玉蝉花愈伤组织的诱导及植株再生研究

以玉蝉花的茎尖和嫩叶为外植体进行愈伤组织诱导和再分化研究,成功建立了通过茎尖愈伤诱导途径的植株再生体系。研究得出:玉蝉花茎尖诱导愈伤的最佳培养基为MS+6-BA 1.0mg/L+NAA 0.5mg/L+2,4-D 1.0mg/L,最高诱导率为51.51%;不定芽诱导的培养基为MS+6-BA 1.0mg/L+NAA 0.5mg/L+KT 1.0mg/L,分化率达到72.31%,平均分化不定芽数为5.81;不定芽生根最佳培养基为MS+NAA 1.5mg/L,生根率为100%。     

云南杜鹃(Rhododendron yunnanense Franch.)无菌叶片高频再生体系的建立

本研究以云南杜鹃(Rhododendron yunnanense Franch.)无菌苗叶片为材料,研究云南杜鹃叶片直接和间接再生植株的方法。结果表明:ZT是理想的云南杜鹃无菌叶片直接分化不定芽和愈伤组织分化不定芽的细胞分裂素,其中以WPM+ZT 4 mg/L+NAA 0.01 mg/L效果最好,叶片分化不定芽率达74%,平均分化不定芽数6.91个,愈伤组织分化不定芽率达76.67%;附加TDZ诱导出的愈伤组织状态好,体积大,疏松,适宜的叶片诱导愈伤组织的培养基为WPM+TDZ 0.5mg/L+2,4-D 1~2 mg/L+水解酪蛋白500 mg/L,愈伤组织诱导率达91.33%以上,较好的生根培养基为1/2 WPM+IAA 1.5 mg/L,生根率达89.33%以上。研究结果为云南杜鹃遗传转化研究奠定了基础。     

黑木相思优良无性系(SR17)组培苗茎段再生体系建立

为建立黑木相思(Acacia melanoxylon R.Br.)茎段高频率再生体系,以优良无性系(SR17)组培苗茎段为外植体,研究培养基中添加TDZ及TDZ与IAA组合使用、不同浓度Ag NO3以及茎段部位对愈伤组织诱导和不定芽再生的影响。结果表明:当TDZ质量浓度为0.05 mg/L时,愈伤诱导率、不定芽分化率和不定芽数最高,IAA 0.05 mg/L配合TDZ使用可使不定芽分化率高达89.4%。同时发现不同质量浓度Ag NO3对不定芽分化率影响不显著,当Ag NO32.5 mg/L时,诱导的愈伤和不定芽容易产生玻璃化。另外发现组培苗中部茎段最有利于不定芽分化。因此选择组培苗中部茎段为外植体,在WPM+TDZ 0.05 mg/L+IAA 0.05 mg/L的诱导培养基上培养30 d,转入MS+6BA 0.5 mg/L+IBA 0.5 mg/L的分化培养基上培养30 d获得最高的不定芽诱导率,且平均每个外植体形成14.3个不定芽。将经过伸长生长的不定芽转入生根培养基1/2 MS+IAA 2.0 mg/L+IBA 0.5 mg/L时,生根率高达95.8%。生根培养10 d,炼苗培养20 d后获得可供移植的组培苗。本研究为黑木相思遗传转化和分子育种提供理论参考。     

‘黑珍珠’番茄植株再生体系的研究

为了研究‘黑珍珠’番茄植株再生,以‘黑珍珠’番茄幼嫩叶片为外植体诱导愈伤组织,通过愈伤组织诱导培养、愈伤组织分化培养、不定芽增殖培养、生根培养和试管苗移栽,建立高效快速的‘黑珍珠’番茄再生体系。结果表明：最适宜的诱导叶片愈伤组织的培养基为MS+ 1.0 mg/L 6-BA+ 0.1 mg/L NAA,叶片外植体愈伤组织诱导率最高可达98.2%;诱导出的愈伤组织在MS+ 1.5 mg/L 6-BA+ 0.2 mg/L IBA培养基上能很好的分化出不定芽;MS+4.0 mg/L KT+ 0.01 mg/L IBA 培养基可实现不定芽芽增殖;最适宜的生根培养基为1/2MS+ (0.05~0.08) mg/L NAA,试管苗移栽成活率达92%。     

