In vitro propagation through axillary bud multiplication in different mulberry genotypes

Axillary buds from 5 genotypes of mulberry belonging to 4 species were cultured on modified MS basal medium. A total of 30 media combinations were tried for all the genotypes. The response of axillary buds and the requirement for growth regulators varied with genotype. In Morus indica BAP (0.25–0.5 mg/l), and in M. alba and M. rotondifolia GA₃ (0.5–1.0 mg/l)were found to induce sprouting. Two genotypes of M. bombycis, namely Schimanochi and Mizusawa, developed healthy shoots on the incorporation of 2,4-D (0.5–1.0 mg/l) and BAP (0.5–2.0 mg/l), respectively. IBA (0.5 mg/l), along with cytokinin/auxin/gibberellin, had no effect on bud growth but helped root induction. Shoots developed from the axillary buds were further multiplied as nodal explants. MS basal medium supplemented with 0.5 mg/l IBA and LS vitamins was found best to produce healthy plantlets in all the genotypes. An average 89% survival was observed on transferring the plantlets to soil.Abbreviations MS Murashige and Skoog (1962) - LS Linsmaier and Skoog (1965) - IBA 3-indole-butyric acid - GA₃ Gibberellic acid - BAP 6-Benzylaminopurine - Kn Kinetin - 2,4-D 2,4-Dichlorophenoxyacetic acid     

Plantlets from somatic callus tissue of the woody legume Sesbania bispinosa (Jacq.) W. F. Wight

In vitro regeneration of plantlets and multiplication of Sesbania bispinosa (Jacq.) W.F. Wight plants from cultured callus tissue were demonstrated. Callus was established from both cotyledons and mature leaflets on Murashige and Skoog (MS) basal medium supplemented with BAP (0.5 mg/l) and 2,4-D (2 mg/l). Callus mediated shoot bud differentiation was studied under defined nutritional, hormonal and cultural conditions. Various concentrations of BAP or kinetin (Kn) with coconut milk (CM) in MS media induced different levels of shoot bud differentiation as well as multiplication. Multiple shoot bud differentiation occurred in most of the primary calli. The best medium for shoot bud differentiation from cotyledon derived callus, contained BAP (2 mg/l) and 15% CM (V/V). More efficient shoot bud organogenesis was recorded with BAP than Kn. Supplementation with CM in MS media accelerated shoot bud organogenesis in differentiating callus tissue. Rooting of differentiated shoots was achieved by a three step culture procedure involving (a) MS solid medium containing IBA (2 mg/l), (b) growth regulator free half strength MS medium with 1% charcoal, and (c) half strength MS liquid medium free of vitamins, growth regulators and charcoal.Abbreviations IAA indoleacetic acid - IBA indole-3-butyric acid - NAA naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzylaminopurine - Kn kinetin - CM coconut milk - MS Murashige and Skoog's medium - SBI shoot bud inducing medium     

In vitro propagation of shoot buds of Carica papaya L. (caricaceae) var. Honey Dew

Shoot buds from the saplings and the fruit bearing plants of Carica papaya L.. var. Honey Dew (papaya) initially treated with Gentamycin were cultured in modified MS media, each with a different hormonal combination, for the establishment of cultures and multiplication and rooting of plants. About 43% of explants from fruit bearing plants and 69% of those from saplings remained free of contamination and retained regeneration capacity when treated in 500 mg/l Gentamycin. For the establishment of the explants a medium containing 1 mg/l GA₃ and 2 mg/l kinetin was necessary. When established buds were transferred to medium containing 1 mg/l NAA and 3 mg/l kinetin, calli were initiated at cut ends of shoot buds; multiplication started on transfer to NAA (0.1 mg/l) and BAP (0.5 mg/l) medium. Cultures have been maintained for the last twenty months without any loss in multiplication rate. Rooting was induced in medium with reduced salt concentration containing 2 mg/l IBA. Shoot elongation was induced after prolonged culture in the same rooting medium.Abbreviations MS Murashige and Skoog, 1962 - SH Schenk and Hildebrandt, 1972 - GA₃ Gibberellic acid - Kn Kinetin - NAA Napthaleneacetic acid - BAP 6 -Benzylaminopurine - IBA Indole-3-butyric acid - IAA Indole-3-acetic acid     

