Transfer of new dwarfing genes from the weed species Avena fatua into cultivated oat A. byzantina

New sources of dwarfing genes were identified from accessions of Avena fatua in Japan and Korea. The dwarfing genes were transferred from backcrossed and self‐pollinated relatives to the cultivated oat ‘Kanota’. In the cultivated form, the dominant dwarfing gene Dw8 showed a relatively lower transmission rate than recessive, semi‐dominant and nondwarfing genes and was characterized by a distinct link with wild gene cluster. This was also supported by the high transmission rate of wild specific SSR alleles. Four dwarf inbred lines (L153, L169a, L169b and L812) were identified as involving a single recessive dwarfing gene(s). The recessive dwarfing genes that showed normal and stable transmission rates in BC₁F₃ were first reported in hexaploid oats. The L169 segregated two different recessive dwarf lines in BC₁, which were selected as semi‐ (L169a) and extreme‐ (L169b) dwarf lines. The L169a was a good genotype with a high grain yield. L288 is a semi‐dwarf line conditioned by a semi‐dominant dwarfing gene, with a unilateral panicle, large florets and good grain quality due to strong resistance to lodging. L342 had a short peduncle, making the panicle compact, and its phenotype was similar to the dwarfness controlled by Dw7, but the dwarfing genes were different.     

Inheritance of agronomic traits from the Chinese barley dwarfing gene donors 'Xiaoshan Lixiahuang' and 'Cangzhou Luodama'

The inheritance of agronomic traits from the barley dwarfing gene donors ‘Xiaoshan Lixiahuang’ and ‘Cangzhou Luodamai’ was studied. The results indicated that dwarf plants, six‐row and short spikes, dense spikelets and naked kernels, respectively, were controlled by one pair of recessive genes, but a toothed awn was determined by one pair of dominant genes in both barley cultivars. The genes for the six characters in ‘Xiaoshan Lixiahuang’ were allelic to those in ‘Cangzhou Luodamai’. Genetic linkage was found among the genes for plant height, spike length and spikelet density. They were located on the long arm of chromosome 3 (3HL) in the order: plant height, spikelet density, spike length. The genes for naked kernels, six‐row spikes and tooth awns were independent of each other, and carried on the long arms of chromosomes 1(7H), 2(H) and 7(5H), respectively. The dwarfing genes were the same as the gene uz in Japanese and Korean barley cultivars.     

Resistance to powdery mildew in selections from Tunisian landraces of barley

Two-hundred and thirty-two accessions of barley landraces collected from Tunisia were screened for resistance to powdery mildew. A number of race-specific genes were detected using the detached leaf technique. Among the 232 accessions tested, 169 were susceptible to powdery mildew, 20 were resistant and 43 showed differential reactions to the three isolates of powdery mildew used. An attempt was made to determine the number of genes, the types of gene, the types of gene action and the gene loci in 20 resistant accessions. Three types of cross were made: (1) the accessions were crossed to the susceptible variety ‘Pallas’, (2) the accessions were crossed with ‘Pallas’ isolines, and (2) accessions with identical powdery mildew reaction patterns were intercrossed. Three isolates of Erysiphe graminis f. sp. hordei were used: Bzm-1, KM 18-75, R13C. A number of different resistance genes were detected among the 19 resistant accessions. Surprisingly, segregation indicating single genes only were detected with the isolates used. Some of these genes could be associated with loci already known. In 19 cases a dominant and in one a recessive mode of inheritance was detected. The recessive gene was not located at the mlo locus. This investigation represents the first systematic study of race-specific genes for powdery mildew resistance in Tunisian landraces. The newly identified sources of resistance may be used in many strategies of breeding for disease resistance.     

