脱落酸对棉花体细胞胚胎发生的影响

【目的】研究脱落酸(Abscisic acid, ABA)对棉花体细胞胚胎发生过程中下胚轴脱分化和再分化的影响,优化体细胞胚胎发生体系和初步解析脱落酸调控棉花体细胞胚胎发生分子机制。【方法】以棉花品种中棉所24(CCRI 24)下胚轴为外植体,设置5个ABA浓度0、0.02、0.04、0.06、0.08μmol·L^-1,分别以A0、A1、A2、A3、A4表示,添加至MSB(MS培养基+B5维生素)培养基诱导愈伤和胚性愈伤,研究ABA对棉花下胚轴初始细胞脱分化、愈伤组织诱导和胚性愈伤组织诱导的影响。【结果】ABA促进下胚轴初始细胞脱分化;显著提高愈伤组织的脱分化率和增殖率;0.02μmol·L^-1ABA显著提高胚性愈伤分化率,0.04~0.08μmol·L^-1ABA显著降低胚性愈伤分化率。ABA处理后胚性愈伤和非胚性愈伤的增殖率均显著提高且质地受到影响。0.02~0.08μmol ABA处理下,LBD和LBD在愈伤起始期上调表达。0.02μmol·L^-1ABA处理下,在愈伤增殖早期和中期BBM、LEC1和AGL15上调表达,愈伤增殖后期FUS3、LEA、ABI3基因上调表达。【结论】脱落酸调控的棉花体细胞胚胎发生与相关标记基因的时空性表达密切相关,这些基因表达水平的增加是ABA调控愈伤和胚性愈伤分化的分子基础。     

干旱棉区棉花营养特性分析

通过对海岛棉和陆地棉叶片营养元素含量测定值的分析,结果显示海岛棉对氮、钾的需求低于陆地棉,对磷、锰、铜、镁的需求高于陆地棉。海岛棉苗期对铜、硼,蕾期对磷、锌、铜,花铃期对镁、锰、铜的需求高于陆地棉。在生育后期,海岛棉叶片养分含量动态变化与陆地棉有差异。因此,在农业生产中海岛棉与陆地棉的施肥方法应有所区别。     

Inheritance of time of flowering in upland cotton under natural conditions

Time to flowering is an essential component of the adaptation and productivity of cotton ( Gossipium hirsutum ) in various agro-ecological zones. This article presents a study of the genetic control of this trait in two crosses obtained from different early-maturity parental lines. In each cross, multiple generations including P₁, F₁, P₂, B₁, B₂ and F₂ were evaluated under two natural field conditions in 2004 and 2005. The data on time to flowering in the F₂ populations had a continuous distribution but deviated from normality. A joint segregation analysis (JSA) revealed that time of flowering in upland cotton was controlled by a mixture of an additive major gene and additive-dominant polygenes. The first- and second-order genetic parameters were all calculated based on the mixture of major gene and polygene inheritance models using JSA. These results suggested that there was considerable genetic diversity and complexity in days to anthesis in upland cotton. This variation can be used to formulate the most efficient breeding strategy and to design cotton for a particular environment.     

Genetic control of somatic embryogenesis in cotton petiole callus cultures

Summary Three commercial varieties (Acala SJ-5, Coker 312 and Paymaster 303) and three exotic accessions (T1, T25 and T169) of cotton (Gossypium hirsutum L.) were tested for ability to undergo somatic embryogenesis. Sections of split petiole were cultured on 3 media and evaluated for embryogenesis after 180 days. Embryogenic T25 and Coker 312 plants were selected and crossed in a diallel with non-embryogenic Acala SJ-5, Paymaster 303, T1 and T169 plants. F₁, F₂ and BC₁ populations were generated and tested for embryogenesis on a medium of MS salts and vitamins (1962) plus (per liter) 4.0 mg NAA, 1.0 mg Kn, 30 g glucose, 100 mg myo-inositol, 2.0 g Gelrite and 0.75 g MgCl₂. Segregation for both occurrence and magnitude of embryogenesis was observed, suggesting the action of more than one gene.     