Salt-Induced Changes in Physio-Biochemical and Antioxidant Defense System in Mustard Genotypes

Salinity stress is a major factor limiting plant growth and productivity of many crops including oilseed. The present study investigated the identification of salt tolerant mustard genotypes and better understanding the mechanism of salinity tolerance. Salt stresses significantly reduced relative water content (RWC), chlorophyll (Chl) content, K⁺ and K⁺ /Na⁺ ratio, photosynthetic rate (P_N), transpiration rate (Tr), stomatal conductance (gs), intercellular CO₂ concentration (Ci) and increased the levels of proline (Pro) and lipid peroxidation (MDA) contents, Na⁺ , superoxide (O₂^•− ) and hydrogen peroxide (H₂O₂) in both tolerant and sensitive mustard genotypes. The tolerant genotypes maintained higher Pro and lower MDA content than the salt sensitive genotypes under stress condition. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) were increased with increasing salinity in salt tolerant genotypes, BJ-1603, BARI Sarisha-11 and BARI Sarisha-16, but the activities were unchanged in salt sensitive genotype, BARI Sarisha-14. Besides, the increment of ascorbate peroxidase (APX) activity was higher in salt sensitive genotype as compared to tolerant ones. However, the activities of glutathione reductase (GR) and glutathione S-transferase (GST) were increased sharply at stress conditions in tolerant genotypes as compared to sensitive genotype. Higher accumulation of Pro along with improved physiological and biochemical parameters as well as reduced oxidative damage by up-regulation of antioxidant defense system are the mechanisms of salt tolerance in selected mustard genotypes, BJ-1603 and BARI Sarisha-16.     

Stress responses in two genotypes of mulberry (Morus alba L.) under NaCl salinity

Changes in biomass yield rates, cell membrane stability (CMS), malondialdehyde (MDA) content and in the levels of physiological stress markers such as proline and glycine betaine in two high yielding genotypes (S1 and ATP, salt tolerant and salt sensitive, respectively) of mulberry under NaCl salinity were studied. Biomass yield rates and CMS were significantly decreased in both the genotypes under stress conditions. Per cent of decrease in biomass yield rate and CMS was relatively less in S1 than in ATP. Salt stress results a significant increase in the accumulation of proline, by 6-fold in S1 and 4-fold in ATP. Glycine betaine content was also increased significantly in stressed plants. However, the per cent increase was more in S1 than in ATP. The level of lipid peroxidation as indicated by MDA formation was greater in ATP than in S1. These results clearly support the better salt tolerant nature of S1 compared to ATP genotype.     

Leaf morphological plasticity and stomatal conductance in three Populus alba L. genotypes subjected to salt stress

The effect of salt stress on leaf morphology and functionality was studied in three Populus alba genotypes differing in tolerance to salinity: 6K3 (sensitive), 2AS11 (moderately tolerant), and 14P11 (tolerant). Plants were subjected to an intense and progressive salt stress from 50 to 250 mM NaCl by 50 mM steps at 10-day intervals. The micromorphological results highlighted phenotypic variation among the three genotypes already in control plants, with the genotype 14P11 having significantly smaller epidermal cells and higher stomatal density. Salt-treated plants modulated differently the expansion of stomata compared with epidermal cells. Regression analysis showed significant correlations between decrease of stomatal area and stomatal conductance (g_s) in genotypes 14P11 and 6K3. So, the common reduction of stomatal area could be an early mechanism to save water in this species. However, only genotype 14P11 showed further significant decrease of this trait under the highest salinity level, combined with a significant reduction in leaf length. In addition, this genotype showed the lowest leaf abscission rate at the end of salt stress period. The genotype 6K3 was severely affected by leaf necrosis and showed the highest leaf abscission rate in salt stress conditions. In the moderately tolerant genotype 2AS11, an intermediate plastic behaviour in both leaf morphology and physiology was observed during the experiment. The phenotypic variation among the three genotypes in terms of micromorphology and stomatal conductance is discussed in relation to plant functionality in salt stress conditions. Overall results suggest that leaf morphological habit contributes to salt tolerance in P. alba.     

Plant regeneration from leaf-derived callus cultures of the tropical pasture legume Stylosanthes scabra Vog.

