Trifoliate Leaf Research Articles

An environmentally benign and cost-effective technique for reducing bird damage to sprouting soybean seeds

Worldwide, birds are considered to be the most destructive pests of soybean during the sprouting and seedling stages. The spotted dove, Spilopelia chinensis (Scopoli) and occasionally feral pigeon, Columba livia Gmelin (Columbiformes: Columbidae) causes heavy damage in newly sown soybean fields in northeast India. Due to adverse side effects of chemicals on ecosystem and protection of the S. chinensis by laws; use of reflective ribbons and protecting nets are very common practices to prevent the bird damage in soybean. Scarring of birds manually by employing labourers is expensive; while the reflective ribbons provide inadequate protection against the birds. Although protective nets are highly effective, they are expensive and unaffordable for small and marginal farmers. Therefore, to find out a cheaper and environmentally friendlier technique, a series of experiments was conducted on soybean variety ‘Bragg’ at the entomology farm during the year 2011–2013. Initially, the foraging behavior and feeding preferences of the doves and pigeons were studied under field conditions, and accordingly different sowing times (STs), planting depths (PDs), and temporary physical barriers (TPBs) were employed to protect the sprouting seeds from the damage. Rice and maize straw along with reflective ribbons were used to create TPBs over the sown field. The doves and pigeons preferred feeding on sprouted seeds only up to the green cotyledon stage. However, the seedling damage was observed up to the first trifoliate leaf stage. An inverse relationship was found between the delay in ST and PD with the bird damage. Significantly lower damage (18.5%) was found in treatments consisting of rice straw cover with reflective ribbon (RSCRR). The bird damage varied significantly with different STs, PDs, and TPBs during 2012–2013. Also, the damage varied significantly for treatments with interactions between ST×PD, ST×RSCRR, PD×RSCRR, and ST×PD×RSCRR. The overall results show that, bird damage was significantly reduced (only 3.45% bird damage); when the soybean was sown during mid-July at a 4.0-cm PD and temporarily covered with RSCRR. Rice straw being cheaper and readily available biomass can further be re-utilized for composting and other agro-processing techniques. This technique can also be applied in other parts of the world with slight modifications in the ST and PD.

Seed-borne nature of a begomovirus, Mung bean yellow mosaic virus in black gram.

The yellow mosaic viruses (YMV) infecting legumes are considered to be the most devastating begomoviruses as they incite considerable yield loss. The yellow discoloration of pods and seeds of infected plants and symptom emergence in the very first trifoliate leaf of the plants in the field were suggestive that the virus may be seed borne, which was investigated in the present study. The distribution of the virus in various parts of the seeds of black gram (Vigna mungo L. Hepper) plants naturally infected in the field was determined by polymerase chain reaction (PCR), Southern blot analysis, and sequencing. Nucleotide sequencing of the PCR amplicons from the seed parts from groups of ten seeds revealed the presence of mung bean yellow mosaic virus (MYMV) in the seed coat, cotyledon, and embryonic axes. The presence of virion particles was confirmed through double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and immunosorbent electron microscopy (ISEM) even in a single whole seed. In confocal microscopy, positive fluorescent signals were obtained using coat protein gene-specific primers in the embryonic axes. However, in the growth tests performed with the same batch of seeds, there was no symptom development in the seedlings though the virus (both DNA A and B components) was detected in 32 % of tested seedlings. In this study, the MYMV was detected in seed coat, cotyledon, and embryo. This study revealed that the MYMV is a seed-borne virus.

