Short Daylight Conditions Research Articles

A comparison of seasonal flexibility in pectoralis muscle fiber type and enzyme activity in migratory and resident sparrow species

The pectoralis muscle in birds is important for flight and thermogenesis. In migratory songbirds this muscle exhibits seasonal flexibility in size, but whether this flexibility reflects changes in muscle fiber type has not been well documented. We investigated how seasonal changes in photoperiod affected pectoralis muscle fiber type and metabolic enzymes, comparing among three closely-related sparrow species: two seasonal migrants and one year-round, temperate climate resident. We quantified fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers histologically, and measured activities of citrate synthase (CS) and lactate dehydrogenase (LDH) in the pectoralis muscle of the three species that were acclimated to long- or short-daylight length conditions. In all species FOG was the predominant fiber type, but song sparrows had FG fibers regardless of daylight length. By contrast, Lincoln's sparrows incorporated FG fibers only under short-daylight length onditions, and house sparrows did not significantly express FG fibers, regardless of conditions. Both migratory species increased LDH activity in short-daylight conditions, but did not alter CS activity. In contrast, resident house sparrows did not alter CS or LDH activity with changes in daylight length. Our findings suggest that the presence of FG fibers is important for seasonal flexibility in LDH activity. Additionally, migratory species exhibited seasonal flexibility in muscle fiber type and enzyme activity, presumably to support migratory flight, while the resident species did not exhibit such seasonal flexibility, suggesting that this consistent phenotype is important year-round, despite changing thermogenic requirements.

Combined effects of temperature, photoperiod, and salinity on reproduction of the brine shrimp Artemia sinica (Crustacea: Anostraca).

Artemia sinica is a brine shrimp species distributed in hypersaline salt lakes in northern China and Siberia and a successful invasive species in some coastal salterns. Although it is a commercially harvested and cultured species, knowledge of its reproductive characteristics is limited, and existing studies are often contradictory. The combined effects of temperature, salinity, and photoperiod on reproduction characteristics are experimentally studied to better understand its reproductive features. There were 36 combinations of three environmental factors (3×3×4), each with three or four levels, namely temperature (16, 25, 30°C), photoperiod (6 L:18 D, 12 L:12D, 18 L:6D), and salinity (50, 100, 150, 200 PSU). In each treatment, 48 to 80 pairs of A. sinica from Yuncheng Salt Lake (Shanxi, China) were cultured. Females were observed daily for reproductive mode and the number of offspring produced. Temperature, photoperiod, salinity, and their interactions significantly affected the lifespan and reproduction of A. sinica. The reproductive period was the longest and accounted for the largest proportion of life span at moderate temperature (25°C). Total offspring, offspring per brood, and offspring per day increased as salinity decreased, and the number of broods per female was highest at 25°C. Temperature, photoperiod, and salinity significantly influenced reproductive modes, and interactions among these factors were identified. Artemia sinica primarily reproduces oviparously under low temperature and short daylight conditions, and ovoviviparously under high temperature and long daylight conditions, with the maximum oviparity ratio recorded in treatments of 16°C, 6L:18D, and 50 or 100 PSU. The maximum ovoviviparity ratio was recorded under 30°C, 12L:12D, and 100 PSU. Unlike that documented for other Artemia species or populations, the brood size of A. sinica kept increasing throughout the reproductive period. It did not decline even in the last two broods. For the same brood number, the sizes of oviparous and ovoviviparous broods were similar. The length of the oviparous interval was often greater than that of the ovoviviparous interval, suggesting that oviparous offspring might require additional energy and time to construct the multi-layered eggshell. Compared to other species and populations, the A.sinica from Yuncheng Salt Lake has a relatively shorter pre-reproductive development time, a preference for ovoviviparity, and relatively higher fecundity and population growth capacity, making it a suitable culture species for obtaining fresh biomass.

