Genomic analysis reveals phylogeny of Zygophyllales and mechanism for water retention of a succulent xerophyte.

Revealing the genetic basis for stress-resistant traits in extremophile plants will yield important information for crop improvement. Zygophyllum xanthoxylum, an extant species of the ancient Mediterranean, is a succulent xerophyte that can maintain a favorable water status under desert habitats; however, the genetic basis of this adaptive trait is poorly understood. Furthermore, the phylogenetic position of Zygophyllales, to which Z. xanthoxylum belongs, remains controversial. In this study, we sequenced and assembled the chromosome-level genome of Z. xanthoxylum. Phylogenetic analysis showed that Zygophyllales and Myrtales form a separated taxon as a sister to the clade comprising fabids and malvids, clarifying the phylogenetic position of Zygophyllales at whole-genome scale. Analysis of genomic and transcriptomic data revealed multiple critical mechanisms underlying the efficient osmotic adjustment using Na+ and K+ as "cheap" osmolytes that Z. xanthoxylum has evolved through the expansion and synchronized expression of genes encoding key transporters/channels and their regulators involved in Na+/K+ uptake, transport, and compartmentation. It is worth noting that ZxCNGC1;1 (cyclic nucleotide-gated channels) and ZxCNGC1;2 constituted a previously undiscovered energy-saving pathway for Na+ uptake. Meanwhile, the core genes involved in biosynthesis of cuticular wax also featured an expansion and upregulated expression, contributing to the water retention capacity of Z. xanthoxylum under desert environments. Overall, these findings boost the understanding of evolutionary relationships of eudicots, illustrate the unique water retention mechanism in the succulent xerophyte that is distinct from glycophyte, and thus provide valuable genetic resources for the improvement of stress tolerance in crops and insights into the remediation of sodic lands.

Long-term outcomes of laser dacryoplasty combined with intubation using a new silicon tube in patients with lacrimal duct obstruction.

AIM: To determine the 15-year outcomes of laser dacryoplasty (LDP) in patients with lacrimal duct obstruction; and to evaluate LDP combined with intubation using a new silicone tube to treat complicated cases. METHODS: Patients with lacrimal duct obstruction and treated with LDP between April 2000 and April 2005 were investigated retrospectively. Totally 116 eyes with completed 15-year follow-up records were included in this study. For complicated cases (52 eyes of 52 patients), both LDP and intubation using a self-made silicon tube were performed. For patients with uncomplicated obstruction (64 eyes of 61 patients), only LDP was performed. Outcomes were assessed based on results of lacrimal irrigation and degree of symptoms during follow-up. RESULTS: At the follow-up time of 15y, 81 eyes achieved full success (69.8%); 21 eyes got improved (18.1%); and 14 eyes were considered failure (12.1%). The success rate was 71.2% (37/52 eyes) for complicated cases; and 68.8% (44/64 eyes) for uncomplicated cases. No statistically significant difference between two groups was observed (P=0.961). No postoperative complication was observed. CONCLUSION: LDP is a well-tolerated, simple, and effective procedure with satisfactory long-term outcomes in selected patients, which make it a good alternative to conventional dacryocystorhinostomy. In addition, intubation with the self-made mono-canalicular silicone tube facilitates the management of complicated cases with few complications.