Enhancement of polygalacturonase activity during auxin induced para nodulation and endorhizosphere colonization of Azospirillum in rice roots.
Effect of different auxins, namely, 2,4-dichlorophenoxyacetic acid (2,4-D), naphthalene acetic acid (NAA) and indole acetic acid (IAA) and Azospirillum brasilense bioinoculation on the enhancement of polygalacturonase (PG) activity in rice roots during para nodulation and endorhizosphere colonization of Azospirillum was studied under in vitro condition. It was observed that Azospirillum bioinoculation could augment PG activity of rice roots to a lesser extent without any root morphogenesis whereas auxin application together with Azospirillum bioinoculation enhanced PG activity of rice roots to a higher level which resulted in better root morphogenesis (para nodule) and endorhizosphere colonisation of A. brasilense. Among the three auxins tested, 2,4-D, even at lower concentration (0.5 ppm) enhanced the rice root PG activity, root morphogenesis and endorhizosphere colonization of Azospirillum while it was 2.0 ppm with NAA and variable with IAA. It is concluded that there is a positive correlation existing among PG activity, degree of root morphogenesis and endorhizosphere colonization of Azospirillum brasilense in rice roots and the degree of correlation is determined by the chemical composition, concentration and mode of action of the auxin utilised.
Department of Agricultural Microbiology, Annamalai University, Annamalai Nagar 608 002, India.
C
C
Sekar
N N
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Prasad
M D
MD
Sundaram
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D016949:Azospirillum / Q000502:physiology*; D004790:Enzyme Induction / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009024:Morphogenesis / Q000187:drug effects; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D009586:Nitrogen Fixation / Q000502:physiology*; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000382:microbiology*; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000382:microbiology; D011096:Polygalacturonase / Q000096:biosynthesis* / Q000235:genetics
D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010940:Plant Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; C030737:indoleacetic acid; D011096:Polygalacturonase