Impact of Nitrate and Ammonium Ratios on Flowering and Asexual Reproduction in the Everbearing Strawberry Cultivar Fragaria × ananassa Albion

Ever-bearing (EB) strawberries are long-day cultivars that show perpetual flowering behavior. Compared to June-bearing short-day cultivars, EB cultivars can initiate flowers with less dependency on light and temperature levels. This leads to a more consistent flowering and fruiting pattern, making EB cultivars favorable for areas with long growing seasons. However, this flowering pattern also brings significant challenges to open-field strawberry nurseries. Consistent flower development in EB cultivars frequently leads to increased labor cost for manual flower removal on nursery ground. The alteration of flowering behavior via fertilizer regimes could be a cost-effective tool for strawberry nurseries. However, while it is known that the source of nitrogen (N) impacts strawberry flowering, its effect on strawberry propagation rates needs further investigation. The objective of this study was to investigate the impact of nitrate (NO3−) to ammonium (NH4+) ratio on flower and daughter plant production in the EB strawberry cultivar ‘Albion’ (Fragaria × ananassa c.v. ‘Albion’). Strawberry plants were grown in a completely randomized design under greenhouse conditions (26.6 °C, 16 h photoperiod). Four treatments of NO3−:NH4+ were implemented: (1) 100%:0%; (2) 80%:20%; (3) 60%:40%; (4) 50%:50%. Strawberry plants fertilized with a 60%:40% NO3−:NH4+ ratio produced 17–31% fewer inflorescences than those fertilized with 100%:0% (8.8 ± 1.19) and 80%:20% (10.3 ± 1.85) ratios. The production of daughter plants remained similar in all four treatments. Our results show that increased ratios of ammonium in combination with decreased ratios of nitrate reduce flowering of EB strawberry cultivars, while propagation rates remain consistent. These results could potentially lead to the development of fertilizer regimes for strawberry nurseries to reduce flower production in EB cultivars.

A Strobilanthes (Acanthaceae) miscellany

SummaryThis paper presents miscellaneous, previously unpublished results arising from the authors’ research into Strobilanthes. S. moylaniae J.R.I.Wood & Scotland from New Guinea and S. dengii J.R.I.Wood & Scotland from Sumatra are proposed as new species, while an unnamed species is described from Sumba Island in Indonesia in the hope that it might be rediscovered. A new subspecies, subsp. subovata J.R.I.Wood & Scotland is described for S. timorensis Nees, while attention is drawn to its plietesial flowering pattern. The new combinations S. benculensis (Bremek.) J.R.I.Wood & Scotland, S. wetarensis (Bremek.) J.R.I.Wood & Scotland, S. javanica (Bremek.) J.R.I.Wood & Scotland and S. serpens (Nees) J.R.I. Wood & Scotland are made. Typification is clarified and where appropriate lectotypes are designated for Hemigraphis hispidula Craib, Lepidagathis setigera Blume, Ruellia crispa L., R. sabiniana Lindl., Strobilanthes duclouxii Benoist, S. erecta C.B.Clarke, S. flava Kurz, S. forrestii Diels, S. scabra Nees, S. secunda T.Anderson and S. thomsonii T.Anderson.

Genetic insights into the regulatory pathways for continuous flowering in a unique orchid Arundina graminifolia

Background Manipulation of flowering time and frequency of blooming is key to enhancing the ornamental value of orchids. Arundina graminifolia is a unique orchid that flowers year round, although the molecular basis of this flowering pattern remains poorly understood. Results We compared the A. graminifolia transcriptome across tissue types and floral developmental stages to elucidate important genetic regulators of flowering and hormones. Clustering analyses identified modules specific to floral transition and floral morphogenesis, providing a set of candidate regulators for the floral initiation and timing. Among candidate floral homeotic genes, the expression of two FT genes was positively correlated with flower development. Assessment of the endogenous hormone levels and qRT-PCR analysis of 32 pathway-responsive genes supported a role for the regulatory networks in floral bud control in A. graminifolia. Moreover, WGCNA showed that flowering control can be delineated by modules of coexpressed genes; especially, MEgreen presented group of genes specific to flowering. Conclusions Candidate gene selection coupled with hormonal regulators brings a robust source to understand the intricate molecular regulation of flowering in precious orchids.

