Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

Effect of UV radiation and its implications on carotenoid pathway in Bixa orellana L.

The current study was undertaken to analyse the effect of short-term UV-B and UV-C radiations in provoking carotenoid biosynthesis in Bixa orellana. Seeds of B. orellana were germinated and exposed to the short term UV pre-treatment under controlled environmental condition for 5days. The UV treated young seedlings response in pigment contents; antioxidant enzyme activity and mRNA gene expression level were analysed. The pigment content such as chlorophyll was increased in both UV-B and UV-C treated seedlings, but the total carotenoid level was decreased when compared to the control seedlings this can be attributed to the plant adaptability to survive in a stressed condition. The ß-carotene level was increased in UV-B, and UV-C treated young seedlings. No significant changes have occurred in the secondary pigment such as bixin and ABA. The activity of the antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase was significantly increased in UV-B treated seedlings when compared to the UV-C treated seedlings and control. The mRNA expression of the genes involved in bixin biosynthesis pathways such as DXS, PSY, PDS, LCY-ß, LCY-ε, CMT, LCD, ADH and CCD genes showed different expression pattern in UV-B and UV-C treated young seedlings. Further we analysed the gene co-expression network to identify the genes which are mainly involved in carotenoid/bixin biosynthesis pathway. Form our findings the CCD, LCY, PDS, ZDS and PSY showed a close interaction. The result of our study shows that the short term UV-B and UV-C radiations induce pigment content, antioxidant enzyme activity and different gene expression pattern allowing the plant to survive in the oxidative stress condition.

Análise de crescimento de Bixa orellana L. sob efeito da inoculação micorrízica e adubação fosfatada / Analyses of Bixa orellana L. growth under the effects of mycorrhizal inoculation and phosphate fertilization

Este estudo objetivou avaliar o desenvolvimento de Bixa orellana L. em condições de viveiro sob efeito da inoculação micorrízica e adubação fosfatada. As plantas foram cultivadas em sacos de polietileno com 0,18 X 0,30 m e capacidade de 1,3 kg de substrato. O delineamento experimental utilizado foi inteiramente casualizado com seis tratamentos e trinta repetições. As dosagens de fósforo utilizadas foram 0, 4.200 e 8.400 g m-3 de substrato. O fungo micorrízico arbuscular (FMA) da espécie Glomus clarum, foi utilizado em metade dos tratamentos (com e sem micorrizas) com inoculação de 2 g do fungo. As avaliações ocorreram 30, 60, 90 e 120 dias após a emergência das plântulas. Determinou-se a massa seca de folhas, área foliar, massa seca total, razão de área foliar, área foliar específica, taxa assimilatória líquida, taxa de crescimento relativo e taxa de crescimento absoluto. O fungo micorrízico facilita a absorção de fósforo pelo urucum, atendendo a sua exigência em relação ao nutriente. A dose de fósforo de 4.200 g m-3 em associação com FMA Glomus clarum ou 8.400 g m-3, com ou sem essa associação, são indicadas para o crescimento de plantas de urucum em viveiro, por promoverem adequadas respostas dos índices fisiológicos, contribuindo com seu desenvolvimento.

This study aimed to evaluate the development of Bixa orellana L. under nursery conditions and subjected to the effects of mycorrhizal inoculation and phosphate fertilization. The plants were grown in polyethylene bags with dimensions of 0.18 x 0.30 m and capacity of 1.3 kg substrate. The adopted experimental design was completely randomized with six treatments and thirty replicates. The used phosphorus levels were 0, 4.200 and 8.400 g m-3 substrate. The arbuscular mycorrhizal fungus (AMF) of the species Glomus clarum was used in half of the treatments (with and without mycorrhizae) with inoculation of 2 g of the fungus. Evaluations occurred at 30, 60, 90 and 120 days after the emergence of seedlings. Leaf dry mass, leaf area, total dry mass, leaf area ratio, specific leaf area, net assimilation rate, relative growth rate and absolute growth rate were determined. The mycorrhizal fungus facilitates phosphorus uptake by annatto, fulfilling its requirement for the nutrient. The phosphorus level of 4.200 g m-3 in association with Glomus clarum or 8.400 g m-3, with or without this association, are indicated for annatto plant growth in nurseries since they promote appropriate responses of physiological indexes, contributing to the plant development.

[Microsporogenesis y microgametogenesis de annatto (Bixa orellana L.)]. / Microsporogénesis y microgametogénesis de onoto (Bixa orellana L.).

A series of buds of increasing maturity were individually sampled in order to examine cytological events of annatto (Bixa orellana L.), genotype Portuguesa. They were fixed in Carnoy II at 12:30 am, time of the highest rate of meiotic division. Three stain solutions were attempted. In the microspores mother cells, the use of acetic orcein 1% resulted in a good nucleus coloration and sharpness. In contrast, a well chromosome resolution was achieved with the application of propionic carmin 2%. The pollen grain mother cells (n = 8 chromosomes) at metaphase I were found in floral buds of 0.5 to 0.6 cm long; tetrad stage in buds of 0.6 to 0.7 cm long, uninucleate stage of microspores in buds of 0.7 to 0.8 cm long and the binucleate stage (pollen) in buds longer than 0.8 cm. Microphotographies showing the sequence of meiotic division (microsporogenesis) and subsequent mitosis to originate pollen grains were included.

Microsporogénesis y microgametogénesis de onoto (Bixa orellana L. ) / Microsporogenesis and microgametogenesis of annatto (Bixa orellana L. )

A series of buds of increasing maturity were individually sampled in order to examine cytological events of annatto (Bixa orellana L.), genotype Portuguesa. They were fixed in Carnoy II at 12:30 am, time of the highest rate of meiotic division. Three stain solutions were attempted. In the microspores mother cells, the use of acetic orcein 1% resulted in a good nucleus coloration and sharpness. In contrast, a well chromosome resolution was achieved with the application of propionic carmin 2%. The pollen grain mother cells (n = 8 chromosomes) at metaphase I were found in floral buds of 0.5 to 0.6 cm long; tetrad stage in buds of 0.6 to 0.7 cm long, uninucleate stage of microspores in buds of 0.7 to 0.8 cm long and the binucleate stage (pollen) in buds longer than 0.8 cm. Microphotographies showing the sequence of meiotic division (microsporogenesis) and subsequent mitosis to originate pollen grains were included