Acta Agronomica Sinica最新文献

The objectives of this study were to map quantitative trait loci (QTLs) for yield related trait in wheat (Triticum aestivum L.) grown in multiple environments, identify chromosomal regions harboring important loci, and validate the stability of these chromosomal regions in different environments. The QTLs for spikelet number per spike (SN), grain number per spike (GN), spike number per plant (PN), 1000-grain weight (GW), and grain yield per plant (GY) were detected using inclusive composite interval mapping method. The 2 mapping populations were the F_8:9 generations of Weimai 8 × Yannong 19 (WY population) and Weimai 8 × Jimai 20 (WJ population), which contained 229 and 485 lines, respectively. Both populations were grown in 4 environments. Numerous QTLs for the 5 traits were identified on 21 chromosomes of wheat, including 9 for SN, 9 for GN, 4 for PN, 7 for GW, and 5 for GY in the WY population and 20 for SN, 16 for GN, 11 for PN, 14 for GW, and 9 for GY in the WJ population. Sixteen and 3 major QTLs with the phenotypic contribution larger than 10% were detected in the WY and WJ populations, respectively. In addition, 5 and 17 QTLs were identified in at least 2 environments in the WY and WJ populations, respectively. Some QTLs were mapped in the same or closely linked marker intervals in both populations. Nine pairs of QTLs and 2 chromosomal regions were inferred to be identical between the 2 populations. These results may enrich the QTL information for yield components of wheat and facilitate marker-assisted selection.

A recombinant inbred line (RIL) population derived from the super hybrid rice (Oryza sativa L.) cross between XQZB and R9308 was used to identify quantitative trait loci (QTLs) for plant height (PH) and heading date (HD) under low and normal nitrogen conditions. Under both nitrogen levels, 9 QTLs for PH were mapped on chromosomes 2, 3, 6, 7, and 8, and 8 QTLs for HD were mapped on chromosomes 4, 5, 6, 7, and 8. Another 4 QTLs were responsible for the differences of PH and HD between the 2 nitrogen levels. A single QTL explained 5.68–18.40% of the phenotypic variation. Two pleiotropic QTLs with high contributions to the phenotypic variations were located near RM5436 on chromosome 7 and between RM5556 and RM310 on chromosome 8, on which the positive alleles originated from R9308. One QTL for HD difference and one QTL for PH difference were involved in the intervals RM5916-RM166 on chromosome 2 and RM2366-RM5767 on chromosome 8, respectively. Both loci were inferred to directly contribute to nitrogen use efficiency in rice.

A reference plasmid, pMD-CCS, was constructed to detect multiple target genes in the insect resistant cotton (Gossypium hirsutum L.) varieties in China. This plasmid contained cowpea trypsin inhibitor (CpTI), Bacillus thuringiensis insecticidal crystal protein (cry1A), and cotton endogenous gene Stearoyl-acyl carrier protein desaturase (Sad1) sequences targeting the key exogenous gene types. The real-time quantitative PCR methods for CpTI and cry1A were established using pMD-CCS as the reference material (RM). The dosagess of CpTI and cry1A from 9 insect resistant cotton varieties were determined. The average CpTI dosages were 0.018–0.020 copies per genome and the average cry1A dosages were 1.377–2.136 copies per genome in the 3 insect resistant cotton varieties including Kemian 3. The average cry1A dosages were 0.887–2.564 copies per genome in 6 varieties including Ezamian 1-F₁. The standard deviations of the quantitative measurement ranged from 0.001 to 0.049. These results demonstrated that pMD-CCS could be used as the RM for the quantitative measurement of CpTI and cry1A genes in insect resistant cotton varieties.

The emissions of methane (CH₄) and nitrous oxide (N₂O) were determined in double rice (Oryza sativa L.) cropping systems with different winter covering crops using the static chamber-gas chromatography technique to assess the effects of different covering crops on the emissions of greenhouse gases. Four cropping systems with different covering corps after double rice seasons, i.e., ryegrass with no-tillage (T1), Chinese milk vetch with no-tillage (T2), rape seed with tillage (T3), and potato with straw mulching and tillage (T4), were compared with the winter fallow after double rice seasons (CK). The results showed that straw recycling of winter crops significantly increased the emission of CH₄ during both rice growing seasons compared to CK. Treatments T4 and T1 had the largest CH₄ emissions during the early rice growing season with 20.713 and 16.068 g m⁻², respectively, and the T4 and T3 had the largest CH₄ emission during the later rice growing season with 60.421 and 48.666 g m⁻², respectively. The 4 treatments with winter covering crops also had larger N₂O emissions than CK in both rice seasons. Compared to the N₂O emission in CK, the emissions of the gas increased by 265% in T1, 320% in T2, 275% in T3, and 65% in T4 during the growth of early rice, and by 158% in T1, 113% in T2, 134% in T3, and 42% in T4 during the growth of late rice. The global warming potentials from paddy fields were ranked as T4 > T3 > T1 > T2 > CK. As a result, straw recycling of winter covering crops has significant effects on increase of CH₄ and N₂O emission from paddy field in double rice cropping system.

