Inheritance of resistance to fruit rot (Phytophthora parasiticaDast.) in tomato (Lycopersicon esculentum Mill.)

Summary Fruit rot disease caused by Phytophthora parasiticaDast. is a limiting factor in tomato production in Himachal Pradesh. 30 to 60 per cent fruits are damaged by this disease. Crosses were made between EC 54725 (Lycopersicon pimpinellifolium), a small tyuited type, resistant to fruit rot and four highly susceptible tomato commercial cultivars (Gola, Sioux, S12, and Lalmani). Studies of F₁'s, F₂'s and back crosses indicated that EC 54725 carries a dominant gene imparting resistance to fruit rot.     

Maternal and Genetic Effects on Seed Weight of Tomato, and Effects of Seed Weight on Growth of Genotypes of Tomato (Lycopersicon esculentum Mill.)

A study was made on the inheritance of seed weight of tomato, and on the effect of seed weight on growth of tomato plants. Use was made of 15 parental genotypes and 105 F₁s produced by diallel crossing (F₁-seeds). From combining ability analysis of variance carried out for weight of F₁-seeds it appeared that the weight of seeds harvested from tomato plants was mainly determined by the maternal genotype and largely independent of the genotype of the male parent. A combining ability analysis of variance for weight of seeds produced by seilfing F₁'s (F₂-seeds) showed, however, that female and male parents contributed equally to the inheritance of seed weight and that the inheritance of seed weight is determined mainly by chromosomal additiveiy acting factors, but that also non-additive gene action occurred. Genotypes with large seeds produced heavier seedlings than genotypes with small seeds, In later growth stages, the correlation between seed weight and plant weight became smaller, presumably, due to a lower relative growth rate of the seedlings from large seeds. For this reason, it is doubtful whether breeding of large seeded tomato cultivars opens up prospects of improving growth and yield of tomato plants.     

番茄果实中番茄红素含量的遗传分析

以5个番茄自交系为材料,完全双列杂交设计,对番茄果实中番茄红素配合力及其遗传参数进行了分析和估算.试验表明:番茄红素的一般配合力为-0.608～0.734,特殊配合力为-0.302～1.208;番茄红素的广义遗传力为57.35%,狭义遗传力为46.36%,其遗传符合加性-显性模型.所以在育种中采用系谱选择以提高和固定高番茄红素性状是有效的,有性杂交育种可在早期世代进行选择.     

番茄遗传转化体系的建立

研究以番茄（Lycopersicon esculentum Mill.）栽培品种“中杂9号”、“毛粉802”和“合作908”为试材,通过对番茄茎段的离体培养,研究不同基因型以及不同激素组合对植株再生的影响。结果表明：以茎段为外植体时中杂9号和毛粉802更适合诱导再生植株形成;IAA与IBA比较,IAA利于芽的形成及正常芽的发育。其中中杂9号最适宜诱导愈伤组织和芽分化培养基为MS＋6-BA2.0mg/L＋IAA0.1mg/L、MS＋6-BA2.0mg/L＋IAA0.4-0.5mg/L,分化率均高达100%,毛粉802最适宜诱导愈伤组织和芽分化培养基为MS＋6-BA2.0mg/L＋IAA0.4-0.5mg/L,分化率高达100%。茎段外植体适宜的生根培养基为MS＋IAA0.5mg/L＋6-BA0.6mg/L,生根率高达80.8%。     

Genetic nature of bacterial wilt resistance in tomato (lycopersicon esculentum Mill.) accession La 1421

The genetic nature of bacterial wilt resistance in tomato was studied in two crosses based on the number of days of survival (quantitative) in the field before the appearance of wilt symptoms. Significant differences were observed between generation means in both crosses (LA 1421 × Cascade and LA 1421 × Caraibo). This study indicates that resistance identified in Lycopersicon esculentum var. cerasiforme LA 1421 may be different from that derived from L. pimpinellifolium. However, the genetic mechanism seems to be complex with a duplicate form of epistasis. Results suggest that selection for resistance from crosses between LA 1421 and Cascade should preferably be delayed until a high level of fixation of genes is attained. The variation observed in the F₂ and BC₂ progeny of the Caraibo cross, suggested that genetic combination between the two resistance sources can lead to higher levels of resistance. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic analysis of salt tolerance during vegetative growth in tomato, Lycopersicon esculentum Mill.