Two cultivars of peanut (Arachis hypogaea) seedlings show different tolerance to calcium deficiency

ABSTRACTThe objectives were to determine whether two peanut cultivars show different tolerance to calcium (Ca) deficiency. The seedlings of cultivars LH11 and YZ9102 at first trifoliate leaf stage were transplanted in nutrient solution for 28 days with 0.01 and 2.0 mmol/L Ca treatments. Low Ca supply did not affect plant growth, root length and surface area of YZ9102, whereas decreased plant biomass, root length and surface area of LH11 seedlings that appeared necrosis in shoot tip. YZ9102 plant had higher Ca concentration and more Ca distribution to leaves than LH11. Under limited Ca condition, LH11 appeared net Ca2+ effluxes in the zones of 0.2 ∼ 1.5 mm from root apex, while YZ9102 roots maintained net Ca2+ influxes. Peanut cultivar YZ9102 seedlings had longer roots and higher capacities of Ca uptake and Ca translocation to shoots than LH11, which might be account for higher tolerance to Ca deficiency compared with LH11.

Iron partitioning at an early growth stage impacts iron deficiency responses in soybean plants (Glycine max L.).

Iron (Fe) deficiency chlorosis (IDC) leads to leaf yellowing, stunted growth and drastic yield losses. Plants have been differentiated into ‘Fe-efficient’ (EF) if they resist to IDC and ‘Fe-inefficient’ (IN) if they do not, but the reasons for this contrasting efficiency remain elusive. We grew EF and IN soybean plants under Fe deficient and Fe sufficient conditions and evaluated if gene expression and the ability to partition Fe could be related to IDC efficiency. At an early growth stage, Fe-efficiency was associated with higher chlorophyll content, but Fe reductase activity was low under Fe-deficiency for EF and IN plants. The removal of the unifoliate leaves alleviated IDC symptoms, increased shoot:root ratio, and trifoliate leaf area. EF plants were able to translocate Fe to the aboveground plant organs, whereas the IN plants accumulated more Fe in the roots. FRO2-like gene expression was low in the roots; IRT1-like expression was higher in the shoots; and ferritin was highly expressed in the roots of the IN plants. The efficiency trait is linked to Fe partitioning and the up-regulation of Fe-storage related genes could interfere with this key process. This work provides new insights into the importance of mineral partitioning among different plant organs at an early growth stage.

Effect of limited supply of assimilates on the relationships between their sources and acceptors

Sink activity in young sunflower and bean plants was determined mainly by their growth rate. The organ with higher RGR (stem in sunflower and apical part with expanded trifoliate leaf- in bean plant) was the dominant acceptor even in conditions of limited supply of assimilates.Specific activity of root - donor of phosphorus, depends on the roofs metabolic and physiological activity only in the case, when supply of P to the aerial parts is not a factor limiting photosynthesis. If the activity of the whole root system is relatively low (like in preshaded series of sunflower) the photosynthetic compensation observed in plants replaced into better conditions coincides with compensation of P-absorption (both calculated per g of dry matter). It may explain the existence of a functional balance between shoot and root activity in the case of a changed proportion between their sizes.

Characterization of Peroxidase Changes in Tolerant and Susceptible Soybeans Challenged by Soybean Aphid (Hemiptera: Aphididae).

Changes in protein content, peroxidase activity, and isozyme profiles in response to soybean aphid feeding were documented at V1 (fully developed leaves at unifoliate node, first trifoliate leaf unrolled) and V3 (fully developed leaf at second trifoliate node, third trifoliate leaf unrolled) stages of soybean aphid-tolerant (KS4202) and -susceptible (SD76R) soybeans. Protein content was similar between infested and control V1 and V3 stage plants for both KS4202 and SD76R at 6, 16, and 22 d after aphid introduction. Enzyme kinetics studies documented that control and aphid-infested KS4202 V1 stage and SD76R V1 and V3 stages had similar levels of peroxidase activity at the three time points evaluated. In contrast, KS4202 aphid-infested plants at the V3 stage had significantly higher peroxidase activity levels than control plants at 6 and 22 d after aphid introduction. The differences in peroxidase activity observed between infested and control V3 stage KS4202 plants at these two time points suggest that peroxidases may be playing multiple roles in the tolerant plant. Native gels stained for peroxidase were able to detect differences in the isozyme profiles of aphid-infested and control plants for both KS4202 and SD76R.

Diel growth patterns of young soybean (Glycine max) leaflets are synchronous throughout different positions on a plant.

