Leafy Research Articles

LEAFY1 and 2 are required for floral organ development in soybean

AbstractThe transition from vegetative to reproductive growth is a vital step for the reproductive success of plants. In Arabidopsis thaliana, LEAFY (LFY) plays crucial roles in inflorescence primordium and floral organ development, but little is known about the roles of its homologs in crop plants such as soybean (Glycine max). Here, we investigated the expression patterns and functions of the two LFY genes (LFY1 and LFY2) in soybean. Both genes were predominantly expressed in unopened flowers and the shoot apical meristem, with LFY2 having the higher transcript abundance. In an in situ hybridization assay, LFY genes produced strong signals in the floral meristem. We next generated lfy1 and lfy2 knockout lines. The lfy2 mutants showed obvious changes in floral organ morphology, but the lfy1 mutants showed no obvious changes in floral organ morphology or pod development. The lfy1 lfy2 double mutants displayed more serious defects in floral organ development than lfy2, resulting in complete sterility. Gene expression analysis revealed differences in expression of the A-class APETALA (AP) genes AP1a and AP1b in the double mutant lines. These results suggest that LFY2 plays an important role in floral organ formation in soybean by regulating the expression of homeotic genes. Our findings increase the understanding of floral development, which could be useful for flower designs during hybrid soybean breeding.

AtSRT1 regulates flowering by regulating flowering integrators and energy signals in Arabidopsis

Epigenetic modifications, such as histone alterations, play crucial roles in regulating the flowering process in Arabidopsis, a typical long-day model plant. Histone modifications are notably involved in the intricate regulation of FLC, a key inhibitor of flowering. Although sirtuin-like protein and NAD+-dependent deacetylases play an important role in regulating energy metabolism, plant stress responses, and hormonal signal transduction, the mechanisms underlying their developmental transitions remain unclear. Thus, this study aimed to reveal how Arabidopsis NAD + -dependent deacetylase AtSRT1 affects flowering by regulating the expression of flowering integrators. Genetic and molecular evidence demonstrated that AtSRT1 mediates histone deacetylation by directly binding near the transcriptional start sites (TSS) of the flowering integrator genes FT and SOC1 and negatively regulating their expression by modulating the expression of the downstream gene LFY to inhibit flowering. Additionally, AtSRT1 directly down-regulates the expression of TOR, a glucose-driven central hub of energy signaling, which controls cell metabolism and growth in response to nutritional and environmental factors. This down-regulation occurs through binding near the TSS of TOR, facilitating the addition of H3K27me3 marks on FLC via the TOR-FIE-PRC2 pathway, further repressing flowering. These results uncover a multi-pathway regulatory network involving deacetylase AtSRT1 during the flowering process, highlighting its interaction with TOR as a hub for the coordinated regulation of energy metabolism and flowering initiation. These findings significantly enhance understanding of the complexity of histone modifications in the regulation of flowering.

Co-regulatory effects of hormone and mRNA-miRNA module on flower bud formation of Camellia oleifera.

Few flower buds in a high-yield year are the main factors restricting the yield of Camellia oleifera in the next year. However, there are no relevant reports on the regulation mechanism of flower bud formation. In this study, hormones, mRNAs, and miRNAs were tested during flower bud formation in MY3 ("Min Yu 3," with stable yield in different years) and QY2 ("Qian Yu 2," with less flower bud formation in a high-yield year) cultivars. The results showed that except for IAA, the hormone contents of GA3, ABA, tZ, JA, and SA in the buds were higher than those in the fruit, and the contents of all hormones in the buds were higher than those in the adjacent tissues. This excluded the effect of hormones produced from the fruit on flower bud formation. The difference in hormones showed that 21-30 April was the critical period for flower bud formation in C. oleifera; the JA content in MY3 was higher than that in QY2, but a lower concentration of GA3 contributed to the formation of the C. oleifera flower bud. JA and GA3 might have different effects on flower bud formation. Comprehensive analysis of the RNA-seq data showed that differentially expressed genes were notably enriched in hormone signal transduction and the circadian system. Flower bud formation in MY3 was induced through the plant hormone receptor TIR1 (transport inhibitor response 1) of the IAA signaling pathway, the miR535-GID1c module of the GA signaling pathway, and the miR395-JAZ module of the JA signaling pathway. In addition, the expression of core clock components GI (GIGANTEA) and CO (CONSTANS) in MY3 increased 2.3-fold and 1.8-fold over that in QY2, respectively, indicating that the circadian system also played a role in promoting flower bud formation in MY3. Finally, the hormone signaling pathway and circadian system transmitted flowering signals to the floral meristem characteristic genes LFY (LEAFY) and AP1 (APETALA 1) via FT (FLOWERING LOCUS T) and SOC1 (SUPPRESSOR OF OVEREXPRESSION OF CO 1) to regulate flower bud formation. These data will provide the basis for understanding the mechanism of flower bud alternate formation and formulating high yield regulation measures for C. oleifera.