Callus cultures of 5 genotypes of S. scabra Vog. were optimally established from leaf tissue on Murashige and Skoog (MS) basal medium supplemented with 0.5–2.0 mg l^-1 2, 4-Dichlorophenoxy acetic acid (2, 4-D) and 1.0–2.0 mg l^-1 6-benzylaminopurine (BAP). On media containing 2, 4-D only, calli were soft, and rhizogenesis occurred on calli of 4 genotypes. Calli formed on media containing BAP only, but not with kinetin only. In the presence of 2, 4-D, BAP inhibited rhizogenesis and promoted better callus growth than kinetin. High frequency shoot induction was achieved for 3 genotypes on MS +2.0 mg l^-1 BAP. Roots formed on shoots when sub-cultured on half-strenght MS without growth regulators. The form of cytokinin used in the callus induction media appeared to affect subsequent shoot organogenesis. Genotypic differences were observed for shoot organogenesis. There was some morphological variation evident among regenerants.     

Differential cytokinin effects on the stimulation of in vitro shoot proliferation from meristematic explants of castor (Ricinus communis L.)

A highly efficient and reproducible method of in vitro propagation using meristematic explants has been developed for castor. Embryo axes and shoot tips were cultured on Murashige and Skoog (MS) medium supplemented with 0.5–10.0 mg/l of adenine, N⁶-benzyladenine (BA), kinetin (Kn), thiadiazuron (TDZ) and zeatin. TDZ (1.0–10.0 mg/l) gave the maximum number of shoots (37.8–40.0) from embryo axes, while BA (2.0 mg/l) was found superior to other cytokinins for obtaining the highest number of shoots (46.7) from the shoot apex. Adenine and Kn at all of the tested concentrations resulted in low proliferation rates from embryo axes. The carryover effect of the cytokinins was tested by subculturing proliferating shoot cultures from various media onto the medium fortified with 0.5 mg/l BA. There was no significant influence of the cytokinins on subsequent proliferation from the two explant types except for TDZ with embryo axes. The number of shoots from TDZ-habituated embryo axes ranged between 36.0 and 81.7, while it varied from 5.7 to 22.0 and 3.7 to 28.3 in axillary buds and embryo axes, respectively, on the other media. For elongation of shoots, gibberellic acid (GA₃) (0.1–1.0 mg/l) was added to the medium supplemented with 0.2–0.5 mg/l BA. Incorporation of GA₃ (0.1 mg/l) significantly enhanced the frequency of elongated shoots but drastically reduced the multiplication ability. Hence, proliferating shoot clusters were periodically transferred to the medium supplemented with 0.5 and 0.2 mg/l BA for further multiplication and elongation. Well-developed shoots were rooted on half-strength MS medium supplemented with 1.0 mg/l indole-3-butyric acid. The rooted plantlets were acclimatized with more than 60% success. Received: 17 June 1997 / Revision received: 3 September 1997 / Accepted: 20 September 1997     

Modulations in key enzymes of nitrogen metabolism in two high yielding genotypes of mulberry (Morus alba L.) with differential sensitivity to salt stress

