Genetic variation of grain sorghum germplasm for resistance to Pseudomonas andropogonis

Pseudomonas andropogonis is the causal agent of bacterial leaf stripe of sorghum (Sorghum bicolor (L.) Moench). Fifty grain sorghum accessions were evaluated for genetic variation to P. andropogonis over a 2-year period. Plants were inoculated at the 7 to 8 leaf stage of juvenile growth with an Idico filler-plug gun calibrated to deliver one ml of inoculum. Disease severity ratings were noted 2 weeks after inoculation on a 0 to 5 scale. For 1993 and 1994, disease severity ratings were significantly different (P < 0.01) among accessions and groups of resistant, intermediate, and susceptible germplasm. Significant differences (P < 0.05) were also observed between years. Resistant accessions included SC 326-6, SC 414-12E, BTX 378, B35-6, and TX 2862. Susceptible entries included TX 2767, TX 430, TAM 428, BTx 623, R 9117, and 90B2662. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breakdown of resistance to sorghum midge, Stenodiplosis sorghicola

Sorghum midge (Stenodiplosis sorghicola Coquillett) is an important pest of grain sorghum worldwide. Several sources of resistance to sorghum midge have been identified in the world sorghum germplasm collection, of which some lines show a susceptible reaction in Kenya. Therefore, we studied the insect density damage relationships for a diverse array of midge-resistant and midge-susceptible sorghum genotypes, and variation in association of glume and grain characteristics with expression of resistance to sorghum midge. AF 28 and IS 8891 showed resistance to sorghum midge both in India and Kenya; DJ 6514 and ICSV 197, which are highly resistant to sorghum midge in India, showed a susceptible reaction at Alupe, Kenya. Sorghum midge damage in general was greater in Kenya than that observed in India at the same level of midge density suggesting that the breakdown of resistance in Kenya is due to factors other than insect density. Glume length, glume breadth, and glume area were positively associated with susceptibility to sorghum midge at both locations. However, under natural infestation, the correlation coefficients were stronger in India than in Kenya. Grain mass at 3 and 6 days after anthesis was positively associated with susceptibility to midge in India, but did not show any association with midge damage in Kenya. Grain growth rate between 3 and 6 days after anthesis was more strongly correlated with susceptibility to midge in Kenya than in India. Variation in the reaction of sorghum genotypes across locations may be partly due to the influence of environment on association between glume and grain characteristics with susceptibility to sorghum midge, in addition to the possible differences in midge populations in different geographical regions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of the A4 cytoplasmic male-sterile lines of sorghum using RFLP of mtDNA

Three sorghum cytoplasmic male sterile lines CSV4 A(V), CSV4 A(G₁) and CSV4 A(M), grouped as A₄, were compared with a milo (A₁) and two other non-milo (A₂ and A₃) cytoplasms for their RFLP patterns of mitochondrial DNA (mtDNA). A 9.7 kb clone from pearl millet mtDNA discriminated each of the three A₄ entries whereas other maize and pearl millet mtDNA clones used could not distinguish this group completely. The molecular differences within the A₄ cytoplasmic group offer some explanation for the inconsistency in the fertility restoration behaviour of these A₄ lines obtained with a definite set of testers in the field. This revised version was published online in July 2006 with corrections to the Cover Date.     

Parental influences on gas exchange rates in grain sorghum

Summary Significant genetic variation in CO₂ assimilation rate (A), stomatal conductance (g), and A: g ratio, which are indicators of intrinsic differences in productivity and water use efficiency (WUE), has been demonstrated in grain sorghum [Sorghum bicolor (L.) Moench] hybrids. The primary objective was to determine the possible parental influence on the components of the A: g relationship in sorghum hybrids across a range of water supplies. Thirty F₁ hybrids resulting from a 6 × 6 diallel crossing pattern constituted the genetic material. Field experiments were conducted using four water supply treatments established through differential irrigation. Carbon assimilation rate (A), g, and leaf water potential (_w) of individual leaves were monitored every 15 to 20 days. Genetic analyses revealed that general- and specific-combining ability effects were evident for A. However, reciprocal and maternal effects were more important in governing the A-g and A-_w relationships. Since the maternal effects were the major determinants in causing reciprocal differences, A can be improved by selecting specific female parents to exploit cytoplasmic factors or physiological characteristics of this parent. Substantial genetic variation in the A-g relationship resulting from significant genetic control of A offers the opportunity to impose selection for high A and stability of A, which might directly contribute to whole plant WUE and productivity in grain sorghum.Abbreviations A carbon assimilation rate - g stomatal conductance to water vapor - GCA General Combining Ability - SCA Specific Combining Ability - WUE Water Use Efficiency     

