Subtropical Fruit Crops Research Articles

Ufa forestry-technical school, of the Ministry of Forestry of the Republic of Bashkortostan, Ufa, Russia

In the Republic of Bashkortostan, in the greenhouse of the year-round operation of the experimental farm of the state-run vocational training school "Ufa forestry-technical school" (Limonary in Ufa city), tropical and subtropical fruit crops have been cultivated for many years. The farm constantly monitors the agrochemical, physico-chemical, biochemical indicators of soil grounds. The agrochemical characteristics of soils during the cultivation of exotic fruit crops have been studied. For fertilizing all cultivated plants of the farm, organic and mineral macro- and micronutrient fertilizers are regularly added at regular intervals. When using fertilizers, the need for nutrient elements of crops is taken into account for successful growth and fruiting by periods of growth and agrochemical data. The study presents a comparative characteristic of soil grounds for 2016 and 2018, which shows: humus content, mobile forms of P2O5 and K2O, mineral forms of nitrogen, pH (salt). The results of agrochemical surveys allow you to adjust the dose of fertilizers for the cultivation of major crops, planting material and for the formation of the crop.

Characterization of watermelon anther and its programmed cell death-associated events during dehiscence under cold stress.

The 'neglected' thermophile fruit crop of watermelon was first used as a model crop to study the PCD associated with anther dehiscence in cold-exposed condition during anther development. Anther dehiscence ensures normal pollen release and successful fertilization at fruit-setting stages in flowering plants. However, most researches pertinent to anther dehiscence are centered on model plant and/or major field crops under optimal growth condition. Due to anther indehiscence in cold condition, crop plants of thermophile tropical or subtropical fruit crops fail to accomplish timely pollination and fertilization, resulting in a great yield loss annually. Herein, we developed an ideal model crop for studying the programmed cell death (PCD) associated with anther dehiscence under low-temperature stress using the S-shaped spiral anther in watermelon as instead. Our results revealed that, including the tapetal cell layers, both cells of the interlocular septum and the stomium were blocked in PCD associated with anther dehiscence at 15°C. Likewise, TUNEL assays visualized the evidence that low temperature at 15°C interferes with not only the PCD of tapetal cells, but also the PCD of interlocular septum and stomium. Furthermore, the expressions of genes correlated with PCD of tapetum and stomium were significantly inhibited at 15°C, suggesting that low temperature affects anther dehiscence by inhibiting PCD of sporophytic tissue-related gene expressions. The findings of the current research provide mechanistic insights into anther indehiscence leading to poor fruit-setting for thermophile fruit crop such as watermelon under adverse cold condition in flowering.

Genetic variability, heritability and genetic advance in litchi (Litchi chinensis)

Litchi (Litchi chinensis Sonn.) is one of the most important subtropical fruit crops of the world. Improvement in this crop is constrained by its narrow genetic base, which is a major bottleneck in reaching the desired objectives. Studies on the nature and extent of genetic variability are highly relevant to yield information that can be useful for genetic improvement programmes. In the present study, 22 litchi genotypes including three new varieties were assessed for the variability, heritability and genetic advance and principal component analysis on the basis of 13 quantitative fruit traits. High phenotypic and genotypic coefficients of variation were recorded for pulp weight (32.86 and 31.11%), seed weight (30.56 and 27.93%), peel thickness (25.07 and 20.21%), pulp thickness (24.79 and 22.22%) and fruit weight (22.65 and 21.17%).The heritability and genetic advance were found maximum for fruit yield/plant. High heritability coupled with high genetic advance was recorded for fruit weight, fruit length, fruit width, pulp weight, pulp thickness, seed weight, peel thickness, peel weight, seed width (y-axis) and yield/plant, indicating ample scope of improvement for these traits through selection. From PCA and variability estimates, fruit weight, pulp weight, peel weight, peel thickness, seed weight and seed size were identified as important traits for identifying high-yielding genotypes.

