ASSESSING THE EFFECT OF SIDEROPHORE PRODUCING BACTERIA FOR THE IRON NUTRITION IN LENTIL AND PEA

Lentil (Lens culinaris Medik., cv. CDC Milestone) was grown for 45 days in a growth chamber using eight Saskatchewan agricultural soils to isolate root associated siderophore-producing and total heterotrophic bacteria. Results indicated that siderophore-producing bacteria and total heterotroph populations ranged between 4.17–6.30 log cfu·g-1 and 7.16–8.08 log cfu·g-1, respectively. The in vitro siderophore production assay of 491 siderophore-producing isolates using SideroTec® kit revealed that siderophore production ranged from 0.04 to 119.27 µg∙mL-1. Isolates that exhibited high siderophore producing potential (n=68) were characterized using Sanger sequencing and were identified as: Bacillaceae, Burkholderiaceae, Enterobacteriaceae, Oxalobacteraceae, Pseudomonadaceae, Rhizobiaceae and Xanthomonadaceae. Next, isolates that exhibited higher siderophore production (n=40) were inoculated on lentil to enhance plant Fe uptake when grown in a sand-soil mixture. Results revealed that 33 isolates significantly increased total Fe uptake in lentil plants, but the ability to increase total Fe uptake in lentil was not associated with the ability of in vitro siderophore production of individual isolates. The most effective five isolates of this study were subsequently tested to enhance Fe uptake in four pea cultivars in a growth chamber study. Results indicated that inoculation significantly increased total Fe uptake in 75% treatments. A study involving phytosiderophore production by four lentil and four pea cultivars was conducted to assess the potential to chelate Fe from nutrient medium during germination. Results of this study, indicated that all lentil and one pea, cultivar CDC Dakota, exhibited positive phytosiderophore activity. However, results from the pea growth chamber study indicated that the pea cultivar that exhibited in vitro phytosiderophore production did not significantly enhance Fe uptake when compared to the remaining non phytosiderophore-producing cultivars. This difference might be attributed to the differences between plant growth conditions and/or plant physiological stages. Overall, significant increases in total Fe uptake by lentil and pea inoculated with siderophore-producing bacteria were observed. Moreover, the significant interactions between bacterial isolates and pea cultivars suggesting that plant species and cultivars might be dependent on their associated siderophore-producing isolates or vice versa for Fe nutrition and plant cultivars were more responsive when inoculated with their suitable siderophore-producing isolates