Chromosome-Scale Reference Genome of Amphicarpaea edgeworthii: A New Resource for Amphicarpic Plants Research and Complex Flowering Pattern

Amphicarpaea edgeworthii, an annual twining herb, is a widely distributed species and an attractive model for studying complex flowering types and evolutionary mechanisms of species. Herein, we have generated a high-quality assembly of A. edgeworthii by using a combination of PacBio, 10× Genomics libraries, and Hi-C mapping technologies. The final 11 chromosome-level scaffolds covered 90.61% of the estimated genome (343.78Mb), which is a chromosome-scale assembled genome of an amphicarpic plant. Subsequently, we characterized the genetic diversity and population structure of A. edgeworthii species by resequencing individuals collected from their natural area of distribution. Using transcriptome profiling, we observed that specific phenotypes are regulated by a complex network of light, hormones, and MADS-box gene families. These data are beneficial for the discovery of genes that control major agronomic traits and spur genetic improvement of and functional genetic studies in legumes, as well as supply comparative genetic resources for other amphicarpic plants.

Reproductive biology of Vatica venulosa Blume (Dipterocarpaceae)

Widjaya AH, Latifah D, Hardwick KA, Suhartanto MR, Palupi ER. 2021. Reproductive biology of Vatica venulosa Blume (Dipterocarpaceae). Biodiversitas 22: 4327-4337. Vatica venulosa Blume is categorized as Critically Endangered A1c ver 2.3, according to the IUCN Red List. A study of the reproductive biology of V. venulosa Blume was carried out in August 2019-February 2020 at the Research Center for Plant Conservation and Botanic Gardens, Bogor, Indonesia. The research observed flower morphology, flower development, type of pollination, fruit and seed structures. V. venulosa is categorized as having a sub-annual flowering pattern. The flowering phenology of V. venulosa from flower bud emergence until fruit senescence takes about 6 months. The flower is hermaphroditic, with position of the pistil is higher/longer than the stamen; and pollen was released prior to stigma being receptive (protandrous). V. venulosa is a cross-pollinated plant, the flower visitors are insect nymphs of Thrips sp. (Thysanoptera: Thripidae), which are white and 1-1.5 mm in size. The percentage of blooming flowers was 32.3-37.9%, fruit set 10.9 %-12.6%. Seed physiological maturity is reached at the age of 101±3-106±3 days after the flowers bloom when the wings are yellow green or green orange in color. V. venulosa seed is a non endospermous seed, and the cotyledons are composed mainly of small clumps of starch, being 42.5% carbohydrate.

Growth and development of domesticated and wild genotypes of red clover (Trifolium pratense L.) in the Middle Urals

В данной статье представлены результаты сравнительной оценки 11 сортов клевера лугового и одного образца-дикороса, проведённой в Пермском НИИ сельского хозяйства в 2018–2019 годах. Все селекционные сорта сформировали полноценные первый и второй укосы или отаву в оба года использования. Дикорастущая форма формировала только один укос, демонстрируя особенность позднеспелого одноукосного типа. Сорта Кретуновский и Ранний 2 показали себя как типичные раннеспелые двухукосные. Другие сорта занимали промежуточное положение. Наибольший сбор сухого вещества обеспечивал образец-дикорос в оба года при крайне различных погодных условиях (1,266 и 1,259 кг/м2 соответственно). Дикорастущая форма и сорт Ранний 2 обеспечивали стабильные урожаи зелёной массы и сухого вещества независимо от возраста и погодных условий. Образец дикорастущего клевера имел более однородный фенотип по сравнению с сортом Пермский местный — стандартом для позднеспелого типа, что указывает на большую генетическую однородность. Согласно всесторонней оценке, включающей степень перезимовки, урожайность зелёной и сухой массы, характер цветения, созревания, формирования и конечный урожай семян, образец-дикорос имеет отличительные признаки позднеспелого (одноукосного) типа и может использоваться в качестве исходного генетического материала для дальнейшей селекции позднеспелых одноукосных сортов клевера лугового, характеризующихся экономически ценными свойствами: высокой устойчивостью к неблагоприятным условиям окружающей среды, высокой и стабильной урожайностью зелёной массы и семян. Исследования будут продолжены с оценкой ряда образцов дикорастущих форм клевера лугового, обнаруженных в 2019 году в природных биоценозах Пермского края. This article deals with the competitive trial of 11 varieties and 1 wild genotype of red clover conducted at the Research Institute of Agriculture in 2018–2019. All the varieties provided good yields of green mass both in the first and second cuts. Wild genotype provided only one cut as long-season one-cut type. “Kretunovskiy” and “Ranniy 2” performed as typical short-season two-cut varieties. Wild genotype produced the highest yield of dry matter (DM) under contrast weather conditions (1.266 and 1.259 kg/m2, respectively). Wild genotype and “Ranniy 2” formed stable yields of green mass and DM regardless of time period and weather. Wild genotype showed homogeneous phenotype compared to “Permskiy mestnyy” — long-season standard variety indicating high genetic uniformity. Such traits as winter hardiness, green and dry mass yields, flowering pattern, seed maturation, formation and production were evaluated. According to this evaluation wild genotype performed as long-season (one-cut) type showing high resistance to unfavorable conditions, high and stable yield of green mass and seeds. Therefore, it can be used a source of economically important traits for future breeding programs of red clover. Further investigations will focus on the evaluation of wild genotypes of red clover found in the Perm region in 2019.

