Mitigating climate change and pandemic impacts on global food security: dual sustainable agriculture approach (2S approach)

MAIN CONCLUSION

Simultaneous application of two sustainability approaches such as the application of biofertilizers to GM plants and microbe bioengineering to enhance physiological response and beneficial interaction with GM plants may have a significant impact on strengthening global food security amid climate change and the pandemic. The second sustainable development goal (SDG 02, Zero Hunger) aims global agricultural sustainability and food security challenges. The agriculture sector has been an integral part of developing countries for millions of farmers and their families. Their contribution provides stability of raw matter related to food availability. But climate change, higher population growth and worldwide pandemics are the main obstacles to food quality, higher crop productivity and global food security. Scientists are concerned with the manifestation of agriculture sustainability in the modern crop management approach to resolving the issues. It is the only way to higher yield productivity by protecting the environment, conserving natural resources, and slowing climate change. Several strategies can be an option to implement, yet the proposed two sustainability approach or 2S approach will be the significant way toward the goal of zero hunger. The first sustainability approach is an application of genetically modified (S1: GMO) Plants and the other is an application of beneficiary plant growth-promoting microbes (S2: Biofertilizers) to the plants for both higher crops and maintenance of the environment. This study summarizes the essential points of S1 and S2 for the widespread utilization of the 2S approach in agriculture and recommends the potential alternatives to be implemented to produce food for all. Simultaneous application of the 2S approach can defeat all threats to gain sustainability in agriculture.

Paired growth of cultivated and halophytic wild rice under salt stress induces bacterial endophytes and gene expression responses

Introduction

Utilizing salt-affected marginal lands in coastal regions can help meet the growing demand for rice. We explored a nature-based solution involving wild halophytic rice (O. coarctata, Oc) and commercial rice BRRI Dhan 67 (O. sativa, Os) grown in close proximity to each other under salt stress.

Methods

This was to investigate whether a paired planting strategy could help complement rice growth and yield under stress. We also investigated the gene expression and endophytic bacterial profiles of both Os and Oc in unpaired and paired conditions without and with salt.

Results

Paired plants exhibited lower salt damage indicators such as smaller reduction in plant height, electrolyte leakage and chlorophyll loss, as well as higher K+/Na+ ratio under saline stress. Some of the 39 endophytic bacteria in the mutualism experiment were unique to Oc and transferred to Os when paired. Differentially expressed genes in leaves of paired Os versus unpaired Os were 1097 (994 up-regulated, 101 down-regulated) without salt and 893 (763 up-regulated, 130 down-regulated) under salt stress. The presence of Oc plants under salt stress influenced major biological processes in Os, including oxidative stress; chitinase activity; phenylalanine catabolic process and response to ABA. Protein binding and serine/threonine kinase activity were primarily affected in molecular function. The downregulated WRKY transcription factor 22 in paired conditions under salt stress played a role in the MAPK signaling pathway, reducing respiratory cell death. The upregulated auxin-responsive protein IAA18 gene, involved in hormone signaling and cell enlargement, was present only in paired plants.

Discussion

Our findings therefore, offer insights into developing more effective cultivation strategies for sustainable rice production.

Effects of multiple halotolerant rhizobacteria on the tolerance, growth, and yield of rice plants under salt stress

Halotolerant bacteria get adapted to a saline environment through modified physiological/structural characteristics and may provide stress tolerance along with enhanced growth to the host plants by different direct and indirect mechanisms. This study reports on multiple halotolerant plant growth-promoting rhizobacteria isolated from the coastal soils in Bangladesh, in fields where the halophytic wild rice Oryza coarctata is endemic. The aim was to find halotolerant bacteria for potential use as biofertilizer under normal/salt-stressed conditions. In this study, eight different strains were selected from a total of 20 rhizobacterial isolates from the saline-prone regions of Debhata and Satkhira based on their higher salt tolerance. 16S rRNA gene sequencing results of the rhizobacterial strains revealed that they belonged to Halobacillus, Bacillus, Acinetobactor, and Enterobactor genera. A total of ten halotolerant rhizobacteria (the other 2 bacteria were previously isolated and already reported as beneficial for rice growth) were used as both single inoculants and in combinations and applied to rice growing in pots. To investigate their capability to improve rice growth, physiological parameters such as shoot and root length and weight, chlorophyll content at the seedling stage as well as survival and yield at the reproductive stage were measured in the absence or presence (in concentration 40 or 80 mmol/L) of NaCl and in the absence or presence of the rhizobacteria. At the reproductive stage, only 50% of the uninoculated plants survived without setting any grains in 80 mmol/L NaCl in contrast to 100% survival of the rice plants inoculated with a combination of the rhizobacteria. The combined halotolerant rhizobacterial inoculations showed significantly higher chlorophyll retention as well as yield under the maximum NaCl concentration applied compared to application of single species. Thus, the use of a combination of halotolerant rhizobacteria as bioinoculants for rice plants under moderate salinity can synergistically alleviate the effects of stress and promote rice growth and yield.