Strong Disease Resistance Research Articles

Development of disease-resistant rice by pathogen-responsive expression of WRKY45.

WRKY45 is an important transcription factor in the salicylic acid signalling pathway in rice that mediates chemical-induced resistance against multiple pathogens. Its constitutive overexpression confers extremely strong resistance against Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae to rice, but has adverse effects on agronomic traits. Here, a new strategy to confer rice with strong disease resistance without any negative effects on agronomic traits was established by expressing WRKY45 under the control of pathogen-responsive promoters in combination with a translational enhancer derived from a 5'-untranslated region (UTR) of rice alcohol dehydrogenase (ADH). Rice promoters that responded to M. oryzae and X. oryzae pv. oryzae infections within 24 h were identified, and 2-kb upstream sequences from nine of them were isolated, fused to WRKY45 cDNA with or without the ADH 5'-UTR, and introduced into rice. Although pathogen-responsive promoters alone failed to confer effective disease resistance, the use of the ADH 5'-UTR in combination with them, in particular the PR1b and GST promoters, enhanced disease resistance. Field trials showed that overall, PR1b promoter-driven (with ADH 5'-UTR) lines performed the best and one had agronomic traits comparable to control untransformed rice. Thus, expressing WRKY45 under the control of the PR1b promoter with the ADH 5'-UTR is an excellent strategy to develop disease-resistant rice, and the line established could serve as a mother line for breeding disease-resistant rice.

Genome Wide Distributions and Functional Characterization of Copy Number Variations between Chinese and Western Pigs.

Copy number variations (CNVs) refer to large insertions, deletions and duplications in the genomic structure ranging from one thousand to several million bases in size. Since the development of next generation sequencing technology, several methods have been well built for detection of copy number variations with high credibility and accuracy. Evidence has shown that CNV occurring in gene region could lead to phenotypic changes due to the alteration in gene structure and dosage. However, it still remains unexplored whether CNVs underlie the phenotypic differences between Chinese and Western domestic pigs. Based on the read-depth methods, we investigated copy number variations using 49 individuals derived from both Chinese and Western pig breeds. A total of 3,131 copy number variation regions (CNVRs) were identified with an average size of 13.4 Kb in all individuals during domestication, harboring 1,363 genes. Among them, 129 and 147 CNVRs were Chinese and Western pig specific, respectively. Gene functional enrichments revealed that these CNVRs contribute to strong disease resistance and high prolificacy in Chinese domestic pigs, but strong muscle tissue development in Western domestic pigs. This finding is strongly consistent with the morphologic characteristics of Chinese and Western pigs, indicating that these group-specific CNVRs might have been preserved by artificial selection for the favored phenotypes during independent domestication of Chinese and Western pigs. In this study, we built high-resolution CNV maps in several domestic pig breeds and discovered the group specific CNVs by comparing Chinese and Western pigs, which could provide new insight into genomic variations during pigs’ independent domestication, and facilitate further functional studies of CNV-associated genes.

High level of hepcidin mRNA expression is associated with high production of immune factors in Tibetan pigs

Hepcidin, an antimicrobial peptide, is considered to be a key homeostatic regulator of iron metabolism. Tibetan pigs are a Chinese indigenous plateau breed with strong disease resistance. It is therefore of interest to look for porcine hepcidin (pHepc) gene expression in Tibetan pigs in order to clarify the involvement of pHepc in interaction of host defenses and iron homeostasis. In this study, the mRNA expressions of pHepc and the immune response-associated factors were determined by real-time PCR in 30-day-old Tibetan pigs and Landrace pigs were chosen as control. The results showed that the expression of pHepc mRNA in most tissues were higher in Tibetan pigs than those of Landrace pigs, which corresponded to the higher serum iron concentration in Tibetan pigs. In addition, compared to Landrace pigs, higher levels of pro-inflammatory cytokines (TNF-α, IL-1α, IL-1β and IFN-γ), pattern recognition receptors (TLR-2, TLR-4, NOD-1 and NOD-2) and chemokines (MCP-1 and IL-8) were detected in Tibetan pigs, which suggested that Tibetan pigs have a strong immunity. The high expression of pHepc may affect the production of immune factors by regulating iron homeostasis, which may partly explain the strong disease resistance of Tibetan pigs.