Mapping of quantitative trait loci controlling cotton leaf curl disease resistance in upland cotton

Cotton leaf curl disease (CLCuD) is a major threat to cotton production in Asia and Africa. Using marker-assisted breeding can be the best sustainable approach to tackle CLCuD. Identification of new QTLs in the indigenous cotton germplasm is necessary to combat CLCuD. The current study was designed to construct a genetic linkage map of bi-parental F2:F3 populations developed from highly tolerant MNH-886 and highly susceptible S-12 cotton cultivars. One hundred seven CLCuD-associated simple sequence repeat (SSR) marker alleles were identified as polymorphic and three new QTLs were found on chromosomes C11, C19 and C21. Two QTLs on chromosomes C11 and C19 were detected in both F2 and F3 populations in the region flanked by SSR markers CIR316 and BNL4094, and BNL285 and BNL3348, respectively. Whereas, one QTL on chromosome C21 was detected in the region flanked by SSR markers JESPR158 and JESPR135 in both F2 and F3 generations. The CLCuD-associated QTLs identified in this study can help fine-tune the molecular mapping of the QTLs on the cotton genome against CLCuD.     

QTL analysis for early-maturing traits in cotton using two upland cotton (Gossypium hirsutum L.) crosses

Making use of the markers linked closely to QTL for early-maturing traits for MAS (Marker-assisted selection) is an effective method for the simultaneous improvement of early maturity and other properties in cotton. In this study, two F₂ populations and their F_2:3 families were generated from the two upland cotton (Gossypium hirsutum L.) crosses, Baimian2 × TM-1 and Baimian2 × CIR12. QTL for early-maturing traits were analyzed using F_2:3 families. A total of 54 QTL (31 suggestive and 23 significant) were detected. Fourteen significant QTL had the LOD scores not only > 3 but also exceeding permutation threshold. At least four common QTL, qBP-17 for bud period (BP), qGP-17a/qGP-17b (qGP-17) for growth period (GP), qYPBF-17a/qYPBF-17b (qYPBF-17) for yield percentage before frost (YPBF) and qHFFBN-17 for height of first fruiting branch node (HFFBN), were found in both populations. These common QTL should be reliable and could be used for MAS to facilitate early maturity. The common QTL, qBP-17, had a LOD score not only > 3 but also exceeding permutation threshold, explaining 12.6% of the phenotypic variation. This QTL should be considered preferentially in MAS. Early-maturing traits of cotton are primarily controlled by dominant and over-dominant effects.     

海岛棉与陆地棉嫁接初试成功

利用海岛棉抗病、生长旺盛、品质优良的特性,以其为砧木,以生育期适中、桃多桃大、高产的陆地棉为接穗进行嫁接,实现嫁接苗抗病、旺长、高产、优质的目的。2006-2007年在4个点以海岛棉为砧木,12个优良抗虫杂交陆地棉为接穗,采用芽接法进行嫁接,具体方法是:海岛棉、陆地棉分别在小棚中同期播种,     

New aspects of soybean somatic embryogenesis

Somatic embryo formation from immature cotyledons was improved in the following ways: by cutting into sections, supplementing culture media with spermine and using solid/liquid/solid type of culture. Cut cotyledons of the eight genotypes examined expressed a higher ability for somatic embryogenesis than whole cotyledons. Of the three polyamines tested, spermine considerably stimulated and putrescine slightly inhibited induction of somatic embryos. The ability of embryoid formation on medium with spermidine depended on the genotype. The solid/liquid/solid type of culture was better than the continuous solid culture. The best nitrogen ion content for the subculture of somatic embryos was 10 mM NH₄NO₃ and 30 mM KNO₃. The possibility of using these modifications in Agrobacterium transformation is discussed.     

