Conservation of microRNA-mediated regulatory networks in response to copper stress in grapevine

Jatropha curcas L. as a bio energy plant belonging to the Euphorbiaceae family is gaining progressive importance over the last years. In 2012 and 2014 field experiments were carried out to assess the effects of cytokinins 6-Benzyladenine (BA) and Forchlorfenuron (CPPU) acting as plant growth regulators (PGRs). Number of flowers per inflorescence, female-to-male ratio of flowers, fruits per infructescence, fruiting rate, number of seeds per fruit, seed size and weight as well as seed oil content were determined. It was suggested that concerning effectiveness of exogenous application of PGRs the developmental stage of flower is very important. Due to that, special interest was laid on the age of inflorescences at the time of application. Our experiments revealed a strong dependence of cytokinin effectiveness on the developmental stage of flowering. So treatment of plants with 6-Benzyladenine at the beginning of flower formation (stage 1) significantly increased the number of male and female flowers per inflorescence, whereas treatment at an advanced flowering stage (stage 2) or at the stage of fully developed flowers (stage 3) had only slight or no effects. In contrast, fruit retention was progressively increased by treatment in stage 2 and 3. Application of Forchlorfenuron significantly increased female-to-male ratio in stage 1 flowers but showed no effects on stage 2 and 3. 6-Benzyladenine as well as Forchlorfenuron showed equal effects on number of fruit inflorescences treated in stage 1. Our results show a significant decrease in seed weight due to BA- and CPPU-application while kernel weight remained stable. Concerning fruits, clusters and oil yield per tree, BA-application showed significant increasing effects. This study indicates that 6-Benzyladenine and Forchlorfenuron can improve yield affecting parameters in J. curcas when the phenological stage of flowering at time of application is precisely considered.     

Paclobutrazol Improved the Reproductive Growth and the Quality of Seed Oil of Jatropha curcas

Jatropha curcas was treated by soil drench paclobutrazol (PBZ) (0, 2, and 3 g m^?1 of canopy diameter) and foliar spray PBZ (0, 500, 800, and 1,200 ppm). The results showed that PBZ treatments greatly retarded vegetative growth and improved reproductive growth. The lengths of new branches were greatly decreased, whereas the number of fruits per inflorescence, fruit-bearing branches per tree, and total fruit load per tree were increased. Only the 2-g soil drench and the 1,200-ppm foliar PBZ spray significantly increased fruit load. The 2-g soil drench PBZ treatment resulted in a decrease in seed S and Cu contents of J. curcas, whereas Mn and B were greatly or moderately increased. A higher dose (3-g soil drench PBZ) reversed the improvement in reproductive growth and alleviated the negative effects on element contents in seeds compared with the 2-g soil drench PBZ. Finally, soil drench PBZ treatments significantly improved seed oil content and oil quality by reducing the oil acid value, increasing stearic acid and oleic acid contents, and reducing palmitic acid and linoleic acid content. The optimum drench dose was below 2 g m^?1 of canopy diameter. The optimum foliar spray concentration of PBZ was not determined in this study but our results suggest that it is higher than 1,200 ppm.     

Genetic variability, heritability and genetic advance of growth and yield components of Jatropha (Jatropha curcas Linn.) genotypes

A total of 113 Jatropha curcas clonal accessions collected from different regions of India were studied to quantify the magnitude of genetic variability present in the test population and to identify important yield-attributing characters useful for developing high-yielding Jatropha cultivars. High heritability was observed for fruits per plant, seeds per plant, 100-seed weight, seed/kernel (S/K) ratio and kernel oil percentage coupled with high genetic advance suggesting that the accessions can be considered improvement. The significant positive association of seed oil content (%) with 100-seed weight suggested the effectiveness of indirect selection for seed oil content through 100-seed weight. Accessions 76, 120, 29, 86 and 84 showed above average higher values for all yield attributes (viz. fruit and seed yield, 100-seed weight, S/K ratio and oil content) suggesting these as best out of the test accessions. Accessions showing higher values for one or the other yield attributes could be selected as parents for further improvement.     

