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Y(a,x) reactions MC-50 cyclotron Stacked-foil activation technique Excitation functionOff line c-ray spectrometry a b s t r a c tThe excitation functions of 89g,m,90,91m,92m Nb, 88,89 Zr, and 87g,m,88,90m,91m Y from alpha-induced reactions on 89 Y were measured from their respective threshold to 45 MeV by using a stacked-foil activation technique at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences. The results were compared with the earlier reported data as well as with the theoretical values obtained from the TENDL-2013 library based on the TALYS1.6 code. Our measurements in the energy region from the threshold energy to 45 MeV are in general good agreement with the other experimental data and calculated results. The integral yields for thick target of the produced radionuclides were also deduced from their measured cross sections and the stopping power of 89 Y. The measured excitation functions find importance in various practical applications including nuclear medicine and improvement of nuclear model calculations.

Populus trichocarpa has been studied as a model poplar species through biomolecular approaches and was the first tree species to be genome sequenced. In this study, we employed a high throughput RNA-sequencing (RNA-seq) mediated leaf transcriptome analysis to investigate the response of four different Populus davidiana cultivars to drought stress. Following the RNA-seq, we compared the transcriptome profiles and identified two differentially expressed genes (DEGs) with contrasting expression patterns in the drought-sensitive and tolerant groups, i.e., upregulated in the drought-tolerant P. davidiana groups but downregulated in the sensitive group. Both these genes encode a 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme required for abscisic acid (ABA) biosynthesis. The high-performance liquid chromatography (HPLC) measurements showed a significantly higher ABA accumulation in the cultivars of the drought-tolerant group following dehydration. The Arabidopsis nced3 loss-of-function mutants showed a significantly higher sensitivity to drought stress, ~90% of these plants died after 9 days of drought stress treatment. The real-time PCR analysis of several key genes indicated a strict regulation of drought stress at the transcriptional level in the P. davidiana drought-tolerant cultivars. The transgenic P. davidiana NCED3 overexpressing (OE) plants were significantly more tolerant to drought stress as compared with the NCED knock-down RNA interference (RNAi) lines. Further, the NCED OE plants accumulated a significantly higher quantity of ABA and exhibited strict regulation of drought stress at the transcriptional level. Furthermore, we identified several key differences in the amino acid sequence, predicted structure, and co-factor/ligand binding activity of NCED3 between drought-tolerant and susceptible P. davidiana cultivars. Here, we presented the first evidence of the significant role of NCED genes in regulating ABA-dependent drought stress responses in the forest tree P. davidiana and uncovered the molecular basis of NCED3 evolution associated with increased drought tolerance.

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