Inheritance and expression of transgenes in T2 and T3 generations of Lotus corniculatus transformed using Agrobacterium tumefaciens

The inheritance and expression of the reporter gene uidA, encoding β-glucuronidase (GUS), was previously analysed in the T₁ generation of 25 independent transformed lines of Lotus corniculatus cv. Leo. In the work reported here, GUS activity in various tissues of seven of these lines was tested in the T₂ generation. Four representative lines were chosen for more detailed study in the T₃ generation. Lines 25 and 38 had multiple, independently segregating transgene inserts; lines 24 and 39 appeared to transmit one segregating transgene insert to their T₁ progeny, although transgene expression was low and was detected in fewer seedlings than expected in line 39. The uidA gene was inherited and expressed in seedlings of T₁, T₂ and T₃ generations of all four lines. In all lines, transgene expression varied between tissues, with more embryos than seedlings having detectable GUS activity. Studies in the T₂ generation showed that use of transgenic plants as female or male parents altered the frequency of expression of the transgene in progeny. By contrast, in the T₃ generation the use of transgenic plants as female or male parents did not effect either frequency of transmission, or expression of the transgene, in any of the four lines. Transgene inheritance was also similar among individual pods within flower heads and between individual flower heads. This revised version was published online in July 2006 with corrections to the Cover Date.     

Agronomic and morphological characterization of Agrobacterium-transformed Bt rice plants

The agronomic and morphological characteristics of Agrobacterium-transformed rice plants carrying the synthetic cry1Ab or cry1Ac gene were investigated. Tremendous variations in plant height, seed fertility, grain size and other traits were seen in 80 T₁ lines, derived from 80 T₀ plants of 9 rice varieties. On average, about 33% T₁ lines had either morphological or agronomic variant plants. Most of the variations in T₁ plants had no significant correlation with transgene insertion and were proved heritable to their progenies. Genetic analysis in T₃ or T₄ generations showed some simple mutations such as chlorophyll deficiency and stunted plants were independent of transgene insertion and seemed to be controlled by a pair of single genes. However, in two independent transgenic progenies of Xiushui 11, all plants homozygous for transgenes showed dwarfism while all hemizygous and null segregants had normal plant heights. Two advanced homozygous Bt lines, KMD1 and KMD2, were developed from these two progenies. Comparison of the agronomic traits of KMD1 and KMD2 with their parent displayed marked differences among them in terms of seedling growth, tillering ability, yield components and yield potential. The genetic variation observed was generally not linked to the transgene locus and was ascribed to somaclonal variation, but other causes might also exist in particular cases. The results are discussed in the context of choosing appropriate transformation methodology for rice breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

GUS基因和NPTⅡ基因表达的相关性及其在转基因棉花检测研究中的应用

利用农杆菌介导转化法,将含有35S启动子驱动NPTII基因和GUS基因以及棉纤维特异表达启动子E6驱动目的基因FB的植物表达载体转入到常规棉花R15中.重点分析了GUS基因和NPTII基因在愈伤诱导阶段、T0代及T1代转基因棉花中的表达情况.综合两个基因的表达来进行转基因棉花的阳性鉴定,可以为转基因棉花后代的纯合选育提供双重保障.7个转基因株系选育到T3代共获得株行51个,卡那霉素检测多数株行阳性率在90%以上,其中21个株行阳性率达100%.     