ANTHOCYANIN PROFILING OF THE BERRY SKINS OF FIVE VITIS AMURENSIS GRAPES AND ONE RELATED HYBRID CULTIVAR

V. amurensis is the world?s most northerly grapevine species and originates in the exceptionally cold climate in northeast China. Many V. amurensis grapes have been widely used because of not only their strong cold tolerance and disease resistance, but also high pigment content. However, there has been no detailed description of the anthocyanin composition and content in V. amurensis grapes. In this study, anthocyanin profiles in the berry skins of five V. amurensis grapes and one hybrid cultivar were analyzed by High Performance Liquid Chromatography-electronic Spray Ionization-tandem Mass (HPLC-ESI-MS/MS). The result showed that both the V. amurensis grapes and the hybrid cultivar contained 3,5-diglucosides of anthocyanidins in high amounts, in addition to 3-monoglucosides of delphinidin, cyanidin, petunidin, peonidin and malvidin that are generally detected in V. vinifera grapes. Furthermore, pelargonidin-3,5-diglucoside and B-type vitisin of certain anthocyanidin-3-glucoside were also identified in trace amount and no acetylated anthocyanins were detected in these samples. These findings will be important for the utilization of this germplasm in grapevine breeding programs and to further uncover biosynthesis and regulation of anthocyanins in V. amurensis grapes.

Tissue specificity and species superiority of cathelicidin gene expression in Chinese indigenous Min pigs

Antimicrobial peptides (AMPs) are components of innate immunity, forming the first-line of defense used by many organisms against the invading pathogens. Min pigs are a Chinese indigenous breed with low mortality and strong disease resistance. In this study, the mRNA expressions of four cathelicidins (PMAP-23, PMAP-37, PR-39, and protegrin-1), the largest family of AMPs in pigs, were determined by real-time PCR in 14-day-old Min pigs and Landrace pigs were chosen as the control. The results showed that expression of four cathelicidin mRNAs in most tissues were higher in Min pigs than those of Landrace pigs, which may partly explain the higher immunity and disease resistance of Min pigs. The cathelicidin molecules were generally expressed at high levels in thymus, spleen, liver, and heart, and at low levels in ileum, jejunum, tongue, and lymph node in both breeds. The peptide pairs with significant correlation in one breed were generally not correlated with these in the other breed, suggesting differential synergistic or antagonistic regulation of cathelicidins in Min pigs and Landrace pigs. The high expression of cathelicidins might be one of the mechanisms by which the Min pigs display strong disease resistance.

Rhizosphere effects of PAH-contaminated soil phytoremediation using a special plant named Fire Phoenix

The rhizosphere effect of a special phytoremediating species known as Fire Phoenix on the degradation of polycyclic aromatic hydrocarbons (PAHs) was investigated, including changes of the enzymatic activity and microbial communities in rhizosphere soil. The study showed that the degradation rate of Σ8PAHs by Fire Phoenix was up to 99.40% after a 150-day culture. The activity of dehydrogenase (DHO), peroxidase (POD) and catalase (CAT) increased greatly, especially after a 60-day culture, followed by a gradual reduction with an increase in the planting time. The activity of these enzymes was strongly correlated to the higher degradation performance of Fire Phoenix growing in PAH-contaminated soils, although it was also affected by the basic characteristics of the plant species itself, such as the excessive, fibrous root systems, strong disease resistance, drought resistance, heat resistance, and resistance to barren soil. The activity of polyphenoloxidase (PPO) decreased during the whole growing period in this study, and the degradation rate of Σ8PAHs in the rhizosphere soil after having planted Fire Phoenix plants had a significant (R2=0.947) negative correlation with the change in the activity of PPO. Using an analysis of the microbial communities, the results indicated that the structure of microorganisms in the rhizosphere soil could be changed by planting Fire Phoenix plants, namely, there was an increase in microbial diversity compared with the unplanted soil. In addition, the primary advantage of Fire Phoenix was to promote the growth of flora genus Gordonia sp. as the major bacteria that can effectively degrade PAHs.

