黄瓜子叶节不定芽的诱导及对甘露糖耐性的研究

为了进一步优化黄瓜组织培养体系,将非杭生素筛选标记用于黄瓜遗传转化中,以黄瓜新津研四号、绿地黄瓜和新津优1号为材料,研究黄瓜3个基因型在两种培养基中诱导不定芽的能力以及3个基因型子叶节对甘露糖的耐性。结果表明,黄瓜3个基因型不定芽诱导能力相似,L4(MS+lmg/L6-BA+0.5mg/L ABA+4mg/LKT)培养基诱导黄瓜不定芽的效果好于LS(MS+2mg/L6-BA +0.025mg/L IAA+4mg/L KT)培养基;当用甘露糖作为黄瓜子叶节遗传转化杭性筛选剂时,适宜筛选浓度为5mg/L。     

棉花子叶节芽分化培养基的优化研究

以陆地棉百棉1号为材料,离体培养子叶节,对芽分化培养基中6-BA和KT的使用浓度进行了优化;6-BA和KT浓度各设置(0.5、1.0、2.0、2.5、3.0、5.0 mg/L)5个梯度,比较了单独使用6-BA、KT和2种激素组合时对诱导多芽发生的差异;结果显示,单独使用6-BA对诱导芽分化效果较好,单独使用KT可以在芽分化的同时,诱导根的生成.组合使用两种激素时,效果优于单独使用;组合使用1.0mg/L6-BA+2.0mg/L KT时效果最佳.     

菏泽市雷电灾害风险区划研究

为了明确不同县区雷电灾害风险的高低、防御和减轻雷电灾害,以闪电定位资料和经济社会资料为基础,采取归一化法、层次分析法、加权综合评价法,统筹考虑致灾因子的危险性、孕灾环境的敏感性、承灾体的易损性和防灾减灾能力4个评价指标,选择9个影响因子建立雷电灾害区划模型,绘制出菏泽市雷电灾害风险区划图。结果得出：曹县和东明是致灾因子危险性高值区,两地的孕灾环境敏感性同样较高,牡丹区和定陶是承灾体易损性高的区域,防灾减灾能力的高值区在牡丹区和东明。曹县和东明是雷电灾害的高风险区,次高风险区为单县和巨野,中等风险区为定陶,次低风险区为成武和郓城,牡丹区和鄄城由于防灾减灾能力强或致灾因子危险性较低划为低风险区。     

黄瓜子叶节离体体细胞再生体系研究

以华北类型自交系L04-203为材料,通过对外植体类型、不定芽诱导培养基、芽伸长培养基等进行研究,建立了以子叶节为外植体通过器官发生方式的黄瓜离体体细胞再生体系.研究表明:附带短下胚轴子叶节为最适外植体;BA/NAA比例对愈伤形成和再生频率有直接影响,NAA为零或低浓度时,在外植体切口处直接形成再生芽,随着NAA浓度增...     

硫辛酸对农杆菌介导的黄瓜子叶节遗传转化的影响

转化效率低一直是黄瓜转基因的瓶颈,本研究旨在采用硫辛酸(LA)和乙酰丁香酮(AS)辅助进行农杆菌转化,研究硫辛酸作为一种新的转化诱导剂对黄瓜遗传转化的影响。结果表明,在添加浓度相同的情况下,仅在培养基中添加LA的转化效率比较仅在菌液中加入LA有显著提高,而当菌液和培养基中同时加入LA与AS的转化频率最高,即采用100 mg/L LA和50 mg/L AS处理后,黄瓜子叶节Hyg抗性芽的再生频率由28.3%升高到86.7%,SouthernBlot验证抗性植株的阳性率为7.5%。因此,在黄瓜遗传转化过程中使用硫辛酸有利于转化细胞的分化,更有助于提高抗性植株的阳性率。     

蓖麻子叶节遗传转化研究

利用前期构建的P450基因的RNAi植物表达载体侵染蓖麻受体材料,旨在获得转P450基因的阳性株。以蓖麻品种通蓖5号为试验材料,利用根癌农杆菌介导法转化蓖麻子叶节,研究影响子叶节遗传转化的若干因素。结果表明:子叶节对Kan较为敏感,适宜筛选质量浓度为250 mg/L;外植体预培养2～3 d,侵染用农杆菌菌液OD600=0.8,侵染时间10 min,共培养3 d,可获得较高的遗传转化效率。再生植株经PCR和Southern Blot检测,证明为转基因植株。     

