Stem Anatomical Descriptors of Four Sesbania Scop. Species And Their Systematic Implication

Stem anatomical features of four Sesbania Scop. species viz. S. bispinosa (Jacq.) W. Wight, S. cannabina (Retz.) Poir., S. sesban (L.) Merr., and S. rostrata Bremek. & Oberm., were examined to add some insights for identification of these species using quantitative anatomical descriptors. Sesbania stem is composed of epidermis, cortex, vascular tissues – phloem, cambium zone and xylem, and pith, which exhibit significant variations among the species in terms of their area and thickness. Sesbania sesban showed the largest area and widest epidermal cells. The close relationship between S. bispinosa and S. rostrata was found in the stem anatomical descriptors. Moreover, S. rostrata and S. cannabina were closer to some extent according to some anatomical descriptors; also rationalizing the external morphological similarities of these species. A dichotomous key of the studied Sesbania species was made. Dendrograms based on Agglomerative Hierarchical Cluster analysis of stem anatomical descriptors also confirmed close relationships identified in previous phylogenetic analyses. Bangladesh J. Plant Taxon. 28(2): 441-449, 2021 (December)

Cellular and Metabolite Changes in the Secondary Phloem of Chinese Fir (Cuninghamia lanceolata (Lamb.) Hook.) during Dormancy Release

Wood in the cold temperate zone is the product of the alternation of the growing season and the dormant period of trees, but our knowledge of the process of dormancy release in trees remains limited. Chinese fir (Cuninghamia lanceolata (Lamb.) Hook.) was used to investigate cellular and metabolite changes in the secondary phloem tissue during dormancy release. The sampling dates were 2 March, 28 March, and 13 April. The microsections of wood-forming tissue were prepared using the paraffin embedding technique to observe the formation of cambium cells; metabolites in secondary phloem cells were extracted using a methanol/chloroform organic solvent system. The results showed that the secondary phloem consists of phloem fibers, sieve cells and phloem parenchyma. The cells were regularly arranged in continuous tangential bands and were in the order of Phloem fiber-Sieve cell-Phloem parenchyma-Sieve cell-Phloem parenchyma-Sieve cell-Phloem parenchyma-Sieve cell-Sieve cell-Phloem parenchyma-. The Chinese fir cambium was in dormancy on 2 March and 28 March, while on 13 April, it was already in the active stage and two layers of xylem cells with several layers of phloem cells were newly formed. The width of the cambium zone increased from 18.7 ± 5.7 μm to 76.5 ± 3.0 μm and the average radial diameter of sieve cells expanded from 15.4 ± 7.5 μm to 21.5 ± 7.4 μm after dormancy release. The cambium zone width and the average radial diameter of sieve cells before and after dormancy release were significantly different (p < 0.01). The phloem parenchyma cells without resin were squeezed and deformed by the sieve cells, and the width of the phloem during the active period was 197.0 ± 8.5 μm, which was larger than that during the dormant period. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based metabolomics was employed to analyze the secondary phloem of Chinese fir on 28 March and 13 April. Thirty-nine differential metabolites during dormancy release were detected. The results showed that the composition of Chinese fir metabolites was different before and after dormancy release. The relative increase in pyruvic acid and ascorbic acid contents proved that the rate of energy metabolism in Chinese fir increased substantially after dormancy release. Changes in cell development and the composition of metabolites revealed that the dormancy release of Chinese fir was at early April and the formation period of phloem tissue is earlier than xylem tissue.

WOX genes expression during the formation of new lateral roots from secondary structures in Populus nigra (L.) taproot

Despite the large amounts of data available on lateral root formation, little is known about their initiation from secondary structures. In the present work, we applied a bending treatment to Populus nigra (L.) woody taproots to induce the formation of new lateral roots. The development of lateral roots was monitored by stereomicroscopic examination of cross-sections. Tissues were sampled from the bending zone in the proximity of the vascular cambium before (time 0) and after the application of bending at three different time points (24, 48, and 72 h) and analyzed for the expression of P. nigra WOX homologs. The initiation of new lateral roots was observed to originate from the vascular cambium zone and was followed by primordium formation and root emergence. PnWOX4a, PnWOX4b, PnWOX5a, PnWOX5b, PnWOX11/12a, and PnWOX11/12b were shown to be expressed during the formation of new lateral roots at different developmental stages. The mechanical stress simulated by bending treatment was shown to activate the molecular mechanism leading to the expression of WOX genes, which are hypothesized to control SLR formation in the cambium zone of poplar taproot.

