Examination of the Most Suitable Preparation Method for Pollen Observation by Scanning Electron Microscope

To examine the most suitable method to prepare pollen for scanning electronmicroscope observation, several fixation methods and dehydration (or drying) methods wereapplied to Arabidopsis and lily pollen obtained from flowers before and after flowering.Light and confocal laser microscope observations revealed that, in both plants, pollenobtained before flowering was swollen and wet, while that obtained after flowering wasshrunken and dry. For scanning electron microscopy, pollen was unfixed or fixed with 50%(eventually 100%) acetone, FAA (5% formalin with 50% ethanol and 5% acetic acid) or 6%glutaraldehyde solutions. It was then dried naturally in air or artificially by either criticalpoint-dry or freeze-dry machines, respectively. The results indicated that, for scanningelectron microscope observation of dry pollen, the most suitable treatment is natural dryingwithout fixation. On the other hand, to observe wet pollen, the combination of FAA orglutaraldehyde fixation with artificial drying using either machines is preferable, andfixation with acetone is unsuitable.テクニカルノー

Mapping of quantitative trait loci related to primary rice root growth as a response to inoculation with Azospirillum sp. strain B510

Azospirillum sp. strain B510 has been known as the plant growth-promoting endophyte; however, the growth-promotion effect is dependent on the plant genotype. Here, we aimed to identify quantitative trait loci (QTL) related to primary root length in rice at the seedling stage as a response to inoculation with B510. The primary root length of “Nipponbare” was significantly reduced by inoculation with B510, whereas that of “Kasalath” was not affected. Thus, we examined 98 backcrossed inbred lines and four chromosome segment substitution lines (CSSL) derived from a cross between Nipponbare and Kasalath. The primary root length was measured as a response to inoculation with B510, and the relative root length (RRL) was calculated based on the response to non-inoculation. Three QTL alleles, qRLI-6 and qRLC-6 on Chromosome (Chr.) 6 and qRRL-7 on Chr. 7 derived from Kasalath increased primary root length with inoculation (RLI), without inoculation, (RLC) and RRL and explained 20.2%, 21.3%, and 11.9% of the phenotypic variation, respectively. CSSL33, in which substitution occurred in the vicinity region of qRRL-7, showed a completely different response to inoculation with B510 compared with Nipponbare. Therefore, we suggest that qRRL-7 might strongly control root growth in response to inoculation with Azospirillum sp. strain B510

Mapping of quantitative trait loci related to primary rice root growth as a response to inoculation with <i>Azospirillum</i> sp. strain B510

<p><i>Azospirillum</i> sp. strain B510 has been known as the plant growth-promoting endophyte; however, the growth-promotion effect is dependent on the plant genotype. Here, we aimed to identify quantitative trait loci (QTL) related to primary root length in rice at the seedling stage as a response to inoculation with B510. The primary root length of “Nipponbare” was significantly reduced by inoculation with B510, whereas that of “Kasalath” was not affected. Thus, we examined 98 backcrossed inbred lines and four chromosome segment substitution lines (CSSL) derived from a cross between Nipponbare and Kasalath. The primary root length was measured as a response to inoculation with B510, and the relative root length (RRL) was calculated based on the response to non-inoculation. Three QTL alleles, <i>qRLI-6</i> and <i>qRLC-6</i> on Chromosome (Chr.) 6 and <i>qRRL-7</i> on Chr. 7 derived from Kasalath increased primary root length with inoculation (RLI), without inoculation, (RLC) and RRL and explained 20.2%, 21.3%, and 11.9% of the phenotypic variation, respectively. CSSL33, in which substitution occurred in the vicinity region of <i>qRRL-7</i>, showed a completely different response to inoculation with B510 compared with Nipponbare. Therefore, we suggest that <i>qRRL-7</i> might strongly control root growth in response to inoculation with <i>Azospirillum</i> sp. strain B510.</p