Development of Soybean EST-SSR Markers and Their Use to Assess Genetic Diversity in the Subgenus Soja

Developing expressed sequence tag-derived SSR （EST-SSR） markers is imperative in genetic research. In this paper, we reported 37 EST-SSR markers which were developed from 286 unigenes obtained from soybean cDNA library. Among the 286 markers designed for the 4 accessions of Glycine max and 6 of its wild progenitor （G. soja） within the subgenus Soja, 209 markers amplified DNA fragments, taking 73.1% and 37 markers appeared to be polymorphic, which was 12.9% of the total. The 37 loci detected a total of 142 alleles, while the PIC values varied from 0.194 to 0.794. Both the number of alleles per locus and PIC value were significantly related to the SSR motif. Six EST-SSR loci may be fixed for different alleles between G. max and G. soja since they were particularly polymorphic among the 6 G. soja accessions. A neighbor-joining tree placed the G. max accessions together as a group within the G. soja, though the average genetic distance among G. soja accessions was much higher. These new EST-SSRs markers will be useful for genetic diversity analysis, genetic mapping construction and gene discovery in Soja subgenus.

A genetic linkage map with 178 SSR and 1901 SNP markers constructed using a RIL population in wheat (Triticum aestivum L.)

The construction of high density genetic linkage map provides a powerful tool to detect and map quantitative trait loci(QTLs) controlling agronomically important traits. In this study, simple sequence repeat(SSR) markers and Illumina 9K i Select single nucleotide polymorphism(SNP) genechip were employed to construct one genetic linkage map of common wheat(Triticum aestivum L.) using 191 recombinant inbred lines(RILs) derived from cross Yu 8679×Jing 411. This map included 1 901 SNP loci and 178 SSR loci, covering 1 659.9 c M and 1 000 marker bins, with an average interval distance of 1.66 c M. A, B and D genomes covered 719.1, 703.5 and 237.3 c M, with an average interval distance of 1.66, 1.45 and 2.9 c M, respectively. Notably, the genetic linkage map covered 20 chromosomes, with the exception of chromosome 5D. Bioinformatics analysis revealed that 1 754(92.27%) of 1 901 mapped SNP loci could be aligned to 1 215 distinct wheat unigenes, among which 1 184(97.4%) were located on o ne single chromosome, and the rest 31(2.6%) were located on 2 to 3 chromosomes. By performing in silico comparison, 214 chromosome deletion bin-mapped expressed sequence tags(ESTs), 1 043 Brachypodium genes and 1 033 rice genes were further added onto the genetic linkage map. This map not only integrated genetic and physical maps, SSR and SNP loci, respectively, but also provided the information of Brachypodium and rice genes corresponding to 1 754 SNP loci. Therefore, it will be a useful tool for comparative genomics analysis, fine mapping of QTL/gene controlling agronomically important traits and marker-assisted selection breeding in wheat.

Proteomic Identification of Rhythmic Proteins in Maize Seedling Leaves

Plant leaves respond to day/night cycling in a number of physiological ways. At the mRNA level, the expression of some genes changes during the 24 h period. To determine which proteins exhibited a rhythmic pattern of expression, proteomic profiles in maize seedling leaves were analyzed by high-throughput two-dimensional gel electrophoresis, combined with MALDI-TOF MS technology. Of the 464 proteins that were detected with silver staining in a pH range of 4-7, 17 （3.66%） showed clock rhythmicity in their abundance. These proteins belonged to diverse functional groups and proteins involved in photosynthesis and carbon metabolism were over-represented. These findings provide a new perspective on the relationship between the physiological functions of leaves and the clock rhythmic system.

Membrane Transporters for Nitrogen,Phosphate and Potassium Uptake in Plants

Nitrogen, phosphorous and potassium are essential nutrients for plant growth and development. However, their contents in soils are limited so that crop production needs to invest a lot for fertilizer supply. To explore the genetic potentialities of crops （or plants） for their nutrient utilization efficiency has been an important research task for many years, in fact, a number of evidences have revealed that plants, during their evolution, have developed many morphological, physiological, biochemical and molecular adaptation mechanisms for acquiring nitrate, phosphate and potassium under stress conditions. Recent discoveries of many transporters and channels for nitrate, phosphate and potassium uptake have opened up opportunities to study the molecular regulatory mechanisms for acquisition of these nutrients. This review aims to briefly discuss the genes and gene families for these transporters and channels, in addition, the functions and regulation of some important transporters and channels are particularly emphasized.

Plant Sensing and Signaling in Response to K＋-Deficiency

Potassium （K＋） is one of the essential macronutrients for plant growth and development. However, K＋ content in soils is usually limited so that the crop yields are restricted. Plants may adapt to K＋-deficient environment by adjusting their physiological and morphological status, indicating that plants may have evolved their sensing and signaling mechanisms in response to K＋-deficiency. This short review particularly discusses some components as possible sensors or signal transducers involved in plant sensing and signaling in response to K＋-deficiency, such as K＋ channels and transporters, H＋-ATPase, some cytoplasmic enzymes, etc. Possible involvement of Ca2＋ and ROS signals in plant responses to K＋-deficiency is also discussed.