Leaf growth is controlled by various internal and external factors. Leaves of dicotyledonous plants show pronounced diel (24 h) growth patterns that are controlled by the circadian clock. To date, it is still uncertain whether diel leaf growth patterns remain constant throughout the development of a plant. In this study, we followed growth from the primary leaves to leaflets of the seventh trifoliate leaf of soybean (Glycine max) on the same plants with a recently developed imaging-based method under controlled conditions and at a high temporal resolution. We found that all leaflets displayed a consistent diel growth pattern with maximum growth towards the end of the night. In some leaves, growth maxima occurred somewhat later - at dawn - as long as the leaves were still in a very early developmental stage. Yet, overall, diel growth patterns of leaves from different positions within the canopy were highly synchronous. Therefore, the diel growth pattern of any leaf at a given point in time is representative for the overall diel growth pattern of the plant leaf canopy and a deviation from the normal diel growth pattern can indicate that the plant is currently facing stress.

RESISTANCE TO ANGULAR LEAFSPOT DISEASE OF STRAWBERRY: INFLUENCE OF SEEDLING AGE

The bacterium Xanthomonas fragariae (Xf) causes the economically important angular leafspot disease to which a high level of resistance has not been found within the cultivated strawberry Fragaria ×ananassa. The 2002 introduction of resistance donors ‘US 4808’ and ‘US 4809’ by the Fruit Laboratory at the Beltsville Agricultural Research Centre, provided sources of resistance at the octoploid level derived from F. virginiana. Moving this resistance through three generations of back crossing to different recurrent F. ×ananassa parents along with screening progeny (12-week-old seedlings) for resistance with a spray inoculation method, followed by selection based on horticultural traits, has created improved resistant genotypes. Selection from mature plants of seedling populations that had not been screened for Xf resistance gave 50% resistant selections – much higher than expected. Therefore, an experiment was designed to determine if some plants develop resistance after 12 weeks of age. Seven controlled crosses were performed in the greenhouse including three resistant (R) × resistant, three resistant × susceptible (S), and one S×S. The S×S cross was included to provide susceptible seedlings, to ensure that the inoculation procedure was effective. Four replicates of seedling sets of 10 to 12 plants per cross were inoculated at 12 or 17 weeks and rated for disease 3 weeks later. The R×R seedlings inoculated at 12 weeks had a mean disease rating of 1.19 compared to 2.28 for seedlings inoculated at 17 weeks. The R×S seedlings inoculated at 12 weeks had a mean disease rating of 2.75 compared to 3.56 for seedlings inoculated at 17 weeks. When seedlings were classified as resistant or susceptible, data analysis showed no significant differences in percent resistant between the inoculation times. These results argue against our hypothesis that older plants show resistance not identified in young seedlings and validate our procedure of screening young seedlings grown to the four to five trifoliate leaf stage. Resistant to susceptible segregation ratios of approximately 3:1 and 1:1 were found in R×R and R×S progeny, respectively, indicating that resistance shows a measure of dominance over susceptibility.

English

The knowledge and understanding of the genetic variability of common bean (Phaseolus vulgaris L.) germplasm is important for the implementation of measures addressed to their utilizations and conservation. The objective of this study was to characterize common bean in Uganda using polymorphic molecular markers for use in hybridization and variety development. Genomic DNA was extracted from plants at the first trifoliate leaf stage growing in pots using the modified cetyl-trimethylammonium bromide (CTAB) method. The gene pool membership (Andean vs. Mesoamerican) for each accession was established with the phaseolin marker. Simple sequence repeat (SSR) alleles were separated by capillary electrophoresis that provided further information on the organization of genetic diversity. The Andean and Mesoamerican genotypes were present in similar frequencies (51 vs. 49%, respectively). All SSR markers tested were polymorphic with mean polymorphism information content (PIC) of 0.8. The model-based cluster analysis of SSR diversity in the STRUCTURE software found three sub populations (K3.1, K3.2 and K3.3) genetically differentiated with moderate Wrights fixation indices (FST) values 0.14, 0.12 and 0.09, respectively and many cases of admixture. The STRUCTURE result was confirmed by Principal Coordinate analysis (PCoA) which also clustered beans in three groups. Most Andean genotypes were included in K3.1 and Mesoamerican genotypes belonged to the K3.2 and K3.3 subgroups. This study sets the stage for further analyses for agronomic traits such as yield, resistance to biotic and abiotic stresses and the need for germplasm conservation.   Key words: Phaseolin, Simple sequence repeat (SSR), hybridization, wrights fixation index (FST), structure.