Assessment of reproductive characteristics of Jatropha curcas L. in south Florida

Jatropha curcas L. (jatropha) is a species identified for biofuel production because of the high quality of the oil produced by its seeds. However, jatropha is undomesticated and little information is available about its reproductive characteristics. Breeding and genetic improvement programs are much needed for the jatropha development as a bioenergy crop. Information about floral display and mode of reproduction are considered essential for breeding programs. In this study, the total number of female flowers, male to female flower ratio, fruit set, in vitro pollen germination, and the formation of fruits by apomixis, self‐pollination, and natural pollination were evaluated in 17 jatropha accessions planted in South Florida. The total number of female flowers per inflorescence and male to female flower ration ranged from 2.8 to 9.1 and 9.9:1 to 55.4 : 1, respectively. During summer 2011, high fruit setting average was observed (75.5%). In vitro pollen germination varied from 64.6% during spring 2011 to 51.6% during fall 2011. The fruit set observed was from 10.1% to 64.0% through natural pollination and apomixes, respectively. Characteristics such as fruit fresh weight, number of seeds per fruit, seed dry weight, and oil content were influenced by mode of reproduction.     

Conservation implications of the reproductive ecology of Agalinis acuta (Scrophulariaceae)

Reproductive ecology of Agalinis acuta was investigated by examining potential for self-fertilization before and at anthesis, reproductive output from outcrossed vs. selfed matings, and effects of browsing, plant size, and conspecific plant density on seed and fruit production. These features of a plant species can provide indirect information pertinent to conservation such as patterns and maintenance of genetic diversity, risk associated with inbreeding depression, and changes in pollinator abundance or effectiveness. The species is self-compatible, with 97% of selfed flowers setting fruit; pollinators were not required for reproduction. However, seed set in self-pollinated fruits averaged 17-20% less than that in open-pollinated fruits. Geitonogamous and facilitated selfing are possible throughout anthesis and autonomous selfing is possible late in anthesis as corollas abscise. Delaying self-pollination until after outcrossing opportunities likely limits selfing rates and thus reduces risks associated with inbreeding but allows reproduction in absence of pollinators. Supplementing pollen on open-pollinated flowers yielded no additional seed set over controls. Neither early-season browsing of primary stems nor conspecific plant density had significant effects on number of fruits per plant, on fruit size, or on number of seeds from open-pollinated flowers. Currently, reproduction appears to be high (about 2400 seeds/plant), and future risks due to lack of genetic diversity are likely low.     

Effects of self-pollination and maternal resources on reproduction and offspring performance in the wild lupine, Lupinus perennis (Fabaceae)

We examined the effects of self-pollination and resource addition to maternal plants of Wild Lupine on seed production in the field, and on offspring performance in the greenhouse. Although 24% of flowers set fruits when open-pollinated, only 11% of flowers set fruits when self-pollinated. Self-pollination significantly reduced fruit and seed production per inflorescence and increased aborted seeds per fruit. Resource addition to maternal plants significantly increased fruit and seed number in the field. Moreover, selfed plants exhibited greater variability in seed production in the absence of resource addition to the maternal plant. We planted a total of 1,306 of the seeds from this experiment in the greenhouse. While self-pollination did not affect the proportion of seeds emerging, it slowed seedling emergence by 5–10%, and reduced offspring biomass by 25–35%. Interestingly, resource addition to the maternal plants significantly decreased proportion of seedlings surviving after 5 months. Moreover, offspring from maternal plants with resource addition expressed more inbreeding depression in the seedling stage compared to offspring from maternal plants without resource addition, for which more inbreeding depression occurred during seed maturation and emergence. These results indicate that conservation efforts using benign environments to increase number of seeds or offspring may face compensating reductions in survivorship at other life stages.     