Double Mutation of Days to Heading 2 and CONSTANS 3 Improves Agronomic Performance of Japonica Rice under Short Daylight Conditions in Southern China.

Some progress has been made in understanding the pathways related to rice heading, but their applications to breeding japonica rice varieties adapted to grow in low-latitude areas ("indica to japonica") are limited. We edited eight adaptation-related genes via a lab-established CRISPR/Cas9 system in a japonica variety, Shennong265 (SN265). All T0 plants and their progeny bearing random mutation permutations were planted in southern China and screened for changes in heading date. We found that the double mutant of Days to heading 2 (DTH2) and CONSTANS 3 (OsCO3) (dth2-osco3), two CONSTANS-like (COL) genes, showed significantly delayed heading under both short-day (SD) and long-day (LD) conditions in Guangzhou and manifested great yield increase under SD conditions. We further demonstrated that the heading-related Hd3a-OsMADS14 pathway was down-regulated in the dth2-osco3 mutant lines. The editing of the COL genes DTH2 and OsCO3 greatly improves the agronomic performance of japonica rice in Southern China.

Military club work with school students of Khanty-Mansiysk okrug in 1941-1945 years

The questions of organization and the results of military training in Ugra schools during the Great Patriotic War are analyzed in this article. Based on the materials of Ugra State archive and the memories of region former teachers and students and using historical genetic and statistical methods the effort to evaluate Khanty-Mansiysk okrugs material and personnel capabilities in organization of military clubs. In addition, the author reveals the main problems that the school education departments faced. For example, the small number of senior classes in the region, the shortage of school premises, the lack of kerosene in short daylight conditions, the lack of clothes and shoes for students and the experienced military instructors small number. The most widespread types of military clubs, the extent of students delivery of various military and physical education standards and their participation in paramilitary games are revealed. The degree of this articles compliance with the general tasks of students pre-conscription military training is assessed. The author comes to the conclusion that the students number who took part in military clubs significantly increased. As a result, more than 80 percent of students could pass the norms on the badges of various societies. Besides the military club work among Ugra students was heavily depended on possibilities of schools, as a result there were a little number in Ugra by the end of the war.

NRL3 Interacts with OsK4 to Regulate Heading Date in Rice

NRL3 is essential for the growth and development of rice leaves. In this study, we found that the loss function of NRL3 also delayed heading date under natural long daylight and short daylight conditions. The yeast two-hybrid and the bimolecular fluorescence complementation proved that NRL3 interacts with OsK4, a Snf1-related kinase. OsK4 localized to the nucleus and expressed in various rice tissues. The rhythmic expression pattern of OsK4 was similar to NRL3 under long daylight and short daylight conditions. Knock-out mutants of OsK4 exhibited early heading under long daylight conditions, indicating that it acts as a negative regulator of heading date in rice. Interestingly, the OsK4 mutant under the nrl3 mutant background rescued the late heading phenotype of nrl3 under long daylight conditions, suggesting that OsK4 functions downstream of NRL3. Moreover, both NRL3 and OsK4 controlled heading date through regulating the expression of Hd3a and RFT1 genes. These findings shed light on the heading date regulation in rice and provide a sound theoretical base to improve regional adaptability of rice.

A Robotic Arm Based Design Method for Modular Building in Cold Region

The robotic arm has emerged as an essential tool for the rapid construction of high-quality buildings due to its ability to repeat instructions, achieve precise positioning and fine operations. The robotic arm can also effectively replace workers to complete building construction under low temperature and short daylight conditions. Thus, it can be forward-looking to construct modular buildings in cold region, but how to realize the construction of modular buildings through human-machine coordination and remote operation is a significant issue. This article discusses the feasibility of robotic arm assembly design methods in the field of architecture by simulating the complete design and construction process of modular buildings. According to parameterized module design, a three-dimensional computer model is transformed into an electronic file that directs the action of the robotic arm to complete assembly via a custom processing program. This article details a theoretical and practical exploration of the construction of modular manipulators and has certain guiding significance for the intelligent design and construction of future buildings.