Somatic embryogenesis, tetraploidy, and variant leaf morphology in transgenic diploid strawberry (Fragaria vesca subspecies vesca 'Hawaii 4').

BackgroundThe diploid (2n = 2x = 14) strawberry model plant Fragaria vesca ssp. vesca ‘Hawaii 4’ was employed for functional analysis of expressed DNA sequences initially identified as being unique to Fragaria and of unknown or poorly understood function. ‘Hawaii 4’ is prominent in strawberry research due to its ease of Agrobacterium-mediated transformation and regenerability, and its status as the source of the first complete strawberry genomic sequence. Our studies of a set of transformants have documented intriguing, construct-associated effects on leaf morphology, and provide important and unexpected insights into the performance of the ‘Hawaii 4’ transformation and regeneration system.ResultsFollowing Agrobacterium-mediated transformation of leaf explants with gene constructs carried by Gateway® vectors, plants were regenerated using a modified version of an established ‘Hawaii 4’ protocol. Expanding upon the findings of prior studies, we documented that plantlet regeneration was occurring via a somatic embryogenic rather than an organogenic developmental pathway. Among transformants, several variations in leaf morphology were observed. Unexpectedly, a particular leaf variant type, occurring in ~17% of all regenerants independent of construct type, was found to be attributable to tetraploidy. The tetraploidy-associated alteration in leaf morphology could be differentiated from the leaf morphology of diploid regenerants on the basis of a quantitative ratio of leaf dimensions: B/A, where B is the width of the central leaflet and A is the overall width of the trifoliate leaf. Variant effects on leaf morphology of four different transgenic constructs were also documented, and were in all cases distinguishable from the effects of tetraploidy.ConclusionsThese results define opportunities to optimize the existing ‘Hawaii 4’ protocol by focusing on treatments that specifically promote somatic embryogenesis. The reported morphological metric and descriptions will guide future transgenic studies using the ‘Hawaii 4’ model system by alerting researchers to the potential occurrence of polyploid regenerants, and to differentiating the effects on leaf morphology due to polyploidy versus transgenic manipulations. Finally, an intriguing spectrum of leaf morphology alterations resulting from manipulation of expressed sequences of uncertain function is documented, providing a foundation for detailed studies of the respective genes and their functional roles.

Evaluation of fungicide application rates, spray schedules and alternative management options for rust and angular leaf spot of snap beans in Uganda

Yield losses due to rust and angular leaf spot (ALS) of snap beans may reach 100% in Eastern Africa. Where susceptible varieties are grown, farmers control these diseases with routine fungicide applications. To determine an optimum application rate and spray schedule for Orius® (tebuconazole 250 g/L), we sprayed 10 mL and 20 mL Orius® per 15 L spray water twice at two trifoliate leaf stage and 50% flowering, and three times at the same stages, with an additional application at pod initiation. In farmers’ fields, we tested the effect of fungicide sprays, use of resistant variety, intercropping, increased plant spacing and farmyard manure on rust and ALS diseases. Application three times of 20 mL Orius® per 15 L spray water reduced rust severity scores by 5.7 and 2.4 in 2010 and 2011, respectively. Lowest rust and ALS severities were observed when a resistant variety, fungicide or farmyard manure was used. Pod yield increments due to disease management ranged between 13% and 242%. Prophylactic fungicide application, use of resistant varieties and farmyard manure can be used to reduce disease severity and improve snap bean quality on smallholder farms.