Hormones regulate the flowering process in saffron differently depending on the developmental stage.

Flowering in saffron is a highly complex process regulated by the synchronized action of environmental cues and endogenous signals. Hormonal regulation of flowering is a very important process controlling flowering in several plants, but it has not been studied in saffron. Flowering in saffron is a continual process completed in months with distinct developmental phases, mainly divided into flowering induction and flower organogenesis/formation. In the present study, we investigated how phytohormones affect the flowering process at different developmental stages. The results suggest that different hormones differentially affect flower induction and formation in saffron. The exogenous treatment of flowering competent corms with abscisic acid (ABA) suppressed both floral induction and flower formation, whereas some other hormones, like auxins (indole acetic acid, IAA) and gibberellic acid (GA), behaved contrarily at different developmental stages. IAA promoted flower induction, while GA suppressed it; however, GA promoted flower formation, whereas IAA suppressed it. Cytokinin (kinetin) treatment suggested its positive involvement in flower induction and flower formation. The expression analysis of floral integrator and homeotic genes suggests that ABA might suppress floral induction by suppressing the expression of the floral promoter (LFY, FT3) and promoting the expression of the floral repressor (SVP) gene. Additionally, ABA treatment also suppressed the expression of the floral homeotic genes responsible for flower formation. GA reduces the expression of flowering induction gene LFY, while IAA treatment upregulated its expression. In addition to these genes, a flowering repressor gene, TFL1-2, was also found to be downregulated in IAA treatment. Cytokinin promotes flowering induction by increasing the expression levels of the LFY gene and decreasing the TFL1-2 gene expression. Moreover, it improved flower organogenesis by increasing the expression of floral homeotic genes. Overall, the results suggest that hormones differently regulate flowering in saffron via regulating floral integrator and homeotic gene expression.

Divergence of flowering-related genes to control flowering in five Euphorbiaceae genomes.

Reproductive growth and vegetative growth are a pair of main contradictions in the process of plant growth. Flowering, as part of reproductive growth, is a key switch in the life cycle of higher plants, which affects the yield and economic benefits of plants to a certain extent. The Euphorbiaceae species, including castor bean (Ricinus communis), physic nut (Jatropha curcas), tung tree (Vernicia fordii), cassava (Manihot esculenta), and rubber tree (Hevea brasiliensis), have important economic values because they are raw materials for the production of biodiesel, rubber, etc. The flowering mechanisms are still excluded in the Euphorbiaceae species. The flowering-related genes of Arabidopsis thaliana (Arabidopsis) were used as a reference to determine the orthologs of these genes in Euphorbiaceae genomes. The result showed that 146, 144, 114, 114, and 149 of 207 A. thaliana genes were respectively matched to R. communis, V. fordii, J. curcas, H. brasiliensis, and M. esculenta. These identified genes were clustered into seven pathways including gibberellins, floral meristem identity (FMI), vernalization, photoperiod, floral pathway integrators (FPIs), and autonomous pathways. Then, some key numbers of flowering-related genes are widely conserved in the Euphorbiaceae genomes including but not limited to FPI genes LFY, SOC1, FT, and FMI genes AG, CAL, and FUL. However, some genes, including FRI, FLC, and GO, were missing in several or all five Euphorbiaceae species. In this study, we proposed the putative mechanisms of flowering-related genes to control flowering and provided new candidate flowering genes for using marker-assisted breeding to improve variety quality.

