QTL Mapping Low-Temperature Germination Ability in the Maize IBM Syn10 DH Population

Chilling injury poses a serious threat to seed emergence of spring-sowing maize in China, which has become one of the main climatic limiting factors affecting maize production in China. It is of great significance to mine the key genes controlling low-temperature tolerance during seed germination and study their functions for breeding new maize varieties with strong low-temperature tolerance during germination. In this study, 176 lines of the intermated B73 × Mo17 (IBM) Syn10 doubled haploid (DH) population, which comprised 6618 bin markers, were used for QTL analysis of low-temperature germination ability. The results showed significant differences in germination related traits under optimum-temperature condition (25 °C) and low-temperature condition (10 °C) between two parental lines. In total, 13 QTLs were detected on all chromosomes, except for chromosome 5, 7, 10. Among them, seven QTLs formed five QTL clusters on chromosomes 1, 2, 3, 4, and 9 under the low-temperature condition, which suggested that there may be some genes regulating multiple germination traits at the same time. A total of 39 candidate genes were extracted from five QTL clusters based on the maize GDB under the low-temperature condition. To further screen candidate genes controlling low-temperature germination, RNA-Seq, in which RNA was extracted from the germination seeds of B73 and Mo17 at 10 °C, was conducted, and three B73 upregulated genes and five Mo17 upregulated genes were found by combined analysis of RNA-Seq and QTL located genes. Additionally, the variations of Zm00001d027976 (GLABRA2), Zm00001d007311 (bHLH transcription factor), and Zm00001d053703 (bZIP transcription factor) were found by comparison of amino sequence between B73 and Mo17. This study will provide a theoretical basis for marker-assisted breeding and lay a foundation for further revealing molecular mechanism of low-temperature germination tolerance in maize.

The Effectiveness of the Sexual Reproduction in Selected Clonal and Nonclonal Species of the Genus Ranunculus

Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (Ficaria verna, Ranunculus auricomus, R. bulbosus, R. cassubicus, R. lanuginosus) and the endangered R. illyricus. The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application). Additionally, the pistil morphology was documented for R. bulbosus, R. illyricus and R. cassubicus using SEM techniques. It was demonstrated that the reproductive efficiency, expressed as the production of viable seeds able to germinate, was significantly higher in the species reproducing sexually (especially in R. lanuginosus) compared to the clonal ones. However, the complexity observed leads to separation of an additional group (cluster) of apomictic species: R. auricomus and R. cassubicus, distinguished by the lowest pollen viability and a low ability of the seeds to germinate. In the vegetatively reproducing R. illyricus, the seed formation efficiency was just 13.2% despite the having highest number of pistils in its flowers. The developed seeds of this species observed in our experiment were viable, but in general effective methods to stimulate their germination have not been proposed yet. Here, the first comparative study concerning the biology of sexual reproduction of R. illyricus is presented in the context of its decreasing distribution in natural habitats.

Allelopathic activity of smooth brome seeds with oil crops

Опыты проводили в двух закладках в 2019–2020 годах на базе обособленного подразделения ФГБНУ «Федеральный научный центр лубяных культур» в Пензенской области. Новизна исследований заключается в том, что впервые изучалось аллелопатическое взаимодействие растений костреца безостого с широким набором масличных культур. Цель работы — изучить аллелопатический эффект в начальные этапы онтогенеза растений. В задачи исследования входило выделение культур с положительным и негативным воздействием на рост и развитие проростков костреца безостого. Объектами исследований служили кострец безостый Пензенский 1, сафлор красильный Александрит, горчица сарептская Люкс, рапс яровой Таврион, конопля Надежда, сурепица яровая Искра, горчица белая Люция, крамбе абиссинская Полёт, гвизоция абиссинская Медея, редька масличная Фиолина, нигелла дамасская Ялита, гибрид подсолнечника P63 LE 10 (XF 3020), озимый рыжик Барон, яровой рыжик Велес, лён масличный Исток. Оценка аллелопатической активности проведена с использованием метода, который предусматривает проращивание семян растений с последующим вычислением процента всхожести. На начальных этапах онтогенеза негативное аллелопатическое воздействие на количество полноценных всходов костреца безостого Пензенский 1 оказывали конопля Надежда (–4,5% к контролю) и сурепица яровая Искра (–12,6% к контролю). Положительное влияние на прорастание и развитие проростков костреца оказывали сафлор красильный Александрит (+8,8% к контролю) и лён масличный Исток (+7,5 % к контролю). Длина проростков костреца достоверно была выше в варианте с льном масличным Исток — 6,19 см (+0,77 см к контролю). Существенное снижение наблюдалось в вариантах с горчицей сарептской, нигеллой дамасской, горчицей белой, рыжиком озимым, подсолнечником, рапсом яровым, рыжиком яровым, сурепицей яровой и коноплёй — от 4,37 до 2,66 см (от –1,05 до –2,76 см). The investigation was carried out in 2019–2020 at the Federal Research Center of Fiber Crops in the Penza region. For the first time allelopathy of wide number of oil crops was analyzed when growing with smooth brome. The aim was to evaluate the effect of allelopathy at early plant ontogenesis and determine plants having beneficial or detrimental effects on smooth brome seedlings. The objects of the study were smooth brome “Penzenskiy 1”, safflower “Aleksandrit”, brown mustard “Lyuks”, spring rapeseed “Tavrion”, hemp “Nadezhda”, spring cress “Iskra”, white mustard “Lyutsiya”, Abyssinian mustard “Polet”, noog “Medeya”, oil radish “Fiolina”, ragged lady “Yalita”, sunflower hybrid P63 LE 10 (XF 3020), winter camelina “Baron”, gold-of-pleasure “Veles”, flax “Istok”. To determine positive or negative effect the germination ability was tested. Hemp and spring crees negatively affected smooth brome in the beginning of its ontogenesis (–4.5 and –12.6%, respectively). Safflower and flax had positive effect on smooth brome (+8.8 and +7.5 %, respectively). The length of smooth brome seedlings was significantly higher when seeding with flax — 6.19 cm (+0.77 cm). Brown mustard, ragged lady, white mustard, winter camelina, sunflower, spring rapeseed, gold-of-pleasure, spring cress and hemp significantly reduced seedling length — from 4.37 to 2.66 cm (from –1.05 to –2.76 cm).

