An induced brachytic mutant of chickpea and its possible use in ideotype breeding

Mutations were induced in chickpea (Cicer arietinum L.) cultivar ‘JG 315’ through treatment of seeds with ethyl methane sulphonate (EMS). One of the mutants, named JGM 1, had brachytic growth (compact growth), characterized by erect growth habit, thick and sturdy stem, short internodal and interleaflet distances and few tertiary and later order branches. It was isolated from M₂ derived from seeds treated with 0.6% EMS for 6 h. Segregation analyses in F₂ progenies of its crosses with normal chickpea genotypes (JG 315, ICC 4929, and ICC 10301) suggested that a single recessive gene controlled brachytic growth in JGM 1. This gene was not allelic to the br gene for brachytic growth in spontaneous brachytic mutant E100YM. Thus, the gene for brachytic growth in JGM 1 was designated br2 and the br gene of E100YM was redesignated br1. Efforts are being made to use JGM 1 in development of a plant type with short internodes and erect growth habit. Such plant type may resist excessive vegetative growth in high input (irrigation and fertility) conditions and accommodate more plants per unit area.     

Allelic relationship between spontaneous and induced mutant genes for stem fasciation in chickpea

Stem fasciation is a morphological abnormality observed in plants where the stem is widened and leaves and flowers or pods are clustered at the apex. Several spontaneous mutants and one induced mutant for stem fasciation are found in chickpea (Cicer arietinum L.). This study was aimed at determining allelic relationship between spontaneous and induced mutant genes controlling stem fasciation and effects of stem fasciation on grain yield. Two spontaneous (ICC 2042 and ICC 5645) and one induced (JGM 2) stem fasciation mutants were crossed in all combinations, excluding reciprocals. The F₁ and F₂ plants from a cross between the two spontaneous mutants had fasciated stem. This indicated the presence of a common gene (designated fas1) for stem fasciation in the two spontaneous mutants. The F₁s of the crosses of the induced mutant JGM 2 with both spontaneous mutants had normal plants and segregated in a ratio of 9 normal : 7 fasciated plants in F₂. Thus, the gene for stem fasciation in the induced mutant JGM 2 (designated fas2) is not allelic to the common gene for stem fasciation in spontaneous mutants. The two genes in dominant condition produced normal non‐fasciated stem. The fasciated and the non‐fasciated F₂ plants did not differ significantly for number of pods per plant, number of seeds per plant, grain yield per plant and seed size, suggesting that it is possible to exploit the fasciated trait in chickpea breeding without compromising on yield.     

Allelic relationships of genes controlling number of flowers per axis in chickpea

Genetic variation for number of flowers per axis in chickpea (Cicer arietinum L.) includes single-flower, double-flower, triple-flower and multi-flower traits. A double-flowered (DF) line ICC 4929, a triple-flowered (TF) line IPC 99-18 and a multi-flowered (MF) line JGM 7 were intercrossed in all possible combinations and flowering behavior of parents, F₁s and F₂s was studied to establish allelic relationships, penetrance and expressivity of genes controlling number of flowers per axis in chickpea. The F₁ from ICC 4929 (DF) × IPC 99-18 (TF) cross were double-flowered, whereas F₁ from ICC 4929 (DF) × JGM 7 (MF) and IPC 99-18 (TF) × JGM 7 (MF) crosses were single-flowered. The F₂ from ICC 4929 (DF) × IPC 99-18 (TF) cross gave a good fit to a 3:1 ratio for double-flowered and triple-flowered plants. The F₂ from ICC 4929 (DF) × JGM 7 (MF) cross segregated in a ratio of 9:3:3:1 for single-flowered, double-flowered, multi-flowered and double-multi-flowered plants. The F₂ from IPC 99-18 (TF) × JGM 7 (MF) cross segregated in a ratio of 9:3:4 for single-flowered, triple-flowered and multi-flowered plants. The results clearly established that two loci control number of flowers per axis in chickpea. The double-flower and triple-flower traits are controlled by a single-locus (Sfl) and the allele for double-flowered trait (sfl ^d ) is dominant over the allele for triple-flower trait (sfl ^t ). The three alleles at the Sfl locus has the dominance relationship Sfl > sfl ^d > sfl ^t . The multi-flower trait is controlled by a different gene (cym). Single-flowered plants have dominant alleles at both the loci (Sfl_ Cym_). The double-flower, the triple-flower and the multi-flower traits showed complete penetrance, but variable expressivity. The expressivity was 96.3% for double-flower and 76.4% for double-pod in ICC 4929, 81.2% for triple-flower and 0.0% for triple-pod in IPC 99-18, and 51.3% for multi-flower and 24.7% for multi-pod in JGM 7. Average number of flowers per axis and average number of pods per axis were higher in JGM 7 than double-flowered line ICC 4929 and triple-flowered line IPC 99-18. The results of this study will help in development of breeding strategies for exploitation of these flowering and podding traits in chickpea improvement.     