Isolation and Functional Characterization of a LEAFY Gene in Mango (Mangifera indica L.).

LEAFY (LFY) plays an important role in the flowering process of plants, controlling flowering time and mediating floral meristem differentiation. Owing to its considerable importance, the mango LFY gene (MiLFY; GenBank accession no. HQ585988) was isolated, and its expression pattern and function were characterized in the present study. The cDNA sequence of MiLFY was 1152 bp, and it encoded a 383 amino acid protein. MiLFY was expressed in all tested tissues and was highly expressed in flowers and buds. Temporal expression analysis showed that MiLFY expression was correlated with floral development stage, and two relative expression peaks were detected in the early stages of floral transition and floral organ differentiation. Moreover, 35S::GFP-MiLFY fusion protein was shown to be localized to the nucleus of cells. Overexpression of MiLFY in Arabidopsis promoted early flowering and the conversion of lateral meristems into terminal flowers. In addition, transgenic plants exhibited obvious morphological changes, such as differences in cauline leaf shape, and the number of lateral branches. When driven by the MiLFY promoter, GFP was highly expressed in leaves, floral organs, stems, and roots, during the flowering period. Exogenous gibberellin (GA3) treatment downregulated MiLFY promoter expression, but paclobutrazol (PPP333) upregulated it. Bimolecular fluorescence complementation (BiFC) assays showed that the MiLFY protein can interact with zinc-finger protein 4 (ZFP4) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (MiSOC1D). Taken together, these results indicate that MiLFY plays a pivotal role in controlling mango flowering, and that it is regulated by gibberellin and paclobutrazol.

Evolution and expression of LEAFY genes in ferns and lycophytes

BackgroundThe LEAFY (LFY) transcription factors are present in algae and across land plants. The available expression and functional data of these genes in embryophytes suggest that LFY genes control a plethora of processes including the first zygotic cell division in bryophytes, shoot cell divisions of the gametophyte and sporophyte in ferns, cone differentiation in gymnosperms and floral meristem identity in flowering plants. However, their putative plesiomorphic role in plant reproductive transition in vascular plants remains untested.ResultsWe perform Maximum Likelihood (ML) phylogenetic analyses for the LFY gene lineage in embryophytes with expanded sampling in lycophytes and ferns. We recover the previously identified seed plant duplication that results in LEAFY and NEEDLY paralogs. In addition, we recover multiple species-specific duplications in ferns and lycophytes and large-scale duplications possibly correlated with the occurrence of whole genome duplication (WGD) events in Equisetales and Salviniales. To test putative roles in diverse ferns and lycophytes we perform LFY expression analyses in Adiantum raddianum, Equisetum giganteum and Selaginella moellendorffii. Our results show that LFY genes are active in vegetative and reproductive tissues, with higher expression in early fertile developmental stages and during sporangia differentiation.ConclusionsOur data point to previously unrecognized roles of LFY genes in sporangia differentiation in lycophytes and ferns and suggests that functions linked to reproductive structure development are not exclusive to seed plant LFY homologs.

Physicochemical properties and homology studies of the floral meristem identity gene LFY in nonflowering and flowering plants.

In flowering plants, the LEAFY (LFY) gene controls floral meristem activity. In early land plants such as mosses and ferns, it, however, has a minimum role in cell division and development of diploid sporophyte. Homology modeling, an accurate and efficient protein structure prediction method, was used to construct a 3D model of the LEAFY protein in nonflowering and flowering plants. The present study examines the following species: Charophyte green algae, Physcomitrella, Ceratopteris, Picea, and Arabidopsis, as they are the popularly used model organisms for developmental studies. LEAFY protein sequences from the model organisms were aligned by multiple sequence alignment. 3D models of the LEAFY protein from all the model organisms was constructed using the PHYRE2 program with 100% confidence, and the constructed models were evaluated using the MolProbity tool. On the basis of the conserved regions, Charophyte green algae shared 38-46% sequence similarity with Physcomitrella sp., 37-46% similarity with Ceratopteris sp., 33-41% similarity with Picea sp., and 32-38% similarity with Arabidopsis sp. The Motif Finder server identified the protein family domain FLO_LFY and LFY_SAM, whose function is floral meristem development. Secondary structure prediction analysis indicated that the LEAFY protein belongs to the alpha (α) protein class, which is stable against mutation and thus limits structural changes in the LEAFY protein. The study findings reveal two distinct clusters of the LFY gene from the common ancestor green algae. One cluster is present in nonflowering plants that include mosses, pteridophytes, and gymnosperms, and the other cluster is present in flowering plants that include orchids, monocots, dicots, and angiosperms.