用核基质结合区(SAR)序列提高小麦最小表达框转基因表达的稳定性

采用最小表达框技术转化植物可以规避由骨架序列引起的安全风险。核基质结合区序列SAR (scaffold attachment region)可作为边界元件与核基质结合阻挡转基因片段邻近染色质区的作用与影响, 提高外源基因稳定性。本研究在最小表达框序列两端添加SAR序列, 提高小麦最小表达框转基因表达的稳定性, 提高转化基因的表达效率。首先, 以GUS为目的基因构建带有SAR序列的最小表达框, 以科农199为受体进行基因枪转化, 同时以不加SAR序列的最小表达框片段为对照。带有SAR序列的最小表达框片段共轰击857个幼胚, T₀代获得40株再生植株, PCR检测到16株阳性植株, 转化效率为1.87%; 对这16个阳性单株进行GUS染色, 15株显色; 从来自4个T₀阳性植株的18个T₁代植株中随机选取18株进行PCR和GUS染色检测, 有15株表现为阳性。不带SAR序列的对照片段轰击1012个幼胚, 获得31株再生植株, 其中5株PCR阳性, 转化效率0.49%, 这5个阳性植株中仅2株为GUS染色阳性; 来自于5个T₀代PCR阳性株系的10个T₁代单株中没有发现PCR和GUS染色阳性株。表明SAR序列可以提高基因枪转基因效率和目的基因表达稳定性。为了创制抗旱转基因小麦, 以来自大豆的抗旱相关转录因子基因GmDREB3为目的基因, Bar基因为筛选标记基因, 转化受体小麦济麦22, 共轰击6045个幼胚, 获得再生植株130株, PCR检测阳性植株30株, 转化效率为0.50%; 随机选取6株PCR阳性植株进行RT-PCR分析, 其中5株可检测到外源基因的转录。进一步对这5株RT-PCR阳性植株插入片段完整性进行分析, 其中4株插入片段基本完整。通过real-time PCR分析, 发现T₀代6个RT-PCR阳性植株的外源GmDREB3的拷贝数为1~3个。以上结果证明, 在最小表达框两端加上SAR序列后可以提高小麦最小表达框转基因表达的稳定性。     

Performance and combining ability in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) populations with diverse parents

Improving fiber quality properties of cotton is important for increasing the efficiency of manufacturing textiles, including enhancing yarn quality and spinning performance. This study was conducted to determine if we could identify valuable cotton cultivars to use as parents in breeding programs with the goal of improving fiber properties. Seven parents were combined in a diallel design and selfed to obtain 21 F₂ populations. Positive general and specific combining ability effects were observed for all traits. General combining ability tended to be larger than specific combining ability, indicating these traits are controlled primarily by additive genetic effects. Correlations among traits were generally positive except for lint yield correlations with fiber strength and length. For improving the fiber quality measures of strength and length, line 7235 shows excellent general combining ability effects. SG125 would provide elite germplasm to increase agronomic measures of lint yield and lint percent. The MD51 genotype has the highest potential among the genotypes tested here to provide germplasm combining both improved yield and fiber strength. These parents, or their selected progeny, should be useful in a breeding program to generate variability from which selection can be used to identify lines with improved fiber and/or agronomic properties.     

Genetic effects of nine <Emphasis Type="Italic">Gossypium barbadense</Emphasis> L. chromosome substitution lines in top crosses with five elite Upland cotton <Emphasis Type="Italic">G. hirsutum</Emphasis> L. cultivars