Isolation of a Spontaneous Chromosome Translocation in Common Wheat

The genes Ms2 for male sterility and Rht10 for dominant dwarfing located on the short arm of chromosome 4D in common wheat arc closely linked. Male sterile, dwarf F₁ plants from the cross of male sterile‘Chinese Spring’× dwarf‘Ai-bian’were backcrossed with the variety‘Chinese Spring, From this offspring a spontaneous chromosome translocation was isolated resulting in a recombinant male sterile and dwarf genotype.     

四倍体小麦地方品种矮蓝麦矮秆性状的遗传分析

四倍体圆锥小麦(Triticum turgidum L.ssp.turgidum)地方品种矮蓝麦是我国重要的小麦矮秆基因资源,经鉴定其矮秆特性对外源赤霉酸敏感。2012年配制矮蓝麦与2个高秆圆锥小麦的正反交组合,2012—2013年在四川绵阳分别种植F1、F2代和F2:3家系,对株高的遗传分析表明,矮蓝麦的矮秆性状受1对隐性基因控制。利用BSA法构建高秆和矮秆池筛选多态性SSR标记,并对矮蓝麦/青稞麦F2分离群体进行连锁分析,将目标基因定位于7AS染色体上,与标记GWM471的遗传距离为2.5 c M。矮蓝麦与矮秆番麦正反交的F1和F2群体表现非常相似的株高变异特征,初步推测矮蓝麦的矮秆基因是Rht22;进一步用高通量SNP和DAr T标记对两品种进行全基因组扫描,发现二者的遗传相似性高达98.7%~99.3%。因此认为,历史上矮蓝麦和矮秆番麦可能是同一品种,是通过人为交流而传播到不同地方。矮蓝麦携带的矮秆基因在人工合成六倍体小麦遗传背景中降低株高能力中等或较弱,在育种中需要聚合其他矮秆基因而被利用。     

Inheritance of morphological traits of periwinkle mutants with modified contents and yields of leaf and root alkaloids

Periwinkle Catharanthus roseus is a medicinally important plant producing anticancer and antihypertension alkaloids. Two mutants, one dwarf and one semidwarf and both, with a high alkaloid content in the roots and one mutant with a wavy leaf margin and a high alkaloid content in its leaves were obtained after induced chemical mutagenesis with ethyl methane sulphonate and N-nitroso-N-ethylurea in the variety ‘Nirmal’, which is resistant to dieback disease. These mutants were evaluated in the M₃ and M₄ generations. The dwarf and semidwarf mutants differed from the parental variety for many morphological characters, while the mutant with the wavy leaf margin differed mainly in leaf size and leaf thickness. Although both dwarf and semidwarf mutants showed a significantly higher alkaloid content in their roots in both generations, only the semidwarf mutant gave a significantly higher (23%) root alkaloid yield than the parental variety. The mutant with the wavy leaf margin showed a significantly higher alkaloid content in the leaves in both the M₃ and M₄ generations and also had a significantly higher (21%) leaf alkaloid yield than the parental variety. All three mutants were found to be controlled by monogenic recessive genes; the genes for ‘dwarfness’ and ‘semidwarfness’ were allelic to each other, with the allele for semidwarfness being dominant over the allele for dwarfness. The gene for the wavy leaf margin was inherited independently of the genes for dwarfness and semidwarfness.     

Inheritance of petal colour and its independent segregation from seed colour in Brassica rapa

The inheritance of petal (flower) colour and seed colour in Brassica rapa was investigated using two creamy‐white flowered, yellow‐seeded yellow sarson (an ecotype from Indian subcontinent) lines, two yellow‐flowered, partially yellow‐seeded Canadian cultivars and one yellow‐flowered, brown‐seeded rapid cycling accession, and their F₁, F₂, F₃ and backcross populations. A joint segregation of these two characters was examined in the F₂ population. Petal colour was found to be under monogenic control, where the yellow petal colour gene is dominant over the creamy‐white petal colour gene. The seed colour was found to be under digenic control and the yellow seed colour (due to a transparent coat) genes of yellow sarson are recessive to the brown/partially yellow seed colour genes of the Canadian B. rapa cvs.‘Candle’ and ‘Tobin’. The genes governing the petal colour and seed colour are inherited independently. A distorted segregation for petal colour was found in the backcross populations of yellow sarson × F₁ crosses, but not in the reciprocal backcrosses, i.e. F₁× yellow sarson. The possible reason is discussed in the light of genetic diversity of the parental genotypes.     