Breeding for salt tolerance in tomato has been impeded by insufficient knowledge of the genetic control of tolerance. The genetic basis of salt tolerance during vegetative growth was investigated by growing a salt-tolerant (PI174263) and a salt-sensitive tomato cultivar (UCT5) and their F₁, F₂ and backcross progeny in saline solutions with electrical conductivity of 0.5 (control) and 20 dS/m (salt-stress). The relative salt-tolerance of each generation was determined as the percentage of growth (i.e. dry matter production) under salt-stress relative to growth under control conditions. In all generations, shoot growth was significantly reduced by salt stress. The reduction was largest in UCT5 (56.1%) and smallest in the F₁ (27.4%), followed by PI174263 (32.3%). Analysis of the absolute and relative growth under salt-stress indicated that genes contributing to vigour might be different from genes conferring tolerance. Generation means analyses of the absolute and relative growth indicated that the majority of the genetic variation among generations were due to simple (additive and dominance) genetic effects; nonallelic interactions, although significant, were far less important. Partitioning of the total genetic variance by weighted least-square regression analysis and variance component analysis indicated that 88% or more of the variation was due to additive genetic effects. A moderate estimate of narrow sense heritability (0.49 ± 0.09) was obtained for shoot DW under salt-stress treatment. The results indicate that tomato salt-tolerance during vegetative growth can be improved by breeding and selection.     

Genetic basis of physiological traits related to salt tolerance in tomato, Lycopersicon esculentum Mill.

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato, Lycopersicon esculentum Mill., were investigated. Parental, F₁, F₂ and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive tomato cultivar (‘UCT5’) were evaluated in saline solutions with electrical conductivity of 0.5 (non-stress) and 20 dS/m (salt stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution were measured. Growth of both parents was reduced under salt stress; however, the reduction was significantly less in PI174263 than ‘UCT5’, suggesting greater salt tolerance of the former. Under salt stress, leaves of PI174263 accumulated significantly less Na⁺ and Cl^? and more Ca²⁺ than leaves of ‘UCT5’. Across parental and progeny generations, growth under salt stress was positively correlated with leaf Ca²⁺ content and negatively correlated with leaf Na⁺ content. In contrast, no correlation was observed between growth and either leaf solute potential or the rate of ethylene evolution under salt stress. Generation means analysis indicated that under salt stress both absolute and relative growth and the Na⁺ and Ca²⁺ accumulations in the leaf were genetically controlled with additivity being the major genetic component. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca²⁺ levels and to exclude Na⁺ from the shoot were essential features underlying its adaptation to salt stress and that these features were highly heritable. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.     

Effect of three anthocyaninless genes on germination in tomato (Lycopersicon esculentum Mill.) I. Seed germination under optimal conditions

The effect of three mutant genes affecting anthocyanin biosynthesis – anthocyaninless of Hoffmann (ah), anthocyaninwithout (aw) and baby lea syndrome (bls) – on tomato germination capacities at 24 ° C was investigated. The study was performed on nine anthocyanin containing lines – Apedice, Apeca, Ailsa Craig, Monfavet 167, Monfavet 168, Por, Piernita, VF 36 and VFNT cherry and 13 isogenic/near isogenic lines (IL/NIL) from them: 4 differing for gene ah, 3 differing for gene aw and 6 differing for gene bls). In the majority of the anthocyaninless IL/NILs germination began earlier than that in the wild type lines. Significant differences were observed in the time to 50% germination between the anthocyanin-containing and the anthocyaninless IL/NILs except for the most rapidly germinating line VFNT cherry. Seed weight, water uptake, effect of testa removal and presence or absence of maternal effects in F1 germination responses were investigated in order to elucidate the causes of the more rapid germination in the anthocyaninless IL/NILs. The increased amount of water uptake by the anthocyaninless lines, the shorter treatment time necessary for their testa removal, the important maternal effects in the genetic variability of the time to 50% germination and the differences in germination capacities between the wild type and the mutant IL/NILs after testa removal, indicated that the seed coat and the endosperm had to be affected by the effects of the three genes in a way that caused enhanced germination. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transfer of Tomato Leaf Curl Virus Resistance from Lycopersicon hirsutum f. glabratum to L. esculentum