Stress-inducible Arabidopsis thaliana RD29A promoter constitutively drives Citrus sinensis APETALA1 and LEAFY expression and precocious flowering in transgenic Citrus spp.

Transgenic 'Duncan' grapefruit (Citrus paradisi Macf.) and 'Valencia' sweet orange (Citrus sinensis [L.] Osbeck) plants ectopically expressing C. sinensis (cv. Washington navel orange) APETALA1 (CsAP1) or LEAFY (CsLFY) genes under control of the Arabidopsis thaliana stress-inducible promoter AtRD29A flowered under non-inductive (warm temperature, well-watered) greenhouse conditions, whereas their wild-type (WT) counterparts did not. The transgenic plants that flowered exhibited no altered morphological features, except the lack of thorns characteristic of juvenile WT plants. The most precocious T0 line, 'Duncan' grapefruit (Dun134-3) expressing the CsAP1 gene, flowered and fruited when it was 4.5years old and the T1 siblings from this line flowered and fruited when they were just over 18months old. In contrast, T1 seedlings from three lines of 'Duncan' grapefruit expressing the CsLFY gene flowered within 3months after germination, but were unable to support fruit development. Transcript levels of corresponding transgenes in leaves were not correlated with earliness of flowering. To further study the activity of AtRD29A, leaves from three 'Carrizo' citrange (C. sinensis×Poncirus trifoliata) rootstock seedlings transformed with the green fluorescent protein (GFP) gene under regulation of the AtRD29A promoter were subjected to drought stress or well-watered conditions. Expression of GFP was not stress-dependent, consistent with the observation of flowering of CsAP1 and CsLFY transgenic plants under non-inductive conditions. Taken together, the results suggest that AtRD29A is constitutively expressed in a citrus background. Despite the loss of control over flowering time, transgenic citrus lines ectopically expressing C. sinensis AP1 or LFY genes under control of the A. thaliana RD29A promoter exhibit precocious flowering, fruit development and viable transgenic seed formation. These transformed lines can be useful tools to reduce the time between generations to accelerate breeding.

Seed germination and morphological characterization of traditional leafy vegetables

Traditional leafy vegetables provide affordable sources of micronutrients to many people in Zimbabwe. They are produced by smallholder farmers with limited knowledge on the agronomic value of high-quality seed and the seed is rarely tested to determine its quality. This study was therefore conducted to evaluate the germination of seeds of three traditional leafy vegetables sourced from five different farmers and the morphological characteristics of the seedlings. The seeds were collected in the growing season of 2015 to 2016, stored at room temperature and tested for germination in the laboratory at regular monthly intervals during storage. Field germination tests were conducted only once. The seeds tested were classified as normal seedlings, abnormal seedlings, fresh non-germinated seeds or dead seeds. Morphological analysis was conducted at seedling stage, including seven qualitative characters and one quantitative character. Mean separation based on the least significance difference at 5% indicated that percentage germination, purity and 1000-seeds weight for all three species significantly differed among sources. The results showed that Cleome gynandra had lowest germination percentages, Amaranthus hybridus was intermediate and Bidens pilosa had highest values throughout the tests. C. gynandra seed exhibited dormancy, showing high levels of fresh non-germinated seed percentage after each test, which is potentially disastrous for the farmers. The combination of pre-chilling, light, potassium nitrate and alternating temperatures as a way of improving germination for C. gynandra needs further validation. Key words: Seed quality, purity, germination, morphological characteristics of seedlings.