Climate change: impact, and mitigation strategies for tropical and subtropical fruits

Global warming and climate change is the greatest concern of mankind in the 21st century. Climate change is projected to cause an increase in temperature, variations in rainfall, and an increase in frequency of extreme events such as heat, cold waves, frost days, droughts, floods, etc. Various plant processes like vegetative growth, flowering, fruiting and fruit quality are highly vulnerable to climate changes. Two major parameters of climate changes that have far reaching implications on plants are more erratic rainfall patterns and unpredictable high temperature spells which are consequently expected to reduce crop productivity. Drought reduced fruit set and increased fruit cracking in pomegranate and litchi. An increase in atmospheric temperature and change of rainfall pattern affected the banana cultivation in some countries. In various fruit crops, moisture stress and high temperature during flowering strongly influences the pollen and ovule quality and consequently the fruit set and yield. The promotion of stigma and stamen sterility in papaya is mainly because of the higher temperature, which caused flower drops as well as sex changes in female and hermaphrodite flowers. Flower drop is quite common in mango, guava, litchi and other fruits, if low temperature prevails during flowering. Studies have clearly shown that the population abundance, geographic range and pollination activities of important pollinator species like bees, moths, and butterflies are declining considerably with changing climate. Higher temperature during fruit growth and development increased the incidence of several physiological disorders like spongy tissue and black tip in mango, cracking of fruits, granulation in citrus, etc. Pest ecology of certain crops is changing due to climate change. Fruit fly in guava, carambola, citrus, etc. is becoming alarming due to hot and humid conditions. Warm and humid conditions are also favorable for pests like beetles, bugs and other sucking pests and diseases like mildew, blight, etc. Development of new varieties with higher yield potential and resistance to multiple stresses (drought, flood, salinity) should be the key to maintain yield. Improvement in germplasm of important tropical and subtropical fruit crops for heat stress tolerance should be one of the targets of breeding programs. Location specific soil and water conservation models, protocol for organic farming, conservation horticulture, development of biotic and abiotic stress tolerance rootstocks, etc., are some of the strategies to mitigate the impact of climate change. This paper briefly discussed the impact and mitigation strategies of climate change on tropical and subtropical fruits.

Functional analysis of a homologue of the FLORICAULA/LEAFY gene in litchi (Litchi chinensis Sonn.) revealing its significance in early flowering process.

Litchi (Litchi chinensis Sonn.) is an important subtropical fruit crop with high commercial value due to its high nutritional values and favorable tastes. However, irregular bearing attributed to unstable flowering is a major ongoing problem for litchi producers. Previous studies indicate that low-temperature is a key factor in litchi floral induction. In order to reveal the genetic and molecular mechanisms underlying the reproductive process in litchi, we had analyzed the transcriptome of buds before and after low-temperature induction using RNA-seq technology. A key flower bud differentiation associated gene, a homologue of FLORICAULA/LEAFY, was identified and named LcLFY (GenBank Accession No. KF008435). The cDNA sequence of LcLFY encodes a putative protein of 388 amino acids. To gain insight into the role of LcLFY, the temporal expression level of this gene was measured by real-time RT-PCR. LcLFY was highly expressed in flower buds and its expression correlated with the floral developmental stage. Heterologous expression of LcLFY in transgenic tobacco plants induced precocious flowering. Meantime, we investigated the sub-cellular localization of LcLFY. The LcLFY-Green fluorescent protein (GFP) fusion protein was found in the nucleus. The results suggest that LcLFY plays a pivotal role as a transcription factor in controlling the transition to flowering and in the development of floral organs in litchi.

Polinizadores y polinización en frutales subtropicales: implicaciones en manejo, conservación y seguridad alimentaria

de la Pena, E., Perez, V., Alcaraz, L., Lora, J., Larranaga, N., Hormaza, I. 2018. Pollinators and pollination in subtropical fruit crops: management and implications for conservation and food-security. Ecosistemas 27(2): 91-101. Doi.: 10.7818/ECOS.1480 The commercialization and consumption of tropical fruits has grown worldwide during the last decade. This trend is expected to continue, due to the increasing world population and the greater demand for these products in western markets. As in most fruit crops, one of the main bottlenecks in production is pollination, which determines fruit-tree and pollinator management to a large extent. Pollination management is therefore a defining factor in the composition and diversity of agro-systems. Because of this, the intensive production of fruit crops in many areas of the world requires adequate management of crops to enable: (1) an optimal production of fruit crops; (2) the conservation of insect communities. This is particularly important in developing countries, where the centers of genetic diversity of these crops are generally found and pollinator diversity is often poorly known and seriously threatened by agricultural intensification. However, some of these crops have been introduced into geographic areas away from the native areas of origin, which is an agronomic challenge but, at the same time, provides an opportunity to study and test under controlled conditions new management strategies. In this work we present a brief review on pollinators and pollination in subtropical fruit crops focusing on three species of international economic relevance such as mango, avocado and cherimoya. With the knowledge acquired on these species in a Mediterranean context, we propose a road-map to develop appropriate management strategies in other fruit crops and geographical areas.