Pollination intensity and potential seed set in Passiflora vitifolia

Summary Initial seed set and fruit set were pollen-limited in a Costa Rican population of Passiflora vitifolia, a self-incompatible species with 200–350 ovules per flower. Pollination intensity was measured by counting the number of allogamous pollen grains on stigmas of the large one-day flowers. Hand-pollinations demonstrated that 25–50 pollen grains are required for fruit set, and >450 are needed for maximum seed set, with a pollen:seed ratio of about 1.6:1.0. Hummingbirds (Phaethornis superciliosus) delivered sufficient allogamous pollen for maximum seed set to only 28% of the flowers examined. Naturally pollinated flowers yielded fewer fruits and fewer seeds per fruit than those pollinated by hand. Most pollen transferred by humming-birds was self-incompatible; emasculated flowers yielded higher seed set than flowers with intact anthers. Visitation rates did not provide a good index of effective pollination.There were significant differences in ovule number, maximum seed set, and maximum per cent seed set among individual vines. More than half of an individual's flowers failed to set fruit, whether pollinated by birds or by hand. In this population, maximum reproductive potential may be limited by maternal resources for fruit development, but seed set varies with pollination intensity. Pollen-limited seed set may be a disadvantage of self-incompatibility, especially in species with many-seeded fruits.     

Costs of defense: correlated responses to divergent selection for foliar glucosinolate content in <Emphasis Type="Italic">Brassica rapa</Emphasis>

The evolutionary response of plant populations to herbivore imposed selection for defense may theoretically be constrained by the costs of defense, yet few studies convincingly demonstrate such costs. We investigated possible constraints on the evolution of defense in rapid cycling Brassica rapa by divergently selecting lines for investment in foliar glucosinolate content, a chemical defense in this species. Costs would then result in a significant correlated response to artificially imposed selection in the direction opposite to the direct response of foliar glucosinolate production. Correlated responses of date of first flowering, total flower number, number of seeds per fruit, and mean seed mass were examined. After three generations of selection, there was a significant direct response in glucosinolate content of the leaves of B. rapa. Furthermore, we found significant correlated responses in both total flower production and number of seeds produced per fruit, but not date of first flowering or mean seed mass. Lines selected for high glucosinolates produced fewer flowers and seeds per fruit compared to those selected for low glucosinolates while lines selected for low glucosinolates showed the opposite response. Thus, costs of defense were demonstrated and may constrain the evolution of foliar glucosinolate production in this plant species.     

Temporal patterns of seed set and decelerating fitness returns on female allocation in Zigadenus paniculatus (Liliaceae), an andromonoecious lily

I describe temporal patterns of seed production in the andromonoecious lily Zigadenus particulatus. Fruit set per flower and seed set per fruit declined through time within plants. Hand pollination experiments showed that this was not due to increasing pollen limitation. Nutrient supplementation had little effect on seed output, but leaf clipping reduced seed production, especially in late-blooming flowers, and removal of early-blooming flowers increased seed set by later flowers. Thus, the temporal pattern of seed output was due to declining availability of photosynthates. Plants with larger bulbs produced larger inflorescences, a greater proportion of hermaphrodite flowers, more fruits per hermaphrodite flower, and more seeds per fruit, but lost a greater fraction of their initial bulb mass as a consequence of fruiting. After controlling for the effects of bulb mass, plants with larger inflorescences produced a greater proportion of male flowers, and plants with more hermaphrodite flowers produced fewer fruits per hermaphrodite flower and fewer seeds per fruit. Thus, the female fitness gain curve was decelerating. The temporal decline in seed output provides a partial explanation for the parallel decline in allocation to pistils. However, a complete explanation for the pattern of gamete packaging requires an understanding of factors controlling male, as well as female, fitness.     

EFFECTS OF POLLEN AND RESOURCES ON SEED NUMBER AND OTHER FITNESS COMPONENTS IN AMELANCHIER ARBOREA (ROSACEAE: MALOIDEAE)

Most Amelanchier arborea flowers have 10 ovules, but the number of filled (embryo-containing) seeds per fruit is usually less than 10 and is highly variable within each individual plant. Because fruit developmental time correlates with seed number, this variation in seed number results in asynchronous fruit ripening. Field experiments tested whether seed number was pollen- or resource-limited. Manipulation of resources in the shoot at the time of fruit initiation by defoliation, girdling, fruit thinning, or foliar feeding had no significant effect on seed number per fruit, although fruit set and seed weight were affected. Supplemental cross-pollination also had no demonstrable effect on seed number. Most ovules that do not become filled seeds are visible as small “undeveloped seeds”; these are not necessarily aborted seeds as this was also the fate of ovules in unpollinated carpels. Alternative hypotheses for the determination of seed number are proposed and discussed.     

