The study evaluates the effect of rhizobacteria having 1-aminocyclopropane-1-carboxylate deaminase
(ACCd) on the development of wheat seedlings. This enzyme has been proposed to play a key role in
microbe-plant association. Three ”uorescent pseudomonads containing this deaminase were selected
from 70 strains of pseudomonads isolated from rhizosphere of wheat (Triticum aestivum L.) and rape
(Brassica napus L.). These bacteria, varied signi“cantly in the ability to both biosynthesize auxins and
hydrolyze ACC.Among them, Pseudomonasbrassicacearum subsp. brassicacearum strain RZ310 presented
the highest activities of ACC deaminase during 96 h of growth in liquid Dworkin and Foster (DF) salt
medium. Additionally, this rape rhizosphere strain did not produce indoles. Two other isolates, Pseudomonas
sp. PO283 and Pseudomonassp. PO366, secreted auxins only in the presence of their precursor.
Phylogenetic analysis of the 16S rRNA gene and four other protein-encoding genes indicated that these
wheat rhizosphere isolates belonged to the ”uorescent Pseudomonasgroup.
Moreover, the effects of these strains on wheat seedling growth under in vitro conditions were markedly
dependent on both their cell suspensions used to grain inoculation and nutrient conditions. Strains tested
had bene“cial in”uence on wheat seedlings mainly at low cell densities. In addition, access to nutrients
markedly changed bacteria action on cereal growth. Their presence generally favored the positive effects
of pseudomonads on length and the estimated biomasses of wheat coleoptiles. Despite these general
rules, impacts of each isolate on the growth parameters of cereal seedlings were unique
The study evaluates the effect of rhizobacteria having 1-aminocyclopropane-1-carboxylate deaminase(ACCd) on the development of wheat seedlings. This enzyme has been proposed to play a key role inmicrobe-plant association. Three ”uorescent pseudomonads containing this deaminase were selectedfrom 70 strains of pseudomonads isolated from rhizosphere of wheat (Triticum aestivum L.) and rape(Brassica napus L.). These bacteria, varied signi“cantly in the ability to both biosynthesize auxins andhydrolyze ACC.Among them, Pseudomonasbrassicacearum subsp. brassicacearum strain RZ310 presentedthe highest activities of ACC deaminase during 96 h of growth in liquid Dworkin and Foster (DF) saltmedium. Additionally, this rape rhizosphere strain did not produce indoles. Two other isolates, Pseudomonassp. PO283 and Pseudomonassp. PO366, secreted auxins only in the presence of their precursor.Phylogenetic analysis of the 16S rRNA gene and four other protein-encoding genes indicated that thesewheat rhizosphere isolates belonged to the ”uorescent Pseudomonasgroup.Moreover, the effects of these strains on wheat seedling growth under in vitro conditions were markedlydependent on both their cell suspensions used to grain inoculation and nutrient conditions. Strains testedhad bene“cial in”uence on wheat seedlings mainly at low cell densities. In addition, access to nutrientsmarkedly changed bacteria action on cereal growth. Their presence generally favored the positive effectsของ pseudomonads ยาวและ biomasses โดยประมาณของข้าวสาลี coleoptiles แม้ มีทั่วไปเหล่านี้กฎ ผลกระทบของแต่ละ isolate ในพารามิเตอร์การเจริญเติบโตของต้นกล้าของธัญพืชไม่ซ้ำกัน
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