Flower Formation Research Articles

Soil drought decreases oil synthesis and increases protein synthesis in cottonseed kernel during the flowering and boll formation of cotton

In cotton production, drought is particularly prominent in the flowering and boll formation stage, which significantly affects the cottonseed yield and quality. As the two main storage products in cottonseed kernel, the formation of oil and protein will be affected inescapably under soil drought. Still, the effects of soil drought on the synthesis of cottonseed oil and protein are poorly investigated. To this end, experiments were conducted using two cultivars with contrasting drought tolerance (Dexiamian 1 and Yuzaomian 9110) under three water levels [soil relative water content: control (75 ± 5)%, mild drought (60 ± 5)% and severe drought (45 ± 5)%] from 2017 to 2019. We examined the responses of metabolic activities in cottonseed kernels to drought. Otherwise, 13 CO 2 and 15 N-urea isotope labeling were applied to verify the trend of oil and protein accumulation under soil drought. Results showed that drought decreased cottonseed yield per plant due to the decreases of single-seed weight and cottonseed number. And drought decreased oil content (% dry weight −1 ) and increased protein content (% dry weight −1 ) in cottonseed kernel. According to the findings, drought decreased 13 C content and limited the flow of carbon into oil synthesis pathway; moreover, drought decreased the expression of GhPEPC1 and GhDGAT and activities of phosphoenolpyruvate carboxylase (PEPCase) and diacylglycerol acyltransferase (DGAT), which restrained oil accumulation. Increased protein content under drought was attributed to the increased translocation of plant nitrogen to cottonseed kernel, higher expression of GhGS and GhGOGAT , glutamine synthetase (GS) and glutamate synthase (GOGAT) activities. The Yuzaomian 9110 was more sensitive to drought stress with a higher loss of cottonseed yield and yield components than Dexiamian 1. This study provides insight into the physiological mechanisms of cottonseed oil and protein synthesis under drought and provides a theoretical basis for the utilization of cottonseed oil and protein in the future. Annotation: PEP, phosphoenolpyruvic acid; OAA, oxaloacetic acid; TCA, tricarboxylic acid cycle; Ace-CoA, acetyl coenzyme A; Mal-CoA, Malonyl mono-CoA; G3P, glyceraldehyde 3-phosphate; DAG, diacylglycerol; TAG, triacylglycerol; NADPH, nicotinamide adenine dinucleotide phosphate; PEPCase, Phosphoenolpyruvate carboxylase; ACCase, acetyl-CoA carboxylase; DGAT, diacylglycerol acyltransferase; GS, glutamine synthetase; GOGAT, glutamate synthase; AST, aspartate aminotransferase; ALT, alanine aminotransferase. • Cottonseed yield was significantly decreased under soil drought. • Drought stress significantly restrained 13 C into oil in cottonseed kernels, and enhanced 15 N into kernels. • The oil content was restrained under drought due to lower carbon substrates and enzyme activities. • The increase of nitrogen accumulation and protein synthesis enhanced kernel protein content under drought.

Advances on the Coloring Mechanism of Double-color Flowers in Plants

Plants with the flower color phenotype of double-color flowers are very precious and attractive and can usually be regarded as valuable germplasm resources for studying and improving flower color. This paper summarizes the coloring mechanism of double-color flowers in plants from three aspects: the formation of double-color flowers, the physiological factors affecting the coloring difference of double-color flowers, and the molecular mechanism affecting the coloring difference of double-color flowers, to provide a theoretical reference for the in-depth study of the coloring mechanism and molecular breeding of double-color flowers in the future.

FRUITFULL is involved in double fruit formation at high temperature in sweet cherry

Sweet cherry (Prunus avium L.) is sensitive to high temperature during pistil development, but the spatial and temporal variability of high temperature and the molecular mechanism of its impact on the formation of double pistils are little known. An analysis of historical and projected climate data was conducted to characterize the spatial and temporal variability of high temperature from June to September at 5 stations in main sweet cherry growing regions of China and a warmer reference site. Several high temperature indices were developed to quantify heat frequency, intensity and duration during pistil development based on observed and projected maximum temperatures. The risk of high temperature was projected to increase under two Representative Concentration Pathways for 2035–2065 and 2070–2100, and the increasing rate was higher in the south station than the north except for Yantai city. Furthermore, to explore the mechanism of double fruit formation at high temperature, we investigated the regulation of FRUITFULL (FUL) during the growth of floral buds in sweet cherry. We identified a AP1/ FUL family gene FUL from sweet cherry, which was grouped with PpCAL, PpMADS6 from Prunus persica, ParFUL from Prunus armeniaca, PyeCAL from Prunus yedoensis, and PdCAL, PdAGL8 from Prunus dulcis by phylogenetic tree analysis. The seasonal expression level of PavFUL was higher in the high multi-pistil rate cultivar during summer stage and enhanced by high temperature. Moreover, overexpression of PavFUL led to multi-silique formation and early flowering in Arabidopsis. In addition, Y2H and BiFC assays revealed that PavFUL interacted with other MADS-box proteins, including PavLFY, PavSOC1, PavAP1, and PavSEP, to co-regulate the flowering and multi-silique formation. Our findings will help decipher the possible mechanism of high temperature-mediated double fruit via affecting FUL and other MADS-box genes in molecular level for tree fruit species.

