Co-overexpression of genes for nitrogen transport, assimilation, and utilization boosts rice grain yield and nitrogen use efficiency

Nitrogen(N)fertilization is necessary for obtaining high rice yield.But excessive N fertilizer reduces rice plant N efficiency and causes negative effects such as environmental pollution.In this study,we assembled key genes involved in different nodes of N pathways to boost nitrate and ammonium uptake and assimilation,and to strengthen amino acid utilization to increase grain yield and nitrogen use efficiency(NUE)in rice.The combinations OsNPF8.9a×OsNR2,OsAMT1;2×OsGS1;2×OsAS1,and OsGS2×OsAS2×OsANT3 optimized nitrate assimilation,ammonium conversion,and N reutilization,respectively.In co-overexpressing rice lines obtained by co-transformation,the tiller number,biomass,and grain yield per plant of the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line exceeded those of wild-type ZH11,the OsNPF8.9a×OsNR2×OsGS1;2×OsAS1-overexpressing line,and the OsGS2×OsAS2×OsANT3-overexpressing line.The glutamine synthase activity,free amino acids,and nitrogen utilization efficiency(NUt E)of the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line exceeded those of ZH11 and other lines that combined key genes.N influx efficiency was increased in the OsAMT1;2×OsGS1;2×OsAS1-overexpressing line and OsNPF8.9a×OsNR2×OsGS1;2×OsAS1-overexpressing line under a low ammonium and a low nitrate treatment,respectively.We propose that combining overexpression of OsAMT1;2,OsGS1;2,and OsAS1 is a promising breeding strategy for systematically increasing rice grain yield and NUE by focusing on key nodes in the N pathway.

Negative thermal diffusivity enhancement in semiconductor nanofluids

Colloidal suspensions of semiconductor InP@ZnS nanoparticles were prepared using single-step procedure without precursor injection. Thermal properties of toluene containing InP@ZnS semiconductor with different sizes (3.1, 4.2, and 4.6 nm) were measured by mode mismatched dualbeam thermal lens technique. This was done in order to measure the effect of the presence of semiconductor nanoparticles and size on the nanofluids thermal diffusivity. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens. The thermal diffusivity of the nanofluids (toluene, containing InP@ZnS semiconductor nanoparticles) it seems to be strongly dependent on the presence of semiconductor nanoparticles and particles size. For the case of nanofluids consisting of InP@ZnS nanoparticles dispersed in toluene, it was observed a decrease in the thermal diffusivity. Such behavior differs from other nanofluids, in the sense that they had shown positive thermal diffusivity enhancement. The minimum diffusivity was achieved for the nanoparticles with lowest size. Plausible explanation for such nanofluids low thermal diffusivity with semiconductor nanoparticles is given. UV-Vis spectroscopy, TEM and high-resolution electron microscopy (HRTEM), and energy dispersive spectroscopy (EDS) techniques were used to characterize the InP@ZnS nanoparticles.

OsNPF5.16, a nitrate transporter gene with natural variation, is essential for rice growth and yield

Rice has a large number of nitrate or peptide transporter family(NPF) genes, but the effects of most members on rice growth and development are unknown. We report that Os NPF5.16, a nitrate transporter gene with natural variation in its promoter sequence, is essential for rice growth and yield. The promoter sequence showed various differences between indica and japonica cultivars, and higher expression of Os NPF5.16 was found in indica cultivars with higher plant weight and more tillers than japonica cultivars.Os NPF5.16 was highly expressed in roots, tiller basal parts, and leaf sheaths, and its protein was localized on the plasma membrane. In c RNA-injected Xenopus laevis oocytes, Os NPF5.16 transport of nitrate at high nitrate concentration depended on p H. Overexpression of Os NPF5.16 increased nitrate content and total nitrogen content in leaf sheath as well as biomass and tiller bud length in rice. Elevated expression of Os NPF5.16 increased rice tiller number and grain yield by regulating cytokinin levels. Inhibition of Os NPF5.16 expression showed the opposite effects. Regulating Os NPF5.16 expression has potential for improving rice grain yield.

Bioinformatics and Expression Analysis of CPMAX2 in Citrange

Transgenic citrange lines with rol ABC genes behave rosette branching and extreme dwarfing.To explore the regulatory mechanism of plant hormones in axillary shoot growth of transgenic citrange,a full length cD NA of CPMAX2 was cloned from citrange [Citrus sinensis(L.) Osb × Poncirus trifoliate(L.) Raf.] by RT-PCR in this study.The expression of CPMAX2 was detected in axillary tender leaves of 3 transgenic citrange lines and the wild type.Additionally,we constructed an over-expression vector CPMAX2-p CAMBIA1301 for further study.The results showed that the c DNA sequence and its putative peptide sequence shared 99.66% and 99.14% of identity with its Citrus sinensis ortholog MAX2.The deduced amino acid sequence contained putatively one F-box and two LRR repeat domains that are highly conserved in MAX2 genes.CPMAX2 was obviously down-expressed in tender leaves of 3 transgenic citrange lines compared with the wild type.The results suggest CPMAX2 play an important role in regulating the rosette shoot growth in transgenic citrange with rol ABC genes.