Identification of a Major Locus for Flowering Pattern Sheds Light on Plant Architecture Diversification in Cultivated Peanut

Flowering pattern is a major taxonomic characteristic differentiating the two main subspecies of cultivated peanut (Arachis hypogaea L.). subsp. fastigiata possessing flowers on the mainstem (MSF) and a sequential flowering pattern, whereas subsp. hypogaea lacks flowers on the mainstem and exhibits an alternate flowering pattern. This character is considered the main contributor to plant architecture and the adaptability of each subgroup to specific growing conditions. Evidence indicates that flowering pattern differentiation occurred during the several thousand years of domestication and diversification in South America. However, the exact genetic mechanism that controls flowering pattern and the molecular changes that led to its historical diversification in peanut are unknown. We investigated the genetics of the flowering pattern in a recombinant inbred population of 259 lines (RILs), derivatives of an A. hypogaea and A. fastigiata cross. RILs segregated 1:1 in both the sequential/alternative and the MSF-plus/MSF-minus traits, indicating a single gene effect. Using the Axiom_Arachis2 SNP-array, MSF was mapped to a 1.7 Mbp segment on chromosome B02 of the cultivated A. hypogaea. Significant haplotype conservation was found for this locus in the USA peanut mini core collection, suggesting a possible selection upon hypogaea/fastigiata speciation. Furthermore, a candidate Terminal Flowering 1-like (AhTFL1) gene was identified within the MSF region, in which a 1492 bp deletion occurred in the Valencia line that leads to a truncated protein product. Remapping MSF in the RIL population with the AhTFL1 deletion as a marker increased the LOD score from 53.3 to 158.8 with no recombination. The same deletion was also found to co-segregate with the trait in two EMS-mutagenized M2 families, suggesting a hotspot for large mutational deletion or gene conversion that may play a role in evolution. BLASTX analysis showed that the most similar homologous gene for TFL1-like in soybean is Det1, which previously was shown to control shoot determination. Sequence analysis of the TFL-1 in a series of domesticated lines showed that TFL1 was subjected to gain/loss events of the deletion, partly explaining the evolution of MSF in Arachis. Altogether, these results support the role of AhTFL-1 in peanut speciation during domestication and modern cultivation.

Flowering Phenology and the Influence of Seasonality in Flower Conspicuousness for Bees

Flowering patterns are crucial to understand the dynamics of plant reproduction and resource availability for pollinators. Seasonal climate constrains flower and leaf phenology, where leaf and flower colors likely differ between seasons. Color is the main floral trait attracting pollinators; however, seasonal changes in the leaf-background coloration affect the perception of flower color contrasts by pollinators. For a seasonally dry woody cerrado community (Brazilian savanna) mainly pollinated by bees, we verified whether seasonality affects flower color diversity over time and if flower color contrasts of bee-pollinated species differ between seasons due to changes in the leaf-background coloration. For 140 species, we classified flower colors based on human-color vision, and for 99 species, we classified flower colors based on bee-color vision (spectral measurements). We described the community’s flowering pattern according to the flower colors using a unique 11 years phenological database. For the 43 bee-pollinated species in which reflectance data were also available, we compared flower color diversity and contrasts against the background between seasons, considering the background coloration of each season. Flowering was markedly seasonal, peaking at the end of the dry season (September), when the highest diversity of flower colors was observed. Yellow flowers were observed all year round, whereas white flowers were seasonal, peaking during the dry season, and pink flowers predominated in the wet season, peaking in March. Bee-bluegreen flowers peaked between September and October. Flowers from the wet and dry seasons were similarly conspicuous against their corresponding background. Regardless of flowering season, the yellowish background of the dry season promoted higher flower color contrast for all flower species, whereas the greener background of the wet season promoted a higher green contrast. Temporal patterns of flower colors and color contrasts were related to the cerrado seasonality, but also to bee’s activity, visual system, and behavior. Background coloration affected flower contrasts, favoring flower conspicuousness to bees according to the season. Thus, our results provide new insights regarding the temporal patterns of plant–pollinator interactions.