FEATURES OF PLANT DEVELOPMENT AND PRODUCTIVE POTENTIAL OF SPRING WHEAT VARIETIES OF DIFFERENT ORIGIN IN THE CONDITIONS OF THE SOUTH OF UKRAINE

Purpose. To study the features of development and productivity potential of spring wheat varieties of different origin during autumn and spring sowing time. Select the best samples for inclusion in the breeding program for the creation of facultative varieties of wheat and the improvement of winter genotype of common wheat. Methods. For the study were taken Varieties of spring wheat of different genetic origin: from Ukraine – Kharkivs’ka 26 (standard), Kharkivs’ka 30 and breeding lines d.104/06 and d.118/06; from Western Europe - Triso, Jara, Typic; from Canada, Glen Lee, AC Superb; from North America - Babax and Trap1. Varieties for two years (2007-2008) were sown in two seasons and three terms: 1st term 06.10.06/09.10.07 (sowing of winter samples); 2nd term 13.11.06/21.11.07 (sowing of winter and spring samples); 3rd term 19.03.07/18.03.08 (sowing of spring samples). In sown in autumn, winter wheat varieties were taken as control: Bezosta 1, Odes’ka 16, Odes’ka 267, Viktoriya odes’ka, Kuyalʹnyk and Kiriya. The size of the plot was 10 m2. Phenological observations were carried out according to the methodology of the State Variety Testing. The reaction to photoperiodic sensitivity was studied by the difference in heading date under short daylight conditions - 10 hours compared to the usual natural day - 16 hours (May-June). The winter was soft for two years, which contributed to the optimal development of the spring wheat plant. Results. One of the main elements that forms productivity is tillering. The difference of the number of stems per 1 m2 and the between the varieties of winter and spring types of development was not observed. The level of tillering depends on the characteristics of the variety, and does not depend on the type of wheat growth habits. Heading of spring varieties when sown at the optimal time occurs very late for our zone on June 1-8. During autumn sowing time, according to the heading date indicator (May 18-29), contrast was not found between the samples of spring and winter wheat. Heading time and maturing occurs at the same time with a difference between varieties of up to 9 days. just like of heading dates, the reaction to photoperiod sensitivity depends on the genetic characteristics of the variety and does not depend on the type of wheat growth habits. The varieties Kuyalʹnyk, AC Superb, Typic, Trap1 are not sensitive to the length of daylight hours with a difference in heading (4-5 days) between short and full days. The yield level for 2 years in spring varieties was significantly lower if compared with winter varieties. Even sowing in autumn and high intensity of regrowth, the same level of tillering, neutral reaction to photoperiodic sensitivity of some varieties are not able to give a yield at least at the level of modern varieties of winter wheat. The best yielding varieties of spring wheat of the second sowing period AC Superb (3.61 t/ha), Babax (3.55 t/ha), Trap (3.35 t/ha), line d.118/06 (3.23 t/ha) were at the level of winter wheat varieties Bezosta 1 (3.44 t/ha) and Odes’ka 16 (3.33 t/ha) and significantly less than variety Kuyalnik (4.48 t/ha). During spring sowing, the yield of spring wheat varieties was low (maximum 2.45 t/ha) due to the specific conditions of the South of Ukraine. There was no significant difference in yield between spring wheat varieties when sown in spring. Conclusions. The results of the study showed that for the South of Ukraine it is expedient to develop a program with crossing winter wheat with spring wheat to obtain facultative forms which would be at the level of winter wheat yields, early maturing and with a neutral reaction to photoperiodic sensitivity. According to the results of this work for the breeding program, a number of varieties of spring wheat were identified: Ukrainian pool - line d.118/06, Kharkivs’ka 30; Western European pool - Triso; Canadian pool - AC Superb; Central American pool - Babax.