Quantitative genetics of behavioral responsiveness in Atlantic cod (Gadus morhua L.)

In selective breeding it is important to understand whether there is genetic variation in behavior as this trait is important for fish welfare and it can possibly be correlated to other production traits. However, behavioral studies in farmed fish are still in their infancy and few automated screening methods have been developed. The aim of this study was to estimate heritability of behavioral responsiveness in farmed Atlantic cod, Gadus morhua L, using automated screening of swimming activity of individual fish. The sampling included 320 fish (offspring of 15 dams and 14 sires) from the Norwegian national cod breeding program. Video recordings of individual fish were taken prior to and after a two minute period of mild stress (rapidly moving light). Observations were made on the percentage of time spent in the central zone of the tank and the swimming speed for each individual. Estimates of heritability for time spent in the central zone both before and after the stress period were intermediate (0.21 ± 0.10 and 0.31 ± 0.13, respectively). Similar estimates of heritability were found for swimming speed before and after the stress period (0.37 ± 0.15 and 0.21 ± 0.11, respectively). The genetic correlation of observed behavior before and after the stress period was strong for both the amount of time spent in the central zone and swimming speed (0.90 ± 0.10 to 0.92 ± 0.11), indicating that families rank similarly before and after the stress period. Results from a challenge test for vibriosis resistance on the same families were made available from the Norwegian national cod breeding program, and revealed slight negative correlations among estimated breeding values for vibriosis resistance and time spent in the central zone before the stress period, as well as for swimming speed before and after the stress period. Thus strong disease resistance may be associated genetically to low behavioral activity and low stress response. The results of this study demonstrate that non-invasive automatic behavioral screening can be used for genetic analyses of behavior related to stress coping mechanisms in fish.

Disease resistance and genetic diversity analysis in selected populations ofMacrobrachium rosenbergii

16 selected populations were injected with bacteria(Vibrio alginolyticus) suspension to know deeply about disease resistance of Macrobrachium rosenbergii. Bacterial challenge experiments demonstrated that there were big differences in disease resistance among the 16 selected populations. Some families exhibited strong disease resistance to bacterial infection,while some families were not resistant to bacterial challenge. Among the 16 selected populations,3 populations( population SCR11-6,SCR11-11 and SCR1116) with strong disease resistance with a survival rate of 80% were identified,7 populations with secondly strong disease resistance,4 populations with normal disease resistance with a survival rate of 65%-70%, and 2 populations with low disease resistance with a survival rate of 49.53% and 35.0% were identified. The genetic structure of 16 selected populations was analyzed assessed by 8 microsatellite markers. The results showed that the number of total alleles was 53. The numbers of allele at each locus ranged from 5 to 9 with an average of 6.625,and polymorphic information content(PIC) was 0.6294- 0.8294,and the average was 0.7323. The mean polymorphism information content in 16 selected populations was 0.4932- 0.6956. The average observed and expected heterozygosity of the 16 selected populations varied from 0.5062 to 0.6513 and from 0.5519 to 0.7332,respectively,and the average genetic similarity coefficient and genetic distance between them was 0.6552 and 0.4344,respectively. Besides,after PCR amplification on the individuals of DP and SP populations,differential bands were calculated and the correlation betw een growth trait and microsatellite loci was established. The results showed that 5 loci were correlated with disease resistant trait,of which MRMB11 had extreme significance of 0.282. These results indicated that 4 of 16 selected populations had strong disease resistance and high genetic diversity. The development of these 8 populations lays foundation for selective breeding of M. rosenbergii with disease resistance.

Callus Induction and Plant Regeneration from Immature Embryos of Zelkova sinica Schneid.