Crosses between Gossypium barbadense L and Gossypium hirsutum L. (Upland cotton) have produced limited success in introgressing fiber quality genes into the latter. Chromosome substitution lines (CSBL) have complete chromosomes or chromosome arms from G. barbadense, line 3-79, substituted for the corresponding chromosome or arms in G. hirsutum in a near isogenic background of TM-1. We top crossed nine CSBL and their parents (TM-1 and 3-79) with five cultivars. Parental lines and their F₂ populations were evaluated in four environments for agronomic and fiber quality traits. The CSBL and their F₂ hybrids showed wide ranges for both agronomic and fiber traits of economic importance. Genetic analysis showed that additive variances were larger than dominance variances for lint percentage, boll weight, lint yield, fiber length, strength, elongation, micronaire, and yellowness; whereas, dominance variances were larger than additive variances only for uniformity of fiber length and equal for fiber reflectance. For all traits, except boll weight and lint yield, significant additive effects of one or more chromosomes from 3-79 in TM-1 background were greater than the corresponding TM-1 chromosome. In addition, we identified specific chromosomes from G. barbadense (3-79) that carry alleles for improvements in specific fiber quality traits in Upland cotton. Favorable additive effects of individual chromosomes or chromosome segments from 3-79 relative to corresponding chromosomes or chromosomes segments from TM-1 were identified in this study as follows: Lint percentage, chromosome/arms 10, 16-15; longer fibers, chromosome/arms 01, 11sh, 26Lo; more uniform fibers, chromosomes/arms 01, 11sh, 10, 17-11; stronger fibers, chromosome/arms 01, 11sh, 12sh, 26Lo, 17-11; fiber elongation, chromosomes/arms 01, 11sh, 26Lo, 10, 17-11; reduced fiber micronaire, chromosome/arms 01, 12sh, 4-15, 16-15, 17-11; fibers with more reflectance, chromosome/arms 10, 4-15, 16-15, 17-11; fiber with less yellowness, chromosome arms 4-15, 17-11. Based on the present study, we concluded that by using CSBL, favorable fiber quality alleles can be introgressed into Upland cotton, thus greatly improving the breeder’s ability for improvement of Upland cotton for a variety of traits. These data should provide useful genetic information to the cotton breeding industry at large.     

Amenability of castor to an <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated <Emphasis Type="Italic">in planta</Emphasis> transformation strategy using a <Emphasis Type="Italic">cry1AcF</Emphasis> gene for insect tolerance

Agrobacterium tumefaciens mediated in planta transformation protocol was developed for castor, Ricinus communis. Two-day-old seedlings were infected with Agrobacterium strain EHA105/pBinBt8 harboring cry1AcF and established in the greenhouse. Screening the T₁ generation seedlings on 300 mg L⁻¹ kanamycin identified the putative transformants. Molecular and expression analysis confirmed the transgenic nature and identified high-expressing plants. Western blot analysis confirmed the co-integration of the nptII gene in the selected transgenic plants. Bioassay against Spodoptera litura corroborated with high expression and identified five promising effective lines. Analysis of the T₂ generation plants proved the stability of the transgene indicating the feasibility of the method.     

Study of heritable variation and genetics of earliness in mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> L. Wilczek)

Fifty-five mungbean lines were evaluated for days to maturity and grain yield per plant. This material showed considerable range of variability for the target traits. Eight genetically diverse parents were selected and used for a full diallel set of crosses to study the mode of inheritance for earliness related parameters (days to flowering, days to maturity and length of reproductive phase) during summer 2005. The F₁ generation of these crosses was sown during the spring of 2006 and the selfed seeds were used to raise the F₂ generation during kharif season. The data recorded from two generations were subjected to genetic analysis. The formal ANOVA showed the significance of both additive and dominance effects for all the traits in both generations. Significance of D, H₁ and H₂ components also confirmed the contribution of both additive and dominance effects in controlling the inheritance of these traits. The estimates of narrow sense heritability were low to moderate except higher estimates for days to maturity in F₂ generation, while the broad sense heritability estimates were relatively higher. Seasonal and environmental effects were also found to be significant. In view of the complex nature of gene action for earliness, it is suggested that breeders should look for transgressive recombinants of earliness and other desirable attributes in later segregating generations to gain higher genetic advance. The variety NM92 was found to be the best source of earliness in mungbean breeding.     