Integrated transcriptome and hormone analyses provide insights into silver thiosulfate-induced "maleness" responses in the floral sex differentiation of pumpkin (Cucurbita moschata D.).

The perfect mating of male and female flowers is the key to successful pollination. The regulation of ethylene with chemicals is a good option for inducing staminate or female flowers. Silver thiosulfate is often used to induce the formation of male flowers in subgynoecious and gynoecious crops, which is important to maintain their progenies. However, its effects on flower sex differentiation in pumpkin (Cucurbita moschata Duch.) and the underlying mechanism remain unclear. In this study, the application of silver thiosulfate to pumpkin seedlings significantly delayed the occurrence of the first female flower and increased the number of male flowers. We next investigated the underlying mechanism by employing transcriptome and endogenous hormone analyses of the treated plants. In total, 1,304 annotated differentially expressed genes (DEGs)were identified by comparing silver thiosulfate-treated and control plants. Among these genes, 835 were upregulated and 469 were downregulated. The DEGs were mainly enriched in the phenylpropanoid biosynthesis and metabolism pathways (phenylalanine ammonia-lyase, peroxidase) and plant hormone signal transduction pathways (auxin signaling, indole-3-acetic acid-amido synthetase, ethylene response factor). Silver thiosulfate significantly reduced the levels of 2-oxindole-3-acetic acid, para-topolin riboside, dihydrozeatin-O-glucoside riboside, and jasmonoyl-l-isoleucine but increased the levels of trans-zeatin-O-glucoside, cis-zeatin riboside, and salicylic acid 2-O-β-glucoside. The levels of auxin and jasmonic acid were decreased, whereas those of salicylic acid were increased. Different trends were observed for different types of cytokinins. We concluded that silver thiosulfate treatment not only affects the expression of auxin synthesis and signaling genes but also that of ethylene response factor genes and regulates the levels of auxin, salicylic acid, jasmonic acid, and cytokinins, which together might contribute to the maleness of pumpkin. This study provides useful information for understanding the mechanism underlying the effect of silver thiosulfate on floral sex differentiation in pumpkin, a widely cultivated vegetable crop worldwide, and gives a production guidance for the induction of maleness using STS for the reproduction of gynoecious lines of Cucurbitaceae crops.

Biofortification of oil quality, yield, and nutrient uptake in Indian mustard (Brassica juncea L.) by foliar application of boron and nitrogen.

Indian mustard (Brassica juncea L.) is an essential oilseed crop that offers important nutrients to human beings. However, the concurrent micronutrient deficiencies including boron (B), sulfur (S), and nitrogen (N) could pose a significant threat to public health. Therefore, this study was conducted at the Punjab Agricultural University, Ludhiana, with nine treatments, i.e., T1-Control (recommended NPK only), T2- borax (0.5%) at flowering, T3-borax (1.0%) at flowering,T4- borax (0.5%) + urea (1.0%) at flowering,T5-borax (1.0%) + urea (1.0%) at flowering, T6-borax (0.5%) at flowering + capsule formation, T7-borax (1.0%) at flowering + capsule formation, T8-borax (0.5%) + urea (1.0%) at flowering + capsule formation, T9-borax (1.0%) + urea (1.0%) at flowering + Capsule formation, replicated three times in a randomized block design for 2 years (2020–2021 and 2021–2022). The foliar application of borax (1.0%) + urea (1.0%) at the flowering and capsule formation stage (treatment T9) was highly efficient in increasing food quality parameters such as crude fiber, total soluble solids (TSS), and protein content with maximum values of 3.77, 24.9, and 27.53%, respectively. Also, maximum yields of seed as well as stover for treatment T9 were 1.376 and 6.625 kg ha−1, respectively. Similarly, the results for B, S, and N concentrations in seed (27.71 mg kg−1, 17.69 mg kg−1, and 2.35%), as well as stover (25.92 mg kg−1, 17.31 mg kg−1, and 0.33%), were maximum in treatment T9. Also, B, S, and N uptake by seed (38.18 g ha−1, 24.40 g ha−1, and 32.05 Kg ha−1) and stover (172.55 g ha−1, 115.44 g ha−1, and 21.99 Kg ha−1) were maximum for the treatment T9 involving borax (1.0%) + urea (1.0%) at the flowering and capsule formation stage. Whereas, the concentration and uptake decreased in the treatments involving the sole application of borax and urea. Therefore, the application of borax (1.0%) and urea (1.0%) at the flowering and capsule formation stage significantly improved the quality parameters, seed and stover yield, nutrient concentration, and uptake over control and could be used to alleviate the B, S, and N deficiency in Indian mustard.

