Search

Taking cold-resistant maize variety Fengdan 3 and cold-sensitive maize variety Zhengdan 958 as test materials, field experiments were conducted in I, II, and III accumulated temperature zones in Heilongjiang Province of Northeast China to study the effects of different accumulated temperature on the photosynthetic performances of different types of cold-resistant spring maize varieties during their grain-filling period. In the three accumulated temperature zones, the tasseling and maturing periods of Fengdan 3 and Zhengdan 958 were prolonged in the order of I > II > and III, and the grain bulk density decreased in the same order. The RuBPCase and PEPCase activities of Fengdan 3 and Zhengdan 958 leaves had different temperature sensitivity. For Fengdan 3, its leaf RuBPCase and PEPCase activities were high in early grain filling period (0-20 days after anthesis), and the variety could ripen in temperature-limited region. For Zhengdan 958, its leaf RuBPCase and PEPCase activities were high within 0-10 days and 40-60 days after anthesis but not sensitive to the active accumulated temperature during 10-40 days after anthesis, and the variety could not ripen in temperature-limited region. The photosynthetic rates of the two varieties were significantly positively correlated with the active accumulated temperature during 0-10 days and 30-40 days after anthesis. The effects of the accumulated temperature in the three zones on the photosynthetic performances were significant at both early and later grain filling stages. For the same varieties, the higher the active accumulated temperature in grain filling period, the higher the grain yield. Zhengdan 958 had higher yield than Fengdan 3. [ABSTRACT FROM AUTHOR]

Taking cold-resistant maize variety Fengdan 3 and cold-sensitive maize variety Zhengdan 958 as test materials, field experiments were conducted in I, II, and III accumulated temperature zones in Heilongjiang Province of Northeast China to study the effects of different accumulated temperature on the photosynthetic performances of different types of cold-resistant spring maize varieties during their grain-filling period. In the three accumulated temperature zones, the tasseling and maturing periods of Fengdan 3 and Zhengdan 958 were prolonged in the order of I > II > and III, and the grain bulk density decreased in the same order. The RuBPCase and PEPCase activities of Fengdan 3 and Zhengdan 958 leaves had different temperature sensitivity. For Fengdan 3, its leaf RuBPCase and PEPCase activities were high in early grain filling period (0-20 days after anthesis), and the variety could ripen in temperature-limited region. For Zhengdan 958, its leaf RuBPCase and PEPCase activities were high within 0-10 days and 40-60 days after anthesis but not sensitive to the active accumulated temperature during 10-40 days after anthesis, and the variety could not ripen in temperature-limited region. The photosynthetic rates of the two varieties were significantly positively correlated with the active accumulated temperature during 0-10 days and 30-40 days after anthesis. The effects of the accumulated temperature in the three zones on the photosynthetic performances were significant at both early and later grain filling stages. For the same varieties, the higher the active accumulated temperature in grain filling period, the higher the grain yield. Zhengdan 958 had higher yield than Fengdan 3.

Taking the two maize varieties Zhengdan 958 and Fengdan 3 grown on the three accumulated temperature zones (I, II and III) in Heilongjiang Provice as test materials, a field investigation was made in 2010 and 2011 to study the effects of PASP-KT-NAA (PKN), a compound of exogenous plant growth regulators, on the grain filling and yield of the varieties under different environmental temperatures. From zone I to III, the air temperature at the grain filling stage had a decreasing trend, with the average minimum temperature being 12.16, 11.40, and 9.56, respectively. The effective accumulated temperature at the mid-ate amt sae stage of grain filling was too low to be sufficient for grain filling, which severely affected the grain filling process. Applying N, P and K promoted the dry matter accumulation of maize grain and the grain filling rate in the three zones, delayed the peak time (Tmax) of the grain filling rate of Fengdan 3 but advanced that of Zhengdan 958, promoted the growth capacity at peak time of grain filling rate and the maximum grain filling rate of the two varieties, and shortened their active grain filling period. Applying N, P, and K increased the grain yield of the two varieties in the three zones obviously, and, as compared with those in zones I and II , the grain yields of Zhengdan 958 and Fengdan 3 in zone III were increased by 8.2% and 5.1% , and 3.4% and 0.8% , respectively. Therefore, applying N, P and K could help maize utilizing the limited accumulation temperature, improve the grain filling rate, decrease the grain water content, and ultimately, increase the maize yield.

MicroRNAs (miRNAs) are endogenous 16-29 nt non-coding small RNAs that were are generally found in species and typically encoded by endogenous genes. They play an important regulatory role at post-transcription level by targeting mRNA cleavage and translation repression. More and more plant miRNAs had been predicted and identified along with the development of bioinformatics and experimental techniques. At stress conditions, plant miRNAs also play a role in adaptation by up-regulating or down-regulating the miRNA expression. The biogenesis, action mode with target genes, bio-logical functions of plant miRNAs, as well as the stress-responsive miRNAs, were reviewed and the methodologies of miRNA study were also briefly summarized in this paper.