Recent development in the propagation of tropical and subtropical fruit crops by cutting

Recent development in the propagation of tropical and subtropical fruit crops by cutting

Exploitation of Potentials of Organic Fruit Production in North East India

North East Region (NER) of India comprises eight states namely Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura. Total geographical area of NER is 2.55 lakh km2, which is about 8% of India’s total area. Physiography of NER is divided into three divisions—Meghalaya plateau, northeastern hills and Brahmaputra valley. NE hills alone accounts for 65% of the total land area, Brahmaputra valley 22% and Meghalaya Plateau covers 13%. Average annual rainfall in the region is 2500mm. Less than 18% of net cropped area is under irrigation. NER enjoys suitable agro climatic condition for growing wide array of horticultural crops. With exception to mandarins and to a certain extent to banana and pineapple, majority of fruit crops in the region are largely grown in homestead gardens. The region has tremendous potential for growing all the subtropical, tropical and temperate fruit crops organically. From the Zone-wise, nutrient-wise consumption pattern of fertilizers during 2014-15 clearly depicts that in South Zone a total of 166.33, in West Zone a total of 84.64, in North Zone a total of 192.32, in East Zone a total of 161.08 while in North East Zone a total of only 82.63. NPK kg per hectare fertilizers are consumed. The major share of whatever little fertilizers consumed in the North East Zone largely goes to the plantation crops like tea, rubber as well as to the cereal crops grown in the region. The low fertilizer consumption pattern in the region clearly depicts farmers’ tendency of non using inorganic fertilizers for fruit production. This situation compelled the fruit production organically by default in the region. However, it would be a challenging task for the fruit growers of the region to produce fascinating fruit crops of the region organically not merely by default but primarily as well as substantially by practice of organic farming. State like Sikkim of the region from the beginning of the current year is already one step ahead in proclaiming to be the first state in the country to be organic. In addition, another NER state Tripura is already in limelight by proclaiming positions as Organic Pineapple Producer among the sixty Agri Export Zones of the country. Mizoram, Meghalaya and Assam states have taken initiative to produce mandarins, lemons, passion fruits and pineapples organically. Manipur Organic Mission Agency is planning organic production of mandarins, lemons and pineapples as a first step in six hill districts of the state. Arunachal Pradesh has formed state Soil Health Mission as an initial step for entry into systematic organic fruit production. With the existing diversified tropical, subtropical and temperate fruit crops in NER, exploitation of potentials of organic fruit production in the region would definitely be a giant step in making the entire NER as the Organic Hub for fruits in the country.

De novo transcriptome assembly for pericarp in Litchi chinesis Sonn. cv. Feizixiao and identification of differentially expressed genes in response to Mg Foliar Nutrient

Abstract Litchi is a subtropical fruit crop indigenous to South China. The pericarp of the variety Feizixiao does not display the overall bright red hue at harvest, i.e. “stay-green” phenomenon. This phenomenon could be solved by Mg foliar nutrient sprays. This study will attempt to discover the molecular mechanisms in litchi pericarp under Mg treatment by sequencing and de novo assembling the transcriptome. We assembled 50809 unigenes with an average length of 735.47 bp; approximately 55.11% (28005) of unigenes could be annotated using the NCBI (National Center of Biotechnology Information) non-redundant (nr) database. Five DGE libraries have been generated from litchi pericarp, and approximately 20 million filtered reads per library were generated. A total of 1226 unigenes were found to be differently expressed in the pair-wise comparisons between any two periods of Mg-treated, and genes encoding key enzymes involved in flavonoid biosynthesis, anthocyanin biosynthesis, ABA signal pathway were identified.

