Characterization of the temporal and spatial expression of wheat (Triticum aestivum L.) plant height at the QTL level and their influence on yield-related traits.

KEY MESSAGE: The temporal and spatial expression patterns of stable QTL for plant height and their influences on yield were characterized. Plant height (PH) is a complex trait in wheat (Triticum aestivum L.) that includes the spike length (SL) and the internode lengths from the first to the fifth internode, which are counted from the top and abbreviated as FIRITL, SECITL, THIITL, FOUITL, and FIFITL, respectively. This study identified eight putative additive quantitative trait loci (QTL) for PH. In addition, unconditional and conditional QTL mapping were used to analyze the temporal and spatial expression patterns of five stable QTL for PH. qPh-3A mainly regulated SL, FIRITL, and FIFITL to affect PH during the booting-heading stage (BS-HS); qPh-3D regulated all internode lengths to affect PH, especially during the BS-HS; before HS, qPh-4B mainly affected FIRITL, SECITL, THIITL, and FOUITL and qPh-5A.1 mainly affected SECITL, THIITL, and FOUITL to regulate PH; and qPh-6B mainly regulated FIRITL to affect the PH after the booting stage (BS). qPhdv-4B, a QTL for the response of PH to nitrogen stress, was stable and co-localized with qPh-4B. All five stable QTL, except for qPh-3A, were related to the 1000 kernel weight and yield per plant. Regions of qPh-3A, qPh-3D, qPh-4B, qPh-5A.1, and qPh-6B showed synteny to parts of rice chromosomes 1, 1, 3, 9, and 2, respectively. Based on comparative genomics analysis, Rht-B1b was cloned and mapped in the CI of qPh-4B. This report provides useful information for fine mapping of the stable QTL for PH and the genetic improvement of wheat plant type.

QTL detection for wheat kernel size and quality and the responses of these traits to low nitrogen stress.

KEY MESSAGE: QTLs for kernel characteristics and tolerance to N stress were identified, and the functions of ten known genes with regard to these traits were specified. Kernel size and quality characteristics in wheat (Triticum aestivum L.) ultimately determine the end use of the grain and affect its commodity price, both of which are influenced by the application of nitrogen (N) fertilizer. This study characterized quantitative trait loci (QTLs) for kernel size and quality and examined the responses of these traits to low-N stress using a recombinant inbred line population derived from Kenong 9204 × Jing 411. Phenotypic analyses were conducted in five trials that each included low- and high-N treatments. We identified 109 putative additive QTLs for 11 kernel size and quality characteristics and 49 QTLs for tolerance to N stress, 27 and 14 of which were stable across the tested environments, respectively. These QTLs were distributed across all wheat chromosomes except for chromosomes 3A, 4D, 6D, and 7B. Eleven QTL clusters that simultaneously affected kernel size- and quality-related traits were identified. At nine locations, 25 of the 49 QTLs for N deficiency tolerance coincided with the QTLs for kernel characteristics, indicating their genetic independence. The feasibility of indirect selection of a superior genotype for kernel size and quality under high-N conditions in breeding programs designed for a lower input management system are discussed. In addition, we specified the functions of Glu-A1, Glu-B1, Glu-A3, Glu-B3, TaCwi-A1, TaSus2, TaGS2-D1, PPO-D1, Rht-B1, and Ha with regard to kernel characteristics and the sensitivities of these characteristics to N stress. This study provides useful information for the genetic improvement of wheat kernel size, quality, and resistance to N stress.

iTRAQ-based proteome profiling of hyposaline responses in zygotes of the Pacific oyster Crassostrea gigas.

Low salinity treatment is proven to be the practical polyploidy inducing method for shellfish with advantages of lower cost, higher operability and reliable food security. However, little is known about the possible molecular mechanism of hypotonic induction. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) based proteomic profiling was pursued to investigate the responses of zygotes of the Pacific oyster Crassostrea gigas to low salinity. A total of 2235 proteins were identified and 87 proteins were considered differentially expressed, of which 14 were up-regulated and 69 were down-regulated. Numerous functional proteins including ADP ribosylation factor 2, DNA repair protein Rad50, splicing factor 3B, tubulin-specific Chaperone D were significantly changed in abundance, and were involved in various biology processes including energy generation, vesicle trafficking, DNA/RNA/protein metabolism and cytoskeleton modification, indicating the prominent modulation of cell division and embryonic development. Parallel reaction monitoring (PRM) analyses were carried out for validation of the expression levels of differentially expressed proteins (DEPs), which indicated high reliability of the proteomic results. Our study not only demonstrated the proteomic alterations in oyster zygotes under low salinity, but also provided, in part, clues to the relatively lower hatching rate and higher mortality of induced larvae. Above all, this study presents a valuable foundation for further studies on mechanisms of hypotonic induction.