Profiling of phytohormones in apple fruit and buds regarding their role as potential regulators of flower bud formation.

Apple (Malus×domestica Borkh.) cropping behavior, if not regulated, is often manifested by high yields of small-sized fruit in so called ON-years, which are usually followed by strongly reduced crop loads in OFF-years. Such cropping pattern is defined as biennial bearing and causes significant losses in apple production. The growth of apple fruit overlaps with the formation of flower buds, which remain dormant until the following spring. Earlier works proposed that some fruit-derived mobile compounds, as e.g., phytohormones, could suppress flower bud formation that thereby leads to biennial bearing. We addressed this hypothesis by analyzing 39 phytohormones in apple seeds, fruit flesh and by measuring phytohormone export from the fruits of the biennial bearing cultivar 'Fuji' and of the regular bearing cultivar 'Gala'. Moreover, we analyzed the same compounds in bourse buds from fruiting (ON-trees) and non-fruiting (OFF-trees) spurs of both apple cultivars over the period of flower bud formation. Our results showed that apple fruit exported at least 14 phytohormones including indole-3-acetic acid and gibberellin A3; however, their influence on flower bud formation was inconclusive. A gibberellin-like compound, which was detected exclusively in bourse buds, was significantly more abundant in bourse buds from ON-trees compared with OFF-trees. Cultivar differences were marked by the accumulation of trans-zeatin-O-glucoside in bourse buds of 'Gala' ON-trees, whereas the levels of this compound in 'Gala' OFF were significantly lower and comparable to those in 'Fuji' ON- and OFF-trees. Particular phytohormones including five cytokinin forms as well as abscisic acid and its degradation products had higher levels in bourse buds from OFF-trees compared with ON-trees and were therefore proposed as potential promotors of flower bud initiation. The work discusses regulatory roles of phytohormones in flower bud formation in apple based on the novel and to date most comprehensive phytohormone profiles of apple fruit and buds.

Terminal heat stress modulates growing degree days, heat use efficiency and yield stability index in brassica juncea

An experiment was planned to visualize the impact of terminal heat stress on yield potentials of late sown mustard cultivars under the changing climatic conditions. A set of fifteen B. juncea genotypes were evaluated at two planting dates during two winter seasons. Late planted genotypes faced heat stress during post anthesis/seed filling stage which negatively influenced the movements of photosynthates to developing sinks thus inhibiting synthetic processes, lowering seed weight and seed yield and may even hamper seed quality. Onset of flowering and siliquing were delayed but the completion of flowering and siliquae formation was earlier in the late planted genotypes. Seed filling was impeded by high temperature in late planting causing ≥50% decline in seed yield. Average accumulated growing degree days (AGDD) for phenological stages were higher in normal sown than the late sown crop. AGDD witnessed an increasing trend for flowering and fruiting behaviour in both the sowing dates. However, 50% flowering in late sown crop took 4 accumulated GDDoC days more. Average heat use efficiency was found to be significantly higher in normal sown genotypes for seed (0.95 kg ha-1 ºC-days-1 ) and biological (0.53 kg ha-1 ºC-days-1 ) yield relative to the late sown genotypes for seed (0.50 kg ha-1 ºC-days-1 ) and biological yield (2.71 kg ha-1 ºC-days-1 ). Seed yield under late sown condition had positive and significant correlation with siliquing duration (r= 0.600*) and reproductive phase (r= 0.558*) whereas, negative with flowering completion (r= -0.573*) and siliqua initiation (r= -0.519*). Based on the results IAN was the best genotype for delayed sowings.