Chitosan Oligosaccharides Stimulate the Efficacy of Somatic Embryogenesis in Different Genotypes of the Liriodendron Hybrid

Liriodendron hybrid (L. chinense × L. tulipifera), an essential medium-sized tree generally famous for its timber, is also used as an ornamental and greenery tool in many places around the world. The Liriodendron hybrid (L. hybrid) tree goes through many hurdles to achieve its maximum strength and vigor, such as loss of habitat, vast genetic variation, and low seed setting rate. The establishment of an effective and well-organized somatic embryogenesis (S.E.) system could be used to overcome these obstacles, rather than the old-fashioned seed culture and organogenesis. This study is based on the impact of chitosan oligosaccharide (COS) and its role in the induction of S.E. on the callus of four genotypes of the L. hybrid. The optimal concentration of COS could enhance the momentum and effectiveness in S.E.’s mechanism, which further improves the growth rate of the L. hybrid tree’s plantlets. This study shows that COS has a prominent role in endogenous hormones like indole acetic acid (IAA), zeatin (Z.T.), and gibberellic acid (GA3). Furthermore, COS improves the growth development, growth speed, as well as the development situation of plant germination ability. COS can also regulate branch development and root growth, which could be linked to the antagonistic effect on growth factors to some extent or by affecting auxin synthesis and polar transport.

Plasticity of maternal environment dependent expression-QTLs of tomato seeds

Seeds are essential for plant reproduction, survival, and dispersal. Germination ability and successful establishment of young seedlings strongly depends on seed quality and on environmental factors such as nutrient availability. In tomato (Solanum lycopersicum) and many other species, seed quality and seedling establishment characteristics are determined by genetic variation, as well as the maternal environment in which the seeds develop and mature. The genetic contribution to variation in seed and seedling quality traits and environmental responsiveness can be estimated at transcriptome level in the dry seed by mapping genomic loci that affect gene expression (expression QTLs) in contrasting maternal environments. In this study, we applied RNA-sequencing to measure gene expression of seeds of a tomato RIL population derived from a cross between S. lycopersicum (cv. Moneymaker) and S. pimpinellifolium (G1.1554). The seeds matured on plants cultivated under different nutritional environments; i.e. on high phosphorus or low nitrogen. The obtained SNPs were subsequently used to construct a high-density genetic map. We show how the genetic landscape of plasticity in gene regulation in dry seeds is affected by the maternal nutrient environment. The combined information on natural genetic variation mediating (variation in) responsiveness to the environment may contribute to knowledge-based breeding programs aiming to develop crop cultivars that are resilient to stressful environments.

Warming impacts potential germination of non-native plants on the Antarctic Peninsula

The Antarctic Peninsula is under pressure from non-native plants and this risk is expected to increase under climate warming. Establishment and subsequent range expansion of non-native plants depend in part on germination ability under Antarctic conditions, but quantifying these processes has yet to receive detailed study. Viability testing and plant growth responses under simulated Antarctic soil surface conditions over an annual cycle show that 16 non-native species, including grasses, herbs, rushes and a succulent, germinated and continued development under a warming scenario. Thermal germination requirement (degree day sum) was calculated for each species and field soil-temperature recordings indicate that this is satisfied as far south as 72° S. Here, we show that the establishment potential of non-native species, in number and geographical range, is considerably greater than currently suggested by species distribution modelling approaches, with important implications for risk assessments of non-native species along the Antarctic Peninsula.

