A secretory phospholipase D hydrolyzes phosphatidylcholine to suppress rice heading time

Phospholipase D (PLD) hydrolyzes membrane phospholipids and is crucial in various physiological processes and transduction of different signals. Secretory phospholipases play important roles in mammals, however, whose functions in plants remain largely unknown. We previously identified a rice secretory PLD (spPLD) that harbors a signal peptide and here we reported the secretion and function of spPLD in rice heading time regulation. Subcellular localization analysis confirmed the signal peptide is indispensable for spPLD secretion into the extracellular spaces, where spPLD hydrolyzes substrates. spPLD overexpression results in delayed heading time which is dependent on its secretory character, while suppression or deficiency of spPLD led to the early heading of rice under both short-day and long-day conditions, which is consistent with that spPLD overexpression/suppression indeed led to the reduced/increased Hd3a/RFT1 (Arabidopsis Flowing Locus T homolog) activities. Interestingly, rice Hd3a and RFT1 bind to phosphatidylcholines (PCs) and a further analysis by lipidomic approach using mass spectrometry revealed the altered phospholipids profiles in shoot apical meristem, particularly the PC species, under altered spPLD expressions. These results indicate the significance of secretory spPLD and help to elucidate the regulatory network of rice heading time.

In-Depth Sequence Analysis of Bread Wheat VRN1 Genes

The VERNALIZATION1 (VRN1) gene encodes a MADS-box transcription factor and plays an important role in the cold-induced transition from the vegetative to reproductive stage. Allelic variability of VRN1 homoeologs has been associated with large differences in flowering time. The aim of this study was to investigate the genetic variability of VRN1 homoeologs (VRN-A1, VRN-B1 and VRN-D1). We performed an in-depth sequence analysis of VRN1 homoeologs in a panel of 105 winter and spring varieties of hexaploid wheat. We describe the novel allele Vrn-B1f with an 836 bp insertion within intron 1 and show its specific expression pattern associated with reduced heading time. We further provide the complete sequence of the Vrn-A1b allele, revealing a 177 bp insertion in intron 1, which is transcribed into an alternative splice variant. Copy number variation (CNV) analysis of VRN1 homoeologs showed that VRN-B1 and VRN-D1 are present in only one copy. The copy number of recessive vrn-A1 ranged from one to four, while that of dominant Vrn-A1 was one or two. Different numbers of Vrn-A1a copies in the spring cultivars Branisovicka IX/49 and Bastion did not significantly affect heading time. We also report on the deletion of secondary structures (G-quadruplex) in promoter sequences of cultivars with more vrn-A1 copies.

Phenotypic and molecular diversity of wheat species (Triticum spp.) in relation to plant height and heading time

Plant height and heading time are important agronomic traits that significantly contribute to the improvement of wheat adaptability and yield. The aim of this study was to evaluate the level of phenotypic variability of these two traits in a collection of wheat species originating from 20 countries, to analyse its molecular diversity based on the microsatellite loci associated with the previously mapped quantitative trait loci, and to estimate potential of microsatellites to detect polymorphism in different wheat species and reveal allelic patterns in relation to the geographical origin. The significant differences in plant height and heading time among different wheat groups were observed, while the differences in means among three different growing seasons were significant only for heading time. The principal coordinate analysis distinguished wheat genotypes by their origin and ploidy level. Wheat varieties from America, South and Southeast Europe, and West and Central Europe had the highest molecular diversity, as was evidenced by the higher number of alleles, number of group-specific alleles, Shannon's information index and gene diversity. The Nei?s genetic identity indicated genetic similarity of geographically distinct groups, such as South and Southeast Europe and Russian (0.901) and South and Southeast Europe and American genotypes (0.638). The studied collection with high observed level of both phenotypic and molecular diversity for plant height and heading time may be a valuable source of variation for wheat breeders to fine adjust these traits to achieve better agronomic performance in certain local environments.