Expression of resistance to Atherigona soccata in F1 hybrids involving shoot fly-resistant and susceptible cytoplasmic male-sterile and restorer lines of sorghum

In recent years, cytoplasmic male‐sterility (CMS) has been recognized as a potential danger to the stability of crop production and resistance to insect pests in sorghum. Therefore, the influence of CMS on the expression of resistance to sorghum shoot fly was studied at the ICRISAT, Patancheru, India using the interlard fishmeal technique. The experimental material consisted of 12 restorer, 12 CMS and the maintainer lines, and their 144 F₁ hybrids. Shoot fly‐resistant CMS lines were preferred for oviposition and had more damage because of deadhearts than the corresponding maintainer lines. The hybrids based on shoot fly‐resistant CMS × resistant restorer lines were significantly less preferred for oviposition than the hybrids based on other cross combinations and exhibited the highest frequency (69.1%) of shoot fly‐resistant hybrids. The hybrids based on glossy and trichomed parents had the highest frequency (>90%) of hybrids with glossy and trichome traits, emphasizing the need to transfer these traits into both parents for better expression in the F₁ hybrids. The expression pattern of trichome density, leaf glossiness and leaf sheath pigmentation in the F₁ hybrids and their parents suggested that the interactions between cytoplasmic and nuclear genes possibly control the expression of traits associated with resistance to sorghum shoot fly in the F₁ hybrids.     

中国高粱地方种质芽期苗期耐盐性筛选及鉴定

日益严重的土壤盐渍化对现代农业生产造成了巨大的危害。高粱既是世界五大粮食作物之一,又是耐盐性很强的抗逆作物。开展高粱耐盐性研究、筛选出一批综合耐盐能力优良的高粱品种对开发利用盐渍化土地、增加粮食产量和维持农业可持续发展具有重要意义。本研究对110份中国高粱地方品种分别进行了芽期200 mmol L~(-1)和苗期100 mmol L~(-1)的NaCl胁迫试验,测定芽期发芽势、发芽率以及苗期的相对叶绿素含量(SPAD)、苗长、根长、苗鲜重、根鲜重、苗干重、根干重等指标。计算芽期、苗期盐胁迫下性状值占对照性状值的百分比表明,参试品种芽期相对发芽势、相对发芽率范围分别为0～98.89%、23.65%～101.79%,盐胁迫下相对发芽势变化差异显著。苗期相对叶绿素含量、相对苗长、相对根长、相对苗鲜重、相对苗干重、相对根鲜重、相对根干重变化范围分别为59.53%～99.91%、52.47%～95.23%、47.87%～100.14%、27.43%～95.28%、30.48%～98.26%、21.62%～100.34%、31.46%～102.13%。采用隶属函数值分析和主成分分析2种方法结合聚类分析对参试高粱芽期和苗期的耐盐能力综合评定,鉴定出芽期高度耐盐材料22份,耐盐材料32份;苗期高度耐盐材料37份,耐盐材料41份;其中,来自内蒙古的朝阳棒槌(00003011)和来自北京的白鞑子帽(00001081)等10个品种在芽期和苗期均表现高度耐盐,可作为后续全生育期耐盐鉴定和耐盐育种的优异资源。对芽期隶属函数值排名以及苗期F值排名结果进行相关性分析表明,芽期与苗期耐盐性没有显著相关性;主成分分析结果表明,反映生物量的指标如苗干重、根鲜重可作为苗期大量材料耐盐鉴定的评价指标。     

