ABSTRACT
The cadaverine (Cad), an organic diamine was examined for its response on growth in salinity and metal stressed B. juncea cv RH-30 vis-à-vis compared the response of ammonium nitrate. The Cad (1 mM) application ameliorated the effect caused by salinity and metal stress on seed germination and plant growth. The plant growth recovery (dry biomass accumulation) was dependent on stress and diamine type. The higher growth recovery potential of Cad under both stresses was due to elevation in photosynthetic pigments, nitrate reductase activity and organic nitrogen as well as soluble protein, It is inferred that growth in stressed seedlings was mediated by Cad through lowering endogenous Cd/Pb and Na+/K+ level in leaf and shoot tissues.
Subject(s)
Cadaverine/pharmacology , Cadmium/metabolism , Lead/metabolism , Mustard Plant/drug effects , Mustard Plant/growth & development , Mustard Plant/physiology , Nitrate Reductase/metabolism , Nitrogen/metabolism , Photosynthesis , Pigments, Biological/metabolism , Stress, PhysiologicalABSTRACT
The bacterial strain Mesorhizobium loti MP6, isolated from root nodules of Mimosa pudica induced growth and yield of Brassica campestris. The isolate MP6 secreted hydroxamate type siderophore in Chrom-Azurol Siderophore (CAS) agar medium. Production of hydrocyanic acid (HCN), indole acetic acid (IAA) and phosphate solubilizing ability was also recorded under normal growth conditions. Root hair curling was observed through simple glass-slide technique. In vitro study showed a significant increase in population of M. loti MP6 in rhizosphere due to root exudates of B. campestris. In dual culture technique the strain showed a strong antagonistic effect against Sclerotinia sclerotiorum, a white rot pathogen of Brassica campestris. The growth of S. sclerotiorum was inhibited by 75 percent after prolonged incubation. Efficient root colonization of mustard seedlings was confirmed by using a streptomycin-resistant marker M. loti MP6strep+. The M. loti MP6 coated seeds proved enhanced seed germination, early vegetative growth and grain yield as compared to control. Also, a drastic decline (99 percent) in the incidence of white rot was observed due to application of M. loti MP6.
A cepa bacteriana Mesorhizobium loti MP6 isolada de nódulos de raiz de Mimosa pudica induziu o crescimento e o rendimento de Brassica campestris. A cepa MP6 secretou sideróforo do tipo hidroxamato em meio sólido Chrom-Azurol Siderophore (CAS). Em condições normais de crescimento, a cepa foi também capaz de produzir de ácido cianídrico (HCN) e acido indolacético (AIA) e solubilizar fosfato. O encurvamento do pelo da raiz foi observado usando a simples técnica de lâmina e lamínula. Estudos in vitro mostraram um aumento significativo na população de M. loti MP6 na rizosfera devido aos exsudatos de B. campestris. Empregando-se técnica de co-cultura, a cepa mostrou um grande efeito antagônico contra o fungo Sclerotinia sclerotiorum, o patógeno da podridão branca de Brassica campestris. Após incubação prolongada, o crescimento de S. sclerotiorum foi inibido em 75 por cento. Uma eficiente colonização de sementes de mostarda foi confirmada pelo emprego da linhagem M. loti MP6strep+ que contém um marcador de resistência à estreptomicina. As sementes cobertas com M. loti MP6 apresentaram aumento da sua germinação,crescimento vegetativo rápido e melhor rendimento quando comparadas ao controle. Além disso, foi observado um drástico declínio na incidência da podridão branca decorrente da aplicação de M. loti MP6.