Six lines, i.e., H-2, H-11, H-17, H-23, H-24, and H-36, resistant to Tomato Leaf Curl Virus (TLCV) have been developed with controlled introgression of L. hirsutum f. glabratum into Lycopersicon esculentum. The disease incidence, 120 days after inoculation, of those lines derived from L. hirsutum f. glabratum ranged from 8.3 to 35.0 %, whereas in susceptible varieties it ranged from 95.0 to 100 %. The coefficient of infection (CI) values in the resistant lines were very low, ranging from 0.25 to 4.55, whereas in susceptible varieties CI values ranged from 60.56 to 88.96. Line H-2 had the highest resistance by showing the least disease incidence and CI values. The fruit size and days to maturity in resistant lines were close to those of cultivated susceptible varieties. These lines have the scope for being used as varieties in the TLCV infested areas or as foundation lines for further genetic improvement.     

Genetic analysis of low-temperature tolerance during germination in tomato, Lycopersicon esculentum Mill.

The genetic basis of low-temperature tolerance during germination of tomato seed was investigated using two approaches. First, a cold-tolerant (PI 120256) and a cold-sensitive tomato cultivar (UCT5) and their reciprocal F₂, F₃ and BC₁ progeny (total of 10 generations) were evaluated for germination at a low (11 ± 0.5°C) and a high (control) temperature 20 ±0.5° C) Weighted least-square regression analysis indicated that in the low-temperature treatment most of the variation resulted from additive genetic effects, and dominance and epistatic interactions were nonsignificant. Partitioning of the total genetic variance into those attributable to the effects of embryo, endosperm, testa and the cytoplasm indicated that additive effects of endosperm and embryo could individually account for 80% and 77% of the total variance, respectively. In the control treatment, greater than 60% of the variation could be explained by individual additive effects of endosperm or embryo and ? 27% of the variation could be explained by embryo dominance effects. Across generations, there was a positive correlation (r = 0.78, P < 0.01) between germination in the control and low-temperature treatments and there were no significant genotype × temperature interactions. The results indicate the presence of similar or identical genes with predominantly additive effects on germination under both low and high temperatures. In the second approach, the effectiveness of directional phenotypic selection to improve tomato cold tolerance during germination was evaluated by selecting (in an F₂ population of the same cross) the fastest germinating seeds under low temperature and comparing the germination of the selected F₃ progeny with germination of an unselected F₃ population. The results indicated that selection was highly effective and significantly improved germination performance of the progeny; a realized heritability of 0.74 was obtained for low-temperature tolerance during germination. It is concluded that in these tomato lines germination under low temperature is genetically controlled, with additivity being the major genetic component, and thus the trait can be improved by phenotypic selection.     

引自美国的大豆资源抗疫霉根腐病基因分析

大豆疫霉根腐病是影响中国大豆生产的主要病害之一, 利用抗病品种是防治该病最经济有效的方法。本研究通过下胚轴创伤接种鉴定了13个大豆疫霉菌株在从美国引进的85个大豆品种(系)上的反应,结果表明, 72个品种(系)抗1个到12个大豆疫霉菌株。通过与14个含有单个已知抗疫霉根腐病基因的大豆品种(系)的反应型比较并结合系谱分析,明确35个品种(系)分别含有Rps1a、Rps1c、Rps1k、Rps2、Rps3c、Rps4、Rps5、Rps6和Rps7抗病基因或基因组合,其中有14个品种(系)含有Rps1a,1个含有Rps1c和2个含有Rps1k,这3个基因能够有效抵御我国大豆疫霉种群,可以直接用于抗病育种。     

不同分子量壳聚糖对番茄生长发育的影响

以番茄合作“908”为试材,研究了不同分子量壳聚糖对番茄种子萌发、生长发育、产量及品质的影响。结果表明：①壳聚糖浸种,CTS7和CTS3分别在0.625mg/ml 和1.25 mg/ml的浓度下,发芽率、发芽指数和活力指数三项指标达最大值;大分子量的CTS7效果最差,中间分子量CTS3和CTS5效果最好。②壳聚糖处理,对番茄幼苗的株高和鲜重影响显著,但对根长和根鲜重影响达不到显著水平的差异。CTS7浓度为1.25 mg/ml时对番茄生长的促进效果最明显,CTS3在2.5 mg/ml时对番茄生长的促进效果最明显。③1.25 mg/ml浓度的CTS5对番茄增产效果最显著,并使番茄中可溶性固形物、Vc含量及总蛋白含量增加,总酸度降低。     

Inheritance of quality traits in processing tomato (Lycopersicon esculentum Mill.)

