Efficient plant regeneration from multiple shoots formed in the leaf-derived callus of Lavandula vera, using the "open culture system".
Abstract To develop an efficient procedure for plant regeneration from leaf-derived callus of Lavandula vera DC, the production of multiple shoots and the formation of roots from these shoots were studied. When calli were cultured in a medium with 4.0×10−7 M N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU), urea-type cytokinin, multiple shoots were obtained from the greenish surface of the callus efficiently at a rate of 52.2%. For multiple shoot development, the shoots were divided into 7–20 shoot clusters with 2–3 shoots and subcultured every 2 weeks. Two modified culture-systems were employed for subculture; a “closed culture system” and an “open culture system”. In the open-system, shoot clusters grew and elongated vigorously. In the closed-system, most of the clusters showed vitrification and did not elongate. In root induction culture, shoot clusters in the open-system were well rooted and grew vigorously, the highest rate of root formation being 74.0%, in the 1 2 MS medium supplemented with 1.0×10−6 M indoleacetic acid (IAA). On the other hand, shoot clusters in the closed-system showed vitrification and did not root well. About seven times more regenerants were obtained from the multiple shoots than from normal shoots treated with 4.4×10−6 M 6-benzylamino purine (BA), a purine-type cytokinin. These results indicate that efficient plant regeneration in L. vera from callus using multiple shoots is possible by means of an open-system.
A Rapid and Efficient Protocol for Clonal Propagation of Phenolic-Rich Lavandula multifida
Lavandula multifida (fernleaf lavender) grows in confined regions of Portugal. This species is known for its interesting chemical profile, rich in phenolic compounds, and significant antifungal and anti-inflammatory properties, making it an interesting plant for industrial exploitation and justifying alternative propagation methods. Therefore, the present study aims the development of an efficient protocol for large scale propagation of this species, assuring plant uniformity and aiming a sustainable industrial exploitation with preservation of natural resources. In vitro cultures were established on Murashige and Skoog medium (MS) with different concentrations of benzyladenine (BA) and zeatin (ZEA). Best multiplication rates (6.14 shoots per explant) were achieved using MS supplemented with 1.0 mg/L ZEA and rooting occurred spontaneously on the propagation medium avoiding additional rooting steps. Moreover, plants flowered during the acclimatization phase, confirming a more rapid in vitro development and shorter breeding cycle. This is a very interesting aspect for essential oil extraction. Trichome morphology was examined by scanning electron microscopy and the secretion analyzed through histochemical tests. Trichomes of micropropagated plantlets were identical to those of field-growing plants, and essential oil production was observed at early stages of development. The present study confirms that micropropagation under controlled conditions could be an interesting alternative for field production of L. multifida, since higher amounts of plants can be obtained in less time with guarantee of genetic stability and phytossanitary quality, very important features regarding essential oil production and commercialization.
Remote estimation of nitrogen and chlorophyll contents in maize at leaf and canopy levels
a b s t r a c t Leaf and canopy nitrogen (N) status relates strongly to leaf and canopy chlorophyll (Chl) content. Remote sensing is a tool that has the potential to assess N content at leaf, plant, field, regional and global scales. In this study, remote sensing techniques were applied to estimate N and Chl contents of irrigated maize (Zea mays L.) fertilized at five N rates. Leaf N and Chl contents were determined using the red-edge chlorophyll index with R2 of 0.74 and 0.94, respectively. Results showed that at the canopy level, Chl and N contents can be accurately retrieved using green and red-edge Chl indices using near infrared (780-800 nm) and either green (540-560 nm) or red-edge (730-750 nm) spectral bands. Spectral bands that were found optimal for Chl and N estimations coincide well with the red-edge band of the MSI sensor onboard the near future Sentinel-2 satellite. The coefficient of determination for the relationships between the red-edge chlorophyll index, simulated in Sentinel-2 bands, and Chl and N content was 0.90 and 0.87, respectively.