Implication of Membrane Androgen Receptor (ZIP9) in Cell Senescence in Regressed Testes of the Bank Vole.

Here, we studied the impact of exposure to short daylight conditions on the expression of senescence marker (p16), membrane androgen receptor (ZIP9) and extracellular signal-regulated kinase (ERK 1/2), as well as cyclic AMP (cAMP) and testosterone levels in the testes of mature bank voles. Animals were assigned to groups based on an analysis of testis diameter, weight, seminiferous tubule diameter and the interstitial tissue area: group 1, not fully regressed (the highest parameters); group 2 (medium parameters); or group 3, regressed (the lowest parameters). Cells positive for p16 were observed only in the seminiferous tubule epithelium. However, in groups 1 and 2, these were mostly cells sloughed into the tubule lumen. In group 3, senescent cells resided in between cells of the seminiferous epithelium. Staining for ZIP9 was found in Sertoli cells. Western blot analysis showed a trend towards a decreased expression of p16 and ZIP9 in the testes of the voles in groups 2 and 3, compared to group 1. In addition, a trend towards an increased expression of ERK, as well as an increase of cAMP and testosterone levels, was revealed in group 2. In the regressed testes, a functional link exists between senescence and androgen levels with implication of ZIP9 and cAMP/ERK signaling pathways.

Effect of the C1473G Polymorphic Variant of the Tryptophan Hydroxylase 2 Gene and Photoperiod Length on the Dopamine System of the Mouse Brain

A decrease in the light in autumn and winter causes depression like seasonal affective disorders (SAD) in sensitive patients, in which the serotonin (5-HT) and dopamine (DA) brain mediator systems are involved. We studied the interaction of the 5-HT and DA brain systems in an experimental SAD model in sexually mature male mice of the congenic B6-1473C and B6-1473G lines with high and low activity of tryptophan hydroxylase 2, a key enzyme of 5-HT synthesis in the brain. Mice of each line (divided into two groups of eight individuals) were kept for 30 days in standard (14 h light/10 h dark) and short (4 h light/20 h dark) daylight. The presence of the C1473G variant in the tryptophan hydroxylase 2 gene did not affect the expression of key genes of DA system: Drd1, Drd2, Scl6a3, Th, and Comt, that encode the D1 and D2 receptors, dopamine transporter, tyrosine hydroxylase, and catechol-o-methyltransferase, respectively. A decrease in the level of DA in the midbrain, as well as of its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum, was detected in B6-1473G mice. Keeping mice in short daylight did not affect expression of the Drd1 gene in all brain structures nor the expression of the Slc6a3 and Th genes in the midbrain. Drd2 expression increased in the midbrain and decreased in the hippocampus, where Comt expression increased. An increase in DA level in the midbrain and DOPAC in the striatum was detected in mice kept in short daylight. This indicates the involvement of the brain's DA system in the reaction to a decrease in daylight duration. No statistically significant effect of the interaction between the presence of the C1473G variant and daylight length on indicators of the activity of DA system was detected. No reasons were found to assert that this polymorphism determines the observed reaction of the brain DA system in keeping of animals under short daylight conditions.

Transcriptome analysis of the molecular mechanism of Chrysanthemum flower color change under short-day photoperiods

Chrysanthemum [Dendranthema morifolium Tzvel.] is an ornamental plant grown under long-term artificial cultivation conditions. In production, early Chrysanthemum blossoms are often promoted by artificial short-day treatment. However, we found that the flower colour of Chrysanthemum blossoms induced by artificial short-day treatment was lighter than those induced by the natural photoperiod. To explore the intrinsic mechanism of colour fading in flowers, we performed full-length transcriptome sequencing of Chrysanthemum morifolium cv. ‘Jinbeidahong’ using single-molecule real-time sequencing and RNA-sequencing under natural daylight (ND) and short daylight (SD) conditions. The clustered transcriptome sequences were assigned to various databases, such as NCBI, Swiss-Prot, Gene Ontology and so on. The comparative results of digital gene expression analysis revealed that there were differentially expressed transcripts (DETs) in the four stages under ND and SD conditions. In addition, the expression patterns of anthocyanin biosynthesis structural genes were verified by quantitative real-time PCR. The major regulators of the light signalling ELONGATED HYPOCOTYL5 genes were markedly upregulated under ND conditions. The patterns of anthocyanin accumulation were consistent with the expression patterns of CHI1 and 3GT1. The results showed that the anthocyanin synthesis is tightly regulated by the photoperiod, which will be useful for molecular breeding of Chrysanthemum.

