Isolation, culture, and regeneration of moth bean Vigna aconitofolia leaf protoplasts

Plant regeneration from protoplasts of immature Vigna sinensis cotyledons via somatic embryogenesis

Protoplasts were isolated from immature cotyledons of Vigna sinensis and cultured in a modified MS Liquid medium containing 0. 2 mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D), 1 mg/l naphthaleneacetic acid (NAA) and 0. 5 mg/l 6-benzylaminopurine (BAP) in the dark at a density of 1 × 10(5)/ml. The protoplasts began to divide in 3-5 days. Sustained cell division resulted in formation of cell clusters and small calli, with the cell division frequency and plating efficiency of cell colonies reaching 27. 7% and 1. 7% respectively. When calli of 2 mm in size were transferred onto MSB medium (MS salts and B5 vitamins) containing 500mg/l NaCl, 500 mg/ 1 casein hydrolysate (CH), 2 mg/l 2,4-D and 0. 5 mg/l BAP for further growth, approximately 5% of the calli developed embryogenically. The embryogenic calli were selected and subcultured on the same composition of MSB medium and were able to maintain somatic embryogenesis capacity in subculture for a long time. When the calli were moved to MSB medium with 0. 1 mg/l indole-3-acetic acid (IAA), 0. 5mg/l kinetin(KT), 3-5% mannitol and 2% sucrose in the light, many somatic embryos formed from the calli. Only part of the embryoids developed further to the cotyledonary stage, and the others died at the globular, heart-shaped or torpedo stages. Finally, some cotyledonary embryoids germinated and developed into plants or shoots. The shoots were readily rooted on 1/2 strength MS medium with 0. 1-0.3 mg/l indole-3-butyric acid (IBA). The plants grew well in soil and were fertile.

Thidiazuron-induced plant regeneration from protoplasts of Vicia faba cv. Mythos

Protoplasts of 10 cultivars of V. faba were isolated from etiolated shoot-tips and tested for their regeneration capacity. After purification, protoplasts were embedded in sodium alginate and cultivated in the medium of Kao and Michayluk (1975) containing 0.5 mg·1(-1) of each 2,4-dichlorophenoxyacetic acid, naphthylacetic acid and 6-benzylaminopurine. Depending on cultivar, division frequencies of up to 40% were obtained. Six weeks after embedding, protoplast-derived calluses were transferred to Gelrite-solidified media with different combinations of growth regulators. A two step protocol (auxin high/low) was tested for its ability to induce somatic embryogenesis. The formation of globular structures was observed, but no embryo formation could be achieved. In contrast, cultivation of protocalluses on medium supplemented with thidiazuron resulted in shoot development in cultivar Mythos. To generate mature plants, the shoots were grafted onto young seedlings. In order to optimize the in vitro-conditions, different concentrations of thidiazuron alone or in combination with naphthylacetic acid were tested, showing that an increase of thidiazuron and the addition of naphthylacetic acid positively affects both the viability of protocalluses and the regeneration frequency.

Plant regeneration from pea protoplasts via somatic embyogenesis

Plant regeneration via somatic embryogenesis was obtained from pea protoplasts. Strong auxins (picloram or 2.4-D) and increased osmolarity of the medium were necessary for embryo induction. Relatively high amounts of embryogenic calli could be obtained in 2 genotypes. After a period on hormone-free medium, a second induction of somatic embryos was possible. Further development of somatic embryos was accomplished on GA3 - containing medium.

Improved protoplast culture and regeneration of shoots in pea (Pisum sativum L.)

An improved system involving a modification of the bead culture system was developed for culturing pea protoplasts. Using this method, sustained divisions and callus growth could be obtained in all 10 cultivars tested. In the best responding cultivar division frequency could be raised from 17% in liquid culture to 80% in the bead system. Shoot regeneration with a reproducible frequency of about 1% could be obtained from protoplast-derived calli in two of the tested cultivars.

