Abstract
The basic leucine zipper (bZIP) transcription factor family regulates plant developmental processes and response to stresses. The common bean (Phaseolus vulgaris), an important crop legume, possesses a whole set of 78 bZIP (PvbZIP) genes, the majority of these (59%) are most highly expressed in roots and nodules, root-derived new organs formed in the rhizobia N2-fixing symbiosis. Crop production is highly affected by salinity in Cuba and other countries. In this work we characterized the adverse effect of salinity to common bean plants of the Cuban CC-25-9-N cultivar grown in fertilized (full N-content) or symbiotic N-fixation (rhizobia inoculated) conditions. We assessed if PvbZIP TF participate in CC-25-9-N common bean response to salinity. Quantitative reverse-transcriptase-PCR (qRT-PCR) expression analysis showed that 26 out of 46 root/nodule-enhanced PvbZIP, that responded to salt stress in roots and/or nodules from fertilized and N2-fixing CC-25-9-N plants. From public common bean transcriptomic data, we identified 554 genes with an expression pattern similar to that of salt-responsive PvbZIP genes, and propose that the co-expressed genes are likely to be involved in the stress response. Our data provide a foundation for evaluating the individual roles of salt-responsive genes and to explore the PvbZIP-mediated improvement of salt tolerance in common bean.
Highlights
Legumes, which comprise one third of the world’s primary crop production for food and feed, are able to establish symbiosis with soil-nutrient scavenging mycorrhizal fungi and nitrogen-fixing soil bacteria, being important for sustainable agriculture
We investigated if PvbZIP transcription factors (TF) participate in the common bean response to salt stress in P. vulgaris CC-25-9-N, a black-seeded cultivar, bred in Cuba by INIFAT (Instituto Nacional de Investigaciones Fundamentales en Agricultura Tropical, La Haban, Cuba) and widely used as a commercial variety in that country
We used quantitative reverse-transcriptase-PCR (qRT-PCR) gene expression analysis to assess the reliability of the RNA-seq data regarding the expression profile of PvbZIP genes in different plant tissues
Summary
Legumes, which comprise one third of the world’s primary crop production for food and feed, are able to establish symbiosis with soil-nutrient scavenging mycorrhizal fungi and nitrogen-fixing soil bacteria (rhizobia), being important for sustainable agriculture. The effective interaction between legumes and rhizobia results in a novel plant organ, the root nodule. The differentiated bacteroids, established in the nodules, reduce atmospheric nitrogen to ammonia, which is in turn assimilated into organic nitrogen by the plant [1]. Salinity is a serious constraint to crop production since it affects around 30% of the arable land worldwide [2]. Legume crop production is adversely affected by salinity, especially under symbiotic. N2 -fixation (SNF) conditions where both rhizobial nodulation and nitrogen fixation are drastically diminished [3,4,5,6]. Salt-stress is complex since it includes both ion toxicity—excess toxic Na+ in the Agriculture 2018, 8, 160; doi:10.3390/agriculture8100160 www.mdpi.com/journal/agriculture
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