Impact of artificial illumination on the development of a leafmining moth in urban trees

Light emission from street lighting or other light sources alters the living conditions for organisms in urban areas. Nowadays, the impact of light at night (ALAN) on urban plants and their trophic environment is not well understood. To gain more insight about herbivore plant’s interaction when exposed to ALAN, outdoor and greenhouse tests were conducted using the horse-chestnut leafminer, Cameraria ohridella, as a test organism due to its adaptive behavior. At the end of the season, the development of chestnut tree leaves and the leafminer were measured at illuminated versus non-illuminated sites in the city of Berlin and the rural area of Brandenburg. Illuminated leaves were larger than those grown in darker rural areas and, extended larval activity was recorded. Additionally, in the greenhouse, infested chestnut seedlings were exposed to two different light regimes; one treatment provided continuous illumination and the other short daylight conditions. After only one week, the mine size was lower on illuminated seedlings, presumably due to reduced leaf senescence. The leafminer developed a lower proportion of diapausing pupae and a higher proportion of free pupae, which leads to a further generation within the season. The results indicate a strong impact of ALAN on plant metabolism, a secondary effect on leafminer development and its larval activity. For urban trees, the consequence might be an increased herbivore / parasite pressure. For herbivores and parasites less adapted to winter damages than the invasive leafminer a reduced dormancy due to direct or indirect effects of ALAN could even threat the population.

Gene expression profiling across ontogenetic stages in the wood white (Leptidea sinapis) reveals pathways linked to butterfly diapause regulation.

In temperate latitudes, many insects enter diapause (dormancy) during the cold season, a period during which developmental processes come to a standstill. The wood white (Leptidea sinapis) is a butterfly species distributed across western Eurasia that shows photoperiod-induced diapause with variation in critical day-length across populations at different latitudes. We assembled transcriptomes and estimated gene expression levels at different developmental stages in experimentally induced directly developing and diapausing cohorts of a single Swedish population of L.sinapis to investigate the regulatory mechanisms underpinning diapause initiation. Different day lengths resulted in expression changes of developmental genes and affected the rate of accumulation of signal molecules, suggesting that diapause induction might be controlled by increased activity of monoamine neurotransmitters in larvae reared under short-day light conditions. Expression differences between light treatment groups of two monoamine regulator genes (DDC and ST) were observed already in instar III larvae. Once developmental pathways were irreversibly set at instar V, a handful of genes related to dopamine production were differentially expressed leading to a significant decrease in expression of global metabolic genes and increase in expression of genes related to fatty acid synthesis and sequestration. This is in line with a time-dependent (hour-glass) model of diapause regulation where a gradual shift in the concentration of monoamine neurotransmitters and their metabolites during development of larvae under short-day conditions leads to increased storage of fat, decreased energy expenditures, and ultimately developmental stasis at the pupal stage.