Genetic relationship between some cytoplasmic male sterility systems in sorghum

Summary Genetic analysis of cytoplasmic male sterility systems in sorghum was undertaken by evaluating a set of 25 A×B crosses and another set of 171 A×R crosses. Male steriles included diverse sources reported from U.S.A. and India. Fertility restoration in crosses was assessed by studying pollen sterility under microscope and seed setting under selfed earheads. Male fertility restorers are identified for diverse cytoplasms. Accordingly the diverse cytoplasms are grouped and listed in the increasing order of their sterility as A₁ & CK 60A A₂ A₄ M31-2A & M35-1A (A₄ tentative) A₃ & VZM2A G₁A (A₅ tentative) and consequently fertility restoration also becomes difficult in the same order for utilization in the breeding programmes. Among the non-milo cytoplasms, A₂ among exotics and maldandi (M31-2A and M35-1A) among Indian sources, can be utilised for practical exploitation in breeding programmes.     

Genetic analysis of biotype I greenbug resistance in sorghum

The greenbug has been a major insect pest of sorghum since 1968. Although sources of genetic resistance have been identified to combat this pest, new and virulent biotypes have successfully overcome these resistance genes. KS 97 was developed and released by the Kansas Agricultural Experiment Station as a new germplasm source of biotype I greenbug resistance in sorghum. The objectives of this study were to evaluate combining ability effects for greenbug resistance in KS 97 and to determine the number of genes responsible for this trait. Six inbred lines, including KS 97 and greenbug resistant and susceptible checks, were intercrossed using a Design-II mating scheme to produce nine F1 hybrids. Responses of seedlings of parent lines and hybrids to biotype I greenbug were evaluated in replicated growth chamber experiments. The results of these studies indicated significant effects of general combining ability (GCA) and specific combining ability (SCA). Greenbug resistance derived from KS 97 was found to be incompletely dominant, and the GCA effect for resistance associated with KS 97 was superior to that associated with PI550610, the resistant check. Segregation studies to determine the number of genes responsible for greenbug resistance in KS 97 were conducted in BC1F1 populations. KS 97 was introgressed into three greenbug-susceptible genetic backgrounds. Segregation analysis indicated a consistent 1:3 (resistant:susceptible) segregation ratio for greenbug resistance across populations. The simplest explanation for these results is that two dominant genes requiring complementary gene action control resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic analysis of feed quality and seed weight of sorghum inbred lines and hybrids using analytical methods and NIRS

Eight lines of grain sorghum and their F1hybrids were evaluated for contents of crude protein (CP), fat (FAT), and starch(STA); protein digestibility (PD); and in vitro dry matter disappearance (IVDMD).The effect of seed weight (SW) on these traits and the potential use of near infrared reflectance spectroscopy (NIRS) to predict them also were investigated. The male lines included three normal-seeded lines (TX2737, TX435, and P954063) and two large-seeded lines (PL-1 and Eastin1). The female lines included common U.S. seed parent lines (Wheatland, Redlan, andSA3042). The lines and their hybrids were grown under dry land conditions at Kansas State University experiment fields in Ashland and Belleville, Kansas, in 1999.The experiments were conducted using a randomized complete block design with four replications at each location. The effect of genotype was significant for all measured traits. The male parent lines were highly variable and expressed high levels of genetic variation in combining ability for CP, PD, STA, and SW. The female parents were genetically more uniform; however, significant general combining ability effects were noted for PD and SW. Significant negative correlations were noted between CP and STA and between SW and STA. Significant positive correlations were found between CP and SW and between FAT and IVDMD. Crude protein content was predicted accurately by NIRS. Fat content and IVDMD could not be predicted by NIRS. The NIRS equations based on ground samples were more accurate than those based on whole-seed samples. This revised version was published online in August 2006 with corrections to the Cover Date.     

