In this paper, the formation control problem is investigated for a team of uncertain underactuated surface vessels (USVs) based on a directed graph. Considering the risk of collision and the limited ...communication range of USVs, the prescribed performance control (PPC) methodology is employed to ensure collision avoidance and connectivity maintenance. An event-triggered mechanism is designed to reasonably use the limited communication resources. Moreover, neural networks (NNs) and an auxiliary variable are constructed to deal with the problems of uncertain nonlinearities and underactuation, respectively. Then, an event-triggered formation control scheme is proposed to ensure that all signals of the closed-loop system are uniformly ultimately bounded (UUB). Finally, simulation results are presented to demonstrate the effectiveness of the proposed control scheme.
Key message
Major and environmentally stable QTL for flag leaf-related traits in wheat were identified and validated across ten environments using six populations with different genetic backgrounds.
...Flag leaf size and posture are two important factors of “ideotype” in wheat. Despite numerous studies on genetic analysis of flag leaf size including flag leaf length (FLL), width (FLW), area (FLA) and the ratio of length/width (FLR), few have focused on flag leaf posture including flag leaf angle (FLANG), opening angle (FLOA) and bend angle (FLBA). Further, the numbers of major, environmentally stable and verified genetic loci for flag leaf-related traits are limited. In this study, QTL for FLL, FLW, FLA, FLR, FLANG, FLOA and FLBA were identified based on a recombinant inbred line population together with values from up to ten different environments. Totally, eight major and stably expressed QTL were identified. Three co-located chromosomal intervals for seven major QTL were identified. The five major QTL
QFll.sicau
-
5B.3
and
QFll.sicau
-
2D.3
for FLL,
QFlr.sicau
-
5B
for FLR,
QFlw.sicau
-
2D
for FLW and
QFla.sicau
-
2D
for FLA were successfully validated by the tightly linked Kompetitive Allele Specific PCR (KASP) markers in the other five populations with different genetic backgrounds. A few genes related to leaf growth and development in intervals for these major QTL were predicated. Significant relationships between flag leaf- and yield-related traits were evidenced by analyses of Pearson correlations, conditional QTL and genetic mapping. Taken together, these results provide valuable information for understanding flag leaf size and posture of “ideotype” as well as fine mapping and breeding utilization of promising loci in bread wheat.
Aims
Nitrogen (N) application is often known to influence various properties in Chinese fir growth, but the regeneration failure and productivity decline in Chinese fir plantations are often affected ...by allelochemical compounds. Little is known about the interactive effect of allelochemicals and N sources on the plant growth in Chinese fir seedlings.
Methods
Chinese fir seedlings were respectively subjected to the addition of ammonium (NH
4
+
), nitrate (NO
3
−
),
p
-hydroxybenzoic acid (
p
HBA) and their combined additions.
Results
The
p
HBA addition alone promoted Chinese fir seedlings growth, but this effect was differentially affected by the interaction with NH
4
+
or NO
3
−
. Both NH
4
+
and NO
3
−
application improved plant growth, but the stimulatory effect of NO
3
−
was weakened with addition of
p
HBA. Although NO
3
−
addition combined with
p
HBA increased N accumulation in roots, the enzymes activities related to N assimilation were significantly decreased. These negative influences were also manifested through the decreased photosynthetic capacity, the reduction in photosynthates production and accumulation, and the destruction of chloroplast structural integrity. Moreover, the C/N ratio in root was obviously decreased and N assimilation was inhibited under the combined treatment of
p
HBA and NO
3
−
, thereby aggravating C − N imbalance.
Conclusions
The Chinese fir seedlings shifted their N uptake preference from NO
3
−
to NH
4
+
when
p
HBA were added in soil. The dominant N source and allelochemicals interaction should be considered for Chinese fir growth.
An aerobic
15
N microcosmic experiment was conducted to compare the inhibitory effects of the biological nitrification inhibitor (BNI), methyl 3-(4-hydroxyphenyl) propionate (MHPP) at rates of 500 ...and 1000 mg kg
−1
with the synthetic nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) at 1% of applied NH
4
+
, on the gross nitrification rate (
n
_gross
) and on the abundance and community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) of two contrasting soils (pH: 5.10 vs. 8.15, clay content 17.8 vs. 30.8). DMPP inhibited 56.6% of
n
_gross
in the acidic soil and 50.3% in the calcareous soil, whereas MHPP inhibited 18.3–55.5% of
n
_gross
in the acidic soil and 14.1–20.2% in the calcareous soil. MHPP used at the high rate showed the same inhibition on
n
_gross
as DMPP in the acidic soil but not in the calcareous soil. DMPP and MHPP likely regulated
n
_gross
by causing niche differentiation between AOA and AOB. Moreover, the community composition of AOB was more sensitive to nitrification inhibitor application than that of AOA, particularly in the acidic soil. However, the response of AOB community composition was less sensitive to the application of MHPP than to that of DMPP. MHPP mainly targeted
Nitrosospira
clusters 3a.2, 3b.2, and 9 of the AOB in the acidic soil.