Terminal heat stress modulates growing degree days, heat use efficiency and yield stability index in brassica juncea

An experiment was planned to visualize the impact of terminal heat stress on yield potentials of late sown mustard cultivars under the changing climatic conditions. A set of fifteen B. juncea genotypes were evaluated at two planting dates during two winter seasons. Late planted genotypes faced heat stress during post anthesis/seed filling stage which negatively influenced the movements of photosynthates to developing sinks thus inhibiting synthetic processes, lowering seed weight and seed yield and may even hamper seed quality. Onset of flowering and siliquing were delayed but the completion of flowering and siliquae formation was earlier in the late planted genotypes. Seed filling was impeded by high temperature in late planting causing ≥50% decline in seed yield. Average accumulated growing degree days (AGDD) for phenological stages were higher in normal sown than the late sown crop. AGDD witnessed an increasing trend for flowering and fruiting behaviour in both the sowing dates. However, 50% flowering in late sown crop took 4 accumulated GDDoC days more. Average heat use efficiency was found to be significantly higher in normal sown genotypes for seed (0.95 kg ha-1 ºC-days-1) and biological (0.53 kg ha-1 ºC-days-1) yield relative to the late sown genotypes for seed (0.50 kg ha-1 ºC-days-1) and biological yield (2.71 kg ha-1 ºC-days-1). Seed yield under late sown condition had positive and significant correlation with siliquing duration (r= 0.600*) and reproductive phase (r= 0.558*) whereas, negative with flowering completion (r= -0.573*) and siliqua initiation (r= -0.519*). Based on the results IAN was the best genotype for delayed sowings.

Analysis of cytokinin content and associated genes at different developmental stages in pak choi (Brassica rapa ssp. chinensis Makino)

Pak choi (Brassica rapa ssp. chinensis Makino) is a typical seed vernalization vegetable. Because premature bolting in spring causes significant economic losses, it is very important to clarify the flower formation mechanism to prevent this. Cytokinins are important plant hormones involved in regulating plant growth and development. To understand the relationship between cytokinin metabolism and flowering of pak choi, in this study, we determined the cytokinin trans-zeatin content in shoot apices of pak choi at different developmental stages by enzyme-linked immunosorbent assay. The results showed that cytokinin levels increased significantly after low temperature treatment at 4 °C, and continued to increase with vegetative growth after transplanting, reaching a peak at the critical period which is immediately prior to flower buds’ differentiation (S0), then decreased thereafter. The levels for low temperature treatment were consistently higher than controls. To explore the molecular mechanism underpinning the cytokinin changes, expression of homologous genes encoding cytokinin metabolic enzymes was analysed by transcriptome sequencing. The expression levels of nine genes (Bra004037, Bra023701, Bra002204, Bra014968, Bra028326, Bra028182, Bra034022, Bra009143 and Bra005869) were consistent with the changes in cytokinin content. The correlation between differentially expressed genes and cytokinin content in different developmental stages of apexes was analysed, and six closely related genes (Bra023701, Bra002204, Bra014968, Bra028182, Bra005869 and Bra009143) were identified. The results help to illuminate the molecular mechanisms controlling flowering of pak choi.

Изменения количества фотосинтетических пигментов в листьях сортов и сортообразцов чечевицы в период вегетации

Changes in chlorophyll a and chlorophyll b contents due to some biotic and abiotic factors have been found in the studied lentil varieties and specimens. In the branching stage, the chlorophyll a content ranged between 4.039 and 7.737 mg/g dry mass. During the whole vegetation period, maximum and minimum values 7.737 and 4.242 mg/g, respectively of the Chl a content was observed in the LIEN-LS-17(34) specimen. In the flowering period, the Chl a content changed in the range of 5.464–8.432 mg/g. The LICTN-17 (3) specimen was distinguished by the high amount 8.432 mg/g of Chl a. In the branching phase of the vegetation period, the Chl b content ranged between 1.526 and 5.672 mg/g. Whereas, in the flowering phase the Chl b content changed in the range of 1.665–2.612 mg/g. The maximum value of the Chl b content in the LICTN-17(3) specimen was equal to 2.612 mg/g. During the bean formation period, the Chl a content increased in some specimens and decreased in others. Thus, in the lentil varieties, the Chl b content reached maximum values 1.745–5.997 mg/g in the flowering and bean formation periods. During the grain filling period the Chl b content in lentil varieties and specimens decreased and amounted to 1.205–3.895 mg/g. The maximum carotenoid content was found during the flowering and bean formation periods in leaves of lentil varieties and specimens. The carotenoid content ranged between 1.88 mg/g and 3.07 mg/g in the leaves of the studied lentil varieties and specimens. The research revealed the highest value of the chlorophyll content in the flowering and bean formation phases. Our research has shown that there is a certain relationship between the chlorophyll content and photosynthetic productivity.