Effect of salinity stress on the performance of nitrogen metabolism was studied in two high yielding genotypes of mulberry with differential sensitivity to NaCl (S1 and ATP, salt tolerant and susceptible, respectively). Three-month-old healthy mulberry plants were subjected to different regimes of NaCl stress [0.0 (control), 0.5, 1.0 and 1.5% NaCl] and leaf samples were collected on 4, 8 and 12 DAT (days after treatment) for the analysis. The activities of nitrate reductase (NR: EC 1.6.6.1), nitrite reductase (NiR: EC 1.6.6.4), protease, glutamine synthetase (GS: EC 6.3.1.2) and its accumulation pattern, glutamate synthase (GOGAT: EC 1.4.1.13), glutamate dehydrogenase (NADH-GDH: EC 1.4.1.2 and NADPH-GDH: EC 1.4.1.4), aspartate aminotransferase (AAT: EC 2.6.1.1) and alanine aminotransferase (ALAT: EC 2.6.1.2) coupled with total protein content, free amino acid level and ammonia content were studied in leaves of both genotypes of mulberry. The total protein content in leaves of both genotypes declined with progressive accumulation of free amino acid levels. Further, the decrease in protein content was less in S1 than ATP, and it was correlated with protease activity, ammonia content and accumulation of free amino acid levels. Higher free amino acid levels were registered for S1 than ATP at 1.0 and 1.5% NaCl stress and on all days of sampling. Ammonia content was increased in both genotypes and comparatively higher ammonia levels were recorded for ATP. Increased NaCl concentrations lead to a decrease in the activity of NR and NiR in both the genotypes, the decrease was more pronounced in ATP than S1. The enhanced activity of GDH (NADH and NADPH) was noticed in both genotypes, whereas the NADPH-GDH activity was found relatively higher in S1. The immunoblot analysis with GS-45 antibodies revealed a specific cross-reaction with 42 and 45 kDa proteins in S1, and only 45 kDa protein in ATP genotype. However, increased GS protein accumulation pattern (both 42 and 45 kDa) was observed in S1 under high NaCl. Whereas, accumulation of 45 kDa protein was unchanged at all levels of stress and slight accumulation in 42 kDa protein at 1.5% NaCl was observed for ATP. Elevation in the enzyme activities of GS, GOGAT were coupled with AAT and ALAT observed in both the genotypes. Higher enzymatic activities of S1 than ATP under salinity stress may be due to efficient capacity of ammonia detoxification. Salt tolerance of S1 supports the higher metabolic activity under salinity leading to lesser amount of ammonia accumulation and higher levels of free amino acid in the tissue. In agreement with these results the physiological significance of enzymatic changes and ammonia assimilation during salt stress in relevance to plant nitrogen metabolism was discussed.     

Laboratory-and Field-Phenotyping for Drought Stress Tolerance and Diversity Study in Lentil (<i>Lens culinaris</i> Medik.)

Drought susceptibility and low genetic variability are the major constraints of lentil (Lens culinaris Medik.) production worldwide. Development of an efficient pre-field drought phenotyping technique and identification of diversified drought tolerant lentil genotype(s) are therefore vital and necessary. Two separate experiments were conducted using thirty diverse lentil genotypes to isolate drought tolerant genotype(s) as well as to assess their diversity. In both of the experiments, significant (p ≤ 0.01) variation in genotype (G), treatment (T) and G X T was observed for most of the studied traits. In experiment I, genotypes were examined for drought tolerance at the seedlings stage under hydroponic conditions by assessing root and shoot traits. Among the 30 genotypes studied, BM-1247, BM-1227 and BM-502 were selected as highly tolerant to drought stress as they showed maximum seedling survivability and minimum reduction in growth parameters under drought stress. In experiment II, the genotypes were assayed for diversity and drought stress tolerance based on morphological traits grown under field condition. Drought stress caused a substantial reduction in yield attributing traits, however, the genotypes BM-1247, BM-981, BM-1227 and BM-502 were categorized as drought tolerant genotypes with less than 20% yield reduction. The field screening result of drought stress tolerance was coincided well with the results of laboratory screening. Genetic divergence study reflected the presence of considerable diversity among the genotypes. Considering laboratory and field screening results, the genotypes, BM-1247, BM-1227, BM-981 and BM- 502 were selected as the best drought tolerant genotypes. This information can be exploited for further breeding in developing drought tolerance in lentil.     

Germination profiling of lentil genotypes subjected to salinity stress

• Salinity is one of the most severe environmental stresses, negatively affecting productivity of salt‐sensitive crop species. Given that germination is the most critical phase in the plant life cycle, the present study aimed to determine seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt‐tolerant lentil genotypes.
• The genetic material consisted of six lentil genotypes whose adaptation to various agroclimatic conditions is not well elucidated. Salinity stress was applied by addition of NaCl at three different levels of stress, while non‐stressed plants were included as controls. Evaluation of tolerance was performed on the basis of germination percentage, seed water absorbance, root and shoot length, seedling water content, seedling vigour index and number of seedlings with an abnormal phenotype.
• Overall, our findings revealed that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the level of stress applied. It is noteworthy, however, that genotypes responded differently to the varying salinity levels. In this context, Samos proved the most salt‐tolerant genotype, indicating its possible use for cultivation under stress conditions.
• In conclusion, the determination of seed germination and early growth potential may be exploited as an efficient strategy to reveal genetic variation in lentil germplasm of unknown tolerance to salinity stress. This approach allows selection of desirable genotypes at early growth stages, thus enabling more efficient application of various breeding methods to achieve stress‐tolerant lentil genotypes.