Characterization of winter wheat (Triticum aestivum L.) germplasm for drought tolerance

Climate change realities such as high-temperature levels are among the causes of drought episodes affecting the productivity and yield stability of crops worldwide. Breeders, therefore, have a daunting challenge to overcome and a large gap to seal in the agricultural sector arising due to drought through the improvement of new tolerant germplasm. It is in this endeavour that the present study, which included nine winter wheat genotypes grown in the greenhouse, was conducted to evaluate their performance under well-watered and drought stress treatments for the traits: heading time, plant height, above-ground biomass, seed number/plant, grain yield/plant, harvest index, root length and root dry mass. A lower grain yield/plant was observed for each studied genotype under drought stress conditions than for those under well-watered conditions. Additionally, grain yield/plant depression varied from 69.64 to 81.73% depending on the genotype. Positive significant correlations between grain yield/plant and heading time, above-ground biomass, and seed number/plant under the drought stress treatment were obtained. Genotypes that recorded high root dry mass had both high above-ground biomass and seed number/plant under drought stress conditions. Positive correlations between grain yield/plant depression and plant height, seed number/plant, and harvest index depressions were also observed. Grain yield for each genotype under drought stress conditions was recorded, and the varieties ‘Plainsman V.’, ‘GK Berény’ and germplasm ‘PC61’, ‘PC110’ showed the best drought tolerance. These genotypes and germplasm will be used in different drought tolerance experiments and breeding programmes.

Nutritional value of forage mass as affected by cutting management of perennial grasses

Работа проведена в 2016–2018 годах на опытном поле лаборатории агротехнологий «Вилга» отдела комплексных научных исследований КарНЦ РАН. Цель работы — установить оптимальный режим скашивания многолетних травостоев с включением интродуцированных видов кормовых трав, обеспечивающий высокие показатели качества кормовой массы в условиях Карелии. В статье представлены результаты научных исследований по оценке питательной ценности биомассы многолетних агрофитоценозов, созданных с включением интродуцированных видов бобовых и злаковых трав — люцерны изменчивой (Medicago varia Mart.) и фестулолиума (×Festulolium F. Aschers. et Graebn.) при двух- и трёхкратном режимах скашивания. Внесение фосфорных и калийных удобрений в дозе Р60К90 на бобово-злаковых и злаковых травостоях проводили однократно перед завершением вегетации растений. Азотные удобрения (аммиачную селитру) в дозе N120 вносили при формировании злакового травостоя дробно под каждый укос: N60 — при двухукосном использовании и N40 — при трёхукосном. Установлено, что в данных условиях травосмеси кострец безостый + люцерна изменчивая + клевер гибридный и фестулолиум + люцерна изменчивая + клевер гибридный обеспечивали высокий уровень урожайности сухой массы (7,55–9,13 т/га), энергетической продуктивности (79,7–94,7 ГДж/га) и питательной ценности (0,81–1,31 т/га сырого протеина) независимо от режима скашивания. На фоне внесения минерального азота в дозе N120 урожайность злакового травостоя выше бобово-злаковых агроценозов, но показатели питательной ценности не соответствовали нормативам кормления высокопродуктивного крупного рогатого скота. В условиях северного земледелия наиболее целесообразным является двухкратный режим скашивания травостоев в период бутонизации – начала цветения бобовых и колошения злаковых трав. Использование агрофитоценозов с включением многолетних бобовых культур без внесения азотных удобрений способствует получению экологически безопасного высокобелкового растительного сырья для заготовки грубых и сочных кормов. Ключевые слова: многолетние травы, люцерна изменчивая, фестулолиум, питательная ценность, режим скашивания. The experiment was carried out at the “Vilga” laboratory in 2016–2018. The goal was to optimize cutting regime for perennial grasses to obtain high-quality forage mass. This article reports on nutritional value of perennial ecosystems with bastard alfalfa (Medicago varia Mart.) and festulolium (×Festulolium F. Aschers. et Graebn.) to be cut twice or three times. Application of Р60К90 was done once before the end of growing season. N120 was divided into two or three fractions and applied before each cut as N60 or N40 depending on cutting regime. Smooth brome + bastard alfalfa + alsike clover and festulolium + bastard alfalfa + alsike clover produced high yields of dry mass (7.55–9.13 t ha-1), energy (79.7–94.7 GJ ha-1) and had high nutritional value (0.81–1.31 t ha-1 of crude protein) regardless of the cutting regime. On the background of N120 gramineous exceeded gramineous-legume mixtures in productivity but had low nutritional value. Cutting legumes at budding – early flowering and gramineous — at heading time twice was more effective under cold conditions. Growing grass mixtures with perennial legumes without fertilization resulted in ecologically-safe high-protein forage mass.