Plasticity of reproductive traits responding to variation in light availability at the rosette stage of the first year in a strict biennial,Pedicularis torta,from a field on the Qinghai–Tibet Plateau,China

Light is a fundamental heterogeneous environmental factor for plants and often varies at both spatial and temporal scales. In the present study, we carried out a shading experiment to investigate the effect of variable light availability at the rosette stage of the first year in the strict biennial species Pedicularis torta (an endemic species of the Qinghai‐Tibet Plateau) on reproductive traits (i.e. total number of flowers per plant, total number of fruits per plant/total number of flowers per plant, the number of seeds per fruit, mean individual seed mass and estimation of the total number of seeds per plant, plant size at maturity in the second year and on the relationships between reproductive traits and plant size at this stage). We found that light availability affected most of the reproductive traits (except for mean individual seed mass), plant size at maturity in the second year, and the relationship between the total number of flowers per plant and plant size at this stage. Our results indicate that reproductive traits respond to changes in light availability during the rosette plant stage.     

Effect of fertilizer application on photosynthesis and oil yield of <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

The use of Jatropha curcas oil as a source of biofuel has been well-explored. However, the physiological and growth studies of J. curcas have received considerably lesser attention. In this study, leaf gas exchange measurements and leaf nitrogen content were determined for four varieties of J. curcas, grown in the field or in pots. Based on stable carbon isotope analysis (δ¹³C) and gas-exchange studies, J. curcas is a C₃ sun plant and the range of leaf photosynthetic rates (or CO₂ assimilation rates, P _Nmax) were typically between 7 and 25 μmol(CO₂) m⁻² s⁻¹ and light saturation generally occurred beyond 800 μmol(quanta) m⁻² s⁻¹. Higher rates of leaf photosynthesis were generally obtained with the mature leaves. In addition, increased foliar P _Nmax were recorded in potted J. curcas variety Indiana with increasing nitrogen (N) nutrition levels. These plants also showed greater growth, increased leaf N content, higher maximum CO₂ assimilation capacity (P _NhighCO2) and chlorophyll (Chl) content, indicating the potential of optimizing the growth of Jatropha by varying fertilizer nutrient levels. A rapid assessment for leaf N using a nondestructive and portable Chl meter had been established for J. curcas. This approach will allow repeated sampling of the same plant over time and thus enable the monitoring of the appropriate levels of soil fertility to achieve good Jatropha plantation productivity. High N nutrition improved the overall plant oil yield by increasing the total number of fruits/seeds produced per plant, while not affecting the intrinsic seed oil content.     

Pollen load size, reproductive success, and progeny kinship of naturally pollinated flowers of the tropical dry forest tree Pachira quinata (Bombacaceae)

Several studies have demonstrated, using controlled pollinations, that the number and identity of pollen grains deposited onto a flower's stigma affect the reproductive success of plants. However, few studies have shown this relationship under conditions of natural pollination. Using the tropical dry forest tree Pachira quinata, we evaluated the relationship between the number of microgametophytes per pistil and the number of sires with respect to the production of fruits and seeds in a natural population of Pachira quinata. Our study demonstrates that fruit and seed production are directly related to the number of microgametophytes per pistil in natural populations of P. quinata. Only 6% of the marked flowers developed into mature fruits and 10% of the marked flowers initiated fruits but later aborted them. A mean of 23 pollen grains were required to produce a seed. Flowers with >400 pollen grains on the stigma always developed into mature fruits, whereas flowers that received <200 grains never matured fruits. Half of the pollen grains transferred to a flower stigma germinated and developed pollen tubes to the base of the style. The number of pollen grains on a stigma explained 34% of the variation in seed number per fruit, and the number of seeds produced per fruit is positively correlated with the size of the seeds. The population of P. quinata studied is predominantly outcrossing, and seeds within fruits are sired by one or a few donors. The total seed crop within trees was sired by three to five donors. Our study examined the implications of the variation in size of microgametophyte loads per pistil with respect to the breeding system and the paternity of progeny under natural conditions. The competitive ability of pollen and pollen tube attrition are important factors regulating fruit production in P. quinata.     