土壤入渗参数的估算方法及其变异性研究进展

土壤入渗参数是地面灌溉中灌溉制度制定、灌水质量评价的重要依据。此文总结了目前地面灌溉中常用的土壤入渗模型,并对入渗参数的各种估算方法做了详述,探讨了各种方法的优缺点,综述了土壤入渗参数的变异性及其对灌水质量的影响,指出了土壤入渗参数估算及其变异性分析中存在的问题,为今后揭示土壤入渗参数的反演及其变异规律提供参考。     

改良大豆子叶节再生体系的研究

采用大豆种子萌发5~6 d后的子叶节作外植体，对农杆菌介导的大豆遗传转化系统及其影响因素进行了研究。结果表明，将子叶节与农杆菌共培养60 h后放入含卡那霉素50 mg/L的诱芽培养基上，待苗长至4~5 cm后放入生根培养基中进行生根，最后移栽到培养土中，效果较好。对大豆遗传转化再生的主要因素，如大豆基因型、诱导出芽所需激素浓度、卡那霉素筛选压力等条件做了一系列的研究，建立了一个比较好的遗传转化系统，其转化率达到2.8%。     

甜高粱茎秆含糖量遗传研究进展

甜高粱(Sorghum bicolor)是普通粒用高粱的一个变种。与粒用高粱相比,甜高粱育种研究进展相对缓慢,特别是茎秆含糖量高的亲本系创造比较滞后。开展甜高粱茎秆含糖量的遗传研究,对甜高粱亲本系选育及杂交种组配具有重要意义。本文从茎秆含糖量的评价指标入手,分别对茎秆含糖量的遗传与子粒产量及其他性状的关系、基因定位等方面的相关研究结果进行了系统地概括和归纳,并分析了当前茎秆含糖量研究的热点和亟待解决的问题。     

野生黑果枸杞叶片不定芽诱导研究

以野生黑果枸杞嫩叶为外植体,对其消毒方法、生长调节剂浓度等方面进行研究,探索建立野生黑果枸杞快繁体系,提高野生黑果枸杞人工繁育速度,为黑果枸杞工厂化生产和后期基因工程改良建立良好基础。通过试验得出采集的嫩叶最佳消毒方法和外植体诱导愈伤及不定芽分化最佳培养基。黑果枸杞愈伤组织诱导后无须更换培养基,可直接诱导出大量不定芽,简化了操作步骤,缩短了培养周期,有效提高了培育效率。     

Genetic and Phenotypic Association between Yield Components in Hybrid Sorghum (Sorghum bicolor (L.) Moench) populations

Summary The magnitude of genetic expression and associations among traits are important for the prediction of response to selection in diverse environments and provide the basis for planning and evaluating breeding programs. In this regard, a cross classification mating design was used to produce hybrid sorghum populations, which were evaluated in a randomized completed block design with three replications at four environments in Northern Cameroon. Data on grain yield, days to anthesis, plant height, inflorescence length, threshing percentage and seed mass were collected and subjected to statistical genetic analyses. Significant genotype × environment interaction effects were observed for all traits. Genetic variance was essentially attributed to additive gene effects, with dominance variance for grain yield being negligible. However, the reverse was observed for threshability. Genetic variance components were much higher for plant height and grain yield than for days to anthesis, seed mass and threshability. Heritability estimates for plant height and inflorescence length were high (77 and 54 percent respectively) while the estimates for grain yield and threshability were low (14 and 5 percent respectively). Grain yield had positive genotypic correlation with most of the traits. Days to anthesis were negatively correlated with vegetative and reproductive traits. These results suggest that improvement of days to anthesis, plant height, and inflorescence length should be faster because of higher heritabilities and greater phenotypic variation. However, selection for earliness and reduced plant height would not be possible without hampering grain yield. Selecting for yield primary components namely inflorescence length and seed weight would be effective for increasing production. In addition, optimizing agronomic practices and improved experimental design would increase the selection efficiencies.     

Molecular mapping of the brace root traits in sorghum (Sorghum bicolor L. Moench)

The presence and morphology of plant brace roots are important root architecture traits. Brace roots contribute significantly to effective anchorage and water and nutrient uptake during late growth and development, and more importantly, have a substantial influence on grain yield under soil flooding or water limited conditions. However, little is known about the genetic mechanisms that underlie brace root traits. In this study, quantitative trait loci (QTLs) for presence of brace roots from the sorghum landrace “Sansui” were mapped and associated molecular markers were identified. A linkage map was constructed with 109 assigned simple sequence repeat markers using a F₂ mapping population derived from the cross Sansui/Jiliang 2. Two QTLs associated with presence of brace roots were localized on chromosomes 6 and 7. The major QTL on chromosome 7 between markers Dsenhsbm7 and Xcup 70 explained about 52.5% of the phenotypic variation, and the minor QTL on chromosome 6 was flanked by Xtxp127 and Xtxp6 and accounted for 7.0% of phenotypic variation. These results will provide information for the improvement of sorghum root architecture associated with brace roots.     