The Propagation of Rosa gallica ‘Tuscany Superb’ by Root Cuttings with the Use of IBA and Biostimulants

The research was aimed at studying the possibility of an alternative method of propagation the difficult-to-root Rosa gallica ‘Tuscany Superb’. The root cuttings of three thickness were rooted using IBA preparations (Chryzotop green, Rhizopon AA 020XX) and biostimulants (Tytanit, Root JuiceTM). The shoots disappeared before the growth of the roots. At the first days of growth, the both shoots and roots elongated upright without polarity. The primordia of the first type of root/shoot buds were situated in cambium zone as the subtending traces of near the rays visible on the cross sections. Moreover, the second types of buds were located in pericycle tissues. The swellings suggested inherence buds were disappearing before rooting. The content of reducing and non-reducing carbohydrates was lower at the time of harvesting the rooted cuttings than before rooting. The thickness of the root cuttings had a significant importance for growth parameters and content of carbohydrates in rooted cuttings. The most useful root cuttings, those achieving the highest mean rooting percentage are thick (76.8%) and medium (67.9%) size. Preparations or biostimulants had a differential influence on rooting process and none of them unequivocally guaranteed an improvement in the rooting percentage of cuttings, parameters of growth or content of carbohydrates. The Rhizopon AA 020XX (90.0%) in thick and Chryzotop green (87.5%) in medium cuttings increased the rooting percentage significantly. Root JuiceTM (0.1%, 0.2%) and Tytanit (0.04%) were also enough positive activity in medium cuttings and can replace IBA preparations. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Effect of Anatomical Structure of Shoots in Different Flowering Phase on Rhizogenesis of Once-blooming Roses

The research was conducted on five once-blooming different origin historical roses. The aims were establishing differences in the anatomical structure of shoots taken in four maturity stages and their natural ability to roots creating. There were hypothesized, that the changes in anatomical structure occur in the time of flowering and may affect the ability of rhizogenesis. Single node one leaf cuttings of chosen cultivars were cut from shoots in four maturity phases: flower buds closed, all flowers open, just after and 7-14 days after petal fall. The cuttings were planted in multipot trays in peat substrate without using rooting stimulators. The anatomical structure of shoots in the place of rhizogenesis were observed, the width of xylem layer and cambial zone, diameter of vascular cells were measured. The percentage of rooted cuttings and forming only a callus were counted. Adventitious roots appeared probably in the cambium zone, pith rays, and also in the zone of phloem and pericycle. The anatomic structure of shoots changes during the period of flowering and influences rooting percentage and the percent of cuttings which developed callus only. The width of the cambium layer of shoots influences the width of the wood layer in all cultivars. The rise of width of cambium tissue have an effect of increase of percentage of cuttings forming a callus only in ‘Hurdals’ and ‘Maiden’s Blush’. The width of the cambium layer in shoots enlarges during full blooming in four of the studied cultivars (‘Hurdals’, ‘Maiden’s Blush’, ‘Mousseuse Rouge’, ‘Semiplena’) and in one it stays at the same level for the whole duration of the experiment (‘Duchesse d’Angoulême’). The specifying in practice the period of taking rose cuttings, individual properties of cultivars and phenological phase of shoot should be taken into consideration.

Regeneration of Vascular Tissues in Broussonetia Papyrifera Stems After Removal of the Xylem

The central cylinder of xylem plus pith was removed from the main stem of 1- to 2- year-old Broussonetia papyrifera (L.) Vent. treelets, leaving only the bark, cambial zone cells and a few immature xylem cells. The immature phloem and xylem cells and original cambium zone cells rapidly produced callus, then the original cambial zone started to produce xylem and phloem. A flat meristem was initiated intermittently inside the callus. Eventually, these islands connected laterally to form a ring of new cambium that began to produce normal xylem inward and phloem outward. About one month later, a concave oblate trunk had formed, which connected distally and proximally with the original trunk.

Root Initiation In Mukhikachu (Colocasia Esculenta)As Influenced By IAA And NAA

In vitro root initiation in Mukhikachu (Colocasia esculenta var. globulifera) was assessed in a factorial experiment using three levels of IAA (0.5, 1.0, and 2.0 mg/l), three levels of NAA (0.5, 1.0, and 2.0 mg/l) and control. Fifty percent intact shoots were used as usual, which was named as normal cut explant and the rest 50 % shoots were cut slantly to expose fresh surface i.e., cambium zone and named as slant cut explant. Low levels of IAA (0.5mg/l) initiated the roots earliest (≈14 DAC) and gave the highest percentage of root (49.71). This treatment also gave the maximum roots/culture (3.63). Root initiation was higher (61.33 %) with slant cut when cultured on a medium containing 0.5 mg/l IAA. The cultures with slant cut end also produced more number of roots and longest roots whereas, the highest root initiation (45.05 %) was given by the treatment 1.0 mg/l NAA, but 2.0 mg/I NAA gave lower percentage of roots (39.89).The maximum number of roots/culture was also obtained by 1.0 mg/l NAA. Slant cut explant performed better regarding root initiation (%), number of roots/culture and length of roots. In this experiment, slant cut explant performed better than that of normal cut and either IAA (0.05 mg/l) or NAA (1.0 mg/l) might be used for root initiation in Mukhikachu. Keywords: Root initiation; Colocasia; IAA; NAA. DOI: http://dx.doi.org/10.3329/bjar.v36i3.9276 BJAR 2011; 36(3): 487-494