Promoting branching of a potential biofuel crop <Emphasis Type="Italic">Jatropha curcas</Emphasis> L. by foliar application of plant growth regulators

Jatropha curcas L. (Euphorbiaceae) has the potential to become a key biofuel crop. Manual pruning (MP) is one of the major management practices in commercial plantations of this crop, resulting in production of more branches and thus increased potential for more inflorescences leading to a higher seed yield. However, this method is time-consuming, labour-intensive and expensive. This study was conducted to determine the potential of different plant growth regulators (PGRs) to increase the number of lateral branches of J. curcas. A single foliar application of N ⁶-benzyladenine (BA) at 12 mM significantly increased branches in both the pot (4.0) and field (13.2) trials compared to MP (1.8 and 5.7, respectively) and control (no new branches) plants. In the field, a single foliar application of 1.0 mM 2,3,5-triiodobenzoic acid (TIBA) resulted in a significant increment in the number of branches (15.9) after 7 months. Of all the PGRs examined, 2,3:4,6-di-O-isopropylidene-2-keto-l-gluconic acid (dikegulac; DK) at 2.0 mM produced the maximum number of branches (18.0) in the field 7 months after application. Concentrations of 2.0 and 3.0 mM of 1,2-dihydro-3,6-pyridazinedione (maleic hydrazide; MH) significantly increased the number of branches, 4 and 7 months after spraying in both the pot trial in the shade house and field, respectively. Under field conditions, J. curcas plants responded better to all the PGRs (DK < TIBA < BA < MH) when treated once, with insignificant variations in other growth parameters. This study indicates that a single foliar application of PGRs under field conditions can be an alternative method to MP for increasing the number of lateral branches of J. curcas.     

Variability in reproductive traits in Jatropha curcas L. accessions during early developmental stages under warm subtropical conditions

Variability in floral, fruit, and seed characteristics, and oil content of 15 accession of Jatropha curcas during early development were assessed during two flowering periods in south Florida subtropical climate. The two flowering periods had leaf flushing in March. Field evaluation using 18 quantitative traits showed significant variation among accessions. The number of female flowers and female : male flower ratio ranged from 1 to 15 and 1 : 8.8 to 1 : 67.8, respectively. Fruit set by natural pollination was 89 and 66% during the first (1st) and second (2nd) flowering periods, respectively. A higher number of female‐type inflorescences were observed during summer. There were significant differences in seed traits, except for number of seeds per fruit. Accession TREC 31 had the highest individual seed dry weight and 100‐seed weight (0.83 g and 79.7 g, respectively). The oil content varied from 19.30% to 35.62%. Seed dry weight had positive correlation with seed fresh weight, seed length, seed thickness, seed width, and 100‐seed weight, but negative correlation with oil content. Based on the cluster analysis using 15 morphological traits, jatropha accessions were grouped into five main clusters and accessions from different geographic regions grouped together in a cluster. Principal component analyses (PCA) revealed morphological variation. The first three components explained 73.5% of the total variation and seed dry weight, 100‐seed weight, total flowers per inflorescence, male flowers per inflorescence and fruit set can be used to distinguish accessions. The PCA also indicated that flowering traits were more influenced by seed origin while seed traits were affected by flowering spans. Although evaluations were performed in plants during the juvenile phase, accessions TREC 31 and TREC 55 had superior averages for almost all characters evaluated. These results provide a preliminary assessment of the high variability in jatropha accessions evaluated and their potential for use in breeding and genetic improvement programs.     

Effects of parentage,prior fruit set and pollen load on fruit and seed production in Campanula americana L

Summary We conducted a controlled crossing experiment to examine the effects of maternal and paternal parentage, the size of the pollen load, and prior fruit production on the proportion of flowers that set fruit, seed number per fruit and seed weight in a natural population of Campanula americana. Effects due to the maternal parent were large for all measures of fruit and seed production, while the paternal parent had a significant effect only upon mean seed weight. As the number of prior fruits on the maternal plant increased the probability that a flower would produce a mature fruit, the number of seeds per fruit, and total seed weight per fruit all decreased. We found no effect of the size of the pollen loads used in this study on fruit or seed production. These results are consistent with those of other studies that suggest in natural plant populations maternal effects, especially environmental maternal effects, can have an overwhelming effect on fruit and seed production and on seed characteristics.     