Influence of nutrients and plant growth regulators on growth parameters and yield of Pigeonpea (Cajanus cajan (L.) Millsp.)

Pigeonpea is the second most important pulse crop after chickpea in India. The yield of pigeonpea is very low due to indeterminate growth habit and poor source-sink relationship. Plant growth regulators are known to influence the source-sink relationship and stimulate the translocation of photo-assimilates thereby helping in effective flower formation, fruit and seed development and ultimately enhance productivity of the crops. With this background, a field experiment was conducted with pigeonpea (CO Rg 7) under irrigated condition in Tamil Nadu Agricultural University, Coimbatore. An experiment was aimed at determining the effect of various nutrients and growth-promoting hormones on the growth parameters and yield of pigeonpea (Cajanus cajan (L.) Millsp.). The Factorial Randomised Block Design was used in the field trial and was replicated three times. At the vegetative stage, the treatments included foliar sprays of growth inhibitors such as M2-Mepiquat chloride (MC) @ 500 pp, M3-Chlormequat chloride (CC) @ 500 ppm and M1- Control. At flower initiation and 15 days later, various plant growth regulators, such as T2-SA (100 ppm), T3-BR (0.1 ppm), T4-Napthyl acetic acid (40 ppm), T5-Nutrients (ZnSO4 @ 0.5 percent + H3BO3 @ 0.3 percent, T6-Mono Ammonium Phosphate @ 2 percent, and T7-TNAU Pulse Wonder @ 1 percent), T8-Nutrient consortia I (1%) and T9-Nutrient consortia II (1%), were used. Among the treatments, the combination of Chlormequat chloride and nutrient consortia treatments (M3T8&M3T9) had better performances in growth parameters and yield of pigeonpea (CO Rg 7). Foliar application of M3T8-Chlormequat chloride and Nutrient consortia I (1%) resulted significantly (P<0.05) in the highest Total dry matter production (64.85; 82.96 g plant-1), Leaf area (1629; 1873 cm-2 plant-1), Leaf area index (1.358; 1.561), Specific leaf weight (7.29; 10.34 mg cm-2) and Seed yield (1133 kg ha-1) when compared to other treatments. The present study that the application of a combined formulation of hormones and nutrients present in the nutrient consortia at the flowering and pod formation stages influenced the growth parameters and resulted in higher seed yield.

ФОТОСИНТЕТИЧНА ПРОДУКТИВНІСТЬ СОЇ СОРТУ АННУШКА ЗАЛЕЖНО ВІД ПЕРЕДПОСІВНОЇ ОБРОБКИ НАСІННЯ МЕТАБОЛІЧНО АКТИВНИМИ РЕЧОВИНАМИ

One of the priority areas for the development of Agriculture in Ukraine is the stable production of oilseeds. Soy is one of the most important and widespread legumes and oilseeds in the world. It is characterized by a high protein and oil content and high nutritional qualities. Soy seeds contain 30–45 % protein, 13–26% fat, 20–32% carbohydrates, as well as minerals, vitamins, enzymes, etc.
 Without the use of fertilizers, it is impossible to obtain a big soybean harvest. Among the main factors that determine the yield of this crop, fertilizers account for 30 %, varieties – 20 %, weather conditions and plant protection – 15 % each, effective fertility and tillage – 10 % each.
 Therefore, the study of the effect of a combination of metabolically active substances (complexes of vitamin E and ubiquinone-10; vitamin E, 4-hydroxibenzoic acid (PHBA) and methionine; vitamin E, 4-hydroxibenzoic acid (PHBA), methionine and magnesium sulfate growth regulator Vympel on assimilation processes in soybean leaves in the main phases of ontogenesis and its performance is worthy of scientific attention.
 It was observed that pre-sowing treatment of seeds with combinations of metabolically active compounds effectively affected the formation of the number of leaves during all phases of plant growth and development. Thus, when using vitamin E in combination with ubiquinone-10, the maximum number of leaves on soybean plants was formed, exceeding the control indicators at all the studied phases and indicators in the variant with a pennant in the flowering and bean formation phase.
 The use of combinations of metabolically active compounds for pre-sowing seed treatment causes certain changes in the pigment composition of soybean leaves at different phases of ontogenesis. It was found that pre-sowing treatment of soybean seeds with a combination of vitamin E + ubiquinone-10 substances allowed to achieve the maximum result, namely, to increase the content of the sum of chlorophylls A and b in soybean leaves to 25.54 mg/g of raw mass, which is 35.42 % more than the control and 16.55 % more than in the variant with Vympel. Pre-sowing treatment of soybean seeds with combinations of substances vitamin E + ubiquinone-10, vitamin E + PHBA + methionine allowed to increase the content of the sum of chlorophylls a and b in soybean leaves by 9.97 mg/g and 8.35 mg/g of raw mass and in the flowering phase. The maximum content of chlorophylls a and b was achieved during the bean formation phase.
 Pre-sowing treatment of soybean seeds with combinations of metabolically active substances vitamin E + ubiquinone-10, vitamin E + methionine + PHBA contribute to the maximum realization of photosynthetic productivity, so further study of the effect of the above substances on leguminous crops is promising.
 Pre-sowing treatment of soybean seeds with metabolically active compounds can be used as elements of technology in the cultivation of legumes.

