Plant-growth-promoting bacteria from rhizosphere of Chilean common bean ecotype (Phaseolus vulgaris L.) supporting seed germination and growth against salinity stress.

Salinity abiotic stress is increasing day by day due to continuous global warming and climate change. This is also becoming one of the major causes behind the reduction in crop production. Plant-bacteria interaction plays an essential role in improving crop yield without using any chemical fertilizers. The present study aims to characterize the interaction between plant-growth-promoting bacteria (PGPB) and their role in mitigating salinity stress for local variety crops. Therefore, in this work, two PGPB, namely, Bacillus proteolyticus Cyn1 and Bacillus safensis Cyn2, were isolated from rhizospheric soil of the Chilean common bean ecotype "Sapito" (Phaseolus vulgaris L.), and their PGPB traits were analyzed. Cyn1 can produce NH3 and HCN and also secrete siderophores, whereas Cyn2 produced NH3 and siderophores but responded negatively to HCN production. Both the isolated bacteria have shown a positive result for ACC deaminase production, phosphate solubilization, and catalase enzyme secretion. Under all three tested abiotic stresses, i.e., temperature, water, and salinity, both the bacteria and their consortium have demonstrated positive responses. Cyn1 under temperature stress and water stress can produce a biofilm network to combat the stress. While under salinity stress, both the PGPB isolates indicated the production of stress components and cytoplasmic inclusion bodies. Based on the response, among all other abiotic stresses, salinity stress was chosen for further plant-bacteria interaction study and growth. Visible root colonization of the bacteria has been observed in comparison to the control. The germination index was 100% for all experimental setups of seed bacterization, both under control conditions and salinity stress. Both bacteria responded with good PGP traits that helped in the growth of healthy plants after the bacterial treatment in final pot experiments. Additionally, the consortium and the plants treated with Cyn1 have demonstrated high production of photosynthetic pigments in both experimental setups. Both B. proteolyticus Cyn1 and B. safensis Cyn2 have shown promising PGP characters and efficient response against toxicity related to salinity. Hence, both of these bacteria and consortium can be used for improved agricultural production of Chilean native common beans in the near future.

Development and characterization of microsatellite markers in Gaultheria pumila Lf. (Ericaceae).

BACKGROUND: Polymorphic microsatellite markers were developed for Gaultheria pumila (Ericaceae) to evaluate genetic diversity and population structure within its native range in Chile. This is a very important Ericaceae endemic to Chile with a large commercial potential. Its resistance to different abiotic conditions makes it a valuable target for genetic improvement. RESULTS: Ten polymorphic simple sequence repeat (SSR) loci were isolated from Gaultheria pumila using new-generation 454 FLX Titanium pyrosequencing technology. The mean number of alleles per locus ranged from 2 to 4. Observed and expected heterozygosity ranged from 0.00 to 1.0 and 0.00 to 0.64, respectively. CONCLUSIONS: From 10 SSR markers developed for G. pumila, 9 markers are promising candidates for analyzing genetic variation within or between natural populations of G. pumila and other species from the same genus.

Regeneration of highland papaya (Vasconcellea pubescens) from anther culture.

PREMISE OF THE STUDY: Vasconcellea pubescens is an important Caricaceae species cultivated in several countries of South America. The objective of this study was to investigate different media compositions and plant growth regulators to induce plant regeneration. METHODS: Anthers were cultured in Murashige and Skoog medium with varying concentrations of naphthalene acetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) plus a cytokinin (N-(2-chloro-4-pyridyl)-N'-phenylurea). The effect of the basal medium supplemented with auxins and cytokinins on shoot regeneration from the induced calli was also evaluated. Addition of maltose to the basal medium was also tested. RESULTS: The combination of 0.54 µM NAA and 22.66 µM 2,4-D induced the highest rate of calli formation. Regeneration via organogenesis was obtained in Murashige and Skoog and Woody Plant Medium supplemented with maltose and containing 8.88 µM 6-benzylaminopurine, 5.71 µM indoleacetic acid, and 2.28 µM zeatin. DISCUSSION: The plant regeneration protocol reported here permits the development of haploid and double haploid plants that can be useful for propagation purposes, allow a better molecular understanding of the species, and facilitate the production of new cultivars.

Development and characterization of microsatellite markers in Gaultheria pumila Lf. (Ericaceae)

BACKGROUND: Polymorphic microsatellite markers were developed for Gaultheria pumila (Ericaceae) to evaluate genetic diversity and population structure within its native range in Chile. This is a very important Ericaceae endemic to Chile with a large commercial potential. Its resistance to different abiotic conditions makes it a valuable target for genetic improvement. RESULTS: Ten polymorphic simple sequence repeat (SSR) loci were isolated from Gaultheria pumila using new-generation 454 FLX Titanium pyrosequencing technology. The mean number of alleles per locus ranged from 2 to 4. Observed and expected heterozygosity ranged from 0.00 to 1.0 and 0.00 to 0.64, respectively. CONCLUSIONS: From 10 SSR markers developed for G. pumila, 9 markers are promising candidates for analyzing genetic variation within or between natural populations of G. pumila and other species from the same genus.