Benefits and costs to pollinating,seed-eating insects: the effect of flower size and fruit abortion on larval performance

Plant–pollinator interactions are well-known examples of mutualism, but are not free of antagonism. Antagonistic interactions and defenses or counter-defenses are expected particularly in nursery pollination. In these systems, adult insects, while pollinating, lay their eggs in flowers, and juveniles consume the seeds from one or several fruits, thereby substantially reducing plant fitness. The outcome of such interactions will depend, for the plant, on the balance between pollination versus seed predation and for the larvae on the balance between the food and shelter provided versus the costs imposed by plant defenses, e.g., through abortion of infested fruits. Here, we examine the costs and benefits to the larvae in the nursery-pollination system Silene latifolia/Hadena bicruris. Using selection lines that varied in flower size (large- vs. small-flowered plants), we investigated the effects of variation in flower and fruit size and of a potential defense, fruit abortion, on larval performance. In this system, infested fruits are significantly more likely to be aborted than non-infested fruits; however, it is unclear whether fruit abortion is effective as a defense. Larger flowers gave rise to larger fruits with more seeds, and larvae that were heavier at emergence. Fruit abortion was frequently observed (ca. 40% of the infested fruits). From aborted fruits, larvae emerged earlier and were substantially lighter than larvae emerging from non-aborted fruits. The lower mass at emergence of larvae from aborted fruits indicates that abortion is a resistance mechanism. Assuming that lower larval mass implies fewer resources invested in the frugivore, these results also suggest that abortion is likely to benefit the plant as a defense mechanism, by limiting both resources invested in attacked fruits, as well as the risk of secondary attack. This suggests that selective fruit abortion may contribute to the stability of mutualism also in this non-obligate system.     

荒漠植物准噶尔无叶豆结实、结籽格局及其生态适应意义

连续2a采用野外记录的方式对荒漠植物准噶尔无叶豆的结实、结籽格局进行了比较研究。结果表明:植株内花序生成格局表现为不同大小的花序在总花序中的比重与其结实率存在显著正相关,其中含有中等花数目的花序所占的比重及其结实率均最高,此种分布格局能够最大程度的保证繁殖成功;果序内果实生成格局表现为单花着生位置(从近柄端算起)与其结实量占总结实量的比例成线性负相关,花序基部的结实比例最高,顶部结实比例近为0;荚果内种子生成格局表现为:中间位置的胚珠败育率最低。另外,年际间荚果内仅有(1.08±0.03)粒和(1.07±0.03)粒种子能够完全成熟,此种结籽格局是准噶尔无叶豆保证后代质量的最佳策略。     

From flowering to dispersal: reproductive ecology of an endemic plant,Astragalus australis var. olympicus (Fabaceae)

Astragalus australis var. olympicus is an endemic plant of the Olympic Mountains, Washington. It is considered a Species of Concern by the U.S. Fish and Wildlife Service. This study focused on the reproductive biology of the plant from flower production through seed germination to identify possible weak points that might contribute to its rarity and impede its conservation. Most plants produced a large mean number of flowers and ovules (314.8 and 4106, respectively), but relatively few of these formed fruits and seeds (25.8 and 3.8%, respectively). In decreasing importance, ovules in fruits were lost to predation, seed abortion, and lack of fertilization. The percentages of these fates differed among sites and years. Excluding pollinators by bagging flowers reduced fruit set by ∼50%, but seed set per fruit and seed mass were unaffected. Germination was affected by scarification, temperature, and moisture availability. About 11% of seeds damaged by predispersal seed predators (weevil larvae) remained viable and were released from dormancy. I hypothesize that predispersal seed predation (over 80% at one site) has a negative effect on population growth. Conservation of this species could benefit from improved fruit set and decreased seed predation.