Wheat microspore embryogenesis during in vitro anther culture

Summary Cytological analysis of microspore embryogenesis during in vitro culture reveals a high mortality in the first week and a latency phase of about one week before the first embryogénic mitosis. Genotypic differences observed during our wheat anther culture do not seem to originate at the induction level but are linked to the different abortion rates.     

Biodegradation of bisphenol A by bacterial consortia

The effect of light on BPA degradation by an adapted bacterial consortium was investigated. BPA was completely degraded up to 50 mg l⁻¹, and the degradation followed first-order reaction kinetics both in the light and in the dark. The degradation half-life of BPA when the consortium was grown in presence of light was 21.9, 17.2, and 12.6 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively; the degradation half-life of BPA in the dark was 13.1, 10.8, and 10.2 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively. Therefore, light inhibited BPA biodegradation. However, under both conditions, BPA was completely depleted. The bacterial consortium effectively utilised BPA as a growth substrate to sustain a cell yield of 0.95 g g⁻¹ and 0.97 g g⁻¹ in the light and dark, respectively. A total of ten and nine biodegradation intermediates were detected in the light and dark, respectively. Three bacterial metabolic pathways and one photodegradation pathway were proposed to explain their occurrence. This study demonstrated that bacterial consortia may assemble a wide range of catabolic pathways to allow for efficient degradation of BPA, converting BPA to principally bacterial biomass and metabolites exhibiting low or no oestrogenic activity.     

Biological pretreatment and bioconversion of agricultural wastes,using ligninolytic and cellulolytic fungal consortia

Agricultural wastes have attractive potential as alternate energy sources. However, a major bottleneck is to identify eco-friendly treatment methodologies to utilize them. The large diversity of unexplored, novel, and potential microorganisms hold great promise and require periodic isolation and characterization of microorganisms for bioprospection. In this study, approximately 100 fungal isolates were tested for their lignocellulolytic enzyme activities, based on plate assay, followed by quantification of enzyme activity. From this, M2E (Inonotus tropicalis) and 2a (Cerrena unicolor) showed good growth and proficient ligninolytic activity; isolates GK1 (Chaetomium globosum) and GK2 (Chaetomium brasiliense) exhibited exceptional cellulolytic activity on lignocellulosic substrates such as rice straw and sugarcane bagasse. Consortia of the potential ligninolytic and cellulolytic isolates were set up to determine their ability to biodegrade the lignocellulosic substrates such as rice straw and sugarcane bagasse. The efficiency of the consortia was determined on the basis of the increase in enzyme activity; it was also evident through scanning electron microscopy, x-ray diffraction analysis of the degraded substrates, and the sugar yield. Experiments were also carried out to compare the biological with the physical pretreatment methods. The consortium of ligninolytic and cellulolytic marine-derived fungi developed in this study prove to have the potential for application in the effective utilization of agricultural wastes.     

Improvement of isolated microspore culture of barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.): the effect of floret co-culture

Barley microspores from five field-grown breeding lines were isolated using an ultra-speed blender and the effect of co-culture with young florets was investigated. Floret co-culture in the induction stage increased the formation of MCS, ELS and green plant regeneration. The florets of teraploid plant were more effective than ones of diploid plant. For line S23, co-culture with florets from tetraploid plants gave rise to 2.6 and 7.8 times more MCS and ELS, respectively, than non-co-culture control, whereas co-culture with florets from diploid plants resulted in 1.8 and 6.1 times more MCS and ELS, respectively, than non-co-culture control (Table 2). Florets subjected to cold treatment for 10–20 days induced a greater response than fresh ones, and florets with uninucleate microspores surpassed binucleate microspores. For microspores culture from 15-day cold pre-treated spikes, 93A floret co-culture gave rise to 3.6 and 6.8 times more MCS and ELS, respectively, than the non-co-cultured control, while SD1 floret co-culture resulted in 1.9 and 4.0 times more, respectively. Similarly, for microspore culture from 20-day cold pre-treated spikes, 93A floret co-culture gave rise to 2.6 and 5.1 times more MCS and ELS, respectively, than non-co-cultured control, while SD1 floret co-culture resulted in 1.5 and 3.0 times more, respectively (Table 3). Some microspores formed dense MCS that did not develop further. Compared with the control, floret co-culture resulted in less dense MCS formation, indicating that the isolated florets were beneficial to the normal development of MCS. Floret co-culture was only effective when the spikes were cold pre-treated before microspore isolation. Spike cold pre-treatment before microspore preparation was crucial for dedifferentiation of cultured isolated microspores, and this could not be replaced by floret co-culture. It is postulated that the florets provided essential substances for in vitro cultured isolated microspores to undergo dedifferentiation and embryogenesis. Both the genotype selection and the physiological status (developmental status and cold treatment) adjustment of the florets for co-culture could improve barley microspore culture. Compared with ovary co-culture, floret co-culture is more efficient. The technique is of simple application in breeding programs and can be a solution for coping with recalcitrant genotypes and or plant donor condition.