Inheritance of siliqua orientation and seed coat colour in Brassica tournefortii

The inheritance of siliqua orientation and seed coat colour in Brassica tournefortii was investigated using four genotypes varying in these two characters. The F₁, F₂ and backcross generations of two crosses were used for studying the segregation pattern of the traits. The plants were classified for seed colour as having brown or yellow seeds and for siliqua orientation as having upright, semi‐spread or spread siliqua. Seed colour was found to be under monogenic control with brown being dominant over yellow. Siliqua orientation was under digenic polymeric gene action: upright siliqua was produced by the presence of two dominant genes and spread siliqua by two recessive genes. The absence of even a single dominant gene resulted in a third type of siliqua orientation, semi‐spread siliqua.     

Genetic Analysis of Resistance to Gall Midge (Orseolia oryzae Wood Mason) in Rice

The inheritance of resistance to rice gall midge (Ranchi biotype) was studied in 12 resistant cultivars by crossing with susceptible cultivars. By the study of F₁, F₂, F₃, B₁ and B₂ generations, it was found that resistance was governed by a single dominant gene in ‘Surekha’, ‘Phalguna’, ‘Rajendra Dhan 202’, ‘IET 7918’‘IET 6187’, ‘BG 404-1’; by duplicate dominant genes in ‘W 1263’, ‘RPW 6-17’ and ‘WGL 48684’ and a monogenic recessive gene in ‘OB 677’ and ‘BKNBR 1008-21’. The allelism test of the resistant genes in the test cultivars with already known genes Gm1 and Gm2 was carried out. A single dominant gene that conveyed the resistance in ‘RPW 6–17’, ‘IET 7918’ and ‘IET 6187’ was allelic to Gm1 and segregated independently of Gm2. The resistance in ‘Phalguna’, ‘Rajendra Dhan 202’, ‘W 1263’ and ‘RPW 6–17’, ‘IR 36’ and ‘WGL 48684’ was governed by Gm2 gene which was independent of Gm1. Two additional genes were identified and designated as Gm3 and gm4. Three test cultivars ‘BG 404-1’, ‘W 1263’ and ‘WGL 48684’ were found to have Gm3 gene for resistance which was non-allelic and segregated independently of Gm1 and Gm2. Thus the cultivars ‘W 1263’ and ‘WGL 48684’ had two resistance genes Gw2 and Gm3 together. The cultivar ‘RPW 6–17’ also had two resistance genes Gm1 and Gm2 together. The recessive gene gm4 which conditioned the resistance in ‘OB 677’ and ‘BKNBR 1008-21’ was nonallelic to and segregated independently of Gm1, Gm2 and Gm3 genes. Linkage studies of the resistance gene with pigment characters were carried out in ‘Purple gora/IR 36’ cross. The resistance gene Gm2 was found to be linked with the genes governing the pigmentation in node, apiculus and stigma with crossover values of 15.78, 31.57 and 35.78 % respectively. By the trisomic analysis, it was found that the Gm2 gene was located on chromosome 3.     

