Abstract
Drought is a global problem for crop productivity. Therefore, the objective of this research was to evaluate five dry-Caribbean Bacillus spp. strains in drought stress amelioration in maize plants. Maize seeds were single-strain inoculated and sown in pots under greenhouse conditions. After 12 days, plants were subjected to 33 days of drought conditions, i.e., 30% of soil field capacity, and then collected to measure leaf and root dry biomass, plant height, antioxidant enzymes, proline accumulation, and P+, Ca2+, and K+ uptake. Results correlated drought stress amelioration with the inoculation of Bacillus spp. strains XT13, XT38 and XT110. Inoculated plants showed increases in dry biomass, plant height, and K+ and P+ uptake. The overall maize antioxidant response to bacterial inoculation under drought stress showed dependence on proline accumulation and decreases in ascorbate peroxidase and glutathione reductase activities. Moreover, results suggest that this stress amelioration is driven by a specific plant-strain correlation observed in antioxidant response changes in inoculated plants under stress. Also, there is a complex integration of several mechanisms, including plant growth-promotion traits and nutrient uptake. Hence, the use of dry-Caribbean plant growth-promoting Bacillus strains represents an important biotechnological approach to enhance crop productivity in arid and semi-arid environments.
Highlights
Drought is a limitation for crop productivity with economic, social, and environmental impacts at the global level [1,2,3]
Phylo3g.eRneesutilctsanalyses of the 16S rRNA gene sequence of strains XT13 (1344 bp), XT14 (1266 bp), XT38 (905 bp), and XT110 (1328 bp) with those of the type species of the genera belonging to the order Bacillales in3d.1i.cSatrtaeinds tChhaartatchteeriszeatisotnraanidnPslbanetlGornogwethd-PtroomtohteingB(aPcGilPlu) Tsrgaietsnus and different species
Our findings showed that the increased uptake of P+ by inoculated plants under drought stress was correlated with antioxidant enzymatic activity and leaf biomass gains supporting its role in stress amelioration (Figure 4)
Summary
Drought is a limitation for crop productivity with economic, social, and environmental impacts at the global level [1,2,3]. Climate change is increasing the severity, duration, and frequency of drought in several crops used for human and animal feeding [4]. This water deficit leads to the reduction of plant growth by the production of reactive oxygen species (ROS), reducing photosynthetic activity, membrane stability, and inducing irreversible damage to biological molecules that trigger cell death [5,6]. The APX enzyme uses ascorbic acid to transform the hydrogen peroxide into water, controlling the ROS concentration; the GR enzyme maintains the redox balance restoring reduced glutathione (GSH), and helps other enzymes to restore the ascorbate used by the APX [9]
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