Profile of gonadotropic hormone secretion in sheep with disturbed rhythm of seasonality

The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L)) and exogenous melatonin on milk yield parameters of sheep during spring and summer was examined to determine the impact of using sheep for milk on the secretion level of gonadotrophic hormones. The research was conducted on 60 sheep lambed in February. After raising the lambs, the sheep were divided into 3 groups and assigned for dairy use (May–September). The mothers in the control Group 1 (G1) were maintained under natural daylight conditions. The sheep in Group 2 (G2) were maintained under conditions of an artificial photoperiod (16 h D : 8 h L). Meanwhile, the mothers in Group 3 (G3) were given melatonin implants. A 6-hour collection of blood from 6 sheep of each group was performed every 4 weeks. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in plasma were measured using radioimmunoassay. The average LH concentration in G1 gradually increased since May (5.32 ± 0.2 ng/ml), reaching the highest value in August (6.70 ± 0.2 ng/ml). In G2, the increase in LH occurred 4 weeks after the introduction of the 16 h D : 8 h L condition (6.26 ± 0.2 ng/ml). The maximum LH concentration in G3 was noted in August (7.31 ± 0.2 ng/ml). The average FSH concentration in G1 gradually increased since May (6.59 ± 0.2 ng/ml), reaching the highest value in August (10.50 ± 2.6 ng/ml). In G2, there was a significant increase in the FSH concentration in June (9.00 ± 0.3 ng/ml). In the final period during lactation, the FSH concentrations in G2 (13.51 ± 1.3 ng/ml) and G3 (13.60 ± 1.9 ng/ml) were higher than in G1. The results indicate that using sheep for milk does not inhibit the secretion of gonadotropic hormones induced by the simulation of short daylight conditions and exogenous melatonin.

Plasticity of the thermal developmental reaction norms in the european peacock butterfly Inachis io (Lepidoptera, Nymphalidae)

The goal of the study was to analyze the plasticity of the developmental thermal reaction norms in the peacock butterfly Inachis io as affected by different photoperiodic conditions and group versus individual keeping. Overwintered imagoes were collected in Stariy Peterhof (Saint-Petersburg, Russia) in May 2010 and 2012–2013. Twelve experimental regimes were used: 4 thermal (16, 18, 20 and 22°C) and 3 photoperiodic (12, 18 and 22 h of light per day). Under short-daylight conditions (12 h), the larvae were shown to develop a little faster than under long-day conditions (22 h), although the thermal developmental thresholds were invariable in both cases. The linear regression coefficient characterizing developmental thermolability was significantly higher only in males more affected during their development by the short-day photoperiod than females. Under the 18-h daylight regime, larval development was less thermolabile and characterized by a lower thermal threshold than under the shorter or longer photoperiod. The influence of the short-day photoperiod on the larval development manifested itself most distinctly in the body mass changes in emerging pupae: under all thermal regimes, the pupae were lighter under the short-than long-day photoperiod. The pupal body mass grew with the rise in temperature, contrary to the temperature–size rule. Individual keeping led to the longer duration and lower thermolability of larval and pupal development, as well as to a reduced pupal body mass. Individual keeping exerted a stronger influence on females than on males.

Peroxidase 4 is involved in syringyl lignin formation in Arabidopsis thaliana

Syringyl lignins result from the oxidative polymerization of sinapyl alcohol in a reaction mediated by syringyl (basic) peroxidases. Several peroxidases have been identified in the genome of Arabidopsis thaliana as close homologues to ZePrx, the best characterized basic peroxidase so far, but none of these has been directly involved in lignification. We have used a knock-out mutant of AtPrx4, the closest homologue to ZePrx, to study the involvement of this basic peroxidase in the physiology of the plant under both long- and short-day light conditions. Our results suggest that AtPrx4 is involved in cell wall lignification, especially in syringyl monomer formation. The disruption of AtPrx4 causes a decrease in syringyl units proportion, but only when light conditions are optimal. Moreover, the effect of AtPrx4 disruption is age-dependent, and it is only significant when the elongation process of the stem has ceased and lignification becomes active. In conclusion, AtPrx4 emerges as a basic peroxidase regulated by day length with an important role in lignification.

