Anti-diabetic activity of Erythrina subumbrans (Hassk.) Merr.

α-amylase inhibitors present in pancreatic region has an operative strategy by controlling the breakdown of starch and helps to minimize the post-prandial hyperglycemia levels. In this study, vegetative (leaf) part of herbal plant Erythrina subumbrans (Hassk.) was assessed for anti-diabetic activity. Aqueous ethanol (80 %) extract was prepared in the different concentration (10, 20, 40, 80, 160, and 320 µg/ml). Acarbose was used as a standard and treated in similar way as that of sample. Control samples were also prepared without standard and sample solutions. A known volume of α-amylase solution was added (0.1mg/mL) was added to standard, sample, control solutions which were preincubated at 37 °C for 15 minutes. Further, known volume of starch solution was added and incubated for 60 min to initiate the reaction. Hydrochloric acid (HCl) and iodine reagent was added to the test tubes and absorbance was measured at 580 nm in UV-Vis spectrophotometer. A strong pancreatic amylase inhibitory activity (>50 %) was obtained from aqueous ethanolic extract with IC50 (half maximal inhibitory concentration) value of 23 µg/ml against standard acarbose with IC50 value of 27 µg/ml. The values endorse Erythrina subumbrans (Hassk.) for further experiments on their potential for managing Diabetes.

New distribution record of the endemic and critically endangered Giant Staghorn Fern Platycerium grande (Fee) Kunze (Polypodiaceae) in central Mindanao

Platycerium grande (Fee) Kunze is an endemic, Critically Endangered species of fern in the Philippines. The known distribution of this species remains limited at present and its population is threatened by various anthropogenic threats especially for ornamental collection. In our recent survey, we found high abundance of this species in Central Mindanao, southern Philippines. It can be distinguished from other species belonging to the genus Platycerium through its frond’s vegetative leaf which is symmetrical with two equally long main lobe. Based on literatures, the known distribution range extend from Zambaonga, Lanao, and Davao (Mt. Apo); and our recent records extends the known distribution of this species in Kalamansig, Sultan Kudarat and South Upi, Maguindanao suggesting this species may still be around in other areas within the known range, however, the species may remain narrowly distributed as multiple threats to this species continue to persist.

The regulation of post-germinative transition from the cotyledon- to vegetative-leaf stages by microRNA-targeted SQUAMOSA PROMOTER-BINDING PROTEIN LIKE13 in Arabidopsis

Germination and early seedling development are critical for successful stand establishment of plants. Following germination, the cotyledons, which are derived from embryonic tissue, emerge from the seed. Arabidopsis seedlings at post-germinative stages are supported mainly by the supply of nutrition from the cotyledons until vegetative leaves emerge and initiate photosynthesis. The switch to autotrophic growth is a significant transition at the post-germinative stage. Here, we provide evidence that down-regulation of SQUAMOSA PROMOTER-BINDING PROTEIN LIKE13 (SPL13) by microRNA156 (miR156) plays an important role in the regulation of the post-germinative switch from the cotyledon stage to the vegetative-leaf stage. Silent mutations created in the SPL13 sequence in the region that is complementary to the miR156 sequence caused the deregulation of the mutant form of SPL13 (mSPL13) mRNA from miR156. Mutant seedlings over-accumulated miRNA-resistant messages and exhibited a delay in the emergence of vegetative leaves compared to wild-type seedlings. The delay was not observed in control transgenic plants expressing non-mutated SPL13, indicating that the phenotype was caused specifically by the silent mutations and deregulation of SPL13 from miR156. Characterization of the SPL13 promoter indicated that this gene is expressed mainly in the hypocotyl and affects leaf primordium development. These results suggest that the repression of SPL13 by miR156 is essential for normal post-germinative growth in Arabidopsis.

Genetics of Mutations Affecting the Development of a Barley Floral Bract

Two groups of mutants that affect the morphology of the lemma, a floral bract of barley, are described. The first comprises phenotypes associated with mutant alleles of calcaroides loci. On the lemma of these mutants, a well-organized neomorphic structure is formed, termed the sac. We provide a morphological description of wild-type (WT) and mutant lemmas, based on scanning electron microscopy (SEM), showing that both consist of similar tissues, but that the mutant is characterized by reversed growth polarity. The sac is a unique structure among grasses, and it is remarkable that recessive mutations at five different genetic loci lead to the same organ. The second group of mutants carry recessive alleles of two leafy lemma genes, both of which are necessary to cause the transformation of the lemma into a structure having all characteristics of a vegetative leaf, as shown by SEM analysis. The presence of sheath, blade, and ligule in the mutant lemma suggests that wild-type lemma development is interrupted at a leaf-like stage. The genes cal a, b, C, d, 23, lel1, and lel2 have now been mapped at precise positions on linkage groups 2, 7, 7, 3, 7, 5, and 7, respectively. The mutants considered in this article are unaffected in other floral organs. A model for lemma development is suggested.

Influence of cellular metabolites on RNA and protein syntheses by Xanthium nuclei of different developmental phases

Leaf nuclei of vegetative and reproductive plants of Xanthium strumarium L. were incubated with the postribosomal supernatant of either phase and changes at the transcriptional level were studied in homologous and heterologous combinations. In the presence of the supernatant of reproductive plants, RNA synthesis by vegetative nuclei was decreased by 25%. Reproductive nuclei were less active in RNA synthesis. Gel electrophoretic studies revealed four RNA bands in vegetative nuclei incubated with reproductive supernatant, including a fast-moving low molecular weight band that could not be detected when the "vegetative" supernatant was used. The adenine/uracil ratios of the newly synthesized RNA of vegetative nuclei treated with vegetative and reproductive supernatants were 1.46 and 1.54, respectively, compared with 1.15 and 1.04 in the reproductive nuclei. Competitive DNA–RNA hybridization experiments indicated that about 2% of the [3H]RNA synthesized by nuclei of vegetative plants in the presence of the supernatant of reproductive plants could not be beaten out by the RNA of vegetative plants. Small quantitative differences, thus, may be expected in the RNA molecules synthesized by nuclei in the presence of the supernatant fraction of vegetative and reproductive plants. The supernatant fraction of the reproductive tissues decreased the incorporation of [3H]alanine and [3H]leucine in both the buffer-soluble and acid-soluble proteins and the nuclei of vegetative plants were more active in protein synthesis. Protein patterns as studied by acrylamide gel electrophoresis revealed alterations when vegetative leaf nuclei were incubated with the supernatant of reproductive tissues.

Level of activity of nitrate reductase at the seedling stage as a predictor of grain nitrogen yield in wheat (Triticum aestivum L.)

The yield of grain nitrogen of 24 wheat cultivars grown in the field was found to be related to the activity of the enzyme nitrate reductase (EC1.6.6.1) in the first vegetative leaf of 21-day-old plants grown in a controlled environment. It was concluded that a cultivar's potential for yielding grain nitrogen could be predicted from the activity of nitrate reductase at the seedling stage. This could enable the plant breeder to identify, early in the selection program, lines worth keeping for more advanced testing. Harvest index for nitrogen varied considerably between cultivars, but was usually largest in cultivars with large yields of grain nitrogen. Improvement in harvest index for nitrogen should go some way towards breaking the inverse relation between grain yield and grain nitrogen percentage in plants grown on a limited supply of soil nitrogen.