Zelkova sinica Schneid. is a popular landscape plant in China because of its wide adaptation, strong disease resistance, large crown, and beautiful fall color. Immature embryos from Z. sinica seeds were cultured on woody plant medium (WPM) supplemented with 4.5 μM 6-Benzylaminopurine (BA) and 5.4 μM α-naphthaleneacetic acid (NAA) to induce callus, and 60% of immature embryos formed callus. The cream-white, friable, nodular callus with proembryogenic structures was then cultured on WPM containing 5.4 μM NAA in combination with 9.0 or 11.2 μM BA to regenerate shoots; approximately five shoots per explant were induced on 70% callus. Shoots were rooted on WPM containing 0.5 μM indole-3-butyric acid (IBA), on which 62.3% shoots developed roots with an average of 4.2 roots per shoot at 4 weeks. The regenerated plantlets were acclimatized and transplanted into the field. This protocol could be used for mass production for field plantation, genetic improvement, and germplasm exchange of Z. sinica.

Molecular Cloning and Functional Characterization of Tibetan Porcine STING

Tibetan pig is well known for its strong disease resistance. However, little is known about the molecular basis of its strong resistance to disease. Stimulator of interferon (IFN) genes (STING), also known as MPYS/MITA/ERIS/TMEM173, is an adaptor that functions downstream of RIG-I and MAVS and upstream of TBK1 and plays a critical role in type I IFN induction. Here we report the first cloning and characterization of STING gene from Tibetan pig. The entire open reading frame (ORF) of the Tibetan porcine STING is 1137 bp, with a higher degree of sequence similarity with Landrace pig (98%) and cattle (88%) than with chimpanzee (84%), human (83%) or mouse (77%). The predicted protein is composed of 378 amino acids and has 4 putative transmembrane domains. Real-time quantitative PCR analysis indicated that Tibetan pig STING mRNA was most abundant in the lung and heart. Overexpression of Tibetan porcine STING led to upregulation of IFN-β and IFN-stimulated gene 15 (ISG15) in porcine jejunal epithelial cell line IPEC-J2 cells. This is the first study investigating the biological role of STING in intestinal epithelial cells, which lays a foundation for the further study of STING in intestinal innate immunity.

Evaluation of M307 of FUT1 gene as a genetic marker for disease resistance breeding of sutai pigs

Alpha (1,2) fucosyltransferase (FUT1) gene has been identified as a candidate gene for controlling the expression of the receptor for ETEC F18. The genetic variations in the position of M307 nucleotide in open reading frame of FUT1 have been proposed as a marker for selecting ETEC F18 resistant pigs. The polymorphisms of M307 in FUT1 of breeding base group for ETEC F18 resistance of Sutai pigs (Duroc×Meishan) was detected and their correlations to some immune indexes, growth and development ability, carcass traits and meat quality were also analyzed, which aimed to investigate feasibility of further breeding for diseases resistance based on M307 of FUT1 for Sutai pigs. After digested by Hin6 I, M307 of FUT1 gene could be divided into three kinds of genotypes, AA, AG, and GG. The frequencies were 0.235, 0.609, and 0.156, respectively. The results indicated that Sutai pigs with the AA genotype in M307 of FUT1 gene not only have relatively strong general disease resistance ability in piglets, but also have higher growth and development ability and stable carcass traits and meat quality. It is entirely feasible to raise the new strains of Sutai pigs resistant to Escherichia coli F18 based on genetic marker of the M307 position in FUT1gene.

Monocytes-macrophages phagocytosis as a potential marker for disease resistance in generation 1 of dwarf chickens