中国高粱地方品种遗传多样性评价及中、外高粱遗传变异水平比较

利用32个高粱(Sorghum bicolor L.)核基因组多态性SSR(simple sequence repeats)位点,以69份国外品种为对照,对12个地区的184份中国高粱地方品种进行了遗传多样性分析。研究结果表明,中国高粱的遗传多样性明显低于国外高粱。中国高粱和国外高粱的等位基因丰度(R_s)和基因多样性(H_e)分别为9.81、0.629和11.52、0.745。中国高粱的遗传多样性明显低于东非(He=0.732)、北美(He=0.707)和南亚(He=0.712)高粱,与南非高粱相当(He=0.609)。不同地区中国高粱地方品种遗传变异水平存在明显差异,12个地区高粱种质等位基因丰度在3.64~4.88之间,基因多样性值在0.517~0.714之间。吉林高粱地方品种遗传变异最为丰富(He=0.714),与北美、南亚高粱相当。中国高粱与国外高粱之间遗传分化明显,而中国高粱地方品种地区间和类型间分化极弱。主成分分析(PCA)能够明显区分中外高粱种质但不能将中国高粱按地区或类型分开。分子方差分析(AMOVA)表明,中外高粱间的遗传变异占全部参试材料遗传变异的20.43%。中国高粱遗传变异主要存在于地区内材料间(占总变异91.94%)或生态区内材料间(占总变异94.97%)。在品种类型方面,中国高粱绝大部分遗传变异存在于穗型内材料间(占总变异97.93%)。本研究支持中国高粱外来说的观点。     

Analysis of resistance mechanism to Atherigona soccata in crosses of sorghum

In sorghum, shoot fly resistance is important for grain yield and fodder value. An experiment was conducted to estimate genetic parameters of sorghum for resistance to shoot fly in 50 hybrids, by crossing 5 × 10 genotypes in line × tester manner. Plant height, number of leaves per plant, number of eggs per plant, trichomes on upper and lower surface per unit area of lamina and dead heart per cent were measured on 14 and 21 days after emergence (DAE) and glossiness of leaves was graded on 14 DAE. The correlation between midparent and hybrid performance, GCA : SCA ratio revealed predominance of non-additive gene effects for the traits studied, which could be exploited through hybrid breeding. Of the parents, SPSFPR 94004A and IS 4777 were the best general combiners for shoot fly resistance. Correlation and path analysis revealed the importance of resistance traits and phenol estimation confirms the resistances against shoot fly.     

上海甜芦粟种质资源收集与初步鉴定

为探究上海甜芦粟地方种质资源的多样性,选取11份地方种质对其主要农艺性状进行鉴定与评价。结果表明:供试种质资源的种子萌芽力、抽穗期、分蘖数、分枝数、茎秆产量、籽粒产量等存在较大差异,其中种子萌芽力在不同温度下的变异系数超过40%;在产量性状中,单株产糖量介于40.31~142.84 g,变异系数最大,为29.19%;茎秆出汁率介于46.60%~56.73%,变异系数最小,为5.55%;糖锤度介于11.42%~16.77%,变异系数略高于茎秆出汁率,为10.88%。相关性分析结果表明:单株产糖量与株高、叶鞘鲜重、节间数呈显著正相关,与茎粗、叶片鲜重、茎秆鲜重呈极显著正相关;茎秆出汁率与茎粗、叶鞘鲜重呈显著正相关P<0.05;糖锤度与所测其他性状之间的相关性未达到显著性水平。在供试种质中,19G016在15℃下发芽最快,其单株产糖量和糖锤度最高,分别为142.84 g和16.77%;19G012抽穗最快,从播种到抽穗仅用82.6 d;19G017的茎秆出汁率最高和分蘖数最少,分别为56.73%和0.6个。该研究结果以及这些丰富的地方种质资源将为甜芦粟品种改良提供基础。     