Key Message
A novel and major QTL for the effective tiller number was identified on chromosomal arm 1BL and validated in two genetic backgrounds
The effective tiller number (ETN) substantially ...influences plant architecture and the wheat yield improvement. In this study, we constructed a genetic map of the 2SY (20828/SY95-71) recombinant inbred line population based on the Wheat 55K array as well as the simple sequence repeat (SSR) and Kompetitive Allele Specific PCR (KASP) markers. A comparison between the genetic and physical maps indicated the marker positions were consistent in the two maps. Additionally, we identified seven tillering-related quantitative trait locus (QTLs), including
Qetn-sau-1B.1
, which is a major QTL localized to a 6.17-cM interval flanked by markers
AX-89635557
and
AX-111544678
on chromosome 1BL. The
Qetn-sau-1B.1
QTL was detected in eight environments and explained 12.12–55.71% of the phenotypic variance. Three genes associated with the ETN were detected in the physical interval of
Qetn-sau-1B.1
. We used a tightly linked KASP marker,
KASP-AX-110129912
, to further validate this QTL in two other populations with different genetic backgrounds. The results indicated that
Qetn-sau-1B.1
significantly increased the ETN by up to 23.5%. The results of this study will be useful for the precise mapping and cloning of
Qetn-sau-1B.1
.
Key message
Eight major and stably expressed QTL for flag leaf morphology across eleven environments were identified and validated using newly developed KASP markers in seven biparental populations ...with different genetic backgrounds.
Flag leaf morphology is a determinant trait influencing plant architecture and yield potential in wheat (
Triticum aestivum
L.). A recombinant inbred line (RIL) population with a 55 K SNP-based constructed genetic map was used to map quantitative trait loci (QTL) for flag leaf length (FLL), width (FLW), area (FLA), angle (FLANG), opening angle (FLOA), and bend angle (FLBA) in eleven environments. Eight major QTL were detected in 11 environments with 5.73–54.38% of explained phenotypic variation. These QTL were successfully verified using the newly developed Kompetitive Allele Specific PCR (KASP) markers in six biparental populations with different genetic backgrounds. Among these 8 major QTL, two co-located intervals were identified. Significant interactions for both FLL- and FLW-related QTL were detected. Comparison analysis showed that
QFll.sau-SY-2B
and
QFla.sau-SY-2B
are likely new loci. Significant relationships between flag leaf- and yield-related traits were observed and discussed. Several genes associated with leaf development including the ortholog of maize
ZmRAVL1
, a B3-domain transcription factor involved in regulation of leaf angle, were predicted in physical intervals harboring these major QTL on reference genomes of bread wheat ‘Chinese spring’,
T. turgidum
, and
Aegilops tauschii
. Taken together, these results broaden our understanding on genetic basis of flag leaf morphology and provide clues for fine mapping and marker-assisted breeding wheat with optimized plant architecture for promising loci.
The halophytic wild relatives within Triticeae might provide valuable sources of salt tolerance for wheat breeding, and attempts to use these sources of tolerance have been made for improving salt ...tolerance in wheat by distant hybridization. A novel wheat substitution line of K17-1078-3 was developed using common wheat varieties of Chuannong16 (CN16), Zhengmai9023 (ZM9023), and partial amphidiploid Trititrigia8801 (8801) as parents, and identified as the 3E(3D) substitution line. The substitution line was compared with their parents for salt tolerance in hydroponic culture to assess their growth. The results showed that less Na
accumulation and lower Na
/K
ratio in both shoots and roots were achieved in K17-1078-3 under salinity compared to its wheat parents. The root growth and development of K17-1078-3 was less responsive to salinity. When exposed to high salt treatment, K17-1078-3 had a higher photosynthesis rate, more efficient water use efficiency, and greater antioxidant capacity and stronger osmotic adjustment ability than its wheat parents. In conclusion, a variety of physiological responses and root system adaptations were involved in enhancing salt tolerance in K17-1078-3, which indicated that chromosome 3E possessed the salt tolerance locus. It is possible to increase substantially the salt tolerance of wheat by the introduction of chromosome 3E into wheat genetic background.
