• Bacillus licheniformis induced resistance against gray mold in pepper plants. • Bacillus licheniformis and Bacillus pumilus inhibited the growth of Botrytis cinerea and Fusarium solani. • Plant growth promoting mechanisms were confirmed by isolated Bacillus strains.
MADS-box transcription factors (TFs) are involved in multiple plant development processes and are most known during the reproductive transition and floral organ development. Very few genes have been characterized in the genome of Humulus lupulus L. (Cannabaceae), an important crop for the pharmaceutical and beverage industries. The MADS-box family has not been studied in this species yet. We identified 65 MADS-box genes in the hop genome, of which 29 encode type-II TFs (27 of subgroup MIKCC and 2 MIKC*) and 36 type-I proteins (26 α, 9 β, and 1 γ). Type-II MADS-box genes evolved more complex architectures than type-I genes. Interestingly, we did not find FLOWERING LOCUS C (FLC) homologs, a transcription factor that acts as a floral repressor and is negatively regulated by cold. This result provides a molecular explanation for a previous work showing that vernalization is not a requirement for hop flowering, which has implications for its cultivation in the tropics. Analysis of gene ontology and expression profiling revealed genes potentially involved in the development of male and female floral structures based on the differential expression of ABC homeotic genes in each whorl of the flower. We identified a gene exclusively expressed in lupulin glands, suggesting a role in specialized metabolism in these structures. In toto, this work contributes to understanding the evolutionary history of MADS-box genes in hop, and provides perspectives on functional genetic studies, biotechnology, and crop breeding.
The Humulus lupulus L. (hops) is traditionally produced in temperate regions, historically attributed to the belief that vernalization was necessary for reproductive transition. Nevertheless, recent studies have revealed the potential for hop plants to flower in tropical and subtropical climates, thereby reshaping cultivation prospects once the developmental disparities are understood and adapted for optimized production. Here, we delved into the hop phenological cycle and the underlying floral regulatory pathways ultimately, seeking to devise strategies to modulate development and enhance production in regions with low latitudes. In contrast to cultivation in temperate regions, hops grown in the subtropical climate of Minas Gerais, Brazil, flower multiple times throughout the year, independently of the season. Hop is a short-day plant, and in Brazil, the photoperiod is consistently inductive due to daylight hours always being below the described threshold (16,5 h of light critical point). We observed that the reproductive transition of hop initiates after a specific number of nodes, 25 to 28, leading us to hypothesize that this process is primarily controlled by endogenous factors. To explore this issue, we first identified in the hop genome families of miRNAs related to reproductive transition, such as the families MIR156 and MIR172, and the PEBP family which includes the FLOWERING LOCUS T (FT). The expression of miR156 decreased along development inversely to miR172 and in synchrony with the upregulation of HlFT3 and HlFT5. These findings strongly support that the reproductive transition in hops under inductive photoperiodic conditions is primarily regulated by endogenous factors related to development and aging throughout the miRNA and FT-associated pathways. Thus, our study shedded light on the intricate molecular mechanisms that underlie hop floral development paving the way for potential advancements in hop production on a global scale.