Mangosteen (Garcinia mangostana L.) is widely cultivated for its prized fruit, but its origins are unclear as this crop has not been found in the wild. Seashore mangosteen (Garcinia celebica L.) has been proposed as a candidate ancestral species for the mangosteen male parent in a hypothesized hybridization event, yet the functionality of the male organs in perfect flowers of G. celebica has not been characterized. The objective of this study was to describe pollen development in G. celebica using light, scanning, and transmission electron microscopy techniques. Male gametophyte development led to viable pollen at anthesis. The tapetum was of the secretory type, and it started to degrade following meiosis II, which corresponded to the complete encasement of a callose wall around the microspore tetrad. Pollen viability, demonstrated with 2,3,5-triphenyl tetrazolium chloride (TTC) assays, was 68%. An in-vitro pollen germination assay was developed, and the rate of germination was remarkably similar to the viability (68%). Male functionality was clearly confirmed by both the high rate of pollen viability and germination. The occurrence of stigmatic exudates on pistillode and its pollen features are consistent with biotic pollination. The perfect flower of G. celebica is thus a functional male flower.
Ascorbic acid (AsA) or Vitamin C is an antioxidant molecule and plays an important role in many biological processes in plants. GDP-D-mannose pyrophosphorylase (GMP or VTC1) catalyzes the synthesis of GDP-D-mannose, which is a precursor for AsA production and is used for cell wall polysaccharide and glycoprotein synthesis. In rice, the OsVTC1 gene consists of three homologs, including OsVTC1-1, OsVTC1-3 and OsVTC1-8. In this study, we characterized wild type (WT) and OsVTC1-1 RNAi lines (RI1-2 and RI1-3) and showed that the transcript levels of most genes in the AsA synthesis pathway, AsA content and leaf anatomical parameters in RNAi lines were reduced, revealing that OsVTC1-1 is involved in AsA synthesis. To further study the role of OsVTC1-1 gene, cell wall monosaccharide composition, transcriptome and proteome were compared, with specific attention paid to their wild type and OsVTC1-1 RNAi lines. Mannose and galactose composition (mole%) were decreased in OsVTC1-1 RNAi lines. Additionally, reduction of cell wall-associated proteins, such as kinesin, expansin, beta-galactosidase and cellulose synthase were observed in OsVTC1-1 RNAi lines. Our results suggest that OsVTC1-1 gene plays an important role in AsA synthesis and in cell wall-related processes.
Launaea sarmentosa (Willd.) Kuntze., an edible perennial herb, is critically considered an endangered species due to its habitat destruction. In vitro L. sarmentosa propagation was therefore conducted to preserve this plant. Two types of explants including leaf and stolon were applied to induce the multiple shoots by culturing on Murashige and Skoog (MS) medium supplemented with BA (0, 1, and 2 mg/L) and 2,4-D (0, 1, 2, and 4 mg/L). The optimal shoot induction medium for both explants was MS medium containing 2 mg/l BA (presented 100 % shoot induction). Roots were induced by various types and concentrations of auxins [1-naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA)]. The highest percentage of rooting (70.00 ± 11.05 %) was obtained from stolon-derived shoots on MS medium supplemented with 0.1 mg/l IAA. One-hundred percent survivability was presented after transforming plantlets into a mixture of soil, sand, and peat moss (1:1:1). Starch, protein, and lipid were accumulated in leaves detected by histochemical technique. The obtained information will be a useful tool for mass propagation of L. sarmentosa and to obtain basic knowledge for plant accumulating substances.
HIGHLIGHTS
This paper highlights 2 types of sarmentosa explant including leaves and stolons have great potential to produce multiple shoots after inoculation in MS medium adding BA. All regenerated plants get success for acclimatization and transplantation to the greenhouse. In vitro plantlets of L. sarmentosa leaves accumulated fat, protein and carbohydrate which might be related with precursor of medicinal properties
GRAPHICAL ABSTRACT
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