As an essential plant micronutrient, copper (Cu) is required as a component of several enzymes, but it can be highly toxic to plants when present in excess quantities. Nitrogen (N) application can ...help to alleviate the phytotoxic effects of heavy metals, including Cu, and different N forms significantly affect the uptake and accumulation of heavy metals in plants. The aim of this study was to determine the effects of different N forms, i.e., ammonium (NH4+) and nitrate (NO3−), on Cu detoxification in wheat seedlings. The inhibition of seedling growth under excess Cu was more obvious in wheat plants supplied with NO3− than in those supplied with NH4+. This growth inhibition was directly induced by excess Cu accumulation and reduced absorption of other mineral nutrients by the plants. Compared with seedlings treated with NO3−, those treated with NH4+ showed a decrease in Cu-induced toxicity as a result of increased antioxidant capacity in the leaves and a lower redox potential in the rhizosphere. Furthermore, treatment with NH4+ decreased the loss of mineral nutrients in wheat seedlings exposed to excess Cu. In conclusion, compared with supplying NO3−, supplying NH4+ to wheat seedlings under Cu stress improved their ability to maintain their nutritional and redox balance and increased their antioxidant capacity, thereby preventing a decline in photosynthesis. According to our results, NH4+ is more effective than NO3− in reducing Cu phytotoxicity in wheat seedlings.
•NH4+ supply decreased the loss of mineral nutrients.•NH4+ supply increased antioxidant enzymes activities.•NH4+ supply prevented the decline in photosynthesis.•NH4+ supply improved the ability to maintain redox potential equilibrium.
The barley chromosome 3H accommodates many semi-dwarfing genes. To characterize these genes, the two-rowed semi-dwarf Chinese barley landrace 'TX9425' was crossed with the Australian barley variety ...'Franklin' to generate a doubled haploid (DH) population, and major QTLs controlling plant height have been identified in our previous study. The major QTL derived from 'TX9425' was targeted to investigate the allelism of the semi-dwarf gene uzu in barley. Twelve sets of near-isogenic lines and a large NILF2 fine mapping population segregating only for the dwarfing gene from 'TX9425' were developed. The semi-dwarfing gene in 'TX9425' was located within a 2.8 cM region close to the centromere on chromosome 3H by fine mapping. Molecular cloning and sequence analyses showed that the 'TX9425'-derived allele contained a single nucleotide substitution from A to G at position 2612 of the HvBRI1 gene. This was apparently the same mutation as that reported in six-rowed uzu barley. Markers co-segregating with the QTL were developed from the sequence of the HvBRI1 gene and were validated in the 'TX9425'/'Franklin' DH population. The other major dwarfing QTL derived from the Franklin variety was distally located on chromosome 3HL and co-segregated with the sdw1 diagnostic marker hv20ox2. A third dwarfing gene, expressed only in winter-sown trials, was identified and located on chromosome 3HS. The effects and interactions of these dwarfing genes under different growing conditions are discussed. These results improve our understanding of the genetic mechanisms controlling semi-dwarf stature in barley and provide diagnostic markers for the selection of semi-dwarfness in barley breeding programs.
Strategies to reduce cadmium (Cd) in rice grain, below concentrations that represent serious human health concerns, require that the mechanisms of Cd distribution and accumulation within rice plants ...be established. Here, a comprehensive hydroponic experiment was performed to investigate the differences in the Cd uptake, chelation and compartmentalization between high (D83B) and low (D62B) Cd-accumulation cultivars contrasting in Cd accumulation in order to establish the roles of these processes in limiting Cd translocation from root to shoot. D83B showed 3-fold higher Cd accumulation in the shoots than the cultivar D62B. However, a short-term Cd uptake experiment showed more Cd uptake by D62B than by D83B. The distribution of Cd in roots and shoots differed significantly. D83B translocated 38% of total Cd taken up to the shoots, whereas D62B retained most of the Cd in the roots. D62B had higher amounts of non-protein thiols (NPTs) and glutathione (GSH) than D83B. The NPT and Cd distribution ratio (CDR) in the anionic form in the roots of D62B increased gradually as Cd concentration increased. In D83B, in contrast, levels of CDR in the cationic form increased significantly from 22.10 to 43.37%, while NPT only increased slightly. Furthermore, the percentage of Cd ions retained in thiol-rich peptides, especially in the HMW complexes, was significantly higher in D62B compared with D83B. However, D83B possessed a greater proportion of potentially mobile (cationic) Cd in the roots and showed superior Cd translocation from root to shoot. Taken as a whole, the results presented in this study revealed that Cd chelation, compartmentalization and adsorption contribute to the Cd retention in roots.
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