Modelling water use of subtropical fruit crops: the challenges

Subtropical fruit crops form an important part of the fruit industry in many countries. Many of these crops are grown in semi-arid regions or subtropical regions where rainfall is seasonal and as a result the vast majority of these perennial, evergreen orchards are under irrigation. This represents a significant irrigation requirement and with more emphasis being placed on the conservation of water and orchard profitability, it is becoming increasingly important to accurately estimate water use of these crops and schedule irrigation accordingly. The FAO-56 procedure is a simple, convenient and reproducible method for estimating water use. However, the transferability of crop coefficients between different orchards and growing regions is not always readily achieved, due largely to differences in canopy size and management practices. In addition, as subtropical crops tend to exhibit a higher degree of stomatal control over transpiration than most other agricultural crops, some measure of canopy or leaf resistance must be taken into account when using models based on atmospheric demand. The challenge is therefore to provide reliable and dynamic estimates of canopy resistance from relatively simple parameters which can be of use to irrigation consultants and farmers for determining the water requirements of these crops. The challenge remains to ensure that these dynamic estimates are realistic and readily applicable to a number of growing regions. The derivation of transpiration crop coefficients, based on canopy cover and height and a dynamic estimate of leaf resistance, provided reasonable estimates of transpiration in three orchards in contrasting climates, suggesting that this approach could prove useful in future for subtropical crops.

Functional Analysis of Abscisic Acid-Stress Ripening Transcription Factor in Prunus persica f. atropurpurea

Red-leaf peach (Prunus persica f. atropurpurea) is an important subtropical fruit crop, and an ideal species for leave color quality research because of the substantial changes that occur during development. It experiences lots of stresses during growth. To understand the mechanism of plant anti-stress, ASR [abscisic acid (ABA), stress, ripening-induced] genes, which are unique to plants, were induced under the application of ABA, stress, and ripening. In this study, we showed that in peach leaves stress could induce antioxidant enzyme activity and anthocyanin production, as well as biosynthesis gene expression, but decrease chlorophyll content. One ASR isoform identified from peach contained ABA stress- and ripening-induced proteins and a water-deficit stress-induced protein (ABA/WDS) domain, and had a high genetic relationship with other species of ASRs. ASR transcript levels were increased under abiotic and biotic stresses, and were also induced by sucrose and ABA. ASR bound the promoter of the hexose transporter, which contained four sugar boxes induced by sucrose that activated downstream gene expression. Overexpression of the PpASR gene conferred tolerance to stresses in tobacco. Transient expression of PpASR in tomato promoted fruit softening and ripening. Taken together, this study provides new evidence on the important role of ASR in cross-signaling between ABA and sucrose to regulate peach anti-stress. The findings of this study also provide new insights into the regulatory mechanism underlying fruit development.

A major subtropical fruit pest accumulates in crop fields and spills over to a wild host

Wild plant species are often considered a source of crop pests in mixed landscapes but this view rarely considers pest spillover in the opposite direction (from crop fields to natural vegetation), or spatiotemporal variability in resources between crop and wild habitats. We investigate how infestation of mango crop (Mangifera indica, Anacardiaceae) and a related wild host (marula, Sclerocarya birrea, Anacardiaceae) by a major subtropical fruit crop pest (Ceratitis cosyra, Diptera: Tephritidae) varies with distance from the boundary between crop and natural vegetation. We determined how infestation of marula is associated with proximity to mango crops at field and landscape scales over two fruiting seasons on three farms in north-eastern South Africa. This is one of few studies to date to consider pest spillover from crop fields to natural vegetation and the only one performed in a biodiverse region with relatively little habitat transformation. Over three sampling periods, C. cosyra infestation of marula always decreased with distance from mango fields. At the landscape scale, marula alongside crop fields were 30 times more likely to be infested than in distant vegetation (1.3–6km from mango), suggesting that spillover occurs from crop fields to natural vegetation. During late mango and marula fruiting, twice as many flies infested marula than mango. However, over the two months post-mango fruiting, up to 25 times more C. cosyra were trapped in mango fields than in bordering natural vegetation. Although pests spillover from crop fields into natural vegetation to use marula as an alternate host, biological control in the natural vegetation may eliminate this habitat as a pest reservoir outside the crop season. Other nearby crops may be more important than wild hosts for maintaining C. cosyra out of mango season. Landscape planning should consider proximity and arrangement of fields containing crops that host shared pests at different times of the year.