Effect of VRN‐1 and PPD‐D1 genes on heading time in European bread wheat cultivars

The variation of the vernalization (VRN‐1) and photoperiod (PPD‐1) genes offers opportunities to adjust heading time and to maximize yield in crop species. The effect of these genes on heading time was studied based on a set of 245 predominantly spring cultivars of bread wheat from the main eco‐geographical regions of Europe. The genotypes were screened using previously published diagnostic molecular markers for detecting the dominant or recessive alleles of the major VRN‐1 loci such as: VRN‐A1, VRN‐B1, VRN‐D1 as well as PPD‐D1. We found that 91% of spring wheat cultivars contain the photoperiod sensitive PPD‐D1b allele. Photoperiod insensitive PPD‐D1a allele has been found mainly in southern region of Europe. For this region the monogenic control of vernalization by VRN‐B1 or VRN‐D1 dominant alleles is common, whereas in the remaining part of Europe, the combination of photoperiod sensitive PPD‐D1b allele with dominant VRN‐A1, VRN‐B1 and recessive vrn‐D1 alleles represents the most frequent genotype. Also, we revealed a significantly later (5–8 days) heading of the monogenically dominant genotypes at VRN‐B1 as compared to the digenic VRN‐A1 VRN‐B1 genotypes.     

Inheritance of a plant type mutant and its utilization in chickpea

Summary A macro-mutant, E 100Y(M) in chickpea (Cicer arietinum L.) was found to affect several plant and seed characters. For plant type monogenic inheritance was observed. A single pair of recessive genes pt/pt was ascribed to this mutant. The mutant locus seemed to be exerting pleiotropic action. The utilization of this mutant for chickpea improvement has been discussed.     

Screening for resistance to clover rot (Sclerotinia spp.) among a diverse collection of red clover populations (Trifolium pratense L.)

Red clover (Trifolium pratense) is an important perennial forage crop that is widely cultivated in Europe. Clover rot remains a major disease in red clover, but resistance breeding is hampered by the lack of available sources of resistance. Moreover, little is known about the factors that influence clover rot resistance. In this paper we evaluated the variation in clover rot susceptibility among a diverse collection of 113 red clover accessions, with the aim of identifying more resistant accessions. Clover rot susceptibility was assessed with a high throughput bio-test on young plants. We found significant variation in clover rot susceptibility, within and among accessions. ‘Tedi’, ‘Maro’ and ‘No 292’ were the most resistant accessions. Fifteen diploid accessions were more susceptible than the average accession with the cultivar ‘Nemaro’ being the most susceptible. Clover rot susceptibility was not correlated with isoflavone levels from Mullaney et al. (Agronomy abstract. ASA, Madison, p 195, 2000). Cultivars were more resistant than landraces and wild accessions and tetraploid cultivars were more resistant than diploid cultivars. Besides the in-depth analysis for clover rot susceptibility, possible correlations with plant architecture and other diseases were investigated. Growth habit, branching, plant yield, flowering date and susceptibility to mildew, virus and rust diseases were investigated in a 3-year field trial. Unlike previously suggested, clover rot susceptibility was not correlated with branching or with plant yield over three years. On the other hand, late flowering accessions and accessions with erect growth habit were less susceptible to clover rot. Clover rot susceptibility was not correlated with susceptibility to rust disease (Uromyces trifolii) or viral diseases, but negatively with susceptibility to mildew (Erysiphe polygoni). Because no completely resistant accessions were found, the best way to improve clover rot resistance would be to select recurrently for resistant genotypes among diverse cultivars and landraces with lower susceptibility. Tetraploidisation of diploid populations with a higher resistance level can provide an additional level of protection.     

Association between advanced generations and genealogy in inbred lines of snap bean by the Ward-Modified Location Model