Identification of QTLs for Salt Tolerance at the Germination and Seedling Stages in Rice

Rice is highly sensitive to salinity stress during the seedling establishment phase. Salt stress is widely occurring in cultivated areas and severely affects seed germination ability and seedling establishment, which may result in a complete crop failure. The objective of the present study is to identify quantitative trait loci (QTLs) related to salt tolerance of the germination and seedling stages in a rice backcross inbred line (BIL) population that was derived from a backcross of an Africa rice ACC9 as donor and indica cultivar Zhenshan97 (ZS97) as the recurrent parent. Under salt stress, ACC9 exhibited a higher germination percentage, but more repressed seedling growth than ZS97. Using the BIL population, 23 loci for germination parameters were detected at the germination stage and 46 loci were identified for several morphological and physiological parameters at the seedling stage. Among them, nine and 33 loci with the ACC9 alleles increased salt tolerance at the germination and seedling stages, respectively. Moreover, several major QTLs were found to be co-localized in the same or overlapping regions of previously reported genes for salt stress. These major loci will facilitate improving salt-tolerance rice in genome-breeding programs.

Pollen fertility differences in the progenies obtained from a cross between eggplant (Solanum melongena L.) as a seed parent and eggplant cytoplasmic substitution lines as pollen parents

To the best of our knowledge, there is no report about pollen fertility of the progenies developed using eggplant (Solanum melongena L.) as a seed parent and eggplant cytoplasmic substitution lines as pollen parents. Pollen fertility of these progenies is very important to use as restorer line in the eggplant’s hybrid breeding program. In this study, pollen fertility was investigated for the progenies which were produced using S. melongena ‘Uttara’ as a seed parent and the eggplant cytoplasmic substitution lines as pollen parents. To assess pollen fertility, pollen stainability and in vitro germination ability were investigated. Although the nuclear and the cytoplasmic genome of the progenies were almost identical to eggplant ‘Uttara’, a clear difference was observed in the pollen fertility due to the difference in the pollen parents having different wild Solanum cytoplasms. The progenies produced using the functional cytoplasmic male sterile (CMS) lines as a pollen parent, whose cytoplasm donor were S. kurzii, S. violaceum and S. virginianum, showed pollen release type and high pollen fertility almost equal to eggplant ‘Uttara’. It is considered that the characteristics of these progenies were almost the same as eggplant. On the other hand, the progenies that produced using the fertility restored lines of the pollen non-formation type CMS lines as a pollen parent, whose cytoplasm donors were S. aethiopicum, S. anguivi and S. grandifolium, showed pollen release type and low pollen fertility, i.e., pollen staining ability was about 54% and pollen germination ability were about 35%. It is considered that the cause of this low pollen fertility was the incompatibility between the eggplant cytoplasm and the eggplant nuclear genome, which seems to be modified in the process of continuous backcrossing under the wild Solanum cytoplasms. It is suggested that complete nuclear substitution is difficult by continuous backcrossing with eggplant in the alloplasmic lines with S. aethiopicum, S. anguivi and S. grandifolium cytoplasm donors. Incompatibility between the normal eggplant cytoplasm and the modified eggplant nuclear genomes of the alloplasmic lines with S. aethiopicum, S. anguivi and S. grandifolium cytoplasms might be a cause for the low pollen fertility of the investigated progenies

Heteromericarpy of Heracleum sosnowskyi Manden. (Umbelliferae = Apiaceae)

Background. Heracleum sosnowskyi Manden. (family Umbelliferae = Apiaceae) is included in the lists of invasive species in many regions of Russia and European countries. Mericarps (fruits conventionally called seeds) of Heracleum L. spp. are characterized by an underdeveloped embryo and a complex morphophysiological type of dormancy; two-stage stratification is needed for their germination.Methods. In the period from 2014 to 2019, fruits of H. sosnowskyi were collected near settlements in Vyborg and Gatchina Districts, Leningrad Province; collecting was carried out from August through March. Seed size and 1000 seed weight were measured. Germination experiments were performed in the laboratory (22–24°C) monthly, from the time of collection in August until May. Seeds were germinated in Petri dishes on filter paper with three replications.Results. Large seeds on marginal umbellules of the central umbel were the largest in size. Their length was from 0.6 to 1.4 cm, width from 5 to 11 mm, and 1000 seed weight from 9 to 18 g. The length of smaller fruits was from 7 to 9 mm, width from 3 to 5 mm, and 1000 seed weight from 10.5 to 11.8 g. Germination of seeds collected in late summer was protracted. Under laboratory conditions, the emergence of the first seedlings was observed after 5–7 days. For the fruits stored in the laboratory, germination was reduced. Germination rate of stratified seeds varied from 55 to 99%.Conclusion. The biometric parameters of H. sosnowskyi mericarps were slightly affected by the place of growth and the year of maturation. Under laboratory conditions, H. sosnowskyi seeds collected in August showed germination rates from 3 to 15%. In years with a warm and long autumn, part of the fruit germinated in the year of maturation and managed to reach their juvenile state. Plump mericarps remained viable for at least three years. Sosnowsky’s hogweed fruits stored under laboratory conditions lost their germination ability within a year.