“Aimengniu” (Aifeng 3//Mengxian 201/Neuzucht) is a backbone parent for cultivar improvement of winter wheat (Triticum aestivum L.) in China. Up to 2007, 26 wheat cultivars have been developed from the crosses using Aimengniu as a parent. To disclose the genetic basis of this backbone parent in breeding process, the genetic and phenotypic differences among 7 Aimengniu-derived sib lines (types) were compared based on the results from 656 molecular markers and 16 agronomic traits. There were obvious variations among the 7 Aimengniu-derived types in the traits surveyed. The Aimengniu-derived type V showed better performance on yield components than other types. A graphical genotype integrated map was constructed using the molecular marker data, which showed the inheritance of fragments from the 3 parents to Aimengniu. Two F₂ populations (Aifeng 3/Neuzucht and Mengxian 201/Neuzucht) were developed to identify quantitative trait loci (QTLs) for yield-related traits in the Aimengniu-derived type V. Eight loci specific to Aimengniu type V were detected on chromosomes 1A, 1B, 2D, 3A, 4D, and 7A, which were associated with QTLs for yield components. These specific loci might discriminate the type V from other types at genomic level.

Abscisic acid (ABA) is an important plant hormone and may be involved in drought resistance in crops. The object of this study was to understand the effects of exogenous ABA on wheat (Triticum aestivum L.) plant under drought stress. After drought stress simulated with polyethylene glycol (PEG) for 72 h at grain-filling stage, flag leaves of Yumai 949 and Shaanmai 5 showed significant increase in malondialdehyde (MDA) content and decreases in relative water content (RWC), chlorophyll content, and yield. Meanwhile, the transcription of psbA gene in photosystem II system was also depressed according to the analysis of reverse transcriptional PCR. Application of exogenous ABA had a significant effect on alleviation of these reactions from PEG stress. Compared to Yumai 949, Shaanmai 5 received smaller injury in plasma membranes and less reduces in RWC, chlorophyll content, yield, and psbA transcriptional level after PEG stress. Moreover, exogenous ABA treatment resulted in restoration of all parameters tested to the levels before stress in Shaanmai 5. This result indicated that the expression of psbA gene was closely related to drought stress resistance subject to wheat cultivar. The primary evidence of ABA regulation on psbA expression may enrich the mechanism of drought resistance and suggest the potential of exogenous ABA to enhance resistance to drought stress in wheat during grain filling period.

The objective of this study was to understand the effects of tillage practice on water consumption characteristics and dry matter accumulation and distribution in wheat (Triticum aestivum L.) plant under high-yielding and flexible irrigation conditions. In a fixed position experiment across 3 growing seasons from October 2007 to June 2010, only one wheat cultivar, Jimai 22, was planted in the field. In the 2007–2008 wheat season, 5 tillage treatments were designed, which were strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), rotary tillage after subsoiling (RS), and plowing tillage (P). The same treatments were arranged in the same field plots in the 2008–2009 and 2009–2010 wheat seasons, except that SRS and RS had no subsoiling. All tillage treatments were irrigated at sowing, jointing, and anthesis stages to designed soil water content based on testing soil moisture before watering. The total water consumption was higher in SRS and RS treatments than in SR and R treatments. Treatment SRS increased the amount of soil water consumption in 0–200 cm soil layers but decreased the soil evaporation, compared to other treatments. Treatments SRS and RS gained the highest amount of dry matter accumulation, grain dry matter partitioning at maturity, and contribution to grain of dry matter assimilation after anthesis, followed by treatment P, and treatments R and SR showed the lowest levels in the above parameters, particularly SR. In the experiment across 3 years, SRS obtained the grain yields of 9409.01 kg ha⁻¹ in 2008, 9613.86 kg ha⁻¹ in 2009, and 9698.42 kg ha⁻¹ in 2010, which were equivalent to that of RS but significantly higher than other treatments. Treatments P and R also exhibited higher yield level than SR treatment. In the 2008–2009 and 2009–2010 growing years, the water use efficiencies of SRS treatment were the highest among treatments, which were 21.39 kg ha⁻¹ mm⁻¹ and 22.09 kg ha⁻¹ mm⁻¹, respectively. Treatment RS also had higher water use efficiency than SR, R, and P treatments. Therefore, SRS is recommended as the optimal tillage practice in high-yielding and water-saving production system in the Yellow-Huai-Hai River Valleys Plain.