胡麻品种内亚7号下胚轴组织培养再生体系的建立

以胡麻品种内亚7号下胚轴为外植体,探索其下胚轴进行组织培养的培养基条件。结果表明,用75%的乙醇和1g/L的HgCl2溶液各处理种子3min是最佳的消毒方法。用MS+3.0mg/L 6-BA+0.25mg/L IAA培养基诱导外植体的出愈率最高,为98.48%,生长速率最大,是愈伤组织生长的最佳培养基。用MS+2.0mg/L 6-BA+0.5mg/L IAA培养基诱导不定芽的分化率最高,为95%,不定芽增殖系数最大,为7.67,是不定芽分化及增殖的最佳培养基;用MS+0.01 mg/L6-BA+0.75mg/L IAA培养基诱导不定芽的生根率最高,为52.26%,是不定芽生根的最佳培养基。由此建立的组织培养再生体系,其出愈率、愈伤组织的生长速率及不定芽的诱导率、增殖率高,生根情况良好,可作为胡麻品种内亚7号的适宜组织培养再生体系。     

杜仲无菌苗组织培养的快速繁殖技术

杜仲是中国特有的珍贵树种,具有重要的医药价值和经济价值。针对杜仲组织培养多存在易污染,不定芽、不定根诱导难等问题。本研究以杜仲无菌苗为材料,研究了最适外植体,不定芽诱导、增殖培养和促进生根的最适基本培养基、植物生长调节剂的种类和浓度。研究结果表明,以杜仲无菌苗茎尖为外植体,以MS为基本培养基,添加0.5 mg/L或1.0 mg/L 6-BA、同时添加0.5 mg/L NAA最适合愈伤组织诱导;单独使用0.5 mg/L的6-BA时虽然愈伤组织诱导率较低,但不定芽诱导率最高,为88.9%,适合进行后续不定芽的增殖试验。以WPM为基本培养基,添加IBA 1.0 mg/L时,生根数最多,生根率达88.9%,且根系较长。研究结果将为实现杜仲组织培养的工厂化生产、杜仲基因工程等提供技术参考。     

色素万寿菊杂交母本未授粉子房培养

以色素万寿菊雄性不育株未授粉子房为外植体,比较研究子房发育期、高低温处理和生长调节剂组合对愈伤组织诱导和分化的影响。结果显示:发育6~10 d,花丝刚好露出花萼,顶部呈圆柱状的花蕾愈伤组织诱导效果最好,为79.2%;低温预处理3 d,高温培养5 d有利于愈伤组织诱导;MS+2,4-D 0.5 mg/L+NAA0.5 mg/L+6-BA 0.5 mg/L+KT 0.5 mg/L为愈伤组织诱导最佳培养基,诱导率高达85.8%;NAA 1.0 mg/L+6-BA3.0 mg/L为不定芽分化适宜培养基,分化率达77.6%;1/2MS+NAA 0.2 mg/L为生根适宜培养基,生根率93.5%。本研究可为建立高效单倍体培养体系以及单倍体育种技术提供基础性资料。     

直接诱导不定芽的矮牵牛再生体系的建立

以矮牵牛的叶片作为外植体,研究了不同浓度的激素配比对叶片直接诱导不定芽、诱导愈伤组织分化不定芽及生根的影响。得到了最适的直接诱导不定芽培养基的激素配6-BA1.5mg/L+IBA0.5mg/L、诱导愈伤组织分化不定芽的培养基的激素配比6-BA1.5 mg/L+NAA0.3~0.5 mg/L及生根培养基IBA0.03~0.05 mg/L。并在时间上,从芽的长势、芽的生根情况进行比较,结果表明：直接诱导的不定芽比诱导愈伤组织分化的不定芽所需的时间短、长势好、生根快。     