Формування інтродукційних популяцій субтропічних плодових культур у Хорольському ботанічному саду

Зазначено, що формування інтродукційних популяцій Asimina triloba (L.) Dunal, Punica granatum L., Zizyphus jujuba Mill., Ficus carica L., Amygdalus communis L., Diospyros virginiana L. у лісостеповій зоні України дає змогу створити біотичні системи субтропічних плодових культур, які характеризуються певною екологічною й генетичною структурою цих видів, де реалізуються гібридизаційні процеси.

Transcriptional changes during ovule development in two genotypes of litchi (Litchi chinensis Sonn.) with contrast in seed size.

Litchi chinensis is a subtropical fruit crop, popular for its nutritional value and taste. Fruits with small seed size and thick aril are desirable in litchi. To gain molecular insight into gene expression that leads to the reduction in the size of seed in Litchi chinensis, transcriptomes of two genetically closely related genotypes, with contrasting seed size were compared in developing ovules. The cDNA library constructed from early developmental stages of ovules (0, 6, and 14 days after anthesis) of bold- and small-seeded litchi genotypes yielded 303,778,968 high quality paired-end reads. These were de-novo assembled into 1,19,939 transcripts with an average length of 865 bp. A total of 10,186 transcripts with contrast in expression were identified in developing ovules between the small- and large- seeded genotypes. A majority of these differences were present in ovules before anthesis, thus suggesting the role of maternal factors in seed development. A number of transcripts indicative of metabolic stress, expressed at higher level in the small seeded genotype. Several differentially expressed transcripts identified in such ovules showed homology with Arabidopsis genes associated with different stages of ovule development and embryogenesis.

Functional analysis of five trypsin-like protease genes in the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae)

Insect midgut proteases catalyze the release of free amino acids from dietary proteins and are essential for insect normal development. To date, digestive proteases as potential candidates have made great progress in pest control. To clarify the function of trypsin-like protease genes in the digestive system of Bactrocera dorsalis, a serious pest of a wide range of tropical and subtropical fruit and vegetable crops, five trypsin genes (BdTry1, BdTry2, BdTry3, BdTry4 and BdTry5) were identified from transcriptome dataset, and the effects of feeding condition on their expression levels were examined subsequently. RNA interference (RNAi) was applied to further explore their function on the growth of B. dorsalis. The results showed that all the BdTrys in starving midgut expressed at a minimal level but up-regulated upon feeding (except BdTry3). Besides, RNAi by feeding dsRNAs to larvae proved to be an effective method to cause gene silencing and the mixed dsRNAs of the five BdTrys slowed larvae growth of B. dorsalis. The current data suggest that trypsin genes are actively involved in digestion process of B. dorsalis larvae and thereafter play crucial roles in their development.

Перспективи використання мигдалю звичайного (Amygdalus communis L.) у лісостеповій зоні України

Перспективи використання мигдалю звичайного (Amygdalus communis L.) у лісостеповій зоні України

Characterization of Botryosphaeriaceae species associated with diseased loquat (Eriobotrya japonica) in Spain

Loquat (Eriobotrya japonica) is an important subtropical fruit crop in Spain and other Mediterranean countries. In recent years, characteristic symptoms of branch canker and dieback have been observed in the main cultivated areas of loquat in Spain. The goal of this study was to identify and characterize the species of Botryosphaeriaceae associated with these symptoms. For this, 36 affected orchards were surveyed between 2010 and 2011 in six provinces of southeastern Spain. Eighty‐four isolates belonging to the family Botryosphaeriaceae were recovered from samples with symptoms. These isolates were characterized by means of phenotypical studies, DNA sequence analyses of the internal transcribed spacer (ITS) and part of the translation elongation factor 1‐α regions, and pathogenicity tests. Ten fungal species were identified: Diplodia malorum, Diplodia olivarum, Diplodia seriata, Diplodia pseudoseriata/Diplodia alatafructa, Diplodia sp., Dothiorella sarmentorum, Neofusicoccum mediterraneum, N. parvum, Spencermartinsia plurivora and S. viticola. In addition, Diplodia eriobotryicola and Dothiorella eriobotryae are newly described. The most frequent species isolated from cankers was D. seriata and, as far as is known, this is the first report of D. malorum, and species belonging to the complex D. pseudoseriata/D. alatafructa, in Spain. All species were pathogenic to 1‐year‐old loquat plants cv. Algerie, with Diplodia sp. and S. viticola as the most virulent.