Nutrient Supply Is Essential for Shifting Tree Peony Reflowering Ahead in Autumn and Sugar Signaling Is Involved.

The flowering time of tree peony is short and concentrated in spring, which limits the development of its industry. We previously achieved tree peony reflowering in autumn. Here, we further shifted its reflowering time ahead through proper gibberellin (GA) treatment plus nutrient supply. GA treatment alone initiated bud differentiation, but it aborted later, whereas GA plus nutrient (G + N) treatment completed the opening process 38 days before the control group. Through microstructural observation of bud differentiation and starch grains, we concluded that GA plays a triggering role in flowering induction, whereas the nutriment supply ensured the continuous developing for final opening, and both are necessary. We further determined the expression of five floral induction pathway genes and found that PsSOC1 and PsLFY probably played key integral roles in flowering induction and nutrient supply, respectively. Considering the GA signaling, PsGA2ox may be mainly involved in GA regulation, whereas PsGAI may regulate further flower formation after nutrient application. Furthermore, G + N treatment, but not GA alone, inhibited the expression of PsTPS1, a key restricting enzyme in sugar signaling, at the early stage, indicating that sugar signaling is also involved in this process; in addition, GA treatment induced high expression of PsSnRK1, a major nutrient insufficiency indicator, and the induction of PsHXK1, a rate-limiting enzyme for synthesis of sugar signaling substances, further confirmed the nutrient shortage. In short, besides GA application, exogenous nutrient supply is essential to shift tree peony reflowering ahead in autumn under current forcing culture technologies.

Comparative Transcriptome and Pigment Analyses Reveal Changes in Gene Expression Associated with Flavonol Metabolism in Yellow Camellia

The accumulation of various pigments leads to the formation of different flower colors in plants. However, the regulation mechanism of yellow flower formation and flower color differences between Camellia nitidssima C.W.Chi (CN) and its hybrids C. ‘Zhenghuangqi’ (ZHQ), C. ‘Huangxuanlv’ (HXL), and C. ‘Xinshiji’ (XSJ), remains largely unknown. Here, we showed that the content of two flavonols, quercetin-7-O-glucoside (Qu7G) and quercetin-3-O-glucoside (Qu3G), was positively correlated with the yellow degree of petals in CN and its three hybrids. Additionally, we performed a comparative transcriptomic analysis of petals of the four yellow camellia plants, which revealed 322 common upregulated and 866 common downregulated DEGs (differentially expressed genes) in the CN vs. ZHQ, CN vs. HXL, and CN vs. XSJ comparison groups. Their regulatory pathway analysis showed that flavonol biosynthesis genes (FLSs and GTs) and transcriptional regulatory genes MYBs were all expressed higher in CN than its three hybrids, which corresponded to differences in the flavonol content among the four yellow camellias. Further, two ethylene synthesis genes (ACSs, ACO) and three ethylene signaling genes (EIN2s, EIN3, ERFs) were all upregulated in the yellow petals of CN. In conclusion, the expression of flavonol-related genes and flavonols (Qu7G and Qu3G) accumulation could play a key role in the formation of yellow flowers in camellia, and the ethylene pathway might be involved in the regulation of yellow flower formation of camellias. This work describes the possible regulatory pathway of yellow camellia, thereby laying a foundation for future verification of genes linked to flower coloring and the breeding of yellow camellia.

The Pea R2R3-MYB Gene Family and Its Role in Anthocyanin Biosynthesis in Flowers.