高粱SSA-1无融合生殖特性及其遗传分析

采用去雄杂交鉴定、遗传分析，对高粱ＳＳＡ－１无融合生殖系的结实特性，无融合生殖频率及其遗传行为进行了鉴定分析。研究结果表明ＳＳＡ－１具有自主结实特性，其自主结实为１３．３－３２．７％。绳索产受两对隐性基因控制，无融合生殖频率为２５．５％－５２．２％，为的兼性无融合生殖类型。该系无杂交不孕性，无融合生殖表达不受授粉方式，父类型等因子的影响，是目前无融合生殖研究以及固定杂种优势的良好基因材料。     

高粱种子对萌发温度的响应分析与耐低温萌发能力鉴定

萌发期的低温是限制种子萌发的一个重要非生物胁迫因子,高粱种子耐低温萌发能力是保证高粱出苗整齐、建立良好群体的基础,因此研究高粱品种对不同萌发温度的响应特征具有重要的理论和应用价值。本试验用来源于不同地区的30份高粱品种,在25℃、20℃、16℃和12℃人工气候箱中进行萌发试验,测定不同温度下高粱品种的发芽势、发芽率、芽长、根长、芽重、根重等萌发指标,分析不同高粱品种的萌发差异;通过主成分分析和聚类分析,对不同高粱品种萌发期耐低温特性鉴定和分类,结果表明,随着萌发温度的降低,高粱芽和根的生长均受到抑制,但根与芽的重量和长度比均增加,说明萌发过程中芽比根对低温更加敏感。30个高粱品种的6个萌发指标相对值之间存在一定相关性。主成分分析表明,相对芽长、相对根长和相对发芽率分别在3个主成分中载荷较大,可作为高粱萌发期耐低温的主要鉴定指标。30个高粱品种按萌发期耐低温能力可分为四大类,辽粘3号极不耐低温,济粱1号等18个品种对低温敏感,冀酿1号等5个品种对低温不敏感,赤杂101等6个品种对萌发期低温具有较强的耐性。     

Grain mould resistance and associated characters of sorghum genotypes

Twenty-two sorghum genotypes were evaluated for grain mould response, 13 morphological and biochemical traits thought to contribute to resistance, and 3 agronomic traits related to utilization. Measurements of grain mould (field grade score, threshed grade score, ergosterol content, and percentage germination) were strongly correlated with one another. Highly significant correlations between measures of grain mould and seed hardness, seed phenol content in acid methanol extract, and glume colour indicated that they strongly affected grain mould response. Harder grain, higher levels of seed phenols, and darker glumes contributed to grain mould resistance. Weaker and less consistent correlations between measures of grain mould and seed colour, seed flavan-4-ol content, glume phenol and flavan-4-ol contents, and glume cover indicated relatively less effect of these traits on grain mould response. Genotype means indicated that combinations of several traits are required to achieve resistance. Germplasm lines, including coloured-seeded lines IS 14375, IS 14387, IS 18144, and IS 18528, and white-seeded lines IS 21443, IS 24495 and IS 25017, showed greatest grain mould resistance. Improved lines generally had poorer grain mould resistance than these landraces. However, the best improved lines were comparable in resistance to white-seeded landraces. B58586, IS 14375 and IS 14387 are hard-seeded guinea sorghum lines that can be used as sources of grain mould resistance for West Africa. SP 33316, SP 33349 and GM 15018 are agronomically elite lines that can be used as sources of grain mould resistance for further improvement of white-seeded sorghum for South Asia and other regions. This revised version was published online in July 2006 with corrections to the Cover Date.     

高粱微卫星分析中遗传完整性样本量的确定

采用微卫星分析高粱不同样本量对遗传多样性指数的影响,从而确定最佳样本量,为遗传完整性研究奠定基础。试验设置了10个样本量梯度,对群体的等位基因数目、有效等位基因数目、香农指数、观察杂合度、预期杂合度、多态位点百分数和稀有等位基因频率的变化趋势进行了分析。结果表明,10～40个样本量范围内,等位基因数目、有效等位基因数目、香农指数、多态位点百分数随着样本量的增大而增大;在40个样本量时,等位基因数目、有效等位基因数目和香农指数达到较高值,分别代表了100个群体98.5%的等位基因数、99.1%的有效等位基因数和98.5%的香农指数,之后样本量继续增加,各指标变化不显著。稀有等位基因频率在40个样本量以上,随着样本量的增加数值变化很小。以稀有等位基因频率、等位基因数、有效等位基因数和香农指数为多样性指标,在高粱遗传完整性研究中样本量大小的确定上达到一致性。因此,建议在用SSR技术对高粱进行遗传完整性分析时,样本量要选择40个单株以上。     