Substitution of a Conserved Glycine in the PHR Domain of Arabidopsis CRYPTOCHROME 1 Confers a Constitutive Light Response

CRYPTOCHROMES (CRYs) are photolyase-like ultraviolet-A/blue light photoreceptors that mediate various light responses in plants. The signaling mechanism of Arabidopsis CRYs (CRY1 and CRY2) involves direct CRY-COP1 interaction. Here, we report that CRY1(G380R), which carries a Gly-to-Arg substitution of the highly conserved G380 in the photolyase-related (PHR) domain of Arabidopsis CRY1, shows constitutive CRY1 photoreceptor activity in Arabidopsis. Transgenic plants overexpressing CRY1(G380R) display a constitutively photomorphogenic (COP) phenotype in darkness, as well as a dramatic early flowering phenotype under short-day light conditions (SD). We further demonstrate that CRY1(G380R) expression driven by the native CRY1 promoter also results in a COP phenotype in darkness. Moreover, overexpression of either the Arabidopsis homolog CRY2(G377R) or the rice ortholog OsCRY1b(G388R) of CRY1(G380R) in Arabidopsis results in a COP phenotype in darkness. Cellular localization studies indicate that CRY1(G380R) co-localizes with COP1 in the same nuclear bodies (NBs) in vivo and inhibits the nuclear accumulation of COP1 in darkness. These results suggest that the conserved G380 may play a critical role in regulating the photoreceptor activity of plant CRYs and that CRY1(G380R) might constitutively phenocopy the photo-activated CRY1 in darkness and thus constitutively mediate CRY1 signaling.

Aanlysis of short photo-periodic sensitive genic male sterility and molecular mapping of rpms3(t) gene in rice (Oryza sativa L.) using SSR markers

A research was conducted on the pollen fertility of rice sterile lines D52S and D38S responsive to photoperiod during the sensitive stage under natural and controlled conditions. Bulk segregant analysis (BSA) and recessive class approach were applied to identify DNA markers that co-segregate with gene conferring male-sterility in D52S mutant rice. The results showed that in day-light higher or equal to 14.00 h, D52S and D38S rice pollen were fertile; however, they were sterile when day-length was less than 14.00 h. They were therefore considered to be short photo-periodic sensitive genic male sterile lines(Short PGMS lines). Under short day-light conditions, the pollen fertility segregation of F2 populations from crosses between D52S/Shuhui527 and D52S/Gui99showed 3:1 ratio of fertile to sterile plants suggestingthat male sterility in D52S was controlled by one recessive gene. Two markers RM244 and RM216 located on chromosome number 10 co-segregated completely with the rpms locus. The locus was mapped to the interval between SSR markers RM2571 (6.6 cM) and RM244 (4.6 cM).

A Gain‐of‐Function Mutation in IAA7/AXR2 Confers Late Flowering under Short‐day Light in ArabidopsisF

Floral initiation is a major step in the life cycle of plants, which is influenced by photoperiod, temperature, and phytohormones, such as gibberellins (GAs). It is known that GAs promote floral initiation under short-day light conditions (SDs) by regulating the floral meristem-identity gene LEAFY (LFY) and the flowering-time gene SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1). We have defined the role of the auxin signaling component INDOLE-3-ACETIC ACID 7 (IAA7)/AUXIN RESISTANT 2 (AXR2) in the regulation of flowering time in Arabidopsis thaliana. We demonstrate that the gain-of-function mutant of IAA7/AXR2, axr2-1, flowers late under SDs. The exogenous application of GAs rescued the late flowering phenotype of axr2-1 plants. The expression of the GA20 oxidase (GA20ox) genes, GA20ox1 and GA20ox2, was reduced in axr2-1 plants, and the levels of both LFY and SOC1 transcripts were reduced in axr2-1 mutants under SDs. Furthermore, the overexpression of SOC1 or LFY in axr2-1 mutants rescued the late flowering phenotype under SDs. Our results suggest that IAA7/AXR2 might act to inhibit the timing of floral transition under SDs, at least in part, by negatively regulating the expressions of the GA20ox1 and GA20ox2 genes.