Genetics of resistance to ascochyta blight was studied using different generations of fifteen crosses of chickpea (Cicer arietinum L.). Six parents comprising two susceptible varieties GL 769, C 214 and four resistant lines GG 1267, GL 90168, GL 96010 and GL 98010 were used to develop one S × S, eight S × R and six R × R crosses and some of the back crosses and F₃ generations were developed. Field screening technique was used to evaluate the different generations for disease reaction using mixture of ten prevalent isolates (ab₁–ab₁₀) of ascochyta blight (Ascochyta rabiei). Inheritance study showed digenic recessive control of resistance in the cross GL 769 × C 214, whereas monogenic recessive control of resistance was found in the crosses GL 769 × GL 98010 and C 214 × GL 98010. Digenic dominant and recessive control of resistance was found in the crosses GL 769 × GG 1267 and C 214 × GG 1267 while the crosses GL 769 × GL 90168 and C 214 × GL 96010 showed the monogenic dominant control of resistance. Trigenic dominant and recessive control of resistance was observed in the crosses GL 769 × GL 96010 and C 214 × GL 90168. Allelic relationship studies showed that three resistant parents viz., GG 1267, GL 96010 and GL 90168 possessed allelic single dominant gene for resistance. Besides, GG 1267 possessed two minor recessive genes for resistance, one of them was allelic to the minor recessive gene possessed by GL 90168 and other with GL 96010. The resistant parents GL 90168 and GL 96010 possessed non-allelic minor gene for resistance. The resistant parent GL 98010 possessed two minor recessive genes for resistance which were allelic to respective single recessive gene for resistance possessed by the susceptible parents GL 769 and C 214. The susceptible parents GL 769 and C 214 also possessed single independent inhibitory dominant susceptibility gene. The inhibitory gene was epistatic to the corresponding recessive gene for resistance.     

Genetic analysis of resistance to green leafhopper, Nephotettix virescens (Distant), in three varieties of rice

The genetics of resistance to green leafhopper, Nephotettix virescens (Distant), in rice varieties ‘IR36’ and ‘Maddai Karuppan’ and breeding line ‘IR20965‐11‐3‐3’ was studied. The reactions of F₁ hybrids, F₂ populations and F₃ lines from the crosses of test varieties with the susceptible variety ‘TN1’ revealed that resistance in ‘IR36’ and ‘Maddai Karuppan’, is governed by single recessive genes while resistance in ‘IR20965‐11‐3‐3’ is controlled by a single dominant gene. Allele tests with the known genes for resistance to green leafhopper revealed that the recessive gene of ‘IR36’ is different from and inherited independently of Glh1, Glh2, Glh3, Glh4, Glh5, Glh8 and Glh9t. This gene is designated as glh10t. The recessive gene of ‘Maddai Karuppan’ and the dominant gene of ‘IR20965‐11‐3‐3’ are also non‐allelic to Glh1, Glh2, Glh3, Glh4, Glh5 and Glh8t. Thus, the dominant gene of IR20965‐11‐3‐3 is designated as Glh11t. The allelic relationships of the recessive gene of ‘Maddai Karuppan’ with glh8 and glh10t should be investigated.     

Genetic Analysis of Resistance to Brown Planthopper in Rice (Oryza sativa L.)

Seventeen rice cultivate resistant to brown planthoppers were genetically analyzed using the Bangladesh insect population. Seven cultivars were found to have a single dominant gene for resistance. These genes segregated independently of the recessive resistance gene bph-5. Tae dominant resistance gene of ‘Swarnalata’ was designated Bph-6. In ten cultivars, resistance is conferred by single recessive genes. In eight cultivars, the resistance genes are allelic to bph-5. However, the recessive genes o: two cultivars are non-allelic to bph-5. The recessive gene of T12 is designated bph-7.     

An analysis of genes for resistance against Indian stem rust races in two bread wheat cultivars

Summary The genetic constitution of two bread wheat accessions from the International Spring Wheat Rust Nurseries (E 5883 and E 6032) has been studied for reaction to four Indian races of stem rust. Analysis of E 5883 has revealed that for each of the races 15C, 21 and 40 a single dominant gene operates for resistance. The dominant gene against race 15C was identified as Sr6. The dominant genes for resistance against races 21 and 40 were found to be different from the genes described so far. Resistance against race 122 is controlled by a single recessive gene producing characteristically a 2 type of reaction. This gene was identified as Sr8.The resistance of E 6032 against each of the races 15C, 21 and 40 is controlled by two genes, one dominant and one recessive, which act independently. Dominant genes effective against 15C, 21 and 40 were conclusively identified as Sr6, Sr5 and Sr9b, respectively. From the correlated behaviour against races 15C and 40 as well as from the phenotypes of the resistance reactions rhe same recessive gene, undescribed so far, operates against the two races. The second recessive gene operating against race 21 was also observed to be different from those so far designated. E 6032 was, however, found to be susceptible to races 122.The presence of Sr6 both in E 5883 and E 6032 against race 15C was further confirmed through F₂ and F₃ segregation data.     

