Staining Starch with Iodine Solution.

Starch is important material in plant tissues, especially for storage tissues. Starches from different plant resources or tissues vary in morphology, content, and physicochemical properties. Starch and iodine can bind specifically to present the shapes and sizes of starch granules in plant tissues. Here, we describe some methods for staining starch in leaf, pollen grain, and starchy seeds with iodine solution. In addition, the isolated starch can also be stained with iodine solution to exhibit its shape and size.

Application of Allele Specific PCR in Identifying Offspring Genotypes of Bi-Allelic SbeIIb Mutant Lines in Rice.

Bi-allelic mutant lines induced by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated (Cas) systems are important genetic materials. It is very important to establish a rapid and cheap method in identifying homozygous mutant plants from offspring segregation populations of bi-allelic mutant lines. In this study, the offspring genotypes of rice bi-allelic starch branching enzyme IIb mutant lines were identified using the allele specific PCR (AS-PCR) method. The target sequences of two alleles were aligned from their 5' to 3' ends, and the first different bases were used as the 3' ends of mismatch primers. Another mismatched base was introduced at the third nucleotide from the 3' end of mismatch primer. The PCR reaction mixture and amplification program were optimized according to the differences of mutation target sequence and mismatch primers. The offspring plant genotypes of bi-allelic mutant lines could be accurately identified using the amplified DNA fragments by agarose gel electrophoresis. This study could provide a method reference for the rapid screening of homozygous mutant plants from offspring segregation population of heterozygous and bi-allelic mutant lines.

Characterization of underutilized root starches from eight varieties of ramie (Boehmeria nivea) grown in China.

Ramie root is an underutilized starch source. In this study, eight ramie varieties were investigated for starch properties. Starch content ranged from 18.6% to 50.1% in dry root. Starches from different varieties showed similar morphology including ellipsoidal, spherical and truncated granules with size D[4,3] from 10.1 to 14.1 µm. Starch had amylose content from 20.8% to 28.5%. All ramie varieties had B-type starches with relative crystallinity from 24.8% to 27.1%, ordered degree from 0.724 to 0.897 and lamellar thickness from 9.1 to 9.6 nm. Starches had gelatinization peak temperature from 70.5 to 73.8 °C and enthalpy from 14.9 to 15.8 J/g. Starches had swelling power and water solubility from 27.9 to 31.9 g/g and from 11.7% to 15.5%, respectively, at 95 °C, and exhibited different pasting properties with breakdown viscosity from 36 to 377 mPa s and setback viscosities from 1295 to 1863 mPa s. Starch pastes exhibited pseudoplastic behavior and different rheological properties. Native, gelatinized and retrograded starches had resistant starch from 81.7% to 83.9%, from 1.7% to 5.1% and from 5.6% to 13.3%, respectively. The eight varieties were divided into 3 groups according to starch properties. This study is helpful for selecting suitable ramie variety as starch source.

Physicochemical properties of a new starch from ramie (Boehmeria nivea) root.

A new starch was isolated from ramie root, and its physicochemical properties were investigated. Ramie dry root contained 45.9% starch. Starch had truncated, ellipsoidal, and spherical granule shapes with size from 7 to 30 µm and D[4,3] about 14.1 µm. Starch contained 38.9% apparent amylose content and 22.4% true amylose content, exhibited B-type crystallinity, and had 26.6% relative crystallinity, 0.82 ordered degree, and 9.2 nm lamellar thickness. Starch had 71.8 °C gelatinization peak temperature and 15.6 J/g gelatinization enthalpy, and exhibited 31.4 g/g swelling power and 17.1% water solubility at 95 °C. Starch had peak, hot, breakdown, final, and setback viscosities at 3048, 2768, 279, 4165, and 1397 mPa s, respectively, and showed peak time at 4.36 min and pasting temperature at 75.0 °C. The native, gelatinized, and retrograded starches contained 15.1%, 94.0%, and 86.5% rapidly digestible starch and 83.3%, 4.0%, and 10.7% resistant starch, respectively. Compared with potato and rice starches, ramie starch was somewhat similar to potato starch but significantly different from rice starch in starch component, crystalline structure, and functional properties. Therefore, ramie starch exhibited the potential to be used as a thickening agent, resistant-digesting food additive, and alternative to potato starch in food and nonfood industries.

A Simple Dry Sectioning Method for Obtaining Whole-Seed-Sized Resin Section and Its Applications.

The morphology, size and quantity of cells, starch granules and protein bodies in seed determine the weight and quality of seed. They are significantly different among different regions of seed. In order to view the morphologies of cells, starch granules and protein bodies clearly, and quantitatively analyze their morphology parameters accurately, the whole-seed-sized section is needed. Though the whole-seed-sized paraffin section can investigate the accumulation of storage materials in seeds, it is very difficult to quantitatively analyze the morphology parameters of cells and storage materials due to the low resolution of the thick section. The thin resin section has high resolution, but the routine resin sectioning method is not suitable to prepare the whole-seed-sized section of mature seeds with a large volume and high starch content. In this study, we present a simple dry sectioning method for preparing the whole-seed-sized resin section. The technique can prepare the cross and longitudinal whole-seed-sized sections of developing, mature, germinated, and cooked seeds embedded in LR White resin, even for large seeds with high starch content. The whole-seed-sized section can be stained with fluorescent brightener 28, iodine, and Coomassie brilliant blue R250 to specifically exhibit the morphology of cells, starch granules, and protein bodies clearly, respectively. The image obtained can also be analyzed quantitatively to show the morphology parameters of cells, starch granules, and protein bodies in different regions of seed.

Comparison of physicochemical properties of very small granule starches from endosperms of dicotyledon plants.

In this study, 6 very small granule starches (VSGSs) were isolated from endosperms of dicotyledon Amaranthus cruentus, Agriophyllum squarrosum, Chenopodium quinoa, Euryale ferox, Mirabilis jalapa, and Vaccaria hispanica. Their morphologies and physicochemical properties were investigated. Most VSGSs with granule size <3 µm were spherical or polygonal, and their apparent amylose contents ranged from 19.4 to 33.1% with A. cruentus starch the lowest and E. ferox starch the highest. All VSGSs had the same A-type crystalline structure with relative crystallinities from 23.3 to 29.6%. Though 6 VSGSs had slight differences in short-range ordered structure and lamellar repeat distance, their lamellar peak intensities exhibited significant differences. The gelatinization temperatures showed significant differences among 6 VSGSs with C. quinoa starch the lowest and M. jalapa starch the highest. The 6 VSGSs had significantly different pasting viscosities with peak viscosities from 1887 to 4579 mPa s, hot viscosities from 1704 to 3479 mPa s, breakdown viscosities from 56 to 1170 mPa s, final viscosities from 2419 to 4811 mPa s, and setback viscosities from 715 to 1821 mPa s. The digestion properties of starches were significantly different among 6 VSGSs. The above results could provide some references for applications of these VSGSs.