Inheritance of leaf hairiness in Gossypium hirsutum L. cotton and its relationship with jassid resistance

Summary Two pairs of genes indicated by H ^P ₁ and H ^A ₂ appear to play a part in the genetic control of pubescence of leaves in the crosses of Pak51 x Empire Red leaf, L11 x Empire Red leaf, AC134 x Empire Red leaf, AC134 x Acala 1517D and L11 x Acala 1517 D. H ^P ₁ seems to induce hair of sufficient length and density and is completely dominant to h ^p ₁.H ^A ₂ allele, seems to induce hairiness but to a smaller degree. It acts additivily to H ^P ₁ giving profusely hairy plants. H ^P ₁ gene is present in the local varieties Pak51, L11 and AC134 producing hair of such length and density as to confer jassid resistance in them. Compared with these, the exotic types viz., Empire Red leaf and Acala 1517D possess H ^A ₂ giving sparsely hairy plants.The exotic variety Deltapine Smooth leaf possesses another gene, E ^A, which displays an epistatic effect on H ^A ₂ gene. The gene E ^A has only a minor effect on the H ^P ₁.Apart from this, the presence of certain intensifying or modifying genes seem to affect the density and length of hair resulting in deviations even in individual groups.M. Sc. Student, Professor and Head, and Reader, respectively of the Dept. of Plant Breeding and Genetics.     

Genetic analysis of in vitro wheat somatic embryogenesis

Summary A spring wheat genotype which produces somatic embryos in vitro, after short and long-term culture, was tested for its ability to sexually transmit this embryogenic trait. Reciprocal crosses were performed between a embryogenic line and a nonembryogenic variety.Immature embryos were cultured on Murashige and Skoog medium plus 2 mg/l 2,4-dichlorophenoxyacetic acid, gelled with 5.5 g/l agarose. Somatic embryogenesis was not expressed in the F₁'s. In contrast, from several hundred immature embryos of the F₂ generation of one cross, 10.7% and 1.6% expressed somatic embryogenesis in short and long-term cultures respectively. These percentages of embryogenic: non-embryogenic fits a model of a few complementary genes. The embryogenic capacity of the F₂ genotypes depends on the presence of recessive alleles at these gene loci. The long-term wheat somatic embryogenesis capacity requires a more complex mechanism than the short-term one.Abbreviations CS Chinese Spring - Aq Aquila - E Embryogenic - NE Nonembryogenic - SC Subculture     

Secondary somatic embryogenesis and applications in plant breeding

Summary Secondary somatic embryogenesis is the phenomenon whereby new somatic embryos are initiated from somatic embryos. Such cultures have been described in at least 80 Gymnosperm and Angiosperm species. In the initial step (primary somatic embryogenesis) such cultures have to be started from plant explants. In general, primary somatic embryogenesis from vegetative plant explants is, indirect and mostly driven by auxin (AUX) or auxin and cytokinin (AUX/CYT) supplemented media, whereas, from zygotic embryos it is direct and driven, to a larger extent, by CYT or growth regulator free media. Primary somatic embryogenesis from floral plant explants is between these two extremes. Indirect and direct somatic embryogenesis should be seen as two extremes of one continuum: in indirect somatic embryogenesis the embryos develop up to the (pre)-globular stage and in direct somatic embryogenesis to mature stages before they are subjected to secondary embryogenesis. In general, secondary embryogenesis requires no growth regulators in species with CYT driven primary embryogenesis. Whereas, continuous exposure to growth regulators is needed in species with CYT/AUX or AUX driven primary embryogenesis.In most species somatic embryos can be converted into shoots, although the frequencies are mostly low. In general, somatic embryos induced by growth regulator free or CYT supplemented media meet more difficulties in shoot development than embryos induced by AUX supplemented media. Applications of secondary somatic embryogenesis for plant breeding are discussed.     

