ABSTRACT
The nectar spur is an important feature of pollination and ecological adaptation in flowering plants, and it is a key innovation to promote species diversity in certain plant lineages. The development mechanism of spurs varies among different plant taxa. As one of the largest angiosperm genera, we have little understanding of the mechanism of spur development in Impatiens. Here, we investigated the initiation and growth process of spurs of Impatiens uliginosa based on histology and hormone levels, and the roles of AUXIN BINDING PROTEIN (ABP) and extensin (EXT) in spur development were explored. Our results indicate that the spur development of I. uliginosa is composed of cell division and anisotropic cell elongation. Imbalances in spur proximal-distal cell division lead to the formation of curved structures. Endogenous hormones, such as auxin and cytokinins, were enriched at different developmental stages of spurs. IuABP knockdown led to an increase in spur curves and distortion of morphology. IuEXT knockdown resulted in reduced spur length and loss of curve and inner epidermal papillae structures. This study provides new insights into the mechanism of spur development in core eudicots.
ABSTRACT
One motile strain designated, YIM DR1026T was isolated from the roots of Psammosilene tunicoides collected from Gejiu, Yunnan province, China. The cells of strain YIM DR1026T were Gram-negative and short-rod shaped. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain YIM DR1026T was a member of the genus Aureimonas and closely related to Aureimonas rubiginis (96.7%). DNA-DNA relatedness values between strain YIM 1026T and Aureimonas rubiginis BCRC 80440T was 38.2 ± 1.5%. The ANI value between YIM DR1026T and other Aureimonas members were below the cut-off level (95-96%) recommended as the average nucleotide identity (ANI) criterion for interspecies identity. Strain YIM DR1026T grew at 4-30 °C (optimum 28 °C), pH 4.0-9.0 (optimum pH 6.0-7.0) and tolerated NaCl (w/v) up to 1% (optimum 0%). Q-10 was sole the respiratory ubiquinone present in YIM DR1026T. Polar lipids of strain YIM DR1026T were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, sulfoquinovosyldiacylglycerol, unidentified aminolipid and unidentified polar lipid. The genomic G + C content was 64.6 mol%. The major fatty acids were C18:1ω7c, C16:0 and summed feature 3 (C16:1ω7c/C16:1ω6c). Based on phenotypic, phylogenetic, chemotaxonomic and genome comparison, strain YIM DR1026T represents a novel species of the genus Aureimonas, for which the name Aureimonas psammosilene sp. nov. is proposed. The type strain is YIM DR1026T (= KCTC 42691T = NBRC 112412T).