Phenology and Dwarfing Gene Interaction Effects on the Adaptation of Selected Wheat (Triticum aestivum L.) Advanced Lines across Diverse Water-Limited Environments of Western Australia

Photoperiod, vernalization, and plant height controlling genes are major developmental genes in wheat that govern environmental adaptation and hence, knowledge on the interaction effects among different alleles of these genes is crucial in breeding cultivars for target environments. The interaction effects among these genes were studied in nineteen Australian advanced lines from diverse germplasm pools and four commercial checks. Diagnostic markers for the Vrn-A1 locus revealed the presence of the spring allele Vrn-A1a in 10 lines and Vrn-A1c in one line. The dominant alleles of Vrn-B1a and Vrn-D1a were identified in 19 and 8 lines, respectively. The most common photoperiod-insensitive allele of Ppd-D1a was identified in 19 lines and three and four copy photoperiod-insensitive alleles (Ppd-B1a and Ppd-B1c) were present in five and one lines, respectively. All the lines were photoperiod-sensitive for the Ppd-A1 locus. All lines were semi-dwarf, having either of the two dwarfing alleles; 14 lines had the Rht-B1b (Rht-1) and the remaining had the Rht-D1b (Rht-2) dwarfing allele. The presence of the photoperiod-insensitive allele Ppd-D1a along with one or two spring alleles at the Vrn1 loci resulted in an earlier heading and better yield. Dwarfing genes were found to modify the heading time—the Rht-D1b allele advanced heading by three days and also showed superior effects on yield-contributing traits, indicating its beneficial role in yield under rain-fed conditions along with an appropriate combination of photoperiod and vernalization alleles. This study also identified the adaptability value of these allelic combinations for higher grain yield and protein content across the different the water-limited environments.

On Generalised Single-Heading Navigation

Introducing the notion of a pseudoloxodrome, we generalise a single-heading navigation to conformally flat Riemannian manifolds, under the action of a perturbing vector field (wind, current) of arbitrary force. The findings are applied to time-optimal navigation with the use of the Euler–Lagrange equations. We refer to the Zermelo navigation problem admitting space and time dependence of both a perturbation and a ship's speed. The necessary conditions for single-heading time-optimal navigation are obtained and the pseudoloxodromes of minimum and maximum time are discussed. Furthermore, we describe winds which yield the pseudoloxodromic and loxodromic time extremals. Our research is also illustrated with the examples in dimension two emphasising the single-heading solutions among the time-optimal trajectories in the presence of some space-dependent winds.

Cause and effect relationship of morphological attributes with yield in a-genome Wheat

Wheat considered to be the most important among all cereal crops, is grown across various agro-ecological zones around the globe. It is the main staple food playing a prominent role in the economy of the country as well as in the cropping system. The present study was conducted to estimate genotypic correlations among morphological traits and yield using 50 accessions of diploid wheat including 2 parents and 48 RILs at F7:8 stage to determine direct as well as indirect effects. The results presented here showed that generally the coefficients of genotypical correlation (rg) depicted higher values in comparison to the coefficients of phenotypic correlation (rp). Among the morphological traits contributing to the grain yield, genotypic as well as phenotypic coefficients of correlation have been evaluated. All the traits displayed positive correlation with each other except emergence percentage (EP) that depicted negative interaction with booting time (BT), flowering time (FT) and heading time (HT) phenotypically. Highest estimates of direct effect i.e., 2.1217 on grain yield have been counted for booting time however, maximum indirect effect counted on grain yield was for heading time via booting time. Therefore, booting time can be successfully employed as an effective trait in the breeding programs focused on increasing wheat yield.