     

In vitro propagation and rhizome formation in Curcuma longa Linn

Turmeric (Curcuma longa Linn.) which is cultivated by underground rhizomes is a slow propagating species. Multiplication and callus induction starting from the rhizome buds and shoot tips of C. longa in MS medium was carried out. A combination of naphthalene acetic acid (NAA; 1.0 mg/l) with kinetin (Kn; 1.0 mg/l) or NAA (1.0 mg/l) with 6-benzylaminopurine (BAP; 2.0 mg/l) was optimum for rapid clonal propagation of turmeric. A concentration of 2.5-3.0 mg/l of 2,4-dichlorophenoxy-acetic acid (2,4-D) was found to be optimum for callus induction. Regeneration of plantlets from a callus was successfully conducted in MS medium supplemented with standard growth hormones for multiplication at 25 +/- 2 degrees C under a 16 h photoperiod. These plantlets were successfully transferred to the field. Plantlets (4-month-old) were incubated in a medium containing different concentrations of sucrose supplemented with NAA (0.1 mg/l) and Kn (1.0 mg/l) at 27 +/- 2 degrees C under an 8 h photoperiod for induction of rhizomes. In vitro rhizome formation was observed in media containing 6 and 8% sucrose.     

Response of Contrasting Rice Genotypes to Zinc Sources under Saline Conditions

Abiotic stresses are among the major limiting factors for plant growth and crop productivity. Among these, salinity is one of the major risk factors for plant growth and development in arid to semi-arid regions. Cultivation of salt tolerant crop genotypes is one of the imperative approaches to meet the food demand for increasing population. The current experiment was carried out to access the performance of different rice genotypes under salinity stress and Zinc (Zn) sources. Four rice genotypes were grown in a pot experiment and were exposed to salinity stress (7 dS m⁻¹), and Zn (15 mg kg⁻¹ soil) was applied from two sources, ZnSO₄ and Zn-EDTA. A control of both salinity and Zn was kept for comparison. Results showed that based on the biomass accumulation and K⁺/Na⁺ ratio, KSK-133 and BAS-198 emerged as salt tolerant and salt sensitive, respectively. Similarly, based on the Zn concentration, BAS-2000 was reported as Zn-in-efficient while IR-6 was a Zn-efficient genotype. Our results also revealed that plant growth, relative water content (RWC), physiological attributes including chlorophyll contents, ionic concentrations in straw and grains of all rice genotypes were decreased under salinity stress. However, salt tolerant and Zn-in-efficient rice genotypes showed significantly higher shoot K⁺ and Zn concentrations under saline conditions. Zinc application significantly alleviates the harmful effects of salinity by improving morpho-physiological attributes and enhancing antioxidant enzyme activities, and the uptake of K and Zn. The beneficial effect of Zn was more pronounced in salt-tolerant and Zn in-efficient rice genotypes as compared with salt-sensitive and Zn-efficient genotypes. In sum, our results confirmed that Zn application increased overall plant’s performance under saline conditions, particularly in Zn in-efficient and tolerant genotypes as compared with salt-sensitive and Zn efficient rice genotypes.     

Plant regeneration from callus cultures of Valeriana wallichii DC.

Petiole expiants of Valeriana wallichii. DC., a threatened medicinal plant, were used for inducing callus. Optimum callus formation was observed on Murashige and Skoogs' (1962) medium supplemented with 3.0 mg/l NAA and 0.25 mg/l Kn. Shoot regeneration was achieved upon transferring the callus to medium containing 1.0 mg/l Kn and 0.25 mg/l NAA. Complete plantlets were obtained on the same medium or upon transfer of the regenerated shoot buds to medium containing 5.0 mg/l Kn and 1.0 mg/l IAA. Nearly a thousand callus regenerated plants were successfully transferred to the field following previously standardized hardening procedures.Abbreviations BAP 6-Benzylaminopurine - 2,4-D 2,4-dichloro phenoxyaceticacid - 2iP 2-isopentenyladenine - IAA indole-3-acetic acid - IBA indole-3-butyric acid - Kn Kinetin - MS Murashige and Skoog's medium (1962) - NAA -napthalene aceticacid - Z Zeatin     

