Dwarf mutations in grass pea (Lathyrus sativus L.): origin, morphology, inheritance and linkage studies

Improvement of German Chamomile (Matricaria recutita L.) for Mechanical Harvesting, High Flower Yield and Essential Oil Content Using Physical and Chemical Mutagenesis

Chamomile (Matricariarecutita L.) is one of the most important medicinal plants with various applications. The flowers and flower heads are the main organs inthe production of essential oil. The essential improvement goals of chamomile are considered to be high flower yield and oil content, as well asthe suitability for mechanical harvesting. The present study aimed to improve the flower yield, oil content and mechanical harvestability of German chamomile via chemical and physical mutagens. Three German chamomile populations (Fayum, Benysuif and Menia) were irradiated with 100, 200, 300 and 400 Gray doses of gamma rays, as well as chemically mutagenized using 0.001, 0.002 and 0.003 mol/mL of sodium azide for 4 h. The two mutagens produced a wide range of changes in the flowers' shape and size. At M₃ generation, 18 mutants (11 from gamma irradiation and 7 from sodium azide mutagenization) were selected and morphologically characterized. Five out of eighteen mutants were selected for morphological and chemical characterization for oil content, oil composition and oil quality in M₄ generation. Two promising mutants, F/LF5-2-1 and B/HNOF 8-4-2, were selected based on their performance in most studied traits during three generations, as well as the high percentage of cut efficiency and a homogenous flower horizon, which qualify them as suitable candidates for mechanical harvesting. The two mutants are late flowering elite mutants; the F/LF5-2-1 mutant possessed the highest oil content (1.77%) and number of flowers/plant (1595), while the second promising B/HNOF 8-4-2 mutant hada high oil content (1.29%) and chamazulene percentage (13.98%) compared to control plants. These results suggest that the B/HNOF 8-4-2 and F/LF5-2-1 mutants could be integrated as potential parents into breeding programs for a high number of flowers, high oil content, oil composition and oil color traits for German chamomile improvement.

Induction of phenotypic diversity in mutagenized population of lentil (Lens culinaris Medik) by using heavy metal

Pulse breeding has been performed in the past by utilizing the genetic variability using conventional method. At the present time, these techniques are insufficient for producing new cultivars to fulfill globally increased food demand. In this situation, induced mutagenesis have been appeared as a new technique which are largely utilized for evolving improved mutants with good quality of agronomic traits and for determining desired genes that control agronomical traits. In the present investigation lentil seeds were mutagenized with different doses (5, 10, 15, 20 and 25 ppm) of lead and cadmium nitrate. M₂ generation was raise from collected seeds of M₁ generation. Distinct morphological mutants were selected with different traits such plant height, growth habit, leaf morphology, flower character, pigmentation and pod size. Different meiotic aberration such as stickiness, precocious separation of chromosome, unequal division, disturbed polarity with laggards, cytomixis, disorientation, unpolarized chromosome, sticky metaphase, multinucleate condition with micronuclei were also observed in this experiment. Some mutants may be utililised directly in selection or some of these are beneficial in breeding programme. Beneficial mutants were determined at lower concentrations both heavy metals with highest mutation frequency in cadmium than lead nitrate.

Mutagenic Effectiveness and Efficiency of Gamma Rays and HZ with Phenotyping of Induced Mutations in Lentil Cultivars

In mutation breeding, mutagenic effectiveness and efficiency are the base parameters to predict the mutagenic potency of any mutagen. Studies on mutagenic effectiveness and mutagenic efficiency of physical mutagen (gamma rays) and chemical mutagen (hydrazine hydrates; HZ) on two cultivars of lentil (Lens culinaris Medik.), viz. DPL 62 (macrosperma) and Pant L 406 (microsperma) have been reported. Dry and healthy seeds were treated with four doses of each gamma rays (100-400 Gy), HZ (0.1-0.4 %) and their combinations. Frequencies of the induced agro-morphological variations into different phenotypic categories were estimated in M2 population that resulted into identification and isolation of wide range of mutants with altered phenotypes. Data on effectiveness and efficiency of various mutagenic treatments calculated on the basis of the frequency of chlorophyll mutations, which showed effectiveness and efficiency were higher at the moderate doses of gamma rays and HZ, while in case of combination treatments; lower doses were most effective and efficient with few inter-varietal exceptions. Phenotyping of the mutants revealed that growth habits was the most sensitive category to which most of the mutant belongs, followed by leaf and flower/pod/seed in both the cultivars studied. Overall, the screened and isolated mutants with economically important agronomic traits can be further propagated in the subsequent generation for development of elite lentil mutant cultivars.

Mutagenic Effectiveness and Efficiency of Gamma Rays and HZ with Phenotyping of Induced Mutations in Lentil Cultivars

In mutation breeding, mutagenic effectiveness and efficiency are the base parameters to predict the mutagenic potency of any mutagen. Studies on mutagenic effectiveness and mutagenic efficiency of physical mutagen (gamma rays) and chemical mutagen (hydrazine hydrates; HZ) on two cultivars of lentil (Lens culinaris Medik.), viz. DPL 62 (macrosperma) and Pant L 406 (microsperma) have been reported. Dry and healthy seeds were treated with four doses of each gamma rays (100-400 Gy), HZ (0.1-0.4 %) and their combinations. Frequencies of the induced agro-morphological variations into different phenotypic categories were estimated in M2 population that resulted into identification and isolation of wide range of mutants with altered phenotypes. Data on effectiveness and efficiency of various mutagenic treatments calculated on the basis of the frequency of chlorophyll mutations, which showed effectiveness and efficiency were higher at the moderate doses of gamma rays and HZ, while in case of combination treatments; lower doses were most effective and efficient with few inter-varietal exceptions. Phenotyping of the mutants revealed that growth habits was the most sensitive category to which most of the mutant belongs, followed by leaf and flower/pod/seed in both the cultivars studied. Overall, the screened and isolated mutants with economically important agronomic traits can be further propagated in the subsequent generation for development of elite lentil mutant cultivars.