Induced Vine Mutant in Vigna mungo

Pure dry seeds of variety T₉ of Vigna mungo were irradiated by 10, 20 and 30 kR of gamma rays at 33 °C followed by post irradiation treatment with 0.25 % EMS in phosphate buffer (pH 7.0) at 30 ± 1 °C. Vine mutants were isolated from segregating families after 20 kR and 10kR ± EMS treatment. The genetic nature of the mutants was tested by crossing with the wild type. The segregation in F² proved the mutant to be monogenic recessive. The mutant showed slight improvement in protein content and marked improvement in yield of seeds.     

Individual and combined effects of plant height reducing genes in periwinkle

Inheritance of an induced bushy mutant (EMS 24-5) of periwinkle (Catharanthus roseus) and its genetic relationship with an earlier reported dwarf mutant (NEU 6-15) was studied by crossing it with its parental variety, Nirmal and the dwarf mutant. The bushy mutant was found to be under the control of a monogenic recessive gene (by), which was inherited independently of the recessive gene (dw ₁ ) involved in the dwarf mutant. The double mutant (bydw ₁ ) recombinant, which was recovered from the F₂ generation of the cross (NEU 6-15) × (EMS 24-5), its parental mutants and variety, Nirmal were used for determining the individual and combined effects of plant height reducing genes dw ₁ and by. Individually, the recessive genes by and dw _1, reduced plant height by 27–30, 64–68%, respectively, while together they reduced plant height by 73–77%. The double mutant recombinant was found to be 63–68 and 25–29% shorter than its parental mutants (EMS 24-5) and (NEU 6-15), respectively. The effects of the recessive gene by on plant height were discernable only after the age of 4 months while those of dw ₁ and combined effects of dw ₁ and by became apparent one to 2 weeks after germination. The double mutant recombinant was found to have higher content of total alkaloids in the roots than parental mutants as well as the variety, Nirmal.     

Fasciation in chickpea: genetics and evaluation

Summary A spontaneous fasciated mutant was detected in the chickpea cv. Amethyst. It was characterised by broad, strap-like stems, irregular leaf arrangement and clustering of pods towards the stem apices. F₂ and F₃ segregations showed that fasciation was controlled by a single, recessive gene for which the symbol fas is proposed. Field trials comparing the fasciated mutant with its non-fasciated isoline showed that fasciation was associated with lower yield, larger seeds, delayed flowering and increased lodging.     

Linkage relationships of genes for leaf morphology,flower color,and root nodulation in chickpea

Summary The allelic and linkage relationships among five chickpea (Cicer arietinum L.) morphological markers were investigated. When crossed with purple-flowered line ICC 640 and with each other, white flowered variety UC5 and mutant line PM974 were shown to carry non-allelic, single recessive genes for white flower color, provisionally designated w1 and w2, respectively. The single recessive gene conferring simple leaves in mutant PM299 was allelic to the previously described slv gene carried by variety Surutato 77, line ICC 10301, and other simple leaf chickpea mutants. In mutant 756M, a filiform leaf trait was controlled by a single recessive gene, fil, which was non-allelic to slv.The fil and w2 genes were linked, with recombination frequencies of 0.05 and 0.14 estimated from results of coupling and repulsion phase crosses, respectively. fil and w1 segregated independently. Root nodulation gene rn3 was closely linked to slv: recombination frequencies of 0.05 and 0.11 were estimated from results of coupling and repulsion phase crosses, respectively. A loose linkage detected between the w2-fil and the rn3-slv linkage groups will be the subject of further scrutiny.     