Plant-specific transcription factor family NAC (NAM, ATAF1/2, CUC2) plays essential roles in various biological processes including development, senescence, morphogenesis, and stress signal transduction pathway. An NAC gene, which was designated GsNAC20 and showed 99% similarity to GmNAC20 (EU440353.1) from Glycine max, was isolated from G. soja using yeast one hybrid method. The GsNAC20 protein possesses a typical NAC DNA-binding domain at the N-terminal and a transcription activation region at the C-terminal. Like GmNAC20, GsNAC20 could bind to MYB1AT element (the core sequence of AAACCA) in vitro, but no transcriptional activation activity was detected in the yeast assay system. Using the transient expression system in tobacco epidermis cells, GsNAC20 was confirmed to be localized in nucleus. The expression of GsNAC20 was induced by drought, low temperature and salt stress, and the expression patterns were different in leaf and root of G. soja. Overexpression of GsNAC20 gene in the transgenetic lines of Arabidopsis thaliana resulted in enhanced sensitivity of the transgenic plants under salt stress. All results prove that GsNAC20 is a new member of the NAC family in G. soja, which is closely related to the stresses of salt and drought.

Very few quantitative trait loci (QTLs) for root traits have been identified in soybean [Glycine max (L.) Merr.], although root system plays important roles in the growth and development of a plant. The aim of this study was to localize QTLs for root traits at seedling stage in soybean. The mapping population contained 165 recombinant inbred lines (RILs), which was derived from the cross between Zhongdou 29 and Zhongdou 32. The seedlings were hydroponically cultured, and the root traits, including length of the main root, number of lateral roots, root weight, root volume, plant weight, shoot weight per plant, and ratio of root weight to shoot weight, were measured at V2 stage. Using composite interval mapping (CIM) method, 20 QTLs associated with roots and aerial part traits were mapped on 8 chromosomes, which included 9 major-effect QTLs on chromosomes 11 and 14 with the phenotypic contributions of 10.5-26.1%. On chromosomes 11 and 14, some QTLs for root traits and aerial part traits were distributed in clusters. This result is consistent with the correlation analysis of phenotypic traits, indicating that the root traits are associated with the shoot traits.

Ga1-S is a gametophytic mutant involved in maize cross incompatibility. The presence of the dominant allele Ga1-S in silks prevents fertilization by pollen carrying the recessive allele ga1. The physiological basis of cross incompatibility is poorly understood. The proteomic profiling of Ga1-S silks pollinated with Ga1-S and ga1 pollen was investigated for isolating genes involved in cross incompatibility in maize. Two near isogenic lines on Ga1-S locus, W22 (GG) and w22 (gg), were used to make reciprocally crosses of GG × GG, gg × GG, and GG × gg. The behaviours of pollen tube growth in the 3 crosses were compared under a fluorescence microscopy, and the proteomic profiles of total silk proteins in W22 (GG) were compared 10 h after pollination by GG or gg pollen. The total silk proteins of GG × GG and GG × gg crosses were extracted using TCA/Acetone method, separated through electrophoresis in 2-dimensional gels, and analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). The results indicated that gg pollen grains germinated well and the pollen tubes were able to enter the GG silk transmitting tract. However, no gg pollen tube reached GG ovule area, which resulted in incompatibility. In the silk proteomes of GG × GG and GG × gg, 25 differentially expressed proteins were identified, including 15 specifically expressed in GG × GG, and 10 specifically expressed in GG × gg. Among these proteins, 12 were annotated in various databases after MALDI-TOF-MS and MASCOT analyses. Proteins 11, 12, 14, 18, 22, and 24 presumably play important roles in the cross-incompatibility of maize.