Monocytes-macrophages play an indispensable role in the immune system. The current study investigated the effect of selection for monocytes-macrophages phagocytosis on disease resistance in generation 1 (G1) of dwarf chickens. Five hundred dwarf chickens of generation 0 (G0) were divided into high and low phagocytic index (PI) groups (HPIG and LPIG, respectively) based on their PI of monocytes-macrophages at 290 d of age. Then, 2 x 2 mating combinations were conducted. Sixty G0 chickens from another dwarf chicken group were used to measure the levels of monocytes-macrophages phagocytosis at different developmental stages. Among a total of 2,500 randomly selected G1 chickens, 2,100 individuals were used for a surviving and growing test under adverse feeding circumstances, and the other 400 individuals were tested for Salmonella Pullorum challenge. The results showed that progenies of HPIG hens (female symbol) were more resistant to Salmonella Pullorum. After challenge, the death rate of progeny from HPIG female symbol (28.9%) was only 58% that of progeny from LPIG female symbol (49.4%, P < 0.001). In addition, the natural infection rate of Salmonella Pullorum before 207 d for offspring from HPIG female symbol (35.0%) was significantly lower than that for offspring from LPIG female symbol (48.3%, P < 0.001). The natural mortality before 56 d in progeny of HPIG female symbol (22.6%) was significantly lower than that in progeny of LPIG female symbol (29.1%) with a P-value of 0.001. The G1 chickens of HPIG G0 female symbol weighed more than those born to LPIG G0 female symbol at 28 and 42 d of age, whereas the difference was not statistically significant at 56 d of age. The heritability of monocytes-macrophages phagocytosis was 0.40, which was moderate. The PI values were at a low level before 126 d and increased dramatically until they declined significantly after 294 d. It could be concluded that phagocytosis of monocytes-macrophages is a marker for breeding excellent progeny with strong disease resistance.

Stable and Extreme Resistance to Common Scab of Potato Obtained Through Somatic Cell Selection

Somatic cell selection with thaxtomin A as a positive selection agent was used to isolate variants of potato cv. Russet Burbank with strong to extreme resistance to common scab. Glasshouse and field trials identified 51 variants with significantly reduced disease incidence (frequency of infected tubers) and severity (tuber lesion coverage) compared with the parent cultivar. The most promising variants exhibited extreme disease resistance, rarely showing lesions, which were invariably superficial and shallower than those on the parent. Resistance traits were consistently expressed both in 10 glasshouse and two field trials at different locations, with varied inoculum and disease pressure. Disease-resistant variants differed in their response to thaxtomin A in tuber slice bioassays. Of 23 variants tested, 10 showed reduced thaxtomin A susceptibility, with the remaining 13 responding similar to that of the parent. Thus, toxin tolerance was not the only factor responsible for observed disease resistance; however, four of the five most disease-resistant variants had enhanced thaxtomin A tolerance, suggesting that this factor is important in the expression of strong disease resistance. Pathogenicity and toxin tolerance remained stable over a 6-year period, demonstrating that selected phenotypes were robust and genetic changes stable. The majority of disease-resistant variants had tuber yields equivalent to the parent cultivar in glasshouse trials. This suggests that selection for disease resistance was not associated with negative tuber attributes and that certain variants may have commercial merit, worthy of further agronomic testing.

Progress in the study of genetic diversity of Mongolian horse

Mongolian horse is a kind of important breed resource of local horses in our country. It has a lot of advantages such as powerful endurance, rough feeding resistance, and strong disease resistance. These advantages have become driving force for in-depth study on Mongolian horse. Genetic diversity can reflect all the genetic information of a species or a variety, namely, it reflects the richness of genetic diversity and confirms the degree of uniqueness of genetic resources through genetic markers. This paper introduces the progress in the study on genetic diversity of Mongolian horse in many aspects such as in cell, biochemical and molecular level, and highlights the various hot gene types and their polymorphisms.

AtNUDT7, a Negative Regulator of Basal Immunity in Arabidopsis, Modulates Two Distinct Defense Response Pathways and Is Involved in Maintaining Redox Homeostasis

Plants have evolved complicated regulatory systems to control immune responses. Both positive and negative signaling pathways interplay to coordinate development of a resistance response with the appropriate amplitude and duration. AtNUDT7, a Nudix domain-containing protein in Arabidopsis (Arabidopsis thaliana) that hydrolyzes nucleotide derivatives, was found to be a negative regulator of the basal defense response, and its loss-of-function mutation results in enhanced resistance to infection by Pseudomonas syringae. The nudt7 mutation does not cause a strong constitutive disease resistance phenotype, but it leads to a heightened defense response, including accelerated activation of defense-related genes that can be triggered by pathogenic and nonpathogenic microorganisms. The nudt7 mutation enhances two distinct defense response pathways: one independent of and the other dependent on NPR1 and salicylic acid accumulation. In vitro enzymatic assays revealed that ADP-ribose and NADH are preferred substrates of NUDT7, and the hydrolysis activity of NUDT7 is essential for its biological function and is sensitive to inhibition by Ca(2+). Further analyses indicate that ADP-ribose is not likely the physiological substrate of NUDT7. However, the nudt7 mutation leads to perturbation of cellular redox homeostasis and a higher level of NADH in pathogen-challenged leaves. The study suggests that the alteration in cellular antioxidant status caused by the nudt7 mutation primes the cells for the amplified defense response and NUDT7 functions to modulate the defense response to prevent excessive stimulation.

