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Due to excessive soil acidification, aluminum in soil has become one of the main factors limiting crop growth and yield. In this study, a high generation of recombinant inbred line (RIL) population constructed from Brassica napus L. varieties Zhong-shuang 11 (ZS11) and 10D130 treated with 2400 µmol L-1 aluminum solution was used as experimental materials. To explore the photosynthetic capacity and chlorophyll fluorescence related traits of rapeseed seedling stage under aluminum toxicity stress, we calculated their relative values (treatment/control) and mapped their QTLs, and screened suitable candidate genes according to the confidence interval of QTLs. The results showed that there was significantly correlation between photosynthetic capacity and chlorophyll fluorescence parameters, but there was no significant correlation between photosynthetic capacity and the chlorophyll fluorescence parameters. Relative Pn, relative Gs, relative Ci, relative ΦPSII, relative Fv/Fo, relative Fv'/Fm', relative qP, relative ETR, relative NPQ, and relative dry weight were investigated and QTLs mapping were analyzed. A total of 16 QTLs related to aluminum stress and photosynthesis were detected. The locus was located on chromosomes A03, A05, A06, A08, A09, A10, C02, and C09, respectively. LOD value was 2.05-3.18, and the phenotypic variation explained was 8.1%-12.3%. The confidence intervals of QTLs for relative Gs and relative Fv'/Fm', relative ΦPSII and relative ETR were found completely overlap at 106.038--109.129 cM of chromosome A03, 145.355-167.417 cM of chromosome A06, respectively. 47 candidate genes that may be related to aluminum stress and photosynthesis were screened, involving organic acid secretion, metal ion transport, hormone regulation, initiation of antioxidant protection, chloroplast self-regulation, and phosphorus uptake regulation. This study lays the foundation for the function research of aluminum resistance and related photosynthetic genes and the breeding of aluminum tolerant and high photosynthetic efficiency rapeseed. [ABSTRACT FROM AUTHOR]

With the aggravation of soil acidification, aluminum toxicity has become one of the important stress factors that affect crop seed germination quality and crop yield. There have been many reports on QTL mapping and candidate gene screening for aluminum tolerance related traits in crops, but few reports on QTL mapping for aluminum tolerance during germination in Brassica napus L. The seed germination test was conducted on the recombinant inbred line population treated with 80 µg mL-1 aluminum solution and with distilled water as control. Germination potential was investigated at 3 d, germination rate was investigated at 7 d, root length, bud length and dry weight were measured, and the relative values of various characters were calculated. Based on 6K SNP chip and combined with high density genetic linkage map, we detected 23 QTLs for five traits in rape germination period. QTLs for relative germination potential, relative germination rate, relative root length, relative bud length and relative dry weight were 9, 1, 4, 5, and 4 respectively, covering A and C genomes, with LOD values from 3.00 to 5.26, and interpretable phenotypic variation from 7.70% to 13.10%. According to the confidence interval sequence of each QTL, 30 candidate genes related to aluminum stress were screened. ALMT1 gene and MATE gene are related to the synthesis and secretion of organic acids, which mainly enhance the aluminum tolerance of plants through the secretion of organic acids such as malic acid, citric acid and oxalic acid. STOP1 gene, NAC gene and RAP2.4 gene all belong to transcription activation factors, which enhance the resistance of plants by inducing the expression of aluminum tolerance genes. ABC transporter, membrane protein transporter, GDSL lipase enhance aluminum tolerance of plants by reducing accumulation of toxic substances on plasma membrane or discharging toxic substances out of body. Peroxidase and cytochrome P450 are genes related to oxidative stress, which have the functions of preventing oxidative damage of plant cells and resisting stress. At the same time, many genes encoding stress proteins were found, which play an important role in various stress reactions. The results of this study provide a theoretical basis for the cultivation of aluminum-tolerant rape varieties and the functional research of subsequent genes. [ABSTRACT FROM AUTHOR]

The development characteristics and improvement measures of aquatic plants were studied in Shijiuyang Constructed Wetland (SCW) at its initial operation stage. SCW was a large-scale wetland aiming to help relieve the source water pollution in Jiaxing City. A checklist of vascular plants in SCW was built, and species composition, life forms, biomass and association distributions were examined. Our objectives were to examine the diversity and community structure of aquatic plants in SCW at its initial operation stage, and to find out the possible hydrophyte improvement measures. The survey results showed that there were 49 vascular plant species belonging to 41 genera, 25 families in SCW, which greatly exceeded the artificially transplanted 13 species. The life forms of present aquatic plants in SCW were dominated by hygrophilous plants (20 species) and emerged plants (17 species), which accounted for 75.5% of the total number of aquatic plants. The aquatic plants transplanted artificially were dominated by emerged plants (accounted for 69.2%), while those naturally developed were predominated by hygrophilous plants (accounted for 47.2%). The horizontal distribution of aquatic plant community in SCW was mixed in the form of mosaics, which made up typical association complex. Except association Aeschynomene indica L., the dominant species of other associations were all those transplanted artificially. The naturally grown species scattered throughout the SCW and only occupied a small percentage. A marked difference was detected on the species and species richness of aquatic plants in different regions of SCW. Biomass of aquatic plant associations in SCW was 167.7 t. SCW has shown a trend of succession heading for quick increase of plant diversity at the primary operation stage. This trend provides a good material base for the future stable community of aquatic plants in SCW. According to the current status of aquatic plants, some suggestions were put forward on the further optimization and utilization of aquatic plant systems in SCW.