转Rs-AFP2基因小麦的分子分析及其纹枯病抗性

Rs-AFP2属于r-硫堇类抗菌肽,主要通过形成离子通道直接破坏细胞来杀灭病原菌。本研究通过基因枪介导法结合对目标基因的分子检测,证明已将外源Rs-AFP2基因转入小麦推广品种扬麦12中。通过逐株抗纹枯病接种鉴定、PCR、PCR-Southern blot、Southern blot和 RT-PCR/荧光定量RT-PCR(Q-RT-PCR)分析,对转Rs-AFP2基因小麦T₁至T₄代植株跟踪检测。结果表明,Rs-AFP2在转基因小麦中能够稳定遗传,以单拷贝整合到小麦基因组中,遗传方式符合孟德尔遗传规律,并能在转录水平上表达。对转Rs-AFP2基因小麦的抗病性、主要农艺性状以及Rs-AFP2表达活性分析结果表明,与受体扬麦12相比,Rs-AFP2表达活性高的转基因小麦植株对纹枯病抗性有明显提高,其抗病性可以遗传,而主要农艺性状没有明显差异,证明可以利用Rs-AFP2基因和基因工程途径创制抗纹枯病小麦新种质。     

Exploring ethyl methanesulfonate (EMS) treated cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) to improve drought tolerance

The Texas High Plains often has extended periods between rainfall events, which can lead to a reduction in the yield and fiber quality of cotton (Gossypium hirsutum L.). It is known that cultivated cotton suffers from low levels of genetic diversity due to the over-use in breeding of similar gene pools, which may hinder breeding for drought tolerance. In this study, for the first time the novel variability or genetic diversity of morphological and agronomic traits possibly created by the chemical mutagen ethyl methanesulfonate (EMS) was evaluated to improve drought tolerance in cotton by traits’ response to different irrigation regimes. EMS is a chemical mutagen that has been shown to cause point mutations in the DNA of many model plants and crop species. Three EMS treated lines were advanced from the M₁ to M₄ generation as bulk-harvested populations. A diverse selection scheme was applied to capture most of the genetic trait-variability or diversity and superior lines in these populations. In 2014–2016 the diversity of these populations was evaluated based on four agronomic and thirteen morphological traits to determine differences in response to multiple irrigation rates. Analyses of these traits showed statistically significant (p?≤?0.05) differences between and within populations when compared to the original non-treated EMS source, with most of the variability being observed in the high irrigation rate. However, none of the EMS treated populations had significantly (p?≤?0.05) better lint yield than the commercial cultivar (control) in 2016. EMS yield performance was possibly constrained by the applied diverse selection scheme of this study. Traits such as total number of bolls, bolls retained at node 7 and below, and those retained between nodes 8 and 12, and bolls retained at node of first fruiting branch may be predictors to improve cotton production (yield) in water limiting environments.     

Quantitative trait loci analysis for net ginning energy requirements in upland cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.)

Cotton cultivars with reduced fiber-seed attachment force have the potential to be ginned faster with less energy. The objective of this study was to identify quantitative trait loci (QTL) for net ginning energy requirement (NGE), and its relationship with other fiber quality traits in upland cotton. Two cotton lines, TAM 182-34 ELS and AR 9317-26, with significant differences in NGE and fiber-seed attachment force, were crossed and 285 F₂ plants derived from a single F₁ plant were planted in the field and leaf samples collected for DNA marker analysis (Population A). Individual F₃ plants and the two parents were planted in replicated progeny rows. The cotton was ginned on a 10-saw laboratory gin stand. Electrical power used by the gin was measured and recorded with a Yokogawa CW121 power meter. Fiber quality attributes were measured using a high volume instrument. A total of 455 SSR marker loci were used to construct a linkage map. Two QTLs were identified for NGE on chromosomes 12 and 20, associated with markers CIR148 and DPL0600, explaining 14 and 8.8% of the phenotypic variation, respectively. NGE shared the same genomic region with fuzz percent on chromosome 12. Population B, consisting of 260 F₂ progeny from the reciprocal cross AR 9317-26 X TAM 182-34 ELS, was used to confirm these QTLs by analyzing SSR markers mapped on Chrs 12 and 20. These QTLs (qNGE-c12 and qNGE-c20) were confirmed and appeared stable. Further validation of significantly associated markers on different populations is necessary prior to implementation in marker-assisted selection.     

