Association mapping of quantitative trait loci for yield-related agronomic traits in rice(Oryza sativa L.)

High yield in rice mainly depends on large grain weight, ideal plant architecture and proper flowering time adapting to various geographic regions. To help achieve higher yield, phenotype variations of heading date（HD）, plant architecture and grain shape in a panel of 416 rice accessions were investigated in this study. A total of 143 markers including 100 simple sequence repeat（SSR） markers and 43 gene-tagged markers were employed in association mapping to detect quantitative trait loci（QTL） responsible for these variations. Among the 7 subpopulations, POP5 in japonica group showed the largest values of HD and grain width（GW）, but the smallest values of grain length（GL） and grain length to width ratio（GLW）. Among the six indica groups, POP7 had the largest values of HD, GL, GLW, and 1 000-grain weight（TGW）. A total of 27 QTLs were detected underlying these phenotypic variations in single year, while 12 of them could be detected in 2006 and 2007. GS3 marker was closely associated with GL, GW and GLW, and widely distributed in different groups. The starch synthesis related gene markers, SSI, SSIIa, SBE1, AGPL4, and ISA1, were linked to plant height（PH）, panicle length（PL）, flag leaf length（FLL）, GW, and GLW. The SSR markers, RM267, RM340 and RM346, were linked to at least two traits. Therefore, these new markers will probably be used to improve rice grain yield or plant architecture when performing marker-assisted selection of proper alleles.

A dCAPS marker developed from a stress associated protein gene TaSAP7-B governing grain size and plant height in wheat

Stress associated proteins（SAPs） are the A20/AN1 zinc-finger proteins which confer to abiotic stresses in plants. In this study, TaSAP7-B, including two AN1 domains, was isolated from B genome of wheat（Triticum aestivum L.）. Sequencing analysis on TaSAP7-B illustrated one In Del（insertion-deletion） and one SNP（single nucleotide polymorphism） in the promoter region while no diversity was observed in the coding region. On the basis of SNP in the promoter region（–260 bp）, a dCAPS（derived cleaved amplified polymorphic sequences） marker SNP-260 was developed for TaSAP7-B. Using a natural population consisting of 262 wheat accessions, significant associations were detected between the marker SNP-260 and agronomic traits, such as plant height（PH）, peduncle length（PL）, length of penultimate internode（LPI）, number of spike per plant（NSP）, and 1 000-grain weight（TGW）. Two genotypes were identified using marker SNP-260 in the natural population. Among them, the genotypes possessing C allele exhibited a higher TGW and shorter PH than the T genotypes. Hence, base C was considered as the superior allele. The dCAPS marker of TaSAP7-B can be instrumental for marker-assisted selection for high grain size and short plant height.

A Comparative Study on Photosynthetic Characteristics of Dryopteris fragrans and Associated Plants in Wudalianchi City,Heilongjiang Province,China

While comparing photosynthetic characteristics of Dryopteris fragrans(L.) Schott to those of several commonly associated plants in its native community, coordination between D. fragrans and its environment was observed. The diurnal net photosynthetic rate(Pn) varied dramatically for all the plants studied. D. fragrans, Woodsia ilvensis and Urtica angustifolia all exhibited unimodal type Pn variation, with low Pn, weak photosynthetic capacity, and dramatic maximal photosynthesis(Pmax) changes. When compared to values for its associated plants, D. fragrans values were of intermediate level, indicating difficulty in adapting to its environment. Moreover, the nitrate reductase activity of D. fragrans was higher than that of only one species, Artemisia gmelinii. With increasing leaf maturity and chlorophyll content, D. fragrans exhibited declining LCP(light compensation point) and a relatively low LSP(light saturation point). Because of its overall relatively weak photosynthetic capacity, D. fragrans exhibited narrow ecological amplitude with respect to light adaptation.

A systematic review of the attractant-decoy and repellent- plant hypotheses: do plants with heterospecific neighbours escape herbivory?

Aims this systematic review highlights the relative support and implica-tions of the attractant-decoy and repellent-plant hypotheses,discuss-ing important linkages between these theories and the opportunity for novel integration into ecological and applied research.Methods an extensive systematic review of the current literature on the attract-ant-decoy and repellent-plant hypotheses was done to describe the following attributes of the research to date:(i)the geographic extent(country and biome)of studies on this topic,(ii)the scope of experi-mental designs used,(iii)the level of support for these hypotheses with respect to the breadth of ecological niches tested,(iv)the level of support for these hypotheses with respect to the classes of herbi-vores examined and,lastly,(v)the ecological impact or purpose of these studies.Herein,we summarize important research gaps in the empirical literature on this topic and identify novel opportunities for critical linkages between ecological and applied theories.Important Findingsa total of 37%of experiments testing these two associated hypotheses were done in North america,frequently in either temperate broadleaf(26%of studies)or taiga ecosystems(15%of studies).the majority of these studies involved experimental manipulations such as removing and transplanting vegetation and either tracked or excluded mammalian herbivores.Ecological implications were primarily examined(59%of studies),but there were also implications described for agriculture and commercial forestry in 22%of studies.the repellent-plant hypothesis was well supported in many ecological systems,particularly for mammalian herbivores,but the attractant-decoy hypothesis has been less frequently tested,thereby representing an important research gap.Insect herbivores were under-represented in all categories except in applied contexts such as commercial forestry and agriculture.there is a clear need for studies to connect these two ecological hypotheses with the management of agriculture and restoration efforts in many ecosystems.research on the co-evolution and facilitation between palatable and unpalatable plants also represents another novel area of future study.