高粱种质材料幼苗期耐盐碱性评价

采用Hoagland营养液砂培法,以NaCl和Na2CO3组成的混合盐碱对高粱幼苗进行胁迫处理,建立高粱幼苗期耐盐碱评价方法,并评价了66份高粱种质材料的耐盐碱性.结果表明:盐浓度在8.0～12.5 g·L-1时,高粱耐盐碱品种‘TS-185’与盐碱敏感品种‘Tx-622B’在幼苗期的耐盐碱性差异明显,表明进行高粱幼苗期耐盐碱性评价时适宜的盐浓度范围为8.0～12.5 g· L-1.在10.0和12.5 g·L-12个盐浓度下,66份高粱种质材料的相对存活率、相对地上部鲜质量和相对株高的差异均达显著水平,表明不同品种的耐盐碱性不同.其中,‘三尺三’为高度耐盐碱品种,‘MN-2735’等16个品种为耐盐碱品种,‘EARLY HONEY’等32个品种为中等耐盐碱品种,‘Tx-622B’等16个品种为盐碱敏感品种,‘MN-4588’为高度盐碱敏感品种.苏丹草类型高粱一般具有较高的耐盐碱性,而保持系对盐碱较为敏感.     

NaCl induced morpho-biochemical and anatomical changes in mulberry (<Emphasis Type="Italic">Morus</Emphasis> spp.)

Mulberry is an economically important tree, used for feeding the silkworm Bombyx mori L. Effect of different levels of NaCl on growth and development of mulberry has been studied using five mulberry genotypes selected on the basis of their performance under in vitro salinity. The study while endorsing the efficacy of in vitro screening of axillary buds of mulberry for salt tolerance, showed genotypic variability in its response to salinity. Salinity reduced growth and development of all genotypes. However, the putative tolerant genotypes showed better performance than the putative susceptible genotypes. Under low salinity (<0.5% NaCl) salt tolerant genotypes showed an increase in chlorophyll and protein concentrations, while in susceptible genotypes both were reduced by 3–58% at 0.5% NaCl and 50–64% at 1.00% NaCl. Leaf thickness increased by 16% at 1.00% NaCl in C776 and reduced by 1.0% in Mandalaya. The increase in chlorophyll concentration and leaf thickness under high salinity can be considered as preliminary selection parameters for salt tolerance in mulberry. The study confirmed the efficacy of in vitro method for screening of large number of genotypes for salt tolerance in mulberry.     

Differential responses of antioxidant system and photosynthetic characteristics in four rice cultivars differing in sensitivity to sodium chloride stress

To keep pace with ever growing global population, progressive and sustained increase in rice production is necessary, especially in areas with extremely variable climatic conditions, where rice crop suffers from numerous abiotic stresses including salinity. Designing an effective phenotyping strategy requires thorough understanding of plant survival under stress. The investigation was carried out with four rice cultivars namely FR13A, IR42, Rashpanjor, and Pokkali that differed in salinity tolerance. The study showed that a genotype with initial vigour had some advantage in preserving shoot biomass under salt stress. Though both FR13A and IR42 showed sensitivity to salinity, FR13A with higher initial biomass maintained greater dry weight under saline condition. Increase of Na⁺:K⁺ ratio under salinity, due to accelerated absorption of Na⁺ and lesser absorption of K⁺ compared to control, was considerably higher in susceptible (118–200 %) than in tolerant (33–48 %) genotypes. While Na⁺ concentration in shoot increased significantly in both tolerant and susceptible genotypes, decrease in shoot K⁺ content was noticed only in susceptible genotypes. The imbalance of Na⁺ and K⁺ contents led to increased H₂O₂ production, causing greater peroxidation of membrane lipids and reduction in chlorophyll content and CO₂ photosynthetic rate. Certain chlorophyll fluorescence parameters could distinguish between salinity tolerant and sensitive genotypes. To protect the plant from oxidative damage, several enzymatic and nonenzymatic antioxidants such as ascorbate were involved. The genotypes with capacity to assemble antioxidant enzymes in time could detoxify the reactive oxygen species more efficiently, leading to greater protection and reduced impact of salt stress.     