Pea (Pisum sativum L.) is one of the most important legume crops in the world, and it has attracted great attention for its high nutritive values. Recently, the crop breeding program has been focused on the crop metabolic engineering (i.e., color, flavor, nutrition) to improve the quality of crop. As a major group of transcription factors forming the ternary MYB–bHLH–WD repeat protein (MBW) complex to regulate the anthocyanin biosynthesis pathway, members of R2R3-MYB gene family have always been the focus of research targets to improve the valuable metabolic product of crops. Until now, few report about the R2R3-MYB gene family of pea has been released. In this study, we identified 119 R2R3-MYB genes in the assembled pea genome (Version 1a), of which 111 were distributed across 14 chromosomes. Combining with the 126 R2R3-MYB protein sequences of Arabidopsis, we categorized 245 R2R3-MYB proteins into 36 subgroups according to sequence similarity and phylogenetic relationships. There was no member from subgroup 12, 15 and 29 existing in pea genome, whereas three novel subgroups were found in pea and named as N1-N3. Further analyses of conserved domains and Motifs, gene structures, and chromosomal locations showed that the typical R2 and R3 domains were present across all R2R3-MYB proteins, and Motif 1, 2, and 3 were identified in most members. Most of them had no more than two introns. Additionally, 119 pea R2R3-MYB genes did not experience large-scale duplication events. Finally, we concluded that several candidate genes may be responsible for the spatiotemporal accumulation of anthocyanins in pea petals. PsMYB116 was predominantly expressed in the dorsal petals to presumably activate the anthocyanin biosynthesis pathway, while PsMYB37 and PsMYB32 may positively regulates the anthocyanin accumulation in the lateral petals. This study not only provides a good reference to further characterize the diverse functions of R2R3-MYB genes but also helps researchers to understand the color formation of pea flowers.

Impact of paclobutrazol on gibberellin-like substances and soluble carbohydrates in pear trees grown in tropical semiarid

Given that Brazilian pear production is unable to meet the annual demand, to consider the possible expansion to non traditional growing regions, turns interesting. Even though under tropical semi-arid conditions pear trees have vigorous vegetative growth, a negative influence on flower bud differentiation and formation affects fruit yield. Our study aimed to evaluate the inhibition efficiency of paclobutrazol (PBZ) on gibberellin biosynthesis, vegetative growth, and carbohydrate production in two pear-treecultivars (‘Santa Maria’ and ‘Hosui’) grown under semi-arid conditions. To this end, two experiments were conducted, one for each pear-tree cultivar. The experimental designs consisted of randomized blocks, with factorial arrangement (5x2x4), corresponding to PBZ doses (0.0, 0.5, 1.0, 1.5, and 2.0 g per linear meter of plant canopy), PBZ application forms (soil and foliar), and evaluation dates (30, 60, 90, and 120 days after application). Both soil and foliar applications inhibited gibberellin biosynthesis in both cultivars, especially after 120 days of application. PBZ affected leaf total soluble carbohydrates and reduced sprout growth in both cultivars. Although PBZ can be potentially used in pear management, further studies are still required to determine specific management practices in tropical semi-arid zones. Highlights: Inhibition of gibberellin biosynthesis is more efficient with soil application of paclobutrazol. Soil application of paclobutrazol results in greater production of carbohydrates. There is a difference in sensitivity to the effects of paclobutrazol among pear varieties. The non-application of paclobutrazol results in late maturation of the branches, compromising floral induction.

Effects of Water-deficit Stress and Gibberellic Acid on Floral Gene Expression and Floral Determinacy in ‘Washington’ Navel Orange

Effects of water-deficit stress and foliar-applied gibberellic acid (GA3) on ‘Washington’ navel orange (Citrus sinensis) floral gene expression and inflorescence number were quantified. Trees subjected to 8 weeks of water-deficit stress [average stem water potential (SWP) −2.86 MPa] followed by 3 weeks of re-irrigation (SWP recovered to > −1.00 MPa) produced more inflorescences in week 11 than trees well-irrigated (SWP > −1.00 MPa) for the full 11 weeks (P < 0.001). After 8 weeks of water-deficit stress, bud expression of flowering locus t (FT), suppressor of overexpression of constans1 (SOC1), leafy (LFY), apetala1 (AP1), apetala2 (AP2), sepallata1 (SEP1), pistillata (PI), and agamous (AG) increased during the re-irrigation period (weeks 9 and 10), but only AP1, AP2, SEP1, PI, and AG expression increased to levels significantly greater than that of well-irrigated trees. Foliar-applied GA3 (50 mg·L−1) in weeks 2 through 8 of the water-deficit stress treatment did not reduce bud FT, SOC1, or LFY expression, but prevented the upregulation AP1, AP2, SEP1, PI, and AG expression that occurred during re-irrigation in water-deficit stressed trees not treated with GA3. Applications of GA3 to water-deficit stressed trees reduced inflorescence number 95% compared with stressed trees without GA3. Thus, GA3 inhibited citrus (Citrus sp.) floral development in response to water-deficit stress through downregulating AP1 and AP2 expression, which likely led to the failed activation of the downstream floral organ identity genes. The results reported herein suggest that bud determinacy and subsequent floral development in response to water-deficit stress in ‘Washington’ navel orange are controlled by AP1 and AP2 transcript levels, which regulate downstream floral organ identity gene activity and the effect of GA3 on citrus flower formation. The water-deficit stress floral-induction pathway provides an alternative to low-temperature induction that increases the potential for successful flowering in citrus trees grown in areas experiencing warmer, drier winters due to global climate change.