Reproductive development of four top flowering annual clovers

A series of field experiments aimed to quantify reproductive development of four clover species, arrowleaf (Trifolium vesiculosum), balansa (T. michelianum), gland (T. glanduliferum) and Persian (T. resupinatum), for introduction to New Zealand dryland pastures. The duration from emergence to flowering was related to the length of, and direction of change in, photoperiod at the time of first trifoliate leaf appearance. Autumn-sown crops that emerged into a decreasing photoperiod had a longer vegetative growth before they turned reproductive. The time to flower became shorter with increasing photoperiod until the longest day of the year, before it began to slow down as photoperiod decreased towards late summer. Prima gland clover flowered earlier (500–1216 degree-days) than Bolta balansa (600–1733 degree-days), Cefalu arrowleaf (940–1834 degree-days) and Mihi Persian (1047–2610 degree-days) clovers. The duration from pollination to physiological maturity was 274–689 degree-days for Cefalu, 185 degree-days for Bolta, 256 degree-days for Prima, and 425 degree-days for Mihi. The differences in flowering time suggests the suitability of Prima gland clover for areas that dry out quickly in late spring, Bolta balansa clover for areas of wet winter and dry summer, and Cefalu arrowleaf and Mihi Persian clovers for areas that receive higher spring rainfall.

Tolerance of Maize (<i>Zea mays</i> L.) and Soybean [<i>Glycine max</i> (L.) Merr.] to Late Applications of Postemergence Herbicides

Seven maize (Zea mays L.) and three soybean (Glycine max (L.) Merr.) field experiments were con- ducted from 2006 to 2009 at various locations in southern Ontario, Canada to determine the to- lerance of these crops to late applications of the maximum labeled herbicide dose. Single and se- quential (simulating a spray overlap) applications were evaluated for visible injury, plant height, and crop yield in the absence of weed competition. Maize exhibited excellent tolerance to herbi- cides applied at the 9- to 10-leaf growth stage as visible injury levels for almost all tested herbi- cides was similar to the untreated control 7 days after treatment (DAT). However, the sequential application of dicamba/diflufenzopyr or foramsulfuron caused 6 and 8% injury 7 DAT and 8 and 14% reduction in maize height 28 DAT, respectively. The observed injury and stunting were tran- sient as there were no differences in yield at harvest. Soybean displayed good tolerance to most herbicides applied at the 7th trifoliate leaf growth stage as visible injury levels were similar to the untreated control. However, thifensulfuron-methyl was injurious regardless of application and imazethapyr was injurious with sequential applications. For example, single thifensulfuron-me- thyl, sequential thifensulfuron-methyl, and sequential imazethapyr application treatments caused 35, 48, and 25% injury 7 DAT, respectively. Sequential thifensulfuron-methyl treatments also caused a 28 and 17% reduction in soybean height 14 and 28 DAT, respectively. Visual injury con- tinued to be detected up to 56 DAT for single thifensulfuron-methyl, sequential thifensulfuron- methyl, and sequential imazethapyr treatments. But, soybean yields were reduced by 10% for on- ly sequential thifensulfuron-methyl application treatments. For all other herbicides tested, the yields at harvest were similar to the untreated control. This research demonstrated that maize had exceptional tolerance to all the herbicides used in this study whereas soybean was tolerant to most of the herbicides used in this study. * Corresponding author.