大豆“南农86-4”突变体筛选及突变体库的构建

应用⁶⁰Co γ射线和甲基磺酸乙酯(EMS)分别对“南农86-4”大豆种子进行诱变，并构建大豆突变体库。结果在M₃代分别获得40份和145份叶、茎、花、种子、子叶等性状变异的材料。在两种方式诱变的M₃代都获得蛋白质和油含量变化的材料，尤其在EMS诱变的M₃代中获得47份蛋白质含量比对照高5个百分点以上的材料，5份蛋白质和油总含量比对照高5个百分点以上的材料。这些突变体可以作为新的种质资源，构建的突变体库也有助于大豆功能基因组研究的开展。     

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.     

Estimation of Outcrossing Rate in Chickpea (Cicer Arietinum L.) Sown in Autumn

Gene flow via outcrossing from transgenic plants to relatives will be one of the most important concerns to grow of the transgenic chickpea (Cicer arietinum L.) in European Union (EU). This report is therefore focused on spontaneous outcrossing rate in chickpea. A total of 39 kabuli type mutants with white flower and one desi type with pink flower were grown to estimate spontaneous outcrossing rate. Outcrossing rate ranged from 0.0 to 1.25% in mutant materials. Since labelling threshold for transgenic contamination in food and feed in European Union (EU) is 0.9%, outcrossing rate of 1.25% is higher than threshold of 0.9% in EU, and this result suggests that cultivation of transgenic chickpea will be under high risk to be contaminated chickpeas in neighbourhood fields.     

EMS Induction of Early Flowering Mutants in Spring Rape (Brassica napus)

Studies were undertaken to induce early flowering mutants by ethyl methanesulphonate (EMS) treatments of Brassica napus seeds. EMS treatments for 12 h of a highly inbred B. napus line TBS had adverse effects on M¹ plant development and fertility only when concentrations were greater than 1%. However, an EMS concentration of 1.5% did not reduce M₁ plant fertility to an extent which significantly reduced production of M₂ seeds. Genetic changes induced by EMS treatment and affecting flowering time were of three main types: (1) Changes within a polygenic system reflected by increased variation in flowering time among M₂ families. As the increase in variation was due primarily to a higher frequency of later flowering plants, these polygenic changes would be of little value in developing better-adapted cultivars. (2) Induction of a recessive mutation at a major gene locus which caused M₃ plants homozygous for the mutant gene to flower at least 20 days earlier than the parental line TB8. (3) Induction of a dominant mutation at a major gene locus which affects flowering time by causing a substantial reduction in vernalization requirement. M₂ plants carrying the mutant gene flowered as early as 59 days before the parental line. These major gene mutations could be rapidly exploited in the development of agronomically superior cultivars for short-season, lower rainfall environments in Western Australia.     

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.     

Harnessing mutant donor plants for microspore culture in Indian mustard [Brassica juncea (L.) Czern and Coss]

Haploid mutagenesis offers several advantages over conventional (seed) approach. However, its potential has not been utilised for Brassica juncea, an important oilseed. In this study, mutant donor plants of three Indian B. juncea genotypes, generated by ethyl methanesulfonate (EMS) and ethyl nitrosourea (ENU), were used for microspore culture. The response of mutant donor plants was about 100 times lower than non-mutant controls; a total of 9,411 embryos were produced from the EMS treated donor plants, while microspores isolated from ENU treated donors did not yield any embryos. The lethality of induced mutations demonstrated itself mainly as the induction of abnormal embryos (80%), failure of germination (70%) and failure of plantlet development (70%). Nine doubled haploid (DH) mutant lines and three non-mutant DH lines obtained through this approach were tested for agronomic and biochemical variation over two growing seasons. High variability was observed and stable mutants were recovered for reduced height (125 vs. 168 cm for the control), appressed pod character, altered fatty acid composition higher protein proportion in de-oiled meal (48%) and a lower glucosinolate content in de-oiled meal (59.5 μM/g) relative to controls. The approach demonstrates that despite severe reduction in efficiency of the DH line production, valuable mutants can be recovered from mutated donor plants.     

Genetic mapping of the barley lodging resistance locus Erectoides‐k

The barley (Hordeum vulgare L.) mutant erectoides‐k.32 (ert‐k.32) was isolated in 1947 from an X‐ray‐mutant population of cultivar ‘Bonus’. The mutant was released as a cultivar in 1958 with the name ‘Pallas’ – one of the first cereal crop cultivars developed from induced mutants. ‘Pallas’ is a semi‐dwarf barley cultivar known for its culm stability and resistance to lodging. In total, eight allelic ert‐k mutants are known that show different phenotypic strength concerning culm length and spike architecture. They represent alternatives to the widely used, but pleiotropic ‘Green Revolution’ alleles of the Sdw1 (semidwarf1/denso) and Uzu1 (semi‐brachytic1) genes in breeding of robust elite barley cultivars. In the present study, we locate Ert‐k to a 15.7‐cM region in the centromeric region of chromosome 6H. Although the interval is estimated to contain approximately 700 genes, the work provides a solid foundation for the identification of the underlying mutations causing the ert‐k lodging‐resistant phenotype. In addition, the linked markers could be used to follow the ert‐k mutant genotype in marker‐assisted selection of new lodging‐resistant barley cultivars.     