Summary The genetic basis of pH, colour and soluble solids in processing tomato is examined. In a first experiment, aimed at identifying the base populations with which to start selection, parents, F₁ and F₂ progenies of an 8 × 8 diallel cross without reciprocals were tested.The results indicate that additive, dominance and additive x additive epistatic effects were noticeable for the three characters. Higher order interlocus interactions were also detected.As to the soluble solids, a trait for which higher order epistatic effects were less marked, the breeding potential of the cross combinations was assessed by calculating the expected mean values at the F generation. Some cross populations having C33 or C35 as parent appeared to be superior.A second experiment was conducted to collect data on the heritability of the foregoing qualitative traits by utilizing the regressions of F₃ offspring on F₂ parents. The low heritability coefficients observed would suggest the ineffectiveness of individual selection in early generations.In both the F₂ and F₃ generations rather low correlation coefficients among the three quality traits were observed.     

甜瓜种质资源对疫病的抗性鉴定研究

旨在通过苗期人工接种鉴定,筛选高抗疫病的甜瓜材料,为甜瓜抗病育种以及抗疫病遗传学研究奠定基础。本研究采用灌根接种法,向植株根茎部土壤注入浓度为1×106个/mL的游动孢子悬浮液,对收集到的166份甜瓜材料进行了抗性鉴定,这些材料中有薄皮类型甜瓜41份,厚皮类型甜瓜104份,野生材料15份,近缘种6份。最终筛选到4份免疫材料,25份高抗材料。在供试的厚皮类型甜瓜中有66%的材料抗性水平在中抗及以上,而薄皮类型中有98%的抗性水平是感病或高感。通过相关性分析,发现厚皮类型甜瓜对疫病的抗性要显著高于薄皮类型甜瓜。通过对不同材料的果实性状进行调查,发现在免疫和高抗材料中有14份单瓜重达到1 kg以上,有8份果实可溶性固形物含量在10%以上。这些兼具高抗、高产和高可溶性固形物的材料,可用于抗病基因的定位、克隆等遗传学研究,也可作为育种亲本将抗病基因转移到农艺性状优良但抗性差的甜瓜品种中。     

14个毛豆品种对大豆疫病的田间抗性鉴定

通过田间小区对比试验,对14个毛豆品种抗大豆疫病的田间抗性进行鉴定,鉴定结果表明：表现明显抗病的品种有皖3126、思源、AGS292#、闽豆1221、通酥823、301#、茶豆和2808,这些品种可以在病区试种推广;表现感病的品种有绿光75、青酥2号和毛豆75。湿度是影响大豆疫病发生危害的最关键因素之一,实施轮作可减轻发病。     

Inheritance of Dry Root Rot (Rhizoctonia bataticola) Resistance in Chickpea (Cicer arietinum)

The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F₁ and F₂ populations of two resistant and two susceptible parents, along with 49 F₁ progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F₂ generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F³ family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.     

Genetics of resistance to early blight (Alternaria solani Sorauer) in tomato (Lycopersicon esculentum L.)