In vitro asymbiotic germination for micropropagation of the recalcitrant terrestrial orchid Chloraea crispa (Orchidaceae).

PREMISE OF THE STUDY: Chloraea crispa is a terrestrial Orchidaceae species native to Chile, characterized by a beautiful and showy inflorescence. The species has a great potential for commercial exploitation in the cut flower industry, but it is essential to improve propagation methods to avoid endangering its natural populations. Because this species is hard to propagate using traditional greenhouse techniques, in vitro techniques offer an effective tool for its large-scale production in terms of germination, growth, and propagation. METHODS: The current study evaluated the effect of the culture medium on the asymbiotic germination of C. crispa seeds, as well as the effects of the plant growth regulators 6-benzylaminopurine and indole-3-butyric acid. Different light regimes were also studied. RESULTS: A significant effect was observed for the interaction between culture media and light regime on the morphogenic response of the seeds. The highest rate of embryonic germination was obtained in Van Waes medium supplemented with 0.1 mg·L-1 of 6-benzylaminopurine. DISCUSSION: For the first time, asymbiotic culture of this species using biotechnology tools has been developed. Plantlets developed very well under in vitro conditions, allowing the possibility to propagate and store genetic material for conservation and domestication purposes.

Meristem culture and subsequent micropropagation of Chilean strawberry (Fragaria chiloensis (L.) Duch.).

BACKGROUND: Vegetative propagation of Fragaria sp. is traditionally carried out using stolons. This system of propagation, in addition to being slow, can spread plant diseases, particularly serious being viral. In vitro culture of meristems and the establishment of micropropagation protocols are important tools for solving these problems. In recent years, considerable effort has been made to develop in vitro propagation of the commercial strawberry in order to produce virus-free plants of high quality. These previous results can serve as the basis for developing in vitro-based propagation technologies in the less studied species Fragaria chiloensis. RESULTS: In this context, we studied the cultivation of meristems and establishment of a micropropagation protocol for F. chiloensis. The addition of polyvinylpyrrolidone (PVP) improved the meristem regeneration efficiency of F. chiloensis accessions. Similarly, the use of 6-benzylaminopurine (BAP) in the culture media increased the average rate of multiplication to 3-6 shoots per plant. In addition, the use of 6-benzylaminopurine (BAP), had low levels (near zero) of explant losses due to oxidation. However, plant height as well as number of leaves and roots were higher in media without growth regulators, with average values of 0.5 cm, 9 leaves and 4 roots per plant. CONCLUSIONS: For the first time in Chilean strawberry, meristem culture demonstrated to be an efficient tool for eliminating virus from infected plants, giving the possibility to produce disease free propagation material. Also, the addition of PVP into the basal MS medium improved the efficiency of plant recovery from isolated meristems. Farmers can now access to high quality plant material produced by biotech tools which will improve their technological practices.

Meristem culture and subsequent micropropagation of Chilean strawberry (Fragaria chiloensis (L) Duch. )

BACKGROUND: Vegetative propagation of Fragaria sp. is traditionally carried out using stolons. This system of propagation, in addition to being slow, can spread plant diseases, particularly serious being viral. In vitro culture of meristems and the establishment of micropropagation protocols are important tools for solving these problems. In recent years, considerable effort has been made to develop in vitro propagation of the commercial strawberry in order to produce virus-free plants of high quality. These previous results can serve as the basis for developing in vitro-based propagation technologies in the less studied species Fragaria chiloensis. RESULTS: In this context, we studied the cultivation of meristems and establishment of a micropropagation protocol for F. chiloensis. The addition of polyvinylpyrrolidone (PVP) improved the meristem regeneration efficiency of F. chiloensis accessions. Similarly, the use of 6-benzylaminopurine (BAP) in the culture media increased the average rate of multiplication to 3-6 shoots per plant. In addition, the use of 6-benzylaminopurine (BAP), had low levels (near zero) of explant losses due to oxidation. However, plant height as well as number of leaves and roots were higher in media without growth regulators, with average values of 0.5 cm, 9 leaves and 4 roots per plant. CONCLUSIONS: For the first time in Chilean strawberry, meristem culture demonstrated to be an efficient tool for eliminating virus from infected plants, giving the possibility to produce disease free propagation material. Also, the addition of PVP into the basal MS medium improved the efficiency of plant recovery from isolated meristems. Farmers can now access to high quality plant material produced by biotech tools which will improve their technological practices.