Inheritance and effects of the photoperiod sensitivity in foxtail millet (Setaria italica P. Beauv)

Photoperiod-sensitive male sterility is a useful tool for exploitation of the heterosis in foxtail millet (Setaria italica P. Beauv), especially of the inter-specific cross using a two-line system. A foxtail millet photoperiod-sensitive male sterile line JG1S was identified in our hybrid breeding program which exhibited complete sterility under natural long daylight conditions (14.5 h d−1) and partial fertility under short daylight conditions (10 h d−1). The genetic basis of photoperiod-sensitive male sterility in JG1S was studied using nine F1×F2 and BCF1 progeny populations descended from crosses between JG1S as the female parent and nine fertile varieties as male parents. The F1 plants showed complete fertility similar to their male parents, indicating this photoperiod-sensitive male sterility was conferred by nuclear recessive gene(s). The testcross F2 and BCF1 that descended from three F1 fit a ratio of 1:3 and 1:1, respectively, while the testcross F2 and BCF1 descended from other six F1 fitted a ratio of 1:15 and 1:3, respectively. Therefore, it was inferred that two pairs of major recessive genes controlled the photoperiod-sensitive male sterility of JG1S. To establish which developmental stages are sensitive to photoperiod, and how the light integral affects plant fertility, two experiments were designed to evaluate the factors on photoperiod-sensitive male sterility by using reciprocal transfer experiments between long daylight (≥14 h d−1) and short daylight (10 h d−1) in specific developmental phases. The effects of photoperiod on the plant sterility and fertility were examined by using experiments in controlled chambers at seven photoperiod regimes (9 h d−1–15 h d−1). Plants were sensitive to photoperiod between the panicle initiation stage and the anthesis stage, with the greatest sensitivity observed in the phase from the panicle initiation stage to the floral primordial initiation stage. The plant fertility rate differed with the variation of photoperiod duration. The 13 h d−1 was a critical photoperiod regime for transformation between plant sterility and fertility. The plants remained completely sterile when photoperiod was 14 h d−1 or longer, and a higher fertility frequency was induced under photoperiod regime of 12 h d−1 or shorter.

Predation by Neoseiulus cucumeris on western flower thrips, and its oviposition on greenhouse cucumber under winter vs. summer conditions in a temperate climate

Abstract In short-term controlled chamber experiments, the influence of light intensity, photoperiod, temperature, and light vs. dark conditions within the diel cycle were investigated on the predation and oviposition rates of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), a biological control agent commonly used in greenhouse crops worldwide. In a 2 × 2 factorial experiment, neither light intensity nor photoperiod had an effect on the number of thrips killed by N. cucumeris at 24 °C. Light intensity, but not photoperiod, had an effect on the number of eggs laid, with more eggs laid at high (83.0 ± 1 Wm −2 ) than low (11.1 ± 0.5 Wm −2 ) light intensity at 24 °C. When simulated seasonal light regimes were compared (summer: high light intensity, long daylength vs. winter: low light intensity, short daylength) at the 2 constant temperatures 20 °C vs. 24 °C, only temperature had an effect. Significantly more thrips were killed at 24 °C than 20 °C irrespective of light regime, which is consistent with light having had no effect in the light intensity × photoperiod assay. There was no significant difference in the predation rate on first instar WFT by starved female N. cucumeris during scotophase vs. photophase when raised either under long L16:D8 h or short L8:D16 h diel cycle. However, N. cucumeris females only laid eggs during the photophase, regardless diel cycle in which they were reared. In the winter season, reduced predation by N. cucumeris appears to be influenced more by cooler temperature, than low light intensity and/or short days alone. However, our results also indicate that poor or delayed establishment and numerical response of N. cucumeris in the winter in northern temperate zones in greenhouses under natural light may result from reduced reproductive rate under low light intensity and short daylight conditions.