Shaping polyploid wheat for success:Origins,domestication,and the genetic improvement of agronomic traits

Bread wheat(Triticum aestivum L.,AABBDD,2 n=6 x=42),which accounts for most of the cultivated wheat crop worldwide,is a typical allohexaploid with a genome derived from three diploid wild ancestors.Bread wheat arose and evolved via two sequential allopolyploidization events and was further polished through multiple steps of domestication.Today,cultivated allohexaploid bread wheat has numerous advantageous traits,including adaptive plasticity,favorable yield traits,and extended end-use quality,which have enabled its cultivation well beyond the ranges of its tetraploid and diploid progenitors to become a global staple food crop.In the past decade,rapid advances in wheat genomic research have considerably accelerated our understanding of the bases for the shaping of complex agronomic traits in this polyploid crop.Here,we summarize recent advances in characterizing major genetic factors underlying the origin,evolution,and improvement of polyploid wheats.We end with a brief discussion of the future prospects for the design of gene cloning strategies and modern wheat breeding.

Potassium Transporter KUP7 Is Involved in K^＋ Acquisition and Translocation in Arabidopsis Root under K^＋-Limited Conditions

Potassium （K^＋） is one of the essential macronutrients for plant growth and development. K^＋ uptake from environment and K^＋ translocation in plants are conducted by K^＋ channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K^＋ uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on Iow-K^＋ medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K^＋ uptake rate and K^＋ content in xylem sap under W-deficient conditions. Thus, the K^＋ content in kup7 shoot was significantly reduced under Iow-K^＋ conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K^＋ transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level inArabidopsis root. Together, our data demonstrated that KUP7 is crucial for K^＋ uptake inArabidopsis root and might be also involved in K^＋ transport into xylem sap, affecting K^＋ translocation from root toward shoot, especially under K^＋-Iimited conditions.

Arabidopsis Di 19 Functions as a Transcription Factor and Modulates PR1, PR2, and PR5 Expression in Response to Drought Stress

The Arabidopsis Di19 （Drought-induced） gene family encodes seven Cys2/His2-type zinc-finger proteins, most with unknown functions. Here, we report that Di19 functioned as a transcriptional regulator and was involved in Arabidopsis responses to drought stress through up-regulation of pathogenesis-related PR1, PR2, and PR5 gene expres- sions. The Di19 T-DNA insertion mutant di19 was much more sensitive to drought stress, whereas the Di19-overexpressing lines were much more tolerant to drought stress compared with wild-type plants. Di19 exhibited transactivation activity in our yeast assay, and its transactivation activity was further confirmed in vivo. DNA-binding analysis revealed that Di19 could bind to the TACA（A/G）T element and chromatin immunoprecipitation （CHIP） assays demonstrated that Di19 could bind to the TACA（A/G）T element within the PR1, PR2, and PR5 promoters, qRT-PCR results showed that Di19 promoted the expressions of PR1, PR2, and PRS, and these heightened expressions were enhanced by CPK11, which interacted with Di19 in the nucleus. Similarly to the Di19-overexpressing line, PRI-, PR2-, and PRS-overexpressing lines also showed the drought-tolerant phenotype. The pre-treatment with salicylic acid analogs INA can enhance plants＇ drought tolerance. Taken together, these data demonstrate that Di19, a new type of transcription factor, directly up-regulates the expres- sions of PR1, PR2, and PR5 in response to drought stress, and its transactivation activity is enhanced by CPK11.

MEDICAL APPLICATIONS OF BIOPOLYESTERS POLYHYDROXYALKANOATES

Microbial polyhydroxyalkanoates （PHAs） are a family of biopolyesters produced by many wild type and engineered bacteria. PHAs have diverse structures accompanied by flexible thermal and mechanical properties. Combined with their in vitro biodegradation, cell and tissue compatibility, PHAs have been studied for medical applications, especially medical implants applications, including heart valve tissue engineering, vascular tissue engineering, bone tissue engineering, cartilage tissue engineering, nerve conduit tissue engineering as well as esophagus tissue engineering. Most studies have been conducted in the authors＇ lab in the past 20＋ years. Recently, mechanism on PHA promoted tissue regeneration was revealed to relate to cell responses to PHA biodegradation products and cell-material interactions mediated by microRNA. Very importantly, PHA implants were found not to cause carcinogenesis during long-term implantation. Thus, PHAs should have a bright future in biomedical areas.

Transcriptome Comparison of Susceptible and Resistant Wheat in Response to Powdery Mildew Infection

Powdery mildew （Pro） caused by the infection of Blumeria graminis f. sp. tritici （Bgt） is a worldwide crop disease resulting in significant loss of wheat yield. To profile the genes and pathways responding to the Bgt infection, here, using Affymetrix wheat microarrays, we compared the leaf transcriptomes before and after Bgt inoculation in two wheat genotypes, a Pm-susceptible cultivar Jingdong 8 （S） and its near-isogenic line （R） carrying a single Pm resistant gene Pm30. Our analysis showed that the original gene expression status in the S and R genotypes of wheat was almost identical before Bgt inoculation, since only 60 genes exhibited differential expression by P = 0.01 cutoff. However, 12 h after Bgt inoculation, 3014 and 2800 genes in the S and R genotype, respectively, responded to infec- tion. A wide range of pathways were involved, including cell wall fortification, flavonoid biosynthesis and metabolic processes. Further- more, for the first time, we show that sense-antisense pair genes might be participants in wheat-powdery mildew interaction. In addition, the results of qRT-PCR analysis on several candidate genes were consistent with the microarray data in their expression patterns. In summary, this study reveals leaf transcriptome changes before and after powdery mildew infection in wheat near-isogenic lines, suggest- ing that powdery mildew resistance is a highly complex systematic response involving a large amount of gene regulation.