Evaluation of chlorophyll fluorescence as a tool for the identification of drought tolerance in upland cotton

Chlorophyll fluorescence (CF) is one tool used by researchers to quantify plant water status during periods of limited water availability. The research reported herein was designed to evaluate a CF-based protocol as a tool for use in cotton, Gossypium spp. breeding programs for the identification of drought tolerant genotypes. Twenty genotypes were selected to represent diverse and distinct US germplasm pools. Replicated tests were performed in Lubbock and College Station, TX in 2006 and 2007. Dryland and irrigated treatments, as main plots, were applied in a randomized complete block design, split to genotypes. CF measurements were taken at mid-bloom and late bloom growth stages. Source leaf tissue was harvested at predawn and subjected to high temperature incubation with CF measurements subsequently taken hourly for 5 h. Drought stressed plants had not mobilized their carbohydrate reserves from their source leaves overnight and thus maintained cell viability and therefore higher CF values throughout the incubation and measurement period with the opposite being true for non-stressed plants. Fiber lint yield and fiber properties were measured for comparison with the CF data. Genotype × treatment effects complicated the classification of genotypic response to drought. Few and inconsistent correlations were found among CF values and lint yield or fiber properties. Data suggested that this procedure provides little potential in selecting plants for drought tolerance when plants are grown under field culture.     

In vitro somatic embryogenesis in turf-type bermudagrass: roles of abscisic acid and gibberellic acid, and occurrence of secondary somatic embryogenesis

Bermudagrass is an important warm‐season turfgrass species that is recalcitrant in regeneration in tissue culture. In a previous report, we observed that somatic embryogenesis of immature inflorescence culture was substantially improved when low levels of 2,4‐dichloro‐phenoxy acetic acid (1 mg/l) and 6‐benzylaminopurine (BAP, 0.01 mg/l) were included in the callus induction medium. The object of this study was to further improve the culture conditions to enhance somatic embryo formation and plantlet regeneration. It was shown that the abscisic acid supplement (2 or 5 mg/l) to the above callus induction medium further enhanced somatic embryogenesis in hybrid bermudagrass (Cynodon dactylon×Cynodon transvaalensis) cv. ‘Tifgreen’. The addition of gibberellic acid (0. 2 mg/l) to the BAP (1 mg/l)‐containing regeneration medium accelerated germination/regeneration of the somatic embryos. Secondary and repetitive somatic embryogenesis, which is rarely reported in monocots, was observed in common bermudagrass (Cynodon dactylon, cv. ‘Savannah’), and a full course of such a development was captured by a periodical microphotography. Scanning electron microscopy further confirmed the observation.     

Assessment of cytoplasmic effects of cytoplasmic male-sterile lines in upland cotton

Paired A- and B-lines, cytoplasmic male-sterile (CMS)-lines and main-tainer lines, respectively, were crossed with R-lines (restorer) to produce A × R, R × B and B × R hybrids, which were used in 1993 and 1996 to predict the performance of three lypes of CMS cotton lines available in China. A significant difference in yield and yield components was revealed between paired A × R and B × R hybrids. This difference was greatly influenced by both CMS cytoplasm and the interaction between cytoplasm and nuclear genotypes. It is suggested that there are detrimental effects of CMS cytoplasm on yield and yield components. General combining ability of near-isogenic CMS lines was also affected by this negative effect. The detrimental effect was closely related to an increased number of immature seeds per boll, which might be caused by partial female sterility associated with CMS cytoplasm. The possibility of developing specific combinations of CMS Upland × Upland restorer hybrids that express enough heterosis for yield to overcome the detrimental effect of the CMS cytoplasm is discussed.     

Inheritance of black leaf mold resistance in tomato

Summary Inheritance of black leaf mold (BLM) (caused by Pseudocercospora fuligena) resistance was studied in four crosses involving two resistant Lycopersicon accessions (PI134417, L. hirsutum and PI254655, L. esculentum) and four susceptible Asian Vegetable Research and Development Center tomato lines (CLN657BC₁F₂-267-0-3-12-7, CL143-0-10-3-0-1-10, CLN698BC₁F₂-358-4-13 and CL5915-93D₄-1-0-3). For each cross, six generations, i.e. P₁, P₂, F₁, F₂, BC₁F₁ and BC₁F₂ were evaluated following inoculations with isolate Pf-2 of P. fuligena. Chi-square analyses of the data based on the ratio of resistant to susceptible plants in the F₂ in three of four crosses gave a good fit to a segregation ratio of 1 R : 15 S, and BC₁F₂ data in three of four crosses gave an acceptable fit to the segregation ratio of 1 R : 63 S. The results indicate that resistance to BLM may be conditioned by two recessive genes acting epistatically in both PI134417 and PI254655.     