콩의 잎 크기와 종실 무게와의 상관

콩 품종육성에 있어 잎의 크기가 종실무게와 관련된 형질의 초기 분리세대에서 조기선발 지표로서 활용 가능성을 구명하고자 재래종, 도입종 및 야생종 등 229개 품종 및 유전자원을 대상으로 단엽과 제1본엽 및 제3본엽과 종실 무게와의 상관관계를 조사 분석한 결과를 요약하면 다음과 같다. 1. 시험재료 229개 품종 및 유전자원의 단엽 면적은 <TEX>$3.2{\sim}33.8cm^2$</TEX>, 제1본엽 면적은 <TEX>$9.2{\sim}29.5cm^2$</TEX>, 제3본엽 면적은 <TEX>$7.2{\sim}58.9cm^2$</TEX>, 종실의 100립 무게는 2.7~39.0 g의 범위를 나타내었다. 2. 엽 면적과 종실 무게간에는 높은 정의 상관이 있었고, 상관의 크기는 단엽(r=<TEX>$0.80^{**}$</TEX>), 제1본엽(<TEX>$0.75^{**}$</TEX>), 제3본엽(<TEX>$0.67^{**}$</TEX>) 순으로 나타났다. 3. 엽의 장폭과 종실무게 사이에는 유의한 정의 상관이 있었고 단엽의 길이(0.71)와 폭(0.79)이 제1본엽, 제3본엽 보다 상관이 높았으며, 엽장보다는 엽폭이 높은 상관을 보였다. 조사된 콩 잎의 장 폭비는 상위엽이 높았다. 4. 콩 종실크기와 관련된 생육 초기선발의 간접지표로서 단엽 크기와 단엽의 폭을 이용하는 것이 제일 유리할 것으로 판단되었다. This study was carried out to examine whether the leaf size is likely to be used as a selection criterion for large seed genotype in soybean (Glycine. max (L.) Merr.) breeding program. Two hundred twenty nine soybean germplasms which had collected in Korea, United States, China and Japan were used in this experiment. The area of unifoliate leaf, middle leaflet of first trifoliate and third trifoliate leaf ranged from <TEX>$3.2cm^2$</TEX> to <TEX>$33.8cm^2$</TEX>, 9.2 to <TEX>$29.5cm^2$</TEX>, and 7.2 to <TEX>$58.9cm^2$</TEX>, respectively. One hundred seed weight also showed great variation from 2.7 to 39.0 gram. The average leaf area of unifoliate, middle leaflet of first trifoliate and third trifoliate leaf were <TEX>$15.7cm^2$</TEX>, <TEX>$18.1cm^2$</TEX> and <TEX>$32.7cm^2$</TEX>, respectively, and that of seed average weight was 17.2 gram per one hundred seed. Significantly positive correlations were observed between seed weight and leaf area of unifoliate (r=<TEX>$0.80^{**}$</TEX>), first trifoliate (r=<TEX>$0.75^{**}$</TEX>) and third trifoliate (r=<TEX>$0.67^{**}$</TEX>), respectively. Both the leaf length and leaf width of unifoliate, middle leaflet of first trifoliate and third trifoliate leaf were significantly positively correlated with seed weight and both the correlations of unifoliate were higher than the other leaves. The correlations of leaf width in soybean leaflet were higher than those of leaf length. Leaf length/width (L/W) ratio of upper leaf was higher than that of lower leaf in the leaf size. Both the leaf area and leaf width of unifoliate leaf are the most suitable predictive characteristics of early selection in related to seed weight for soybean breeding program.

Effect of nickel on plant water relations and growth in green gram

Effect of nickel on water potential (ψw), osmotic potential (ψs), turgor potential (ψp) and relative water content (RWC) was studied in the first trifoliate leaf of green gram [Vigna radiata (L.) Wilczek] in order to establish its possible influences on growth through altered water relations. Plants were grown on silica with nutrient solution containing 1, 10, 100 and 1,000 μM, Ni as NiC12·6H2O. The effect of Ni on water relations was highly concentration dependent. The growth promoting concentration of Ni (1 μM) resulted in the highest ψw and ψp, and lowest ψs. The growth inhibiting concentrations of Ni (10, 100 and 1,000 μM) significantly decreased ψw and ψp. At 1,000 μM Ni significantly increased ψs. At 1 μM Ni significantly increased RWC, while it was adversely affected at 10–1,000 μM Ni concentrations. One μM Ni treatment increased chlorophyll contents and growth, while higher concentrations (10–1,000 μM) of Ni significantly decreased the chlorophyll contents and growth.

