Transgenic antibiotic resistance may be differentially silenced in germinating pollen grains

Target pollen isolation using automated infrared laser-mediated cell disruption

Single-cell analysis is important to understand how individual cells work and respond at the cell population level. Experimental single-cell isolation techniques, including dilution, fluorescence-activated cell sorting, microfluidics, and micromanipulation, have been developed in recent decades. However, such applications typically require large cell populations and skilled professionals. Additionally, these methods are unsuitable for sequential analysis before and after cell isolation. In this study, we propose a method for target cell isolation using automated infrared laser-mediated disruption of pollen grains in pollen populations. Germination of the target pollen was observed at the same location as that before laser irradiation, and germinated pollen grains were enriched in the cell population. Pollination of laser-irradiated bulk pollen populations also showed that the target pollen preferentially germinated on the stigma. This method is expected to facilitate physiological analyses of target cells at the single-cell level and effectively produce seeds derived from target pollen.

Pollen germination is impeded by tap water

Pollen germination in vitro is totally inhibited in tobacco (Nicotiana tabacum) and other species if tap water is used to prepare the germination medium. This effect is already fully present if tap water accounts for only 25% of the medium. Furthermore, the pollen grains deteriorate rapidly and the culture medium turns yellowish-brown. The water toxicity is not caused by one or several compounds regularly monitored by the water authorities but can be removed by ion exchange purification. Although the factor(s) responsible for the inhibition were not identified, the study clearly shows the presence of such a contaminant in three different Orange County (Southern California) water wells. The fact that a fundamental botanical process like pollen germination is inhibited by a factor in drinking water not included in water quality control causes some general health concern. In addition, crop yield might be largely reduced if overhead spray irrigation with this water is utilized. The experiments also suggest that pollen germination in vitro could serve as a sensitive and simple bioassay for water quality.

Haploid transformation in Brassica napus using an octopine-producing strain of Agrobacterium tumefaciens

Microspore-derived embryos of Brassica napus were transformed using the disarmed octopine-producing LBA4404 strain of Agrobacterium tumefaciens containing the binary vector pBin19. Octopine-producing strains have previously been reported to be ineffective in transforming Brassica. Four actively growing yellow/ green sectors were selected from the embryos on 50 mg/l kanamycin and plants regenerated. Analysis for NPT-II activity in these young plants initially indicated no expression of the bacterial NPT-II gene. The plants were nevertheless grown to maturity, selfed and S1 seed was collected. Three of the S1 plants produced microspores which were from 4 to 20 times more tolerant to kanamycin than the original parent. Southern analysis revealed that one plant (EC-1) had a single site of insertion and the other two plants (EC-2 and EC-6) had two sites of insertion with sequence homology to the bacterial NPT-II gene. Microspores from the EC-2 and EC-6 transgenics produced embryos on approximately five times the level of kanamycin tolerated by microspores from untransformed plants, while the EC-1 transgenic produced microspores with more than 20 times the tolerance to kanamycin. Analysis of S1 progeny of the EC-1 transgenic indicated that 100% of the progeny exhibited the trait through both Southern analysis and by expressing tolerance to kanamycin in microspore-derived embryos.