Monosomic analysis of Helminthosporium leaf blight resistance genes in wheat

A set of 21 monosomic (2n ‐ 1) and the disomic (2n) lines of the ‘Chinese Spring’ cultivar were crossed with ‘Chirya‐3′, the CIMMYT synthetic wheat line which has been identified as highly resistant for Helminthosporium leaf blight disease (HLB), in order to locate the genes governing disease resistance. The F₁ and segregating populations were challenged and screened against the most virulent pure mono‐conidial HLB isolate KL‐8 (Karnal, India). The F₁ progenies of the crosses were found to be susceptible because of the recessive nature of resistance. The F₂ progeny of the control cross (‘Chinese Spring’בChirya‐3’), segregated in the ratio of 1: 15 (resistant: susceptible), indicating that resistance to HLB was controlled by a pair of recessive genes. While the F₂ progeny of 19 monosomic crosses segregated in the ratio of 1: 15 (resistant: susceptible), the progeny of the remaining two crosses, 7B and 7D, deviated significantly from the ratio, revealing that 7B and 7D were the critical chromosomes for resistance genes that were located one on each chromosome. Moreover, the critical lines, 7B and 7D, confirmed the digenic complementary recessive nature of gene action by fitting well with the overall pooled F₂ segregation ratio of 13: 51 (resistant: susceptible) as expected for digenic complementary recessive resistance. The F₃ segregation ratios of the critical crosses, based on their pooled F₂ analysis, was estimated as 19: 32: 13 (non‐segregating susceptible: segregating as susceptible and resistant: non‐segregating resistant). F₃ progenies when tested with these ratios showed goodness‐of‐fit, confirming that the two pairs of recessive resistance genes were located on chromosomes 7B and 7D.     

Crossability percentages of bread wheat collections from Tibet,China with rye

Summary The crossability percentages of 282 accessions of wheat (Triticum aestivum L.) collected in Tibet, China with rye (Secale cereale L.) have been tested. Five collections have a similar to and 277 accessions have a lower crossability percentage than Chinese Spring or are non-crossable with rye. The accessions with high crossability percentage occur along the highway near Lhasa. No landraces with higher crossability than Chinese Spring and rare landraces with similar crossability to Chinese Spring indicated that the landraces in Tibet region are different from those in Sichuan, Shaanxi and Henan provinces in the distribution frequency of high crossability, and there is no distribution of recessive kr4 alleles.     

Inheritance of Resistance to Yellow Mosaic Virus in some Vigna Species

Inheritance of resistance to Yellow Mosaic Virus (YMV) was studied in crosses of mungbean, black-gram and their interspecific crosses with Vigna sub-lobata. Resistance to YMV was recessive in the three Vigna species. The segregation ratios in F₂ and back crosses indicated that the resistance was digenic recessive in the crosses of mungbean and in interspecific crosses of mungbean with blackgram and Vigna subiobata but YMV resistance was monogenic recessive in blackgram crosses.     

Long-peduncled dwarf: A new mutant type induced in barley

Summary A new mutant, long-peduncled dwarf, was induced by EMS in C 164 barley. The mutant was characterised by a markedly shorter stature but longer peduncle than the normal plant. The dwarfing of the mutant was due to very short internodes other than the peduncle. The mutant was fully fertile and not associated with any chromosome aberration. The mutant trait was inherited as a single recessive gene designated as lpd. The trait being new may find a significant place in genetic research and also in plant breeding.