Morphological variation of starch granules in S<Subscript>1</Subscript> cassava progenies

The need to develop new cassava (Manihot esculenta Crantz) varieties with different starch characteristics has greatly motivated new research. The aim of this study was to evaluate morphological alterations in starch granules as well as genetic gains in segregating S₁ cassava populations. Starch from accessions (S₀): BGM0222, BGM1378 and BGM1662 and from their self-fertilized progenies (S₁): F0222, F1378 and F1662, with 78, 80 and 76 individuals, respectively, were evaluated for the following traits: area (ArStGr, µm²), perimeter (PrStGr, µm), length (LeStGr, µm) and number of starch granules (NuStGr). Moreover, some agronomic traits of the S₁ progenies were evaluated at harvest such as: plant height (PlaHei), shoot yield (ShoYi), root yield (RoYi), starch yield (StYi), and root dry matter content (DMC). With the selection of transgressive individuals in S₁ progenies, it is possible to obtain selection gains for values higher and lower than the average of the S₀ genitors, whereas selection gains can reach up to 16.58, 8.39, 7.87 and 34.18% for ArStGr, LeStGr, PrStGr, and NuStGr, respectively. Average size of the starch granule varied from 9.8 to 12.37 µm among individuals in an S₁ progeny. Positive and high correlations between the individuals were found for some morphological characteristics of the cassava starch granule but not strongly correlated with agronomic traits. Therefore, it is possible to select S₁ cassava individuals for agronomic characteristics without losing other important starch traits. Cassava-segregating populations allow the obtainment of individuals with different morphological characteristics as for starch granules, enabling obtainment of genetic gains with the selection.     

Genetic analyses of agronomic traits in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.)

The consumption of products made from Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) has increased in recent years in Japan. Increased consumer demand has led to recognition of the need for early varieties of this crop with high and stable yields. In order to accomplish this, more information is needed on the genetic mechanisms affecting earliness and yield. We conducted genetic analysis of 3 agronomic traits (days to flowering, plant height and total seed weight per plant) to segregate F₂ and F₃ populations derived from a cross between Tartary buckwheat cultivars ‘Hokuriku No. 4’ and ‘Ishisoba’. Broad-sense heritability estimates for days to flowering, plant height and total seed weight were 0.70, 0.62 and 0.75, respectively, in F₃ population. Narrow-sense heritability for total seed weight (0.51) was highest, followed by heritability for days to flowering (0.37), with heritability for plant height (0.26) lowest. Later flowering was associated with increased plant height and higher yields. From the F₄ generation, we identified twelve candidate plants with earlier maturity and reduced plant height compared to ‘Hokuriku No. 4’, but almost the same total seed weight. These results suggest that hybridization breeding using the single seed descent (SSD) method is an effective approach for improving agronomic characteristics of Tartary buckwheat.     

Agrobacterium-mediated genetic transformation and production of semilooper resistant transgenic castor (Ricinus communis L.)

Summary Semilooper resistant transgenic castor plants were produced through Agrobacterium-mediated genetic transformation method. Two castor cultivars, Jyothi and VP1 were transformed using the super-binary vector pTOK233 carrying gus A and hpt genes. Putative transformants were regenerated following selection on the hygromycin containing medium. GUS positive primary transformants, when subjected to Southern analysis, revealed stable integration of gus A into their genomes. In the T₁ generation, a monogenic segregation ratio of 3 GUS positive: 1 GUS negative plants was observed. Furthermore, transformation experiments were carried out with the Agrobacterium pSB111 super-binary vector carrying a synthetic delta endotoxin gene cryIAb and the herbicide resistance gene bar both driven by cauliflower mosaic virus 35S promoter. Putative transformants were regenerated through selection on the phosphinothricin containing medium and Basta tolerant transformants were subjected to molecular analysis. PCR analysis revealed the presence of both bar and cryIAb genes in the Basta tolerant primary transformants. Southern analysis of PCR positive plants with cryIAb probe showed a 3 Kb band upon HindIII digestion and a > 6 Kb band with BamHI digestion, thus suggesting stable integration of cryIAb intact expression cassette and independent nature of the transformants. The primary transformants subjected to ELISA disclosed varied levels of Cry protein. These transgenics expressing cryIAb – when bioassayed against freshly hatched semilooper larvae – induced substantial (> 88%) insect mortality. Southern analysis of 2T₁ plants revealed the presence of cryIAb gene, indicating stable inheritance of the transgene into the next generation. In T₁, all the Southern-positive plants for cryIAb invariably exhibited tolerance to Basta, denoting co-segregation of both bar and cryIAb genes. Transgenics, expressing cryIAb exhibited ample resistance against the castor semilooper.     