The efficacy of CRISPR-mediated cytosine base editing with the RPS5a promoter in Arabidopsis thaliana

CRISPR/Cas9-mediated genome editing is an important and versatile technology in modern biological research. Recent advancements include base-editing CRISPR tools that enable targeted nucleotide substitutions using a fusion protein comprising a nickase variant of Cas9 and a base deaminase. Improvements in base editing efficiencies and inheritable of edited loci need to be made to make CRISPR a viable system in plants. Here, we report efficiency of cytosine base editors (CBEs) in Arabidopsis thaliana by applying the strong endogenous RPS5a promoter to drive the expression of nickase Cas9 and either rAPOBEC1 from rat (BE3) or the PmCDA1 activation-induced cytidine deaminase from sea lamprey (AIDv2). Compared with the strong heterologous CaMV35S promoter of viral origin, the RPS5a promoter improved CBE efficiency by 32% points with the number of T1 plants showing over 50% conversion ratio when the LFY gene was targeted. CBE induced nonsense mutations in LFY via C-to-T conversion, which resulted in loss-of-function lfy phenotypes; defects in LFY function were associated with the targeted base substitutions. Our data suggest that optimal promoter choice for CBE expression may affect base-editing efficiencies in plants. The results provide a strategy to optimize low-efficiency base editors and demonstrate their applicability for functional assays and trait development in crop research.

Impact of Cooking Conditions of Sweet Potato Leaves (Ipomoea batatas) on the Hematological and Biochemical Parameters of the Rats (Wistar)

Leafy vegetables contain nutrients and micronutrients that are essential for the proper functioning of the body of living things. The latter can be affected when cooking leafy vegetables. The objective of this work was therefore to study the impact of varying cooking parameters of sweet potato leaves on body mass and hematological and biochemical parameters in the rats. To do this, the sweet potato leaves were cooked in 500 ml of water according to three cooking conditions by varying the leaf quantity and the cooking time: cooking n° 1 (300 g; 7.93 min), cooking n° 2 (400 g; 10 min) and cooking n° 3 (441.4 g; 15.07 min). Contents of protein, fiber, vitamin C, β-carotene, vitamin B9, polyphenol, flavonoid, iron and zinc of the precooked leaves were determined. The female rats were divided on the basis of their body weight into 4 groups of 5 rats each and were fed with pellets (reference food). The control batch received distilled water. Batches 1, 2 and 3 received, by force-feeding for 30 days, aqueous extracts of sweet potato leaves from cooking n° 1, cooking n° 2 and cooking n° 3, respectively. During the experiment, three blood samples were taken (day 0, day 15 and day 30) to assess the levels of white blood cells, red blood cells, hemoglobin, blood platelets and serum iron, and blood sugar. The results indicated that the aqueous extracts of precooked sweet potato leaves caused an increase in weight and, levels of hematological parameters and serum iron, and a decrease in blood sugar in rats. In addition, the cooking conditions of sweet potato leaves significantly influenced the weight and the levels of hemoglobin, blood platelet and serum iron in rats; while they did not significantly affect blood sugar and levels of white blood cell and red blood cell in rats. The cooking condition which gave the most satisfactory results was cooking n° 3 (441.4 g; 15.07 min). These results suggest that sweet potato leaves could be used in the treatment of anaemia, and hypertension, hence their importance in nutrition and health. However, it would be necessary to adopt a cooking condition that best preserves the virtues of sweet potato leaves.