A genetic study of popping quality in Sorghum (Sorghum bicolor (L.) Moench)

Summary Two crosses of sorghum, Sorghum bicolor (L.) Moench (IS 1054 × ICSV-1, and IS 5604 × IS 1054) were evaluated in parental, F1, F2, and backcross generations for the variation in their popping quality as measured by pop volume (ml). Dominance was in the direction of low pop volume. Dominance and additive gene effects, in that order, governed most of the variation, while significant dominance x dominance type of interaction effects could also be detected. There was no evidence for higher order gene interactions.Approved as Journal Article 630 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, P.O. 502 324, Andhra Pradesh, India.     

Genetic analysis of threshability in grain sorghum [Sorghum bicolor (L.) Moench]

The ease with which seeds are detached from panicles is one of the early domestication traits. Genotypes with sticky panicles are hard to thresh, and whenever threshed, the grain tends to remain attached to the glume which reduces market value and processability. This study was conducted to determine the genetic mechanisms underlying the threshability trait in sorghum. Four seed parents and eleven pollinators differing for threshability were intercrossed in Design II mating scheme and the resulting hybrids and the parents were grown in four environments. Threshability was estimated as the ratio of seed yield to panicle weight (TW) and proportion of seeds without sticky glumes (TG). Variation was significant among the entries, inbreds and hybrids with GCA for TG and TW varying markedly. Mean TG for inbred and hybrids of low threshable genotypes was not markedly different indicating that threshability trait is under the control of additive genes with dominant or partially dominant effects. Segregation analysis indicates that the TG trait may be under the control of few major genes with approximately one to three loci affecting the trait.     

Genetic divergence among a non-restorer collection of sorghum (Sorghum bicolor (L.) Moench) and its relationship with heterosis

Summary A genetic diversity analysis in a collection of 171 non-restorer lines of sorghum (Sorghum bicolor (L.) Moench) using D² technique and canonical variate analysis indicated that considerable variation in grain yield has been added to the collection by the addition of lines derived from random mating populations. The efficiency of D² and canonical variate techniques in distinguishing extremely diverse genotypes was confirmed. However, the two techniques showed weak correspondence in their clusters. The F₁ hybrids of 15 diverse lines exhibited no relationship between heterosis or per se performance of crosses and diversity in their parents. Therefore, traditional plant breeding methods are being advocated.Approved by ICRISAT as Journal Article no. 435.     

Mapping of QTLs underlying flowering time in sorghum [Sorghum bicolor (L.) Moench]

Due to its critical importance in crop yield, the photoperiodic regulation of flowering time is considered an important trait in sorghum breeding programs. In this study, quantitative trait loci for flowering time were detected using an F₂ population derived from a cross between Kikuchi Zairai, a late-flowering cultivar originating from Japan and SC112, an early-flowering cultivar originating from Ethiopia. F₂ plants were grown with their parents under a natural day length and a 12 h day length. Two linkage maps were constructed using 213 simple sequence repeats markers. Nine quantitative trait loci controlling flowering time were identified in F₂ plants grown under a natural day length, whereas 7 QTLs were identified under a 12 h day length. Five QTLs controlling flowering time were shared under both of the day length conditions.     

Isolation and characterization of resistance gene analogs (RGAs) from sorghum (Sorghum bicolor L. Moench)

Degenerate primers designed based on known resistant genes (R-genes) and resistance gene analogs (RGAs) were used in combinations to elucidate RGAs from Sorghum bicolor, cultivar M 35-1. Most of the previously tried primer combinations resulted in amplicons of expected 500–600 bp sizes in sorghum along with few novel combinations. Restriction analysis of PCR amplicons of expected size revealed a group of fragments present in a single band indicating the heterogeneous nature of the amplicon. Many of these were cloned and some were considered for analysis. The nucleotide sequence of different cloned fragments was done and their predicted amino acid sequences compared to each other and to the amino acid sequences of known R-genes revealed significant sequence similarity. A cluster analysis based on neighbor-joining (N-J) method was carried out using sorghum RGAs (SRGAs) together with several analogous known R-genes resulting in two major groups; cluster-I comprising only SRGAs and cluster-II comprised of known R-gene sequences along with three SRGAs. Further analysis clearly indicated similarity of SRGAs in overall sense with already known ones from other crop plants. These sequences can be used as guidelines to detect, map and eventually isolate numerous R-genes in sorghum.     

