Cytokinin regulates the activity of the inflorescence meristem and components of seed yield in oilseed rape.

The number of flowers and seed-bearing structures formed by the inflorescence meristem and the formation of ovules in the female reproductive part of the flowers are important yield-related traits of crop plants. It has been shown that cytokinin is a pivotal factor regulating these traits. Here, we explore the impact of mutation of CYTOKININ OXIDASE/DEHYDROGENASE (CKX) genes encoding cytokinin-degrading enzymes on these yield-related traits in oilseed rape (Brassica napus L.). We describe the identification of four BnCKX3 and two BnCKX5 genes as regulators of reproductive development in the allotetraploid B. napus. RNA-seq analysis and in situ hybridization showed expression of these genes in reproductive organs. Loss-of-function mutants for each of these CKX gene copies were identified by targeting induced local lesions in genomes (TILLING) and combined by crossing. Sextuple ckx3 ckx5 mutants showed an increased cytokinin concentration and larger and more active inflorescence meristems. They also produced up to 72% more flowers with gynoecia containing 32% more ovules and up to 54% more pods on the main stem. The weight of seeds harvested from the main stem of plants grown in the greenhouse or in the field was increased by 20-32%. Our results show that cytokinin regulates inflorescence meristem and placenta activity in oilseed rape. The work demonstrates the potential to achieve yield enhancement in a dicot crop plant by modulating the cytokinin status through mutagenesis of specific CKX genes.

Predictors of anxiety after stroke: a systematic review of observational studies.

BACKGROUND: Anxiety disorders or symptoms are relatively common after stroke. A better understanding of the predictors of anxiety in stroke patients may improve the management of these disorders. The current review was conducted to determine the predictors of anxiety after stroke. METHODS: Relevant articles concerning population, hospital, or rehabilitation-based studies were identified by searching 10 electronic databases up to May 2014. Methodological quality appraisal, including the validity of prognostic models and data extraction were conducted by 3 reviewers. RESULTS: A total of 18 studies were identified. Data from 3 population-based studies including 8130 patients, 8 hospital-based studies including 1199 patients, and 7 rehabilitation-based studies including 1103 patients were evaluated. Prestroke depression, stroke severity, early anxiety, and dementia or cognitive impairment after stroke were the main predictors of poststroke anxiety. Older age, physical disability or impairment, and use of antidepressant drugs were not associated with the presence of anxiety. Limitations of studies included wide variation in screening tools and cutoff scores, variability in the time frame of screening for anxiety, use of extensive exclusion criteria, and questionable statistical internal and external validity of the models. CONCLUSIONS: Lack of methodological and statistical rigor affects the validity of proposed models to predict anxiety after stroke. Future research should focus on testing proposed models on both internal and external samples to ultimately inform future clinical practice.

Relaxation training after stroke: potential to reduce anxiety.

OBJECTIVE: To consider the feasibility of setting up a relaxation group to treat symptoms of post stroke anxiety in an in-patient post-acute setting; and to explore the effectiveness of relaxation training in reducing self-reported tension. METHOD: A relaxation group protocol was developed in consultation with a multidisciplinary team and a user group. Over a period of 24 months, 55 stroke patients attended group autogenic relaxation training on a rehabilitation ward. Attendance ranged between one and eleven sessions. Self-reported tension was assessed pre and post relaxation training using the Tension Rating Circles (TRCs). RESULTS: The TRCs identified a significant reduction in self-reported tension from pre to post training, irrespective of the number of sessions attended; z = -3.656, p < 0.001, r = -0.67, for those who attended multiple sessions, z = -2.758, p < 0.01, r = -0.6 for those who attended a single session. DISCUSSION: The routine use of relaxation techniques in treating anxiety in patients undergoing post-stroke rehabilitation shows potential. Self-reported tension decreased after attendance at relaxation training. The TRCs proved acceptable to group members, but should be validated against standard anxiety measures. Further exploration of the application of relaxation techniques in clinical practice is desirable. Implications for Rehabilitation Anxiety is prevalent after stroke and likely affects rehabilitation outcomes. Relaxation training is a well proven treatment for anxiety in the non-stroke population. A significant within session reduction in tension, a hallmark symptom of anxiety, was evidenced via group relaxation training delivered in a post-acute, in-patient stroke unit setting. Relaxation training a shows promise as a treatment for anxiety after stroke.

Cytokinin regulates the activity of reproductive meristems, flower organ size, ovule formation, and thus seed yield in Arabidopsis thaliana.

The size and activity of the shoot apical meristem is regulated by transcription factors and low molecular mass signals, including the plant hormone cytokinin. The cytokinin status of the meristem depends on different factors, including metabolic degradation of the hormone, which is catalyzed by cytokinin oxidase/dehydrogenase (CKX) enzymes. Here, we show that CKX3 and CKX5 regulate the activity of the reproductive meristems of Arabidopsis thaliana. CKX3 is expressed in the central WUSCHEL (WUS) domain, while CKX5 shows a broader meristematic expression. ckx3 ckx5 double mutants form larger inflorescence and floral meristems. An increased size of the WUS domain and enhanced primordia formation indicate a dual function for cytokinin in defining the stem cell niche and delaying cellular differentiation. Consistent with this, mutation of a negative regulator gene of cytokinin signaling, ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6, which is expressed at the meristem flanks, caused a further delay of differentiation. Terminal cellular differentiation was also retarded in ckx3 ckx5 flowers, which formed more cells and became larger, corroborating the role of cytokinin in regulating flower organ size. Furthermore, higher activity of the ckx3 ckx5 placenta tissue established supernumerary ovules leading to an increased seed set per silique. Together, the results underpin the important role of cytokinin in reproductive development. The increased cytokinin content caused an ~55% increase in seed yield, highlighting the relevance of sink strength as a yield factor.

New insights into the phylogeny of Pleopeltis and related Neotropical genera (Polypodiaceae, Polypodiopsida).

The fern family Polypodiaceae plays an important role in Neotropical epiphyte diversity. Most of its American representatives are assembled in a monophyletic clade that, apart from the grammitids, nearly exclusively comprises species restricted to the New World. The phylogenetic relationships of these ferns are still insufficiently understood and many taxonomic problems, such as natural circumscriptions of the genera Polypodium and Pleopeltis, were unresolved. Here we address one of the two main lineages within New World Polypodiaceae including Pecluma, Phlebodium, Pleopeltis, and Polypodium. Our study is based on DNA sequence data from four plastid regions that were generated for 72 species representing all putative major taxonomic groups within this lineage. The analyses reveal three major clades: (1) Polypodium plus Pleurosoriopsis; (2) Pecluma plus Phlebodium, and some species of Polypodium; and (3) Pleopeltis and related genera. The last clade contains species of Pleopeltis and Polypodium as well as Microphlebodium, Neurodium, Dicranoglossum, and Pseudocolysis. All species included in the clade display conspicuous persistent peltate laminar scales that are not found in other species of this lineage. Our results suggest a reconsideration of the generic concept of Pleopeltis with peltate laminar scales being the genus' key character.