The genetic nature of early blight resistance in tomato was studied in three crosses at seedling and adult plant stages. A six generation mean analysis of the cross Arka Saurabh (susceptible) × IHR1939 (resistance) and its reciprocal cross revealed that the resistance to early blight was conferred by recessive polygenes at both seedling and adult plant stages. This polygenic early blight resistance revealed the importance of additive and additive × additive gene effects at seedling stage and higher magnitude of dominance and dominance× dominance gene effects at adult plant stage. Evaluation of parents, F₁, F₂ and backcross generations of IHR1816 (resistance) × IHR1939 (resistance) revealed that the early blight resistance genes in IHR1816 (Lycopersicon esculentum NCEBR-1) and IHR1939 (Lycopersicon pimpinellifolium L4394) are independent. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heritability of early blight resistance in a Lycopersicon esculentum×Lycopersicon hirsutum cross estimated by correlation between parent and progeny

Sixteen‐hundred BC₁ plants of a cross between an early blight (EB) susceptible tomato (Lycopersicon esculentum Mill.) breeding line (‘NC84173’ maternal and recurrent parent) and a resistant accession (‘PI126445’) of the tomato wild species Lycopersicon hirsutum Humb. and Bonpl. were grown in a field in 1998. This population was segregating (among other traits) for growth habit, self‐incompatibility and earliness in maturity. To eliminate confounding effects of these factors on disease evaluation and h² estimation, plants that were self‐incompatible, indeterminate and/or late‐maturing were eliminated. The remaining plants (146), which were self‐compatible and determinate (sp./sp.) in growth habit, with early‐ to mid‐season maturity, were evaluated for EB resistance and self‐pollinated to produce BC₁S₁ seed. The 146 BC₁S₁ progeny families, consisting of 30 plants per family, were grown in a replicated field trial in 1999 and evaluated for EB resistance and plant maturity. For each of the 146 BC₁ plants and corresponding BC₁ families, the area under the disease progress curve (AUDPC) and final disease severity (final percentage defoliation) were determined and used to measure disease resistance. The distributions of the AUDPC and final percentage defoliation values in the BC₁ and BC₁S₁ generations indicated that resistance from ‘PI126445’ was quantitative in nature. Estimates of h² for EB resistance, computed by correlation between BC₁S₁ progeny family means and BC₁ individual plant values, ranged from 0.69 to 0.70, indicating that EB resistance of ‘P1126445’ was heritable. Across BC₁S₁ families, a small, but significant, negative correlation (r = ‐0.26, P < 0.01) was observed between disease resistance and earliness in maturity. However, several BC₁S₁ families were identified with considerable EB resistance and reasonably early maturity. These families should be useful for the development of commercially acceptable EB‐resistant tomato lines.     

Pleiotropic effects of male sterility genes in hybrid tomatoes (Lycopersicon esculentum Mill.)

Summary The influence of seven recessive male-sterile alleles on early marketable yield, total marketable yield and average fruit weight in heterozygous F1 hybrid tomatoes was studied. Differences were found between nearisogenic F1 hybrid pairs, in the mutants ms-14, ms-17 and ms-18 for percentage of early marketable yield; in the mutants ms-17, ms-31 and ms-47 for average fruit weight; and in the mutants ms-14, ms-17 and ms-33 for total marketable yield. These differences may be attributed to pleiotropic effects of male-sterility alleles or genes highly linked to these alleles. The direction and the magnitude of the pleiotropic effect on a specific characteristic were found to be dependent on the general genetic background of the parental lines and the specific combining ability of the F1 hybrid. Interactions found in crosses between male-sterile and male-fertile female lines and parental lines suggest that male-sterility alleles affect the general combining ability of female lines. Such differences were demonstrated to be statistically significant for percentage of early marketable yield with mutant ms-18, for average fruit weight with mutants ms-47, and for total marketable yield with mutant ms-17 and ms-33. The absence of uniformity with respect to the pleiotropic effects and occasional deviations in the general combining ability are discussed.     

Relationship between Tolerance to Phytophthora Rot and Soybean Yield

Phytophthora rot is a major soybean disease in the Eastern US corn belt. The objective of this experiment was to determine the genetic relationship between tolerance to phytophthora rot and agronomic traits measured in environments where the disease was not a factor. A set of 66 random lines from a broad-based population was evaluated for agronomic traits in seven field environments and for tolerance in greenhouse tests. Pairs of resistant and susceptible isolines were used to determine whether phytophthora rot was present in the field environments. The phenotypic correlation between tolerance and yield in five environments where phytophthora was negligible was non-significant (r =?0.09). There was a positive correlation between tolerance and seed weight (r = 0.31) and a negative correlation between tolerance and plant height (r=–0.25). None of these correlations is large enough to hinder development of agronomically acceptable, tolerant cultivars.