有3种矮秆基因的材料,其降秆强度最大,其次为含有2种矮秆基因的组合类型。