Phylogenetic relationship of salt tolerance in early Green Revolution CIMMYT wheats

Twenty-five genotypes of early CIMMYT hexaploid wheat (Triticum aestivum L.) were screened for salt tolerance in a glasshouse experiment at 150 mol m⁻³ NaCl in sand culture. The genotypes Na(20)TPP, Penjamo 62, and Inia 66 exceeded all the lines in grain yield per plant under salt stress, whereas Nainari 60 and Norin 10 were the lowest of all genotypes. However, Jaral 66 and Yaqui 54 were the lowest of all the genotypes in all growth and yield attributes. Considerable variation in accumulation of Na⁺ and Cl⁻ in different plant parts of 25 genotypes of early CIMMYT wheat under salt stress was observed. The genotype Noreste 66 was the lowest in leaf Na⁺ and Cl⁻, and it had highest leaf K/Na ratio and K versus Na selectivity of all the genotypes, but in terms of growth and grain yield, it was moderately tolerant. The other genotype Norin 10 was the highest in leaf Na⁺ and Cl⁻ of all genotypes, but its leaf K/Na ratio and K versus Na selectivity were considerably low. However, in shoot biomass it was the highest and in grain yield the lowest of all genotypes. In view of phylogenetic lineage of the genotypes, most of the genotypes have evolved from Norin 10, so the trait of high uptake of Na⁺ and Cl⁻ in most genotypes may have been inherited from Norin 10. The ion exclusion trait in the moderately salt tolerant genotype Noreste 66 was possibly inherited from Yaqui 50 as it was the only among all putative parents which showed low uptake of toxic ions. Overall, owing to the complex nature of the salt tolerance trait being controlled by polygenes, it was not easy to draw relationships between degree of salt tolerance and pattern of uptake of toxic ions and maintenance of leaf K/Na ratios. However, from the phylogenetic lineage of the 25 genotypes it was possible to draw relationships between degree of salt tolerance and mechanism of ion uptake between parents and progeny.     

Effect of genotype and medium composition on linseed (<Emphasis Type="Italic">Linum usitatissimum</Emphasis>) ovary culture

Breeding linseed (Linum usitatissimum L.) using haploid techniques allows breeders to develop new cultivars in a shorter time period. Many research groups successfully created new linseed genotypes through anther culture; however ovary culture has been the subject of only a few earlier studies. In the present study, the effect of genotype and growth regulators combination on callus induction and shoots regeneration in ovary culture of nine commercially important linseed cultivars was investigated. Ovaries were cultured on modified MS medium supplemented with three different combinations of plant growth regulators. Variable callogenic responses were expressed by all of the genotypes tested on different induction media. The results suggested that specific combination of growth regulators for callus induction must be designed for each genotype. Shoot regeneration from ovary derived callus is a critical phase of the whole gynogenetic process. Differences in adventitious shoot formation frequency among genotypes were demonstrated and four responsive genotypes have been selected. Ovary derived callus from cultivar ‘Mikael’ manifested the highest adventitious shoot formation frequency with a high number of shoots per explant. The optimum ratio of growth regulators for shoot regeneration was shown to depend on the genotype. Cultivars ‘Linola’, ‘Mikael’ and ‘Szaphir’ showed the highest shoot regeneration frequency when callus had originated on induction medium supplemented with 2 mg L⁻¹ BAP and 2 mg L⁻¹ NAA, while combination of 1 mg L⁻¹ BAP and 2 mg L⁻¹ IAA promoted shoot formation in ovary-derived callus of ‘Barbara’. The highest rate of shoots per explant has been obtained in second subculture.     

Effect of culture medium composition on callus formation and regeneration in oil flax anther culture

Regeneration ability in callus cultures from anthers of two hybrid genotypes of oil flax was studied on N6 and LMA-1 nutrient media at various concentrations of cytokinine 6-benzylamynopurine (BAP). It was shown that callus grew and developed better at BAP concentrations of 2 mg/l, comparing with 4 and 6 mg/l. Shoot and root regeneration was observed in F1 genotype 6-8-gnezdny x M22 only and did not depend on BAP concentration in the medium and on the medium composition itself. Transfer onto fresh medium often stimulated dedifferentiation of the regenerated structures.