Fluorimetric Determination of the Genetic Variability Existing for Chilling Tolerance in Sweet Sorghum and Sudan Grass

Chilling temperatures drastically inhibited the photochemical quenching of chlorophyll fluorescence (q_Q) measured in intact leaves photosynthesizing under steady-state conditions. This effect appeared, however, to be characteristic of chilling-susceptible plant species and was not observed in plants which are known to be chilling-tolerant, indicating that the measurement of q_Q can serve in practice to estimate rapidly the relative chilling tolerance of crop plants. A large number (28) of sweet sorghum (Sorghum bicolor) and Sudan grass (Sorghum sudanense) genotypes were screened for chilling tolerance using this rapid q_Q method. Although sweet sorghum and sudan grass obviously behaved as chilling-sensitive plants, a considerable variation for chilling susceptibility was observed among the different genotypes tested. Some sweet sorghum varieties, such as ‘Dale’ and ‘Keller’, and most of the sudan grass varieties appeared to possess a certain degree of resistance towards low temperature stress, indicating the existence of useful germplasms in Sorghum for improving stress tolerance.     

Compensation in grain weight and volume in sorghum is associated with expression of resistance to sorghum midge, Stenodiplosis sorghicola

Sorghum midge, Stenodiplosis sorghicola (Coquillett) is one of the most important pests of grain sorghum worldwide. We studied the inheritance of resistance to sorghum midge and compensation in grain weight and volume in panicles of sorghum hybrids and their parents under uniform infestation (40 midges per panicle for two consecutive days). Sorghum midge damage ranged from 8.2 to 82.4% in the maintainer lines (B-lines) of the females parents (A-lines), and 9.0 to 67% in the male parents (restorer lines). Hybrids involving resistant × resistant parents were highly resistant, while those involving resistant ×susceptible and susceptible × resistant parents showed moderate susceptibility. Susceptible × susceptible hybrids were susceptible. Compensation in (percentage increase) grain weight and volume in midge-infested panicles of midge-resistant parents and their F₁ hybrids was greater than in midge-susceptible parents and hybrids. General combining ability effects for midge damage, and grain weight and volume were significant and negative for the midge-resistant females (ICSA 88019 and ICSA 88020), whereas those for the midge-susceptible females (ICSA 42 and 296A) were significant and positive. However, the reverse was true in case of compensation in grain weight and volume. Inheritance of compensation in grain weight and volume and resistance to sorghum midge is controlled by quantitative gene action with some cytoplasmic effects. Resistance is needed in both parents to realize full potential of midge-resistant hybrids. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic diversity of high-molecular-weight glutenin subunit compositions in landraces of hexaploid wheat from Japan

The high-molecular-weight (HMW) glutenin subunit composition of seed storage protein of 174 Japanese hexaploid wheat (Triticum aestivum) landraces have been examined by using sodium dodecyl sulfate polyacrylamide gel electrophoresis system. Twenty four different, major glutenin HMW subunits were identified, and each of the landraces contained three to five subunits and 17 different glutenin subunit patterns were observed for 13 alleles in the landraces. On the basis of HMW glutenin subunits composition, Japanese landraces showed a specific allelic variation, close to Japanese commercial wheats in HMW glutenin subunits, different from those in alien hexaploid wheats. Further, it could be concluded that all common glutenin alleles can be found in the 174 landraces originated from Japan. The variation detected in the glutenin subunits is useful for variety identification, has a bearing on our understanding of hexaploid wheat genetic resource evolution in Japan, and raises questions concerning the nature of this genetic variation. This revised version was published online in July 2006 with corrections to the Cover Date.