Comparative morpho-physiological and biochemical responses of lentil and grass pea genotypes under water stress

Background:

Both lentil (Lens culinaris Medik.) and grass pea (Lathyrus sativus L.) in the family Fabaceae are two important cool-season food legumes, often experiencing water stress conditions during growth and maturity.

Objective:

The present study was undertaken to ascertain the response of these two crops under different water stress regimes.

Materials and Methods:

Different morpho-physiological and biochemical parameters were studied in a pot experiment under controlled environmental conditions. Along with control (proper irrigation, 0 stress), three sets of plants were subjected to mild (6 d), moderate (13 d) and severe (20 d) water stress by withholding irrigation at the appropriate time.

Results:

Compared with control, plant growth traits and seed yield components reduced significantly in both crops with increasing period of water stress, resulting in lowering of dry mass with more severe effect on lentil compared with grass pea. Foliar Relative Water Content (RWC) (%), K⁺/Na⁺ ratio, chlorophyll (chl) a, chl a/b ratio, stomatal conductance and net photosynthetic rate declined considerably in both crops under water stress. Leaf-free proline level increased significantly in both crops, but it decreased markedly in nodules of lentil and remained unchanged in grass pea. Nodulation was also affected due to water stress. The impairment in growth traits and physio-biochemical parameters under water stress was manifested in reduction of drought tolerance efficiency of both crops.

Conclusion:

Impact of water stress was more severe on lentil compared with grass pea, and modulation of growth traits signified necessity of a detailed strategy in breeding of food legumes under water stress.

Superoxide-dismutase deficient mutants in common beans (Phaseolus vulgaris L.): genetic control, differential expressions of isozymes, and sensitivity to arsenic

Two common bean (Phaseolus vulgaris L.) mutants, sodPv 1 and sodPv 2, exhibiting foliar superoxide dismutase (SOD) activity of only 25% and 40% of their mother control (MC) cv. VL 63 were isolated in EMS-mutagenized (0.15%, 8 h) M2 progeny. Native-PAGE analysis revealed occurrence of Mn SOD, Fe SOD, Cu/Zn SOD I and Cu/Zn SOD II isozymes in MC, while Fe SOD, and Mn SOD were not formed in sodPv 1 and sodPv 2 leaves, respectively. In-gel activity of individual isozymes differed significantly among the parents. SOD deficiency is inherited as recessive mutations, controlled by two different nonallelic loci. Gene expressions using qRT PCR confirmed higher expressions of Cu/Zn SOD transcripts in both mutants and the absence of Fe SOD in sodPv 1 and Mn SOD in sodPv 2. In 50 μM arsenic, Cu/Zn SODs genes were further upregulated but other isoforms downregulated in the two mutants, maintaining SOD activity in its control level. In an F2 double mutants of sodPv 1 × sodPv 2, no Fe SOD, and Mn SOD expressions were detectable, while both Cu/Zn SODs are down-regulated and arsenic-induced leaf necrosis appeared. In contrast to both mutants, ROS-imaging study revealed overaccumulation of both superoxides and H2O2 in leaves of double mutant.

Flavonoid-deficient mutants in grass pea (Lathyrus sativus L.): genetic control, linkage relationships, and mapping with aconitase and S-nitrosoglutathione reductase isozyme loci

Two flavonoid-deficient mutants, designated as fldL-1 and fldL-2, were isolated in EMS-mutagenized (0.15%, 10 h) M₂ progeny of grass pea (Lathyrus sativus L.). Both the mutants contained total leaf flavonoid content only 20% of their mother varieties. Genetic analysis revealed monogenic recessive inheritance of the trait, controlled by two different nonallelic loci. The two mutants differed significantly in banding patterns of leaf aconitase (ACO) and S-nitrosoglutathione reductase (GSNOR) isozymes, possessing unique bands in Aco 1, Aco 2, and Gsnor 2 loci. Isozyme loci inherited monogenically showing codominant expression in F₂ (1 : 2 : 1) and backcross (1 : 1) segregations. Linkage studies and primary trisomic analysis mapped Aco 1 and fld 1 loci on extra chromosome of trisomic-I and Aco 2, fld 2, and Gsnor 2 on extra chromosome of trisomic-IV in linked associations.

Genetic improvement of grass pea for low neurotoxin (β-ODAP) content

Grass pea is a promising crop for adaptation under climate change because of its tolerance to drought, water-logging and salinity, and being almost free from insect-pests and diseases. In spite of such virtues, global area under its cultivation has decreased because of ban on its cultivation in many countries. The ban is imposed due to its association with neurolathyrism, a non-reversible neurological disorder in humans and animals due to presence of neurotoxin, β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP) in its seedlings and seeds. The traditional varieties of grass pea contain 0.5-2.5% β-ODAP. Exploitable genetic variability for β-ODAP has been observed for development of low ODAP varieties, which along with improved agronomic and detoxification practices can help reduce the risk of lathyrism. Collaborative efforts between ICARDA and NARS have resulted in development of improved varieties such as Wasie in Ethiopia, Ratan, Prateek and Mahateora in India, and BARI Khesari-1 and BARI Khesari-2 in Bangladesh with <0.10% β-ODAP. Soil application of 15-20 kg ha(-1) zinc sulphate, early planting, and soaking seeds in water have shown significant effects on β-ODAP. Because of the often cross-pollination nature, the current breeding procedures being followed in grass pea requires paradigm shift in its approach for a possible genetic breakthrough.