Comparison of the evolution of orchids with that of bats

The evolution of orchids and bats is an example of DNA’s own evolution which has resulted in structures and functions which are not necessarily related to any obvious advantage to the organism. The flowers of orchids resemble: humans, apes, lizards, frogs and even shoes. The faces of bats resemble plant leaves but also horseshoes. These similarities are not accidental because they emerge repeatedly in different genera and different families. This evolutionary situation bewildered botanists and zoologists for many years, but is now elucidated by the molecular unification of plants and animals derived from the following evidence: (1) Contrary to expectation, plant and animal cells (including those of humans) could be fused and the human chromosomes were seen dividing in the plant cytoplasm. (2) Orchids, bats and humans have about the same number of genes: orchids, 21,841; bats, 21,237 and humans circa 20,000. (3) These three groups contain the same homeotic genes which decide: flower formation (orchids), body segmentation (bats) and body segmentation (humans). The leaf pattern, is formed in plants by the LEAFY master gene, but this pattern even appears in minerals, which have no genes, an indication that pure atomic processes are responsible for its emergence at the organism level. (Less)

Analysis of Some Heavy Metal Contents in Selected Vegetables and Fruits from States in Nigeria

The consumption of fruits and vegetables is on the increase as these produce have nutritive values associated to the presence of essential metals that helps boost humans’ immune system, thus, avoiding health problems. However, there is also the presence of some non-essential metals in fruits and vegetables that are detrimental to humans. This study was carried out in order to determine the concentrations of some potentially toxic heavy metals namely; Lead (Pb), Cadmium (Cd), Nickel (Ni) and Zinc (Zn) in some leafy vegetables namely; cucumber (Cucumis sativus), watermelon (Cucurbita lanatus), tomatoe (Solantum lycopersium) and pepper (Capsicum annuum), brought from Kano state as well as those cultivated in Edo state. 25 samples consisting of 4 different vegetables were each purchased from two major markets known to be a major depot for vegetables in Benin City as well as those produced in Benin City, Edo State, Nigeria. Edible portions of the samples were used for analysis while bruised or rotten samples were removed. Samples for analysis were dried using the oven-dry method at 105°C for 24 hours to obtain the moisture content and then grounded. About 1.0g of the samples were each weighed and digested in a mixture of 10mls Nitric – Perchloric acid in a 250 ml Kjeldahl flask under a fume hood. The content was mixed and heated gently at 120 - 200°C for about 45 minutes on a hot plate. Heavy metals were present in all the vegetables analyse at various levels. Cadmium (Cd) concentration ranges between 0.02 – 0.47 mgkg-1, Lead (Pb) was within the range of 0.03 – 11.12 mgkg-1, Zinc (Zn) concentration ranges between 0.15 – 73.69 mgkg-1, and Nickel (Ni) concentration ranges between 0.07 – 35.54 mgkg-1 respectively in all the vegetables from the two states. Cd and Pb were observed to be higher than that of the Maximum Permissible Limit (MPL) stipulated by the World Health Organization (WHO).

Determinate growth habit of grain legumes: role in domestication and selection, genetic control

This review is devoted to the analysis of molecular genetic mechanisms of controlling the type of growth habit of grain legumes (pea, soybean, common bean, vigna); it provides information about known homologous genes TFL1, LFY, AP1, FUL, FT, and FD. Significant changes in plant architecture were during domestication of grain legumes. Many wild relatives of legumes are characterized by an indeterminate growth habit type, cultivated plants are characterized by indeterminate and determinate types. In plants with a determinate growth habit type, terminal inflorescence is formed at transition from the vegetative phase to the reproductive phase. These plants are characterized by a complex of features: simultaneous maturation of beans, resistance to lodging, etc. In indeterminate type of growth habit, the apical shoot meristem remains active during plant life. The main genes responsible for the plant transition to flowering are the homologs of the Arabidopsis genes LFY, TFL1, AP1. TFL1 gene is responsible for maintenance of growth of the shoot apical meristem; its homologs were identified in pea (PsTFL1a), soybean (Dt1/GmTFL1), common bean (PvTFL1y), cowpea (VuTFL1). The identification and characterization of the genes responsible for the type of stem growth habit are necessary for the successful selection of modern varieties suitable for mechanized cultivation. Design of molecular markers that diagnose this important breeding trait at early plant development stages, will help to determine the type of stem growth habit.