Transgenic barley by particle bombardment. Inheritance of the transferred gene and characteristics of transgenic barley plants

Summary Transgenic barley plants (Hordeum vulgare L. cv. Kymppi) were obtained by particle bombardment of various tissues. Immature embryos and microspore-derived cultures were bombarded with gold particles coated with plasmid DNA carrying the gene coding for neomycin phosphotransferase II (NPTII), together with plasmid DNA containing the gene for -glucuronidase (GUS).Bombarded immature embryos were grown to plants without selection and NPTII activity was screened in small plantlets. One plant proved to be transgenic (T₀). This chimeric plant passed the transferred nptII gene to its T₁ progeny. The presence of the nptII gene was demonstrated by the PCR technique and enzyme activity was analyzed by an NPTII gel assay. Four T₀ spikes and 15 T₁ offspring were transgenic. The integration and inheritance was confirmed by Southern blot hybridization. Transgenic T₂ and T₃ plants were produced by isolating embryos from green grains of transgenic T₁ and T₂ plants, respectively and growing them to plants. After selfing, the ratio of transgenic to non-transgenic T₂ offspring was shown to follow the rule of Mendelian inheritance. The general performance of transgenic plants was normal and no reduction in fertility was observed.Microspore-derived cultures were bombarded one and four weeks after microspore isolation. After bombardment, cultures were grown either with or without antibiotic selection (geneticin ^R or kanamycin). When cultures were grown without selection and regenerated plants were transferred to kanamycin selection in rooting phase, one out of a total of about 1500 plants survived. This plant both carried and expressed the transferred nptII gene. The integration was confirmed by Southern blot hybridization. This plant was not fertile.     

Enhanced resistance to a lepidopteran pest in transgenic sugar beet plants expressing synthetic <Emphasis Type="Italic">cry1Ab</Emphasis> gene

Two diploid sugar beet genotypes of agronomical importance were transformed using Agrobactrium tumefaciens harboring pBI35Scry containing a synthetic cry1Ab gene. Leaf blade with attached shoot bases, a highly regenerative tissue, were used as explant substratum for transformation. PCR screening with cry1Ab-specific primers showed the presence of transgene in more than 50% of the regenerated kanamycin-resistant plants after treatment with the antibiotic. A transformation rate of 8.8–12.2% (depending on genotype) was achieved as revealed by genomic DNA dot blotting. The intact integration of transgene cassette into the genome was furthermore confirmed by Southern blot analysis. The expression of the cry1Ab gene encoding a truncated endotoxin (67 kDa) at about 0.1% of total soluble protein was achieved in the leaves of transgenic plants as shown by Western blot analysis. Bioassays under in vitro conditions with Spodoptera littoralis, one of the most important pests in sugar beet fields, demonstrated enhanced resistance against this pest. The inheritance of the inserted transgene was confirmed in F₁ plants obtained through crossing of T₀ plants with a cytoplasmic male sterile line. Transgenic plants are currently grown in a greenhouse and will be subjected to further bioassay analyses against other lepidopteran pests of sugar beet.     

