SUMMARYThe ICK/KRP cyclin-dependent kinase (CDK) inhibitors are important plant cell cycle factors sharing only limited similarity with the metazoan CIP/KIP family of CDK inhibitors. Little is known about the specific functions of different ICK/KRP genes in planta. In this study, we created double and multiple mutants from five single Arabidopsis ICK/KRP T-DNA mutants, and used a set of 20 lines for the functional investigation of the important gene family. There were gradual increases in CDK activity from single to multiple mutants, indicating that ICK/KRPs act as CDK inhibitors under normal physiological conditions in plants. Whereas lowerorder mutants showed no morphological phenotypes, the ick1 ick2 ick6 ick7 and ick1 ick2 ick5 ick6 ick7 mutants had a slightly altered leaf shape. The quintuple mutant had larger cotyledons, leaves, petals and seeds than the wild-type control. At the cellular level, the ICK/KRP mutants had more but smaller cells in all the organs examined. These phenotypic effects became more apparent as more ICK/KRPs were downregulated, suggesting that to a large extent ICK/KRPs function in plants redundantly in a dosage-dependent manner. Analyses also revealed increased expression of E2F-dependent genes, and elevated RBR1 as well as an increased level of phospho-RBB1 protein in the quintuple mutant. Thus, downregulation of multiple ICK/ KRP genes increases CDK activity, upregulates the E2F pathway and stimulates cell proliferation, resulting in increased cell numbers, and larger organs and seeds.

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The combinations of hollow MoS 2 micro@nano-spheres were successfully fabricated through a one-step hydrothermal method. A possible growth mechanism was presented in detail based on time-dependent experimental facts. Besides, the photocatalytic activities of the samples were evaluated by monitoring the photodegradation of methylene blue (MB). The adsorption value of 150 mg g À1 shows a strong adsorption capability in the dark. After irradiation for only 30 min, the remaining MB in solution is about 9.7%. Moreover, the humidity sensing properties of the samples were measured for the first time. The results revealed high sensitivity at high RH, small humidity hysteresis, fast response and recovery times, and good stability. The greatest sensitivity is 32.19 nF/% RH and the maximum hysteresis is $6.3% RH.For humidity cycling of 17.2-89.5-17.2% RH, the response and recovery times are $140 s and $80 s, respectively. Capacitance fluctuations for one month are less than AE7% at various relative humidities (RHs).

Information on genetic diversity and population structure of a tetraploid alfalfa collection might be valuable in effective use of the genetic resources. A set of 336 worldwide genotypes of tetraploid alfalfa (Medicago sativa subsp. sativa L.) was genotyped using 85 genome-wide distributed SSR markers to reveal the genetic diversity and population structure in the alfalfa. Genetic diversity analysis identified a total of 1056 alleles across 85 marker loci. The average expected heterozygosity and polymorphism information content values were 0.677 and 0.638, respectively, showing high levels of genetic diversity in the cultivated tetraploid alfalfa germplasm. Comparison of genetic characteristics across chromosomes indicated regions of chromosomes 2 and 3 had the highest genetic diversity. A higher genetic diversity was detected in alfalfa landraces than that of wild materials and cultivars. Two populations were identified by the model-based population structure, principal coordinate and neighbor-joining analyses, corresponding to China and other parts of the world. However, lack of strictly correlation between clustering and geographic origins suggested extensive germplasm exchanges of alfalfa germplasm across diverse geographic regions. The quantitative analysis of the genetic diversity and population structure in this study could be useful for genetic and genomic analysis and utilization of the genetic variation in alfalfa breeding.