Flowering in Persian walnut: patterns of gene expression during flower development

BackgroundFlower development and sufficient fruit set are important parameters with respect to walnut yield. Knowledge about flowering genes of fruit trees can help to conduct better molecular breeding programs. Therefore, this study was carried out to investigate the expression pattern of some flowering genes (FT, SOC1, CAL, LFY and TFL1) in Persian walnut (cv. Chandler) during the growing season and winter dormancy.ResultsThe results showed that walnut flower induction and initiation in Shahmirzad, Iran occurred in early June and late September, respectively. After meeting chilling and heat requirement, flower differentiation and anthesis occurred in late-March and mid-April to early-May, respectively. Study of flowering gene expression showed that the expression of the FT gene increased in three stages including before breaking of bud dormancy, from late March to late April (coincided with flower differentiation and anthesis) and from late May to mid-June (coincided with flower induction). Like FT, the expression of SOC1 gene increased during flower induction and initiation (mid-May to early-August) as well as flower anthesis (mid-April to early-May). LFY and CAL genes as floral meristem identity genes are activated by FT and SOC1 genes. In contrast with flowering stimulus genes, TFL1 showed overexpression during winter dormancy which prevented flowering.ConclusionThe expression of FT gene activated downstream floral meristem identity genes including SOC1, CAL and LFY which consequently led to release bud dormancy as well as flower anthesis and induction. Also, TFL1 as a flowering inhibitor gene in walnut showed overexpression during the bud dormancy. Chilling accumulation reduced TFL1 gene expression and increased the expression of flowering genes which ultimately led to overcome dormancy.

Distribution of groundnut rosette disease and sequence diversity of groundnut rosette virus associated satellite RNA (Sat-RNA) in Western Kenya

Production of groundnuts (Arachis hypogaea L.) in Western Kenya is mainly constrained by groundnut rosette disease (GRD) which cause up to 100% yield loss. This disease expresses different symptoms as a result of variations in the groundnut rosette virus (GRV) associated satellite-ribonucleic acid (GRV Sat-RNA). Over the past 20 years, no work had been done to document the status of the disease in Kenya. Additionally, no sequences of any of the GRD associated viruses were available in the GeneBank from Kenya. This study determined the distribution of GRD and the genetic diversity of GRV Sat-RNA. Sampling was done in main groundnut growing areas of Western Kenya during the long and short rain seasons in 2016/2017. Total RNA was extracted from the leafy samples collected using RNeasy Mini Kit (Qiagen) according to the manufacturers’ protocol and used for double stranded cDNA synthesis using the SuperScript II kit. DNA libraries were sequenced on the Illumina MiSeq platform (Illumina). Reads were used for de novo assembly and contigs aligned to the viral genomes database using CLC Genomics Workbench 10.1.2. The assembled contigs were subjected to a BLASTn search against the GenBank database. Average GRD incidence was 53 and 41% in the short and long rain seasons, respectively. Chlorotic rosette was the dominant symptom followed by green rosette and mosaic. Nucleotide sequences of Sat-RNA revealed identities of 88 to 100% between the Kenyan isolates and those from Malawi, Nigeria and Ghana. All Kenya isolates clustered closest with green rosette variants of Malawi except one which clustered with chlorotic/yellow blotch variants. Rosette is widely distributed in Western Kenya and occurs wherever groundnuts are grown. The variations of GRD symptoms in Western Kenya could be due to the existence of different variants of Sat-RNA or other agents. Key words: Groundnuts, satellite-ribonucleic acid (Sat-RNA), diversity, Western Kenya.

AfLFY, a LEAFY homolog in Argyranthemum frutescens, controls flowering time and leaf development