亚洲棉EMS诱变条件优化与突变体筛选

【目的】明确适于亚洲棉诱变的甲基磺酸乙酯(EMS)最佳浓度和处理时间,创制优异亚洲棉突变体。【方法】用体积分数0.4%~1.5%EMS溶液浸泡处理亚洲棉石系亚1号种子4~8 h,分析不同时间、不同浓度的EMS溶液处理对石系亚1号种子萌发和生长的影响,并对M1、M2代突变株的形态学特征进行了初步鉴定。【结果】0.6%EMS溶液处理8 h,石系亚1号种子的发芽率、发芽指数分别为51%、18.84,诱变效果最佳。以该参数大规模诱变处理约23 000粒石系亚1号种子,共筛选获得M1代变异材料5559株,突变频率为48.37%;M2代变异材料825份,突变频率为14.17%,其中叶型、株型的突变频率最高,分别为8.0%,5.9%;M3代变异株系57个,变异性状遗传频率为31.30%,M3代新增突变频率为18.26%。【结论】本研究建立了亚洲棉种子EMS诱变体系,构建了亚洲棉石系亚1号M2突变群体,获得了36份可稳定遗传的突变体株系,为棉花功能基因组研究奠定了材料基础。     

Heritability and predicted gain from selection in components of crop duration in divergent chickpea cross populations

Genetic analysis of ten quantitative traits related to crop duration in chickpea was carried out using three F ₂ sib-populations; 272-2 × CDC Anna, 298T-9 × CDC Anna and 298T-9 × CDC Frontier. F ₃ and F ₄ families from these populations were further evaluated for traits found important in the initial study. Also, 112 recombinant inbred lines (RILs) of chickpea cross ICCV 2 × JG 62 were evaluated for days to flowering, days to maturity and reproductive period. An analysis of the F ₂ population data using the mixed model approach revealed that the additive component of variance was significant for days to flowering, days to first podding and days to first pod maturity, while dominance genetic variance was significant for morphological components of crop duration such as height to first pod and height at flowering. Comparatively high heritability estimates (39–48%) were obtained for days to flowering, days to first pod maturity, percent pod maturity at four months after planting and days to maturity based on offspring-parent (F ₄ and F ₃ generations) regression and/or analysis of variance for the RIL population. The predicted gain from selection as a percentage of the population mean was low (5% or less) for these key components of crop duration owing to the low variability detected within the populations, the exception being percent pod maturity. To maximize gain from selection in these traits, it is therefore, essential to increase genetic variability among the progenies, potentially through multi-parent crosses that may involve gene introgression from across desi and kabuli types of chickpea and from wild progenitors.     

Two genes and linked RAPD markers involved in resistance to Fusarium oxysporum f. sp. Ciceris race 0 in chickpea

The inheritance of resistance to fusarium wilt race 0 of chickpea and linked random amplified polymorphic DNA (RAPD) markers were studied in two F₆:₇ recombinant inbred line (RIL) populations. These RILs were developed from the crosses CA2156 × JG62 (susceptible × resistant) and CA2139 × JG62 (resistant × resistant), and were sown in a field infected with fusarium wilt race 0 in Beja (Tunisia) over 2 years. A1:1 resistant to susceptible ratio was found in the RIL population from the CA2156 × JG62 cross, indicating that a single gene with two alleles controlled resistance. In the second RIL population (CA2139 × JG62) a 3:1 resistant to susceptible ratio indicated that two genes were present and that either gene was sufficient to confer resistance. Linkage analysis showed a RAPD marker, OPJ20600, linked to resistance in both RIL populations, which is present in the resistant parent JG62.     