Physiological disorders in perennial woody tropical and subtropical fruit crops: A review

The productivity as well as the quality of fruit crops is affected to a greater extent due to various physiological disorders. The extremes of environmental variables like temperature, moisture, light, aeration and nutritional imbalances result in disturbances in the plant metabolic activities leading to these disorders. While the symptoms may appear disease-like, they can usually be prevented by altering environmental conditions. In fruit crops, the deficiency of micronutrients causes many more disorders than that of macronutrients. These disorders have become widespread with diminishing use of organic manures, adoption of high density planting, use of rootstocks for dwarfing, disease and salt tolerance, unbalanced NPK fertilizer application and extension of horticulture to marginal lands. To get high quality fruit and yields, micronutrient deficiencies have to be detected before visual symptoms are expressed. This article presents a critical review on cause and characteristics of physiological disorders in important woody perennial fruit crops, viz. mango, litchi, guava, citrus, aonla, pomegranate, sapota, cashew, coconut, bael, ber and jackfruit, besides providing an insight into the gaps and researchable issues. The critical analysis of the nature, origin and causative factors of these non-pathogenic disorders will help in formulation of management strategies, reducing the loss to a significant level.

Analysis of Alternative Splicing Landscape in Pineapple (Ananas comosus)

Pineapple (Ananas comosus L. Merrill) is an important tropical and subtropical fruit crop and possesses crassulacean acid metabolism (CAM) photosynthesis. Recent release of its genome sequences makes it possible to identify genes transcribed with alternatively spliced isoforms in this plant. Mapping the assembled transcripts generated by next-generation sequencing technology and existing expressed sequence tags as well as mRNA sequences to the published pineapple genome, we identified and analyzed alternative splicing (AS) events. We identified a total of 10,348 AS events involving 13,449 assembled putative unique transcripts, which were mapped to 5146 pineapple gene models that equivalent to 29.7 % of total expressed gene models. Consistent with previous findings in other plant species, intron retention (61.9 %) remains to be the dominant type among the identified AS events. Comparative genomic analysis of genes which generated pre-mRNAs having AS revealed a total of 481 genes conserved among Oryza sativa (ssp japonica), Sorghum bicolor, Zea mays, and pineapple, with 51 of them were also conserved with Brachypodium distachyon. Gene Ontology classification revealed that the products of these genes which generate AS isoforms are involved in many biological processes with diverse molecular functions. We annotated all assembled transcripts and also associated them with predicted gene models. The annotated information of these data provides a resource for further characterizing these genes and their biological roles. The data can be accessed at Plant Alternative Splicing Database ( http://proteomics.ysu.edu/altsplice/ ).

Development of Highly Polymorphic Expressed Sequence Tags-Simple Sequence Repeat Markers and Their Application in Analysis of Genetic Diversity of Chinese Bayberry (Morella rubra)

Chinese bayberry (Morella rubra) is an economically important subtropical evergreen fruit crop native to China and other Asian countries. For facilitating cultivar discrimination and genetic diversity analysis, a total of 38 high-quality and highly polymorphic expressed sequence tags-simple sequence repeat (EST-SSR) markers, with little or no polymerase chain reaction (PCR) stutter bands, including 21 screened from those obtained previously and 17 newly developed markers, were developed. The average number of alleles (Na) per locus was 5.6, and polymorphism information content varied from 0.34 to 0.86, with a mean value of 0.57. With these markers, all 42 Chinese bayberry accessions analyzed were successfully discriminated and the phylogenetic relationship between accessions was revealed. The accessions can be separated into two groups with six subgroups. The grouping of four main cultivars in three subgroups and 12 white-fruited accessions, each with little or no anthocyanin accumulation in ripe fruit, into five subgroups suggested the preservation of broad diversity among cultivated populations. These EST-SSR markers and the findings obtained in this study can assist the discrimination of cultivars and lines and contribute to genetic and breeding studies in Chinese bayberry.