Flowering is important for plant propagation and survival, and it is also closely related to human life. Identifying the molecular mechanisms underlying flower development is essential for plant improvement and breeding. Flower development is a complex physiological process that is regulated by multiple genes. LFY genes play important roles in the floral meristem transition and act as crucial integrators in regulating the floral gene network. Argyranthemum frutescens is an ornamental species cultivated for floral displays, yet little is known about molecular mechanisms driving its flower development. In this study, the LEAFY gene homologue, AfLFY, was identified and cloned from A. frutescens, and its role and expression patterns were characterized. Two distinct copies of AfLFY were found in the A. frutescens genome and both sequences contained a 1248 bp open reading frame that encoded 415 amino acids. The putative protein sequences have a typical LFY family domain. In addition, AfLFY was expressed at the highest levels in young leaves of the vegetative stage and in the shoot apical bud meristem of the reproductive stage. Phylogenetic analysis showed that AfLFY was most closely related to DFL from Chrysanthemum lavandulifolium. Subcellular localization studies revealed that AfLFY localized to the nucleus. Heterologous expression of AfLFY in transgenic tobacco plants shortened its period of vegetative growth, converted the lateral meristems into terminal flowers and promoted precocious flowering. In addition, transgenic plants exhibited obvious morphological changes in leaf shape. qRT-PCR analysis indicated that the expression levels genes related to flowering, FT, SOC1, and AP1 were significantly upregulated in AfLFY transgenic plants. Our findings suggested that the AfLFY gene plays a vital role in promoting flowering and leaf development in A. frutescens. These results laid a foundation for us to understand the mechanism of AfLFY in regulation flowering, and the results will be helpful in improving A. frutescens through molecular breeding.

Visual quality and waste of leafy vegetable and fresh herbs in a typical retail market

Because of their high perishability, leafy vegetables and fresh herbs are transported to the market soon after harvest. It is very likely that most of the damage caused in the farm and during transport will result in food discard only later in the retail market or in the household. Inadequate handling and marketing strategies in the store are expected to further contribute to waste. The study was designed to address the following questions: (1) what is the visual quality of leafy vegetables and fresh herbs received in the retail market; (2) what is the volume of discard of these produce in the retail market (3) what are the main causes of discard and (4) how these variables are influenced by the vegetable species, the suppliers and the stores evaluated. The study was conducted in 4 stores of a regional supermarket chain in Distrito Federal – Brazil, for a period of 6 months. It was evaluated: (1) number of produce items received and discarded; (2) visual quality of produce at reception; (3) cause of discard. The operations in each shop were described based on observations and discussion with the store staff. When considering the sum of all produce, the discard (expressed as units per day and corrected for quantity purchased) was influenced by all the factors studied, namely store, supplier and day of the week. Delivery of produce with any signs of wilting and yellowing was negligible but produce with bruised and old leaves which should have been trimmed in the farm were frequent. Visual quality was important to determine shelf life and preference by the consumer but how important it was depended on other factors such as the produce considered and the workflow in the store. The percentage of discard varied from 8.7 % to 97.0 % of the number of units purchased. Smaller waste volume was observed for spring onion, parsley, coriander, collard, leak and green leaf lettuce. Waste volume equal to or above 50 % was observed for vegetables baby romaine lettuce, broad leaved endive, wild chicory and mustard greens and fresh herbs sage and thyme. The vegetable and fresh herbs discard in the Brazilian retail market is in great measure the result of technological constraints and are not intentional. The implications of this situation in the definitions of food waste and food loss are discussed.

Impact of aerobic rice-leafy vegetables intercropping systems on weed management

Field experiments were carried out in summer 2017 and 2018 at Zonal Agricultural Research Station (ZARS), University of Agricultural Sciences, GKVK, Bengaluru, India on red sandy loam soil. The main objective was to evaluate the impact of rice grown in aerobic conditions intercropped with leafy vegetables on weed management, wherein the sole rice and intercrops of four leafy vegetables: palak (Spinacia oleracea L.), coriander (Coriandrum sativum L.), amaranth (Amaranthus spp L.), methi (Trigonella foenum-graecum L.) were designed in randomized complete block design (RCBD) of 9 treatments replicated four times. The results revealed that the greater the crop biomass, the higher the weed suppression achieved. Sole rice was densely populated by weeds and also had higher weed biomass compared to the intercrops. However, intercrops suppressed efficiently the weeds, increased growth and rice equivalent yield over the sole rice crop. The intercropping systems with leafy palak (spinach) were the most suppressive of weeds. The rice + leafy vegetable palak recorded significantly lower weed density (138.4 no. m-²), dry weight at harvest (148.04 g m-²), higher rice grain, rice straw and palak leaf yield (7651; 9687 and 25508 kg ha-¹, respectively) and higher net monetary return (₹ 156269 ha-¹) over the sole rice.