Effect of foliar-applied urea on symbiotic parameters, yield and monetary returns of irrigated chickpea

A field experiment was conducted at five locations in Punjab, India to study the effect of foliar application of urea (nitrogen) on the symbiotic parameters, growth, yield, quality, and monetary parameters of chickpea under irrigated conditions. The experiment consisted of foliar application of 2% urea at flowering stage, pod formation stage, at both the stages (flowering + pod formation), and control (no application) treatment. Application of 2% urea at flowering and pod formation stages recorded the highest number of nodules, dry weight of nodules, plant height and yield parameters. Improvement in these parameters led to significantly higher chickpea yield, by a margin of 26.0, 39.7, 14.1, 12.6 and 22.4 per cent as compared to control at Ludhiana (2017-18), Ludhiana (2018-19), Bathinda, Ballowal Saunkhri and Faridkot, respectively. On the basis of pooled mean of all the trials, foliar application of urea at both stages (flowering as well as pod formation) improved the grain yield by 19.3% over control, protein content by 12.7% and net monetary returns by 30.4% as compared to control treatment. It can be concluded that foliar application of 2% urea at flowering as well as pod formation stages should be done in chickpea under irrigated conditions for obtaining higher grain yield and net returns along with improved protein content, which can help in the fulfillment of protein requirement of the vegetarian population.

Characterization of Okra Species, Their Hybrids and Crossability Relationships among Abelmoschus Species of the Western Ghats Region

Wild relatives of okra represent a good source of variation for breeding programs, particularly for traits related to biotic and abiotic stresses and fruit quality. However, wild species remain largely unexploited for okra breeding. The cultivated okra accession Abelmoschus esculentus cv. ‘Arka Anamika’ was crossed with three wild accessions: Abelmoschus manihot, Abelmoschus ficulens and Abelmoschus moschatus. The crossability was estimated based on fruit set, seed set and germination rate. The results of cross compatibility studies revealed that the crosses are compatible only when cultivated A. esculentus is used as a female, and reciprocal crosses were not successful in any of the three wild species. Higher fruit set (87.2%) and seed germination (92%) were obtained from the crosses ‘Arka Anamika’ × Abelmoschus manihot. The interspecific F1s exhibited normal growth, flowering and fruit formation, but the hybrids were completely sterile on selfing due to abnormal meiosis. Characterization of the parents and interspecific hybrids revealed that the interspecific hybrids were generally more vigorous than the parents and displayed greater alliance towards their wild parent. The sterile F1s were further treated with 0.1% colchicine to restore fertility. The three interspecific crosses showed considerable differences in mean performance and heterosis over mid parent and better parent. The cross ‘A. Anamika’ × A. manihot displayed positive heterosis over mid parent and better parent for the yield traits, viz., fruit yield per plant, number of fruits per plant, number of primary branches per plant and plant height. The information obtained in the study on crossability relationship, phenotypic characterization and heterosis in interspecific hybrids will assist breeders in the development of prebreeding material.

Procedure for the efficient acquisition of progeny seeds from crossed potato plants grafted onto tomato.

Potato, Solanum tuberosum L. is an important crop. However, it is difficult to breed potato cultivars by applying conventional crossing methods because potato has a tetraploid genome and is vegetatively propagated. Flower formation and tuber development occur simultaneously. Many potato cultivars hardly produce any fruits after crossing and fail to produce seeds. We report an improved procedure for obtaining progeny seeds by grafting potatoes onto tomatoes. The rate of fruit formation was more than 19% when the grafted potatoes were used for the crossing experiments, whereas crossing using the ungrafted plants showed a rate of 1.1%. This result suggests that our procedure results in the easy acquisition of null-segregant progenies by crossing mutant lines. It is also expected to improve conventional potato breeding.