Production of Common Sour Orange × Carrizo Citrange Hybrids Using Embryo Rescue

Citrus rootstock breeding is important in improving resistance to diseases, insect pests, and adverse environmental conditions. The majority of citrus species and cultivars have nuceller embryony, which causes some problems for breeding programs. This disadvantage can be eliminated by using embryo rescue. In this research, Common sour orange × Carrizo citrange were crossed in order to produce new rootstocks and immature embryos. The embryos were gathered from the crossed plants 80, 100, and 120 days after pollination. The immature embryos were transferred to 0, 0.5, and 1 mg/L GA3 containing medium to germinate them. In general, the later after pollination that the embryos were harvested, the higher the germination rate. Those harvested at 80 days averaged 32% over all treatments, while those harvested at 100 days averaged 77%, and those harvested at 120 days averaged 98% germination. Embryos on control media averaged 67% germination over all treatments, while those with 0.5 mg/L GA3 averaged 62%, and those with 1 mg/L GA3 in the media averaged 78% germination. The percentage of embryos developing trifoliate leaves for those harvested at 80 days averaged 51% over all treatments, while those harvested at 100 days averaged 24%, and those harvested at 120 days averaged 41%. Embryos on control media averaged 36% trifoliate leaf development over all treatments, while those with 0.5 mg/L GA3 averaged 35%, and those with 1 mg/L GA3 in the media averaged 44% germination.

Obtaining citrus hybrids by in vitro culture of embryos from mature seeds and early identification of hybrid seedlings by allele-specific PCR

Two trifoliate oranges (Poncirus trifoliata var. monstrosa and P. trifoliata cv ‘Xiaoganzhi’) were used separately as pollinators to cross with Shantou-Suanju (Citrus sunki Hort. ex. Tan.) for breeding new citrus rootstocks. Embryos from the seeds of mature fruits were rescued and individually cultured in vitro. On average, 9.0–10.0 embryos per seed were harvested from the two crosses. The zygotic seedlings were only derived from large- to medium-sized embryos. The small embryos were not able to germinate or develop into seedlings. The numbers of seedlings per seed produced from the two crosses were similar, ranging from 1 to 11 and 1 to 14, at average of 4.17 and 4.90, respectively, with in vitro culture in this study. A dominant trifoliate leaf trait from P. trifoliata was used as a morphological marker to discriminate hybrid from nucellar seedlings. Of 43 and 14 zygotic seedlings were obtained from 98 and 65 seeds of the two crosses, respectively. In addition to the use of morphological marker, single nucleotide polymorphism based allele specific PCR (AS-PCR) was also successfully employed as a handy tool to confirm and identify zygotic seedlings.

A temporal regulatory mechanism controls the different contribution of endoplasmic reticulum and plastidial ω-3 desaturases to trienoic fatty acid content during leaf development in soybean (Glycine max cv Volania)

We analyzed the molecular mechanism controlling ω-3 fatty acid desaturases during seed germination and leaf development in soybean. During germination, soybean seeds were characterized by a high 18:2(Δ9,12) level (more than 50%) and reduced 18:3(Δ9,12,15) content (10%). Interestingly, transcripts from all endoplasmic reticulum (GmFAD3A and GmFAD3B) and plastidial (GmFAD7-1/GmFAD7-2 or GmFAD8-1/GmFAD8-2) desaturase genes were detected during seed germination. Upon germination, soybean trifoliate leaf development was accompanied by an increase in linolenic acid (18:3(Δ9,12,15)). Our data showed that transcripts corresponding to the endoplasmic reticulum ω-3 desaturases GmFAD3A and GmFAD3B decreased with leaf development. No changes in the expression profile of the plastidial ω-3 desaturases GmFAD7-1 and GmFAD7-2 genes were detected. On the contrary, GmFAD8-2 transcript levels increased while GmFAD8-1 transcripts decreased during leaf development. Given this expression profile, our data suggested the existence of a temporal regulatory mechanism controlling ω-3 desaturases during leaf development in which the endoplasmic reticulum ω-3 desaturases would be more important in young leaves while plastidial ω-3 desaturases might contribute to 18:3(Δ9,12,15) production in mature leaves. Photosynthetic cell cultures showed 18:3(Δ9,12,15) levels similar to those from leaves. No changes in the 18:3(Δ9,12,15) content or expression of the ω-3 desaturase genes were detected along the cell culture cycle. A comparison of our data with those available in Arabidopsis or wheat suggested that the regulatory mechanism controlling the expression and activity of both endoplasmic reticulum and plastidial desaturases during leaf development might differ among plant species.