巴戟天胚乳诱导愈伤组织及三倍体再生

目的:利用巴戟天种子内胚乳为外植体进行离体培养获得三倍体。方法:选取未成熟巴戟天种子内胚乳,置于不同培养基上诱导愈伤组织和分化再生植株,并对植株倍性进行根尖染色体鉴定。结果:在MS+2,4-D(2,4-二氯苯氧乙酸)2.0 mg/L+6-BA(6-苄基嘌呤)1.0 mg/L培养基上诱导获得愈伤组织,诱导频率达58.9%。愈伤组织在MS+6-BA1.0~2.0 mg/L+IBA 0.1~0.5 mg/L分化培养基上分化出不定芽。不定芽在1/2 MS+IBA 0.5 mg/L上诱导生根,生根率100%。再生植株根尖细胞染色体数目为2 n=3 x=33。结论:利用巴戟天胚乳培养获得三倍体是创造多倍体新种质的有效途径。     

野生软枣猕猴桃组织培养及褐变处理

以野生软枣猕猴桃嫩芽、幼嫩叶片以及茎段作为外植体,研究野生软枣猕猴桃组织培养整个过程,以建立快速高效的野生软枣猕猴桃再生体系。结果表明：最适宜的诱导叶片、茎段愈伤组织的培养基分别为MS+0.5 mg/L 6-BA+1.0 mg/L NAA和MS+0.5 mg/L 6-BA+0.1 mg/L NAA;诱导出愈伤组织在MS+0.6 mg/L 6-BA+0.05 mg/L NAA培养基上能很好地分化不定芽苗;诱导幼芽产生丛生芽的培养基为MS+1.0 mg/L 6-BA+0.1 mg/L NAA;较适宜的生根培养基为1/2MS。愈伤组织继代中发现细胞生长素NAA可以防止愈伤褐化。在愈伤组织分化中,发现将分化出的芽苗再次愈伤化,可以提高分化率。     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

Flag Leaf Senescence, as Evaluated by Numerical Image Analysis, and its Relationship with Yield under Drought in Durum Wheat

Senescence was evaluated at different stages of the grain‐filling period in eight durum wheat varieties using numerical image analysis (NIA). The varieties were grown under early, severe drought conditions on the high plains of Sétif in Algeria. After flowering, three different irrigation treatments were applied. Treatment effect was small, while a genotypic effect was noted for most of the senescence parameters. Senescence correlated to biomass, while the maximal rate of senescence, V_smax, correlated to thousand‐kernel weight. The potential of the method of numerical image analysis for monitoring flag leaf senescence, detecting genotypic variability and selecting genotypes with delayed senescence is discussed.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Cowpea (Vigna unguiculata): Genetics,genomics and breeding

Cowpea, Vigna unguiculata (L.), is an important grain legume grown in the tropics where it constitutes a valuable source of protein in the diets of millions of people. Some abiotic and biotic stresses adversely affect its productivity. A review of the genetics, genomics and breeding of cowpea is presented in this article. Cowpea breeding programmes have studied intensively qualitative and quantitative genetics of the crop to better enhance its improvement. A number of initiatives including Tropical Legumes projects have contributed to the development of cowpea genomic resources. Recent progress in the development of consensus genetic map containing 37,372 SNPs mapped to 3,280 bins will strengthen cowpea trait discovery pipeline. Several informative markers associated with quantitative trait loci (QTL) related to desirable attributes of cowpea were generated. Cowpea genetic improvement activities aim at the development of drought tolerant, phosphorus use efficient, bacterial blight and virus resistant lines through exploiting available genetic resources as well as deployment of modern breeding tools that will enhance genetic gain when grown by sub‐Saharan Africa farmers.     

Screening for resistance to take-all in wheat,triticale and wheat-triticale hybrid lines

Summary Fifteen triticale and wheat-triticale hybrid lines were evaluated for resistance to the take-all fungus Gaeumannomyces graminis var. tritici and compared with five wheat and two rye lines in inoculated field and pot trials. The triticale and wheat-triticale hybrid lines varied in rye chromosome number and degree of resistance expressed. One line, Venus with seven pairs of rye chromosomes consistently showed levels of resistance intermediate between wheat and rye. A trend was observed where increasing rye chromosome content led to greater resistance but exceptions showed that variation within triticales could not be ascribed to rye chromosome content alone.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.