애기장대 AtERF11 유전자에 의한 Pseudomonas syringae에 대한 병 저항성 유도

본 연구는 Affymetrix Arabidopsis DNA chip을 이용하여 비 병원성 인자인 AvrRpt2 단백질에 의해서 특이적으로 전사 과정이 조절되는 애기장대 유전자들을 분리하고 병 저항성 방어체계와 관련한 이들 유전자들의 기능 분석을 시도하였다. 그 중에서 먼저 식물 호르몬인 ethylene의 신호 조절에 관여하는 ERFs (ethylene-responsive element binding factors) 전사조절 유전자 family 중에서 Bla subfamily 그룹으로 알려져 있는 AtERF11 유전자의 병 저항성 관련 기능을 규명하였다. 저항성 유전자 RPS2가 없는 경우에는 비 병원성 인자인 AvrRpt2 단백질은 기주 식물체내의 기초 병저항성을 감소시키고 병원성 세균의 증식을 향상시켜서 병증을 증대시키는 effector로 작용한다는 기존의 연구결과와 유사하게, 저항성 유전자 RPS2가 없는 조건에서 AtERF11 유전자의 발현이 AvrRpt2 단백질의 작용에 의해서 특이적으로 감소되는 것을 확인하였다. 이러한 결과를 바탕으로 AtERF11 유전자는 식물체의 병 저항성 방어기작에 있어서 positive regulator로서 작용하기 때문에 effector로 작용하는 AvrRpt2 단백질에 의해서 조절되는 것으로 추측하였다. 본 가설을 증명하기 위해 AtERF11의 발현을 증폭시킨 애기장대 형질전화체를 제작하고 P. syringae pv. tomato DC 3000에 대한 병저항성을 실험하였다. AtERF11 유전자가 대량 발현하는 형질전화 된 애기장대에서는 야생종에 비해 대략 100배 이상 세균의 증식이 억제되는 강력한 병저항성을 가진다는 것을 검증하였다. AvrRpt2 protein triggers hypersensitive response (HR) and strong disease resistance when it is translocated from a bacterial pathogen Pseudomonas sp. to host plant cells containing a cognate RPS2 resistance protein through Type III Secretion System (TTSS). However, AvrRpt2 protein can function as the effector that suppresses a basal defense and enhances the disease symptom when functional RPS2 resistance protein is absent in the infected plant cells. Using Affymetrix Arabidopsis DNA chip, we found that many genes were specifically regulated by AvrRpt2 protein in the rps2 Arabidopsis mutant. Here, we showed that expression of AtERF11 that is known as a member of B1a subcluster of AP2/ERF transcription factor family was down regulated specifically by AvrRpt2. To determine its function in plant resistance, we also generated the Arabidopsis thaliana transgenic plants constitutively overexpressing AtERF11 under CaMV 355 promoter, which conferred an enhanced resistance against a bacterial pathogen, Pseudomonas syringae pv. tomato DC3000. Thus, these results collectively suggest that AtERF11 plays a role as a positive regulator for disease resistance against biotrophic bacterial pathogen in plant.