Light‐induced systemic regulation of photosynthesis in primary and trifoliate leaves of Phaseolus vulgaris: effects of photosynthetic photon flux density (PPFD) versus spectrum

The objectives of this work using Phaseolus vulgaris were to examine whether the light spectrum incident on mature primary leaves (PLs) is related to leaf-to-leaf systemic regulation of developing trifoliate leaves (TLs) in photosynthetic characteristics, and to investigate the relative importance of spectrum and photosynthetic photon flux density (PPFD) in light-induced systemic regulation. Systemic regulation was induced by altering PPFD and the spectrum of light incident on PLs using a shading treatment and lighting treatments including either white, blue, green or red light-emitting diodes (LEDs). Photosynthetic characteristics were evaluated by measuring the light-limited and light-saturated net photosynthetic rates and the amounts of nitrogen (N), chlorophyll (Chl) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39). Shading treatment on PLs decreased the amounts of N, Chl and Rubisco of TLs and tended to decrease the photosynthetic rates. However, we observed no systemic effects induced by the light spectrum on PLs in this study, except that a higher amount of Rubisco of TLs was observed when the PLs were irradiated with blue LEDs. Our results imply that photoreceptors in mature leaves have little influence on photosynthetic rates and amounts of N and Chl of developing leaves through systemic regulation, although the possibility of the action of blue light irradiation on the amount of Rubisco cannot be ruled out. Based on these results, we concluded that the light spectrum incident on mature leaves has little systemic effect on developing leaves in terms of photosynthetic characteristics and that the light-induced systemic regulation was largely accounted for by PPFD.

Arbuscular mycorrhizal fungi induce sucrose cleavage for carbon supply of arbuscular mycorrhizas in citrus genotypes

Arbuscular mycorrhizas (AMs) must gain carbohydrates (mainly glucose) through sucrose cleavage from their plant hosts. Using the AM fungus Funneliformis mosseae inoculated or non-inoculated citrus genotypes [red tangerine (Citrus tangerina Hort. ex Tanaka), kumquat (Fortunella margarita Lour. Swingle), and trifoliate orange (Poncirus trifoliata L. Raf.)], we tested the hypothesis that the sucrose cleavage would depend on sucrose-cleaving enzyme types and/or host genotypes for carbon supply to the AM development. Mycorrhizal inoculation significantly increased biomass production and glucose contents of leaf, root, and total plant, irrespectively of citrus genotypes. In contrast, under mycorrhization similar leaf sucrose contents were observed between these three citrus genotypes, whereas significantly higher sucrose contents were in roots of red tangerine and kumquat, and in total plant (leaf plus root) of red tangerine and trifoliate orange. Root AM colonization was significantly positively correlated with leaf and total plant glucose but not with root glucose or with sucrose in either leaf and/or root. Root AM colonization increased the activity of leaf acid invertase (AI) and sucrose synthase (SS) and root neutral invertase (NI) in trifoliate orange, leaf SS and root AI in kumquat, and root NI in red tangerine, but decreased leaf NI in all three citrus genotypes, leaf SS in red tangerine, root AI in red tangerine and trifoliate orange, and root SS in kumquat and trifoliate orange. These results support our hypothesis that the sucrose cleavage highly depended on both citrus genotypes and sucrose-cleaving enzyme types/activity, and thus may provide higher glucose as carbon source to support their fungal partners.