Plant regeneration from cell suspension cultures of Vigna aconitifolia

Plant regeneration has been achieved routinely from established cell suspension culture lines of Vigna aconitifolia (moth bean), a highly drought tolerant grain legume. The cultures originated from three-week-old leaf callus. Several media including MS, B5, AA, SL, PCM, SH and L-6 were tested for their effects on cell growth. Maximum growth was observed in L-6 medium containing 44.5 μM 2,4-D. After 6 to 8 weeks the suspensions were filtered through 500, 250, 125 and 60 μm sieves, respectively, for four to five subcultures. An embryogenic cell line (VA-686) was obtained from the cell fraction collected below 250 μm. The VA-686 cell line is being maintained on L-6 medium with 4.5 μM 2,4-D and 2.3 μM Zeatin. Somatic embryogenesis was induced by transferring the cells to L-6 medium with 4.6 μM zeatin in which green cell clusters were produced. The somatic embryos developed from most of the cell clusters when plated on L-6 agar medium with 2.3 μM BA.Plantlets were obtained from the embryos on L-6 medium with 10.0 μM IBA. The regenerated plants were grown to maturity in the greenhouse.

Callus induction from protoplasts of V. unguiculata, V. sublobata and V. mungo

Protoplasts were isolated from hypocotyl of V. mungo (L.) Hepper or hypocotyl-derived callus of V. sublobata (Phaseolus sublobata Roxb.) and V. unguiculata (L.) Walp (syn. V. sinensis (L.) Saviex Hassk) using an enzyme solution comprising Cellulase 2.5%, Macerozyme, Hemicellulase and Driselase each at a 0.5% level in 0.5 M sorbitol. Isolated protoplasts were cultured in Murashige and Skoog's (1962) basal liquid medium supplemented with BA, NAA, 2,4-D (1 mg/l each) and sucrose (14%). After four weeks, protoplast colonies were transferred to the same medium with a reduced level of sucrose (7%). Colonies proliferated into actively growing calli. Further attempts to regenerate plants from such calli were not successful. However, protoclones of V. unguiculata differentiated roots on auxin/cytokinin supplemented media. Alternative methods for shoot differentiation from protoplastderived cultures were tried by the use of Agrobacterium tumefaciens "shooter" strains pGV 2215 or pGV 2298 or wild type strain B6S3.

An evaluation of Ficoll density gradient centrifugation as a method for eliminating microbial contamination and purifying plant protoplasts

Ficoll density gradient centrifugation was used to generate sterile protoplasts from non-sterile Pteridium cultures. The method was found to drastically reduce levels of fungal and bacterial contamination introduced prior to centrifugation whilst concentrating and purifying protoplasts.

Callus production from leaf protoplasts of various cultivars of bean (Phaseolus vulgaris L.)

High yields of viable protoplasts were obtained by enzymatic treatment from cotyledonary leaves of various greenhouse grown Phaseolus vulgaris L. cultivars. The protoplasts divided and formed cell clusters in a liquid medium. Early transfer before 10 days in the same medium was necessary for the development of cell colonies. When transferred to solid medium, the colonies gave rise to proliferating green calli. Deep green patches developed on these calli but failed to form shoots.

Polyamine levels as related to growth, differentiation and senescence in protoplast-derived cultures of Vigna aconitifolia and Avena sativa

We have previously reported that aseptically cultured mesophyll protoplasts of Vigna divide rapidly and regenerate into complete plants, while mesophyll protoplasts of Avena divide only sporadically and senesce rapidly after isolation. We measured polyamine titers in such cultures of Vigna and Avena, to study possible correlations between polyamines and cellular behavior. We also deliberately altered polyamine titer by the use of selective inhibitors of polyamine biosynthesis, noting the effects on internal polyamine titer, cell division activity and regenerative events. In Vigna cultures, levels of free and bound putrescine and spermidine increased dramatically as cell division and differentiation progressed. The increase in bound polyamines was largest in embryoid-forming callus tissue while free polyamine titer was highest in root-forming callus. In Avena cultures, the levels of total polyamines decreased as the protoplast senesced. The presence of the inhibitors alpha-difluoromethyl-arginine (specific inhibitor of arginine decarboxylase), alpha-difluoromethylornithine (specific inhibitor of ornithine decarboxylase) and dicyclohexylamine (inhibitor of spermidine synthase) reduced cell division and organogenesis in Vigna cultures. Addition of low concentration of polyamines to such cultures containing inhibitors or removal of inhibitors from the culture medium restored the progress of growth and differentiation with concomitant increase in polyamine levels.