Induction of Gynogenesis in Japanese Crucian Carp ( Carassius cuvieri)

Diploid gynogenesis was induced in Japanese crucian carp ( Carassius cuvieri) eggs using UV-irradiated genetically inactive spermatozoa from mirror carp ( Cyprinus carpio L.) or blunt snout bream ( Megalobrama amblycephala), with or without cold shock. The optimal radiation dosage was 4200 mJ/cm 2 and 3600 mJ/cm 2 for mirror carp and blunt snout bream sperm, respectively. At this dosage and without cold shock, the yields were (32.4±3.3)% vs. (33.8±1.4)% gynogenetic haploids and (0.7±0.3)% vs. (0.5±0.3)% hybrid diploids, respectively. At the optimal UV dosage but with cold shock (2 min after fertilization, 0–4°C for 40 min), the hatching rates were (27.8±2.1)% and (29.4±3.3)%, respectively. From hatching to feeding, (15.7±3.4)% and (23.6±4.1)% normal gynogenetic diploids were recorded, respectively. Survival of normal gynogenetic diploids was 56% out of the hatched fry when using irradiated spermatozoa of mirror carp, which was lower than that (up to 80%) when using irradiated spermatozoa of blunt snout bream. This indicated that the sperm of blunt snout bream, with distant genetic relation to the maternal Japanese crucian carp, was more effective than that of mirror carp to induce diploid gynogenesis. The nature of the gynogenetic progeny was identified with external appearance, chromosome number and gonad structure. The presence of only females in gynogenetic progeny probably suggested XX genotype in the female Japanese crucian carp. The gynogenetic diploids have potential values such as faster growth and stronger disease resistance than the normal Japanese crucian carp. All gynogenetic progeny possessed 100 chromosomes whereas all J x B crosses were triploid with 124 chromosomes. The formation of the new triploid hybrids in J x B crosses may be useful in aquaculture.

Current Trends in Cabbage Breeding

Summary Cabbage is an important vegetable crop of the family Brassicaceae and is grown in many countries of the globe. There are different types of cabbage depending upon shape, size, and color. It is a highly cross-pollinated crop where heterosis in F1 hybrid progeny has been exploited so largely in developing countries too. Due to high yield, strong disease resistance, wide adaptability, good quality, and uniform economic characters. The rate of conversion from open pollinated varieties to hybrid varieties and seed replacement ratio is very high in this crop. There are different temperature requirements for fresh vegetable and seed production purposes. The self-incompatibility and male sterility systems are present in the crop, which facilitates easy and cheaper hybrid seed production. For the successful seed production program we need suitable production area, congenial environment, and stable parents. The present review deals with the vegetative, reproductive biology, breeding methods, heterosis breed...

Transgenic carrots with enhanced resistance against two major pathogens, Erysipheheraclei and Alternariadauci

In vitro assay indicated that the human lysozyme has lytic activity against phytopathogenic fungi and bacteria. A human lysozyme gene was placed under control of the constitutive CaMV 35S promoter and the resulting expression plasmid was introduced into two cultivars (cv.) of carrot, Kurodagosun (K5) and Nantes Scarlet (NS), by Agrobacterium tumefaciens-mediated method. Seven and fourteen transgenic plants of cv. K5 and cv. NS were regenerated, respectively, and the obtained transgenic carrots of T0 generation was tested for disease resistance against Erysiphe heraclei, a pathogenic fungi causing powdery mildew. Among the tested lines, the transgenic plant No. 12-1 and 8-1 of cv. NS showed a fairly strong resistance against E. heraclei. The strong disease resistance was also confirmed in T1 generation. Disease resistance against another pathogen of leaf blight, Alternaria dauci, were also tested using T1 transgenic lines. Significant enhanced resistance was observed in the No. 12-1 of cv. NS. Accumulation of synthesized human lysozyme protein was observed in this line, a finding consistent with observed disease resistance.

Hybrid Seed Production in Cabbage

Summary Cabbage (Brassica oleraceaL. var capitataL.), an important vegetable crop belonging to the family Cruciferae, is grown in many countries espeically in Europe, North America, and Asia. As per botanical characteristics, it can be classified as common cabbage, heading cabbage, and savoy. It is a cross pollinated crop showing strong heterosis in F1 hybrid progeny. Due to high yield, strong disease resistance, wide adaptability, good quality and uniform economic characteristics, hybrid cabbage have been widely used in many countries. The present review deals with vegetative and reproductive biology of the crop and the recent approaches for hybrid seed production in cabbage.