Flatpea (Lathyrgs sylvestris L.) is a potentially valuable forage legume but contains high levels of 2,4-diaminobutyric acid (DABA), a compound that can have adverse effects on some animals, including rats and poultry. To increase genetic variability in foliar DABA content and other traits of interest, three approaches were utilized: (1) regeneration of flatpea plants from tissue culture to produce potential somaclonal variants, (2) seed irradiation and screening of potentially mutated progeny, and (3) intercrossing among flatpea accessions. Low-frequency whole plant regeneration of flatpea was obtained from hypocotyl-derived callus cultures. Auxin concentrations above 5.0 µM resulted primarily in root formation without shoots. Conditions for optimum whole plant regeneration were as follows: callus was initiated on a modified Schenk-Hildebrandt low-ammonium medium containing 5.0 µM IAA (indole acetic acid) and 2.5 µM zeatin for callus initiation; after two subcultures, calli were transferred to a regeneration medium containing 0.1 µM IAA and 1.0 µM zeatin. Calli and regenerated root tissue contained 47 and 381 as much DABA as leaf tissue from 'Lathco' flatpea plants, respectively. Initial tests established that the effective range of gamma irradiation for seed treatment was between 10.0 and 17.5 kR. Within this range, reduction in percentage of both seedling height and plant survival was a linear function of dose. Individual M₂ plants that contained reduced levels of DABA were identified. No significant trend in DABA concentration with increasing gamma irradiation was apparent. Flatpea pollination methods were evaluated prior to utilization of intercrossing for inducing genetic variability. Appropriate flower stages for emasculation were determined by in vitro germination of pollen. Lines that produced high numbers of seeds per pollination were identified by crossing in all possible combinations among seven flatpea accessions. Cross-pollinations resulted in significantly higher seed set than selfing. Pollination using caged honeybees was the most efficient method of hybridization. Greater range and coefficient of variation in DABA concentration were observed for flatpea accessions than for intercrossed progeny produced by honeybee pollination. / Ph. D.

A₂bu composed 20-40% of total free amino acids in flatpea tissues and constituted 2-4% of the tissue dry weight. Higher concentrations of A₂bu were found in the leaves than in the roots. A₂bu concentration in leaves and stems increased slightly with plant age. Higher nitrogen availability increased the content of A₂bu in flatpea, a response accompanied by an increase in the contents of soluble protein and other nitrogenous compounds. When exogenous nitrogen supply was decreased, A₂bu levels decreased significantly. Rhizobium infection had no effect on the A₂bu production by flatpea. Ammonium was toxic to flatpea growth. Together with typical toxic symptoms, A₂bu elevation was observed in flatpea plants fed with ammonium. Water-deficit stress also elevated A₂bu content of flatpea. The elevation of A₂bu concentration in aerial tissues of flatpea under stress may not be high enough to decrease the value of flatpea as a forage. 4-Aminobutyric acid (Abu), homoserine (Hse), and asparagine (Asn) were the other major free amino acids in flatpea. As with A₂bu, levels of Hse were higher in the leaves than in the roots. The opposite was true for Abu and Asn. The concentration of Abu in the stems increased consistently with plant age. In response to stress conditions, Abu accumulated in flatpea, especially in stems and roots. Asn was the most prevalent free amino acid in the roots of flatpea. Asn levels in roots increased with plant age and accounted for the greatest portion of the increase in the free amino acid pool in the roots of plants subjected to the water stress or supplied with nitrogen in the form of ammonium ions. Levels of Hse in flatpea were changed little in response to the experimental treatments. Relative amounts of major amino acids in flatpea changed with respect to plant organs and experimental factors. If expressed as ratios, the resulting values suggest metabolic relationships. / Ph. D. / incomplete_metadata

Baigiamajame darbe 2012–2013 m. tirta netikrosios miltligės (Peronospora viciae (Berk) Caspary) įtaka skirtingos geografinės kilmės miškinio pelėžirnio (Lathyrus sylvestris L.) cenopopuliacijų morfologiniams ir sėklų produktyvumo rodikliams. Darbo objektas – iš skirtingų Lietuvos rajonų surinktos dvylika miškinio pelėžirnio cenopopuliacijų, augančių vienodos agrotechnikos sąlygomis. Darbo tikslas – įvertinti netikrosios miltligės įtaką skirtingų cenopopuliacijų miškinio pelėžirnio morfologinias ir sėklų produktyvumo rodikliams. Darbo metodai – įvertinti skirtingų miškiniopelėžirnio cenopopuliacijų stiebo aukštis, žiedynų, ankščių, sėklapradžių ankštyje skaičius, ankšties produktyvumo, vieno stiebo sėklų produktyvumas. Atsparumas netikrajai miltligei įvertintas 5 balų sistema, atsparumo įtaka ankščiau išvardintiems rodikliams įvertinta naudojantis programa STATISTIKA 8. Rezultatai. Tyrimo metų duomenimis, miškinio pelėžirnio stiebo aukščiui, žiedynų skaičiui ir ankščių produktyvumui lemiamą įtaką turėjo cenopopuliacijos genotipas ir tyrimo metų meteorologinės sąlygos. Didesnis miškinio pelėžirnio stiebo aukštis teigiamai įtakojo ankščių (r=0,7539) ir sėklų skaičių (r = 0,6223). Stabiliausias iš tirtų rodiklių tyrimo metais buvo sėklapradžių (vid. 12,4 vnt.) skaičius ankštyje (V = 4,7), labiliausi – ankščių (vid. 21,6 vnt.; V = 36,5) ir subrandintų sėklų skaičiaus (vid. 151,1 vnt., V = 39,8) rodikliai. Miškinio pelėžirnio atsparumas netikrajai miltligei įtakojo... [toliau žr. visą tekstą] / Influence of downy mildew (Peronospora viciae (Berk) Caspary) on morfological and seed productivity parameters of different geographical origins flat pea (Lathyrus sylvestris L.) cenopopulations have been investigated in 2012-2013. Subject of the research – 12 flat pea (Lathyrus sylvestris L.) cenopopulations from different geographical origins of Lithuania, grown on equal agrotechnic conditions. Aim of the research – estimate an influence of downy mildew on flat pea morfological and seed produktivity parameters. Methodology – to evaluate stem height, number of inflorescence, pods, ovules per pod and pod productivity, one stalk of seed productivity of different flat pea coenopopulations. Resistance to downy mildew is rated by 5-point scale, impact of resistance on above listed parameters estimated using the statistics program STATISTICA 8. Results. The research data shows, that genotype of coenopopulation and meteorological conditions had a decisive influence on flat pea stem height, number of inflorescences and pod productivity. Height of stem influenced positively pod (r = 0,7539 ) and seed number (r = 0,6223 ). The most stabile from the investigated parameters were number of ovules (mean 12,4 pcs.) per pod (V = 4,7 ), most labile – number of pods (mean 21,6 pcs., V = 36,5 ) and the number of mature seeds (mean 151,1 pcs., V = 39.8). The flat pea resistance to downy mildew influenced such parameters as the number of pods, number ovules in pod and especially stem seeds... [to full text]