From the digital images of the red complex which resulted in the interaction of nitrite with N-(1-naphthyl) ethylenediamine dihydrochloride and P-Aminobenzene sulfonic acid, it could be seen that the solution colors obviously increased with increasing the concentration of nitrite ion. The JPEG format of the digital images was transformed into gray-scale format by origin 7.0 software, and the gray values were measured with scion image software. It could be seen that the gray values of the digital image obviously increased with increasing the concentration of nitrite ion, too. Thus a novel digital imaging colorimetric (DIC) method to determine nitrogen oxides (NO(x)) contents in air was developed. Based on the red, green and blue (RGB) tricolor theory, the principle of the digital imaging colorimetric method and the influential factors on digital imaging were discussed. The present method was successfully applied to the determination of the daily changes curve of nitrogen oxides in the atmosphere and NO2- in synthetic samples with the recovery of 97.3%-104.0%, and the relative standard deviation (RSD) was less than 5.0%. The results of the determination were consistent with those obtained by spectrophotometric method.

A molecular linkage map for the maize hybrid of cross between Ye478 and Dan340 was constructed by using 150 co-dominant SSR markers. The total map length was 1 478.7 cM with an average interval of 10.0 cM. Composite interval mapping was used to identify the plant height (PH) and ear position (EH) QTL at 5 environments based on the phenotypic data of 397 F2:3 families. Then 21 PH and 25 EH relevant QTL were identified. The mean contribution of 12.2% and 14.9% QTL for plant height was identified at the interval of umc2025 - umc1035 on chromosome 1 and umc1822 - bnlg1118 on chromosome 5, respectively. Meanwhile, the mean contribution of 10.2% and 22.8% to ear position were identified at the interval of phi029 - umc1102 on chromosome 3 and phi109188 - bnlg1118 on chromosome 5. The main QTL for PH and EH were both found at the regions of Bin5.05 - 5.07 on chromosome 5. The additive and partial dominant effects were the main genetic basis for plant height and ear position in maize. The effect of population size and environments on QTL mapping were analyzed.

The development of genomics and bioinformatics offers new tools for comparative gene mapping. In this paper, an integrated QTL map for Sugarcane mosaic virus (SCMV) resistance in maize was constructed by compiling a total of 81 QTL loci available with the Genetic Map IBM2 2005 Neighbors as reference. These 81 QTL loci were scattered on 7 chromosomes of maize, and most of them was clustered on chromosome 3 and 6. By using meta- analysis method, we identified one and two "consensus QTLs" on chromosomes 3 and 6, respectively. These three QTLs cover the genetic distances of 6.44 cM, 6.16 cM and 27.48 cM on the genetic map IBM2 2005 Neighbors, respectively. Four positional candidate resistant genes were identified within the "consensus QTL" on chromosome 3 via comparative genomics strategy. These results suggested that application of the combined meta-analysis within a species with sequence homologous comparison in a related model plant is an efficient approach to identify the major QTL and its candidate gene(s) for the target traits. The results of this study provided useful information for identifying and cloning of the major gene(s) conferring resistance to SCMV in maize.

Maize (Zea mays L.) breeders have begun selecting for more compact plants for higher density planting in order to increase yield per unit area. Leaf angle and leaf orientation are very important traits affecting maize plant type (compactness). In this study, a genetic linkage map containing 138 simple sequence repeat (SSR) markers was constructed based on a mapping population consisting of 500 F2 individuals from the cross between inbred lines Ye478 and Dan340. This SSR linkage map spans a total of 1 394.9 cM with an average interval of 10.1 cM. Quantitative trait loci (QTL) for leaf angle and leaf orientation were identified in 397 F2:3 families. Six QTL for leaf angle were detected that could explain 41.0% of the phenotypic variation; while, eight QTL were detected for leaf orientation that could explain 60.8% of the phenotypic varia-tion. Single QTL contribution to phenotypic variation ranged from 2.9% to 13.6%. Additive and partial dominance were the main genetic effects for leaf angle and leaf orientation; in addition, nine pairs of locus interactions were detected for the two traits, indicating that epistatic interactions at the two-loci level also play a measurable role in the genetic basis of the two traits.

The unicellular alga Chlamydomonas offers a simple life cycle, easy culture and isolation of series of mutants, established the techniques and tool kit for molecular genetics and genetics analysis. It is now becoming the model organism for studies on photosynthesis in plant, flagellar assembly and function, cell cycle and circadian rhythms, signal transduction, light perception and cell recognition. It is summarized the progress of study on Chlamydomonas as a model organism in this paper.