Kinetic parameters of ammonium uptake and genetic expression of OsAMT1 transporters in varieties of rice (Oryza sativa L.)

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2020-12-14T00:05:05Z No. of bitstreams: 1 2010 - Vinicius Miranda de Souza .pdf: 1202821 bytes, checksum: 7e37c98b6c9ac7587812ebf3ed48136a (MD5) Made available in DSpace on 2020-12-14T00:05:05Z (GMT). No. of bitstreams: 1 2010 - Vinicius Miranda de Souza .pdf: 1202821 bytes, checksum: 7e37c98b6c9ac7587812ebf3ed48136a (MD5) Previous issue date: 2010-02-25 CNPq - Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico Varieties of rice (Oryza sativa), improved and landrace of Maranh?o, were genetically grouped using the RAPD technique. Among the varieties, four contrasting varieties for the grouping by RAPD were selected for studies of ammonium uptake kinetics and expression of ammonium transporters (OsAMT1;1, OsAMT1;2 and OsAMT1;3) under the high-affinity system (HATS). The varieties were grown in a growth chamber in hydroponic system. For the experiment of ammonium uptake kinetics, were separated two groups of plants at 28 days before seeding, and after 24 hours of N strarvation, rice plants were transferred to pots with two concentrations of ammonium, 0.2 mM and 1.5 mM, where we collected samples of solution for the measuring the kinetics of depletion of ammonium, and after 24 hours for the concentration 0.2 mM and 48 hours for the concentration 1.5 mM, the plants were collected and samples of root, sheath and leaves were assessed for fresh weight, amino-N, soluble sugars and N-ammonium. In a second experiment, the same varieties were transferred to pots with nutrient solution with a concentration of 0.2 mM ammonium and root samples were collected two and four hours after the beginning of the experiment for evaluation by real-time RT-PCR for expression of the ammonium transporters (OsAMT1;1, OsAMT1;2 and OsAMT1;3), and the enzymes to assimilate (GS1.2 and NADH-GOGAT1). The results indicate that local varieties have a higher expression of the transporters, which this is associated higher rates of uptake (Vmax) and affinity for ammonium in nutrient solution (KM). Moreover, local varieties had lower values of Cmin indicating that local varieties are adapted to soils with low concentrations of N. Focus on the variety Manteiga, which showed the highest levels of expression between the parameters analyzed and had the lowest Cmin among the varieties analyzed. Variedades de arroz (Oryza sativa) melhoradas e locais do Maranh?o foram agrupadas geneticamente utilizando a t?cnica de RAPD. Dentre as variedades, quatro variedades contrastantes quando ao agrupamento pela t?cnica de RAPD foram selecionadas para estudos de cin?tica de absor??o e express?o dos transportadores de am?nio OsAMT1;1, OsAMT1;2 e OsAMT1;3, sob o sistema de alta afinidade (HATS). As variedades foram cultivadas em c?maras de crescimento, em sistema hidrop?nico. Para o experimento de cin?tica de absor??o de am?nio foram separados dois grupos de plantas ao 28 dias ap?s germina??o, e ap?s 24 horas de defici?ncia de N, as plantas de arroz foram transferidas para potes com duas concentra??es de am?nio, 0,2 mM e 1,5 mM onde foram coletadas amostras de solu??o para a realiza??o da cin?tica de deple??o de am?nio e ap?s 24 horas para a concentra??o de 0,2 mM e 48 horas para a concentra??o de 1,5 mM, as plantas foram coletadas e amostras de raiz, bainha e folha foram avaliadas quanto ao peso fresco, teores de N-amino, a??cares sol?veis e N-am?nio. Em um segundo experimento, as mesma variedades foram transferidas para potes com solu??o nutritiva com concentra??o de 0,2 mM de am?nio, e amostras de raiz foram coletadas as duas e quatro horas ap?s inicio do experimento para avalia??o por real-time RT-PCR da express?o dos transportadores de am?nio OsAMT1;1, OsAMT1;2 e OsAMT1;3, e das enzimas de assimila??o GS1.2 e NADH-GOGAT1. Os resultados indicam que as variedades locais apresentam uma maior express?o dos transportadores, o que est? associado com maiores taxas de absor??o (Vm?x) e afinidade pelo am?nio em solu??o nutritiva (KM). Al?m disso, as variedades locais apresentaram menores valores de Cm?n indicando que as variedades locais s?o adaptadas a solos com baixas concentra??es de N. Destaque para a variedade Manteiga, que apresentou os maiores n?veis de express?o entre os par?metros analisados e teve o menor Cm?n dentre as variedades analisadas.