Bacterial wilt of dry beans (family Fabaceae) caused by the actinobacterial agent Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) is one of the most important diseases threatening edible legume production around the globe. Despite the economic losses due to the bacterial wilt disease, the pathogen has not so far been investigated for its genomic features, pathogenicity determinants and virulence strategies. Here we present the first complete genome sequence of a highly virulent bacteriocin-producing Cff strain P990. The bacterium has a circular chromosome consisting 3,736 kbp with the G+C% content of 71.0%. Furthermore, a 147 kbp circular plasmid (pCff1) with 66.1% G+C% content as well as two circular plasmid-like DNAs with the size of 25 kbp and 22 kbp were detected within the genomic contents of Cff. Phylogenetic analyses revealed that only a few number of Curtobacterium sp. strains deposited in the public databases could be classified within the species C. flaccumfaciens. Comparative genomics of Cff using the genome sequences of actinobacterial plant pathogens revealed the presence of a set of unique low G+C% content genomic islands in the Cff genome. Homologues of pathogenicity-determinant loci capable of producing 1,4-beta-xylanase (xysA), pectate lyase (pelA1 and pelA2), serine protease (chpC, chpG, and pat-1), and sortase (srtA) were detected in Cff genome. The genomic data presented here extends our understanding of the Cff genomic features and pave the ways of research on functional and interaction genetics to combat the risk of bacterial wilt disease in the 21st Century’s dry bean industry.

Saffron (Crocus sativus L.) and its wild relatives, Crocus caspius and Crocus speciosus are of considerable significance in the pharmaceutical, nutraceutical, and ornamental bulbs industry. Towards the ultimate goal of the conservation of wild Crocus species and establishment of an efficient workflow for in vitro production of Crocuses, efficient protocols were developed for disinfection and in vitro production of cormlets in C. sativus and its wild allies C. caspius and C. speciosus. Moreover, the differential expression of the Somatic Embryogenesis Receptor-like Kinase (SERK) gene was evaluated as a potential molecular marker during embryogenesis between embryogenic and non-embryogenic calli. A highly efficient disinfection recipe and a low-cost TDZ-free protocol have been successfully developed for in vitro cormlet production in three Crocus species. MS medium containing 10.18 μM 2, 4-D þ 4.44 μM BAP was most efficiently induced callus and somatic embryo formation. The highest conversion frequency and maximum cormlet weight were achieved in MS containing 5.37 μM NAA þ 8.88 μM BAP. The SERK expression was significantly much higher in embryogenic calli than non-embryogenic in all Crocus species. The current low-cost and easy-to-use recipe suggests a promising in vitro propagation workflow for mass production of uniform pathogen-free cormlets of Crocus species, as well as a platform to better conservation of wild Crocus species and effective gene and genome editing using CRISPR-Cas9 in future studies.

Main conclusion A robust workflow for the identification of miRNAs and their targets in saffron was developed. MicroRNA-mediated gene regulation in saffron is potentially involved in several biological processes, including the biosynthesis of highly valuable apocarotenoids.

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