Mapping QTL for resistance to botrytis grey mould in chickpea

Botrytis grey mould (BGM) caused by Botrytis cinerea Pers. ex. Fr. is the second most important foliar disease of chickpea (Cicer arietinum L.) after ascochyta blight. An intraspecific linkage map of chickpea consisting of 144 markers assigned on 11 linkage groups was constructed from recombinant inbred lines (RILs) of a cross that involved a moderately resistant kabuli cultivar ICCV 2 and a highly susceptible desi cultivar JG 62. The length of the map obtained was 442.8 cM with an average interval length of 3.3 cM. Three quantitative trait loci (QTL) which together accounted for 43.6% of the variation for BGM resistance were identified and mapped on two linkage groups. QTL1 explained about 12.8% of the phenotypic variation for BGM resistance and was mapped on LG 6A. It was found tightly linked to markers SA14 and TS71rts36r at a LOD score of 3.7. QTL2 and QTL3 accounted for 9.5 and 48% of the phenotypic variation for BGM resistance, respectively, and were mapped on LG 3. QTL 2 was identified at LOD 2.7 and flanked by markers TA25 and TA144, positioned at 1 cM away from marker TA25. QTL3 was a strong QTL detected at LOD 17.7 and was flanked by TA159 at 12 cM distance on one side and TA118 at 4 cM distance on the other side. This is the first report on mapping of QTL for BGM resistance in chickpea. After proper validation, these QTL will be useful in marker-assisted pyramiding of BGM resistance in chickpea.     

Identification of low lectin mutants in soybean

Lectin is one of the known antinutritional factors that deteriorate the soybean protein quality and development of cultivars with low lectin content will help to improve nutritional quality of soybean [Glycine max (L.) Merrill]. Therefore, attempts were made to induce mutations for low lectin content in the cultivar ‘MACS 450’. Soybean cultivar ‘MACS 450’ was subjected to combination treatments of γ‐rays and ethyl methane sulphonate (EMS) with an objective to induce variability for low lectin content. The treatments of different combinations of γ‐rays and EMS were 50 Gy + 0.2% EMS, 50 Gy + 0.4% EMS, 100 Gy + 0.2% EMS and 100 Gy + 0.4% EMS. Of the 3200 treated M₁ seeds sown, 16 400 M₂ plants were raised. In M_2, 72 plants were identified for low lectin content [<40 × 10⁵ haemagglutination unit (HAU)/mg] and were carried up to M₅ generation. In M₅ generation, lectin content in ‘MACS 450’ was 39.23 to 50.0 × 10⁵ HAU/mg, and was compared with the nine true breeding lines identified having low lectin content, ranging from 2.3 × 10⁵ to 27.46 × 10⁵ HAU/mg. Three mutants were found to possess very low lectin content (ranging from 2.0 × 10⁵ to 3.0 × 10⁵ HAU/mg). Thus, the identified mutant lines with low lectin content will greatly improve soybean protein quality, thereby reducing financial burden on the soybean industry for processing soybean meal and also making it suitable for human consumption. All the mutants showed normal seed development, having soluble protein content similar or higher than that in the parent (32.0 mg/ml). This indicates that the change in lectin content does not have any negative impact on the plant growth and protein content.     

理化诱变小豆京农6号突变体的鉴定

选用小豆品种京农6号种子,分别采用甲基磺酸乙酯(EMS)(0.5%、0.9%和1.4%处理12h和24h)、电子束(100、300、600Gy)、60Co-γ(400Gy)诱变处理,将处理后的种子种于大田,鉴定后代植株性状的变异。观察表明,EMS诱变的变异类型最丰富、60Co-γ射线次之、电子束产生的变异类型较单一。EMS处理小豆以浓度0.5%和0.9%处理24h为宜;0.5%EMS处理的粒色和荚色变异突出,有鲜红、黄白、绿白粒色和黑荚、褐荚、黑褐荚变异;0.9%处理的叶形变异突出,有鸡爪叶、剑叶、肾形叶、小密叶等突变类型;电子束诱变后,M2变异率分别为4.09%、3.64%和2.22%。400Gy60Co-γ射线处理种子,后代变异率为7.23%。通过两年的鉴定筛选,获得937个EMS诱变M3代株系,934个60Co-γ射线和电子束诱变M2代株系,已得到株高、叶形、叶色、粒形、粒色、荚色、无分枝、多分枝、叶簇生、分枝簇生、光叶、蔓生、有限结荚习性、株型松散、育性、成熟特性等突变体材料1490份。本研究为小豆基因遗传分析、基因定位与克隆及其进一步的基因功能分析奠定了基础,为小豆育种提供了重要的材料。