新选育陆地型中长绒棉品系性状分析

通过远缘杂交将棉属野生种蕾蒙德氏棉、松散棉、异常棉的优异基因转育到栽培品种中,经过多年多目标定向选择,选育出3个陆地型中长绒棉品系,其纤维2.5%跨距长度32.35~34.46mm,比强度32.20~40.25cN/tex,马克隆值3.85~4.28,且各品系的长度、比强度、马克隆值三者之间均协调较好,适纺高织纱。产量表现虽不及丰产陆地棉,但其绝对产量已达1050kg/hm~2以上,若能优质优价,则可直接用于生产。     

陆地棉Nudix基因家族的全基因组鉴定及表达分析

[目的]Nudix是一类能够催化各种核苷二磷酸衍生物水解的酶,具有维持遗传物质稳定,响应逆境胁迫等生物学功能.本研究旨在对陆地棉Nudix基因进行全基因组分析,为深入研究Nudix基因家族参与棉纤维生长发育调控机制提供参考.[方法]通过生物信息学方法对陆地棉基因组(ZJU_v2.1)的Nudix基因进行全基因组鉴定,并...     

Inheritance of leaf angle in Triticum aestivum L.

Summary A 6×6 diallel was prepared to study the inheritance of leaf angle in T. aestivum L. Genetic analysis in terms of diallel cross parameters and graphic analysis indicated the control of additive gene effects in the expression of this character. The results of F₁ analysis were supported by the analysis of F₂ data.     

Inheritance and mapping of male sterility restoration gene in upland japonica restorer lines

Several upland Japonica breeding lines, WAB450-11-1-3-P40-HB (Abbreviated as WAB450-11), WAB450-11-1-2-P61-HB (WAB450-13), WAB450-l-B-P-91-HB (WAB450-14), IRAT216, IRAT359, and IRAT104, possessing restoring ability for the Dian 1 type cms (cms-D) line Dianyu 1A were recently identified at Food Crops Research Institute, Yunnan Academy of Agricultural Sciences, P. R. China. In this study, the inheritance of restoring ability in these lines was characterized through the production of backcross populations to the male-sterile and maintainer Dianyu 1 lines. Each of the restorer lines was used to pollinate Dianyu 1A to form a F₁ hybrid which was then backcrossed (1) with Dianyu 1B producing a BC₁F₁ population and (2) to the female parent Dianyu 1A producing a BC₅F₂ population. The lines were also crossed with the japonica restorer line C57, carrying the restorer gene Rf1 that was introgressed from indica, to form F₁ hybrids, these hybrids were then testcrossed with Dianyu 1A to study the allelic relationship of their restorer genes to Rf1. The inheritance in these testcross populations indicated that the complete restoring ability of WAB450-11, WAB450-13, WAB450-14, IRAT216, IRAT359, and the partial restoring ability of IRAT104 were controlled by dominant genes, and the gene in WAB450-13, WAB450-14, and IRAT216 was allelic or identical to Rf1. When 136 SSR markers were used to score 143 BC₁F₁ individuals from Dianyu 1A/WAB450-13//Dianyu 1B, the japonica Rf1 allele was found to be located between RM171 and RM6100 on the long arm of chromosome 10, an interval corresponding to that known for the indica Rf1 allele. The distance between RM171 and Rf1 is 2.8 cM, and that between Rf1 and RM6100 is 4.9 cM. Similar linkage results were obtained from mapping 89 individuals of the corresponding BC₅F₂ population (Dianyu 1A/6/Dianyu 1A/WAB450-13).