Soyabean-seed Yield Response in Row- and Hill-plots under a Recurrent Selection Programme

Several studies have indicated a possible link between genome size and earliness in maize. In this study, an original maize population, South African photo-period insensitive maize composite II (C₀) and several selected generations were analyzed for days to flowering, plant height, ear height, and yield. The selection criterion was earliness. Over six cycles of selection a 14-day decrease in days to flowering was obtained with no significant reduction in grain yield. In the initial population (C₀) and the most advanced selection (C₆) 101 plants were analyzed for nuclear DNA content. A significant decrease in the mean nuclear DNA content of the C₀ population (102 AU) was observed with respect to the C₀ population (105 AU). This reduction was the result of a decrease in frequency of plants in the C₆ population with large genome sizes. Therefore it was concluded that selection for earliness resulted in selection against plants with large genome sizes. Hence, the nucleotype of a maize plant can be modified by selection such as early flowering time.     

AFLP标记与棉花重要农艺性状的关联研究

 以陆地棉（Gossypium hirsutum L.）品种中棉所8号和海岛棉（Gossypium barbadense L.）品种Pima 90-53杂交产生的包含91个单株的BC₁F₂群体及其衍生BC₁F_2:3群体为材料,利用逐步多元回归分析确定分子标记与重要农艺性状的相关关系,为分子标记辅助选择提供依据。试验材料分别种植在保定市郊和沧州青县两个点,每个株行考察衣分、子指、铃重、皮棉重、子棉重5个产量性状和2.5%纤维跨距长度、马克隆值、纤维整齐度、纤维伸长率、纤维比强度5个品质性状。以20对AFLP引物组合产生的125个位点对10个重要农艺性状进行多元线性回归分析,发现其中4对引物组合产生的15个位点与10个性状有着显著相关性（P≤0.05,P≤0.01）,而后通过逐步多元回归分析获得6个位点,对9个农艺性状所解释的表型变异为6.2%～30%。结果表明,与9个农艺性状显著相关的6个AFLP位点可以用于未来的分子标记辅助育种计划。     

Transgenic cotton, expressing Amaranthus caudatus agglutinin, confers enhanced resistance to aphids

To evaluate the possible antiaphid function of Amaranthus caudatus agglutinin (ACA) in allogenetic plants, transgenic cotton plants expressing the ACA gene under the control of a phloem‐specific promoter were generated via Agrobacterium‐mediated gene transformation. Based on the results of Southern blot analyses, six plants with single or lower copy transgene and favourable agronomic traits were selected for further studies. ACA expression levels ranged from 0.02% to 0.45% of total soluble protein as determined by Western blot analysis in the six selected transgenic plants. Insect bioassays using nymphs of cotton aphid (Aphis gossypii Glover) showed that five of the six transgenic plants significantly inhibited the population growth of cotton aphid, with the highest inhibition rate of 64.5%. These results shed some new light on the antiaphid function of the ACA gene as well as the promising application of the gene for obtaining aphid‐resistant transgenic cotton plants to reduce the yield loss and honeydew contamination of fibre by aphids.     

<Emphasis Type="Italic">Agrobacterium</Emphasis> mediated transformation of indica rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) for insect resistance

The rice leaffolder (RLF), Cnaphalocrocis medinalis is an important pest of rice that causes severe damage in many areas of the world. The plants were transformed with fully modified (plant codon optimized) synthetic Cry1C coding sequences as well as with the hpt and gus genes, coding for hygromycin phosphotransferase and β-glucuronidase, respectively. Cry1C sequences placed under the control of doubled 35S promoter plus the AMV leader sequence, and hpt and gus genes driven by cauliflower mosaic virus 35S promoter, were used in this study. Embryogenic calli after cocultivation with Agrobacterium were selected on the medium containing hygromycin B. A total of 67 hygromycin-resistant plants were regenerated. PCR and Southern blot analyses of primary transformants revealed the stable integration of Cry1C coding sequences into the rice genome with predominant single copy integration. R₁ progeny plants disclosed a monogenic pattern (3:1) of transgene segregation as confirmed by molecular analyses. These transgenic lines were highly resistant to rice leaffolder (RLF), Cnaphalocrocis medinalis as revealed by insect bioassay.