Farmer and formal breeding of sorghum (Sorghum bicolor (L.) Moench) and the implications for integrated plant breeding

Sorghum (Sorghum bicolor (L.) Moench) is the fifth most important cereal crop worldwide and it is the fourth most important crop in Ethiopia. The national average yield amounts 1302 kg/ha. In order to assess the achievement in farmer breeding various types of research were undertaken. These include survey research to quantify the trend in productivity, the level of and reasons for adoption of improved varieties, yield performance and preference evaluation of farmers’ varieties (FVs) and improved varieties (IVs). As per the trend analysis over the last four decades, total production and yield per hectare has increased by 11.63 and 14.2%, respectively. However, area allocated to sorghum has decreased over years by −2.93%. The lack of consistent productivity is attributed to the fluctuation of environmental factors. Sorghum production in Ethiopia is predominantly based on varieties developed by farmers. The share of IVs is very low. FVs and IVs are adopted by 87.3 and 12.7% of the farmers, respectively. Besides, the adoption of IVs is limited to the lowland crop ecology. The comparative yield of FVs is higher than IVs by 132%. On top of yield, farmers do prefer their varieties for other multipurpose values namely feed, fuel wood and construction material. FVs under production are identified in each wereda. Farmer breeding has been successful compared to four decades of formal breeding. On the other hand, both farmer and formal breeding are not without weaknesses; a comparative balance sheet is outlined for both. Ideotypes for the three major crop ecologies are suggested and integrated plant breeding is anticipated to develop the proposed ideotypes thereby increase sorghum productivity in the region.     

Variability and Correlations in Grain Sorghum Genotypes (Sorghum bicolor [L.] Moench) Under Drought Conditions at Different Stages of Growth

Twenty-two genotypes of grain sorghum were grown under drought conditions by omitting one irrigation during stages of before flowering period, kernel filling period, and physiological maturity period at Assiut Univ. Farm in 1987 and 1988 seasons. The results obtained revealed that considerable variation existed among genotypes for all the studied traits. The most effective moisture stress treatment in reducing grain yield, panicle weight and plant height was during flowering stage. While 1000-kernel weight was much affected by moisture stress during grain filling period. The genotype x year interaction (σ²_gy) was large compared to genotype x irrigation treatment (σ²_gl) indicated that genotypes responded differently when they were grown from year to year. The genotypic variance (σ²_g) for all traits were large reflecting the importance of genetic variability. Both phenotypic and genotypic correlations among traits showed that plant height and 1000-kernel weight were highly correlated with grain yield, while leaf area index was low associated with plant height.     

Quantitative-genetic parameters of sorghum [Sorghum bicolor (L.) Moench] grown in semi-arid areas of Kenya

Low and erratic rainfall constitutes a major constraint to sorghum production, and impedes sorghum improvement in semi-arid tropics. To estimate quantitative-genetic parameters for sorghum under variable stress conditions, three sets of factorial crosses between four by four lines each were grown with parents and a local cultivar in eight macro-environments in semi-arid areas of Kenya. Fourteen traits were recorded including grain yield, above-ground drymatter, harvest index, days to anthesis, leaf rolling score, and stay-green. Environmental means for grain yield ranged from 167 to 595 g m-2. Mean hybrid superiority over mid-parent values was 47, 31, and 9% for grain yield, above-ground drymatter, and harvest index, respectively. Differences among both lines and hybrids were highly significant for all traits. Genotype × environment interaction variances were larger than genotypic variances for grain yield, above-ground drymatter, and harvest index. Corresponding heritabilities ranged between 0.72 and 0.84. Variation among hybrids was determined by GCA and SCA effects for most characters. Predominance of additive-genetic effects was found for grain yield components, plant height, and leaf rolling score. Lack of variation in GCA was noted among female lines for major performance traits. While low leaf rolling score was correlated with high grain yield, there was no such association for stay-green. Hybrid breeding could contribute to sorghum improvement for semi-arid areas of Kenya. To increase selection progress for major performance traits, genetic variation among female lines should be enhanced. Importance of genotype × environment interaction underlines the necessity of evaluating breeding materials under a broad range of dryland conditions.