Pepper Plantlets Research Articles

Establishment of an acclimatization protocol for pepper (Piper nigrum L.) plantlets post-in vitro stage

This study was conducted with the aim of determining the factors that affect the growth and development of in vitro-derived pepper plantlets variety Vinh Linh in greenhouse. The results indicated that gradual adaptation of in vitro plantlets to ex vitro environment by placing enclosed plantlets-containing culture vessels in greenhouse for 2 weeks improved the survival and growth of pepper plantlets upon transfer to acclimatization substrate. The plantlets were required to reach the weight of 0.7-0.9 g before transplanting into nursery bags containing substrate that was red soil:cow dung:coconut husk:rice husk (5:2:2:1). Alternative application of NPK 0.2% and foliar fertilizer Nupe 0.2% every 2 weeks positively affected plant growth and the plants were ready for transplanting into the field after about 5 months. The research results establish an acclimatization protocol for pepper plantlets post-in vitro stage that helps to complete the protocol for pepper production using micropropagation method.

Growth of black pepper plantlets under different substrates and irrigation levels

Optimization of the use of water and the possibility of using residues as substrate in the black pepper production chain can yield economic and environmental benefits. The objective of this study was to evaluate the biometric and physiological traits of black pepper plantlets (Piper nigrum L.), cv. Bragantina, at different irrigation levels and soilless substrates. Plantlets were grown for 120 days on three substrates [biosolid + crushed coconut fiber (3:1, by volume); biosolid + granitic rock powder (3:1, by volume); and biosolid + crushed coconut fiber + granitic rock powder (2:1:1, by volume)] and at five irrigation levels [36 % (very low); 55 % (low); 85 % (moderate); 100 % (well-irrigated); and 126 % of the reference irrigation level (over-irrigated)]. The biometric traits evaluated increased as the irrigation levels increased, with the exception of root dry mass, which was not influenced by this factor, nor water use efficiency, which decreased as the irrigation levels increased. In general, plants grown with a mixture of the three wastes (biosolid + crushed coconut fiber + granitic rock powder) exhibited higher values for biometric variables and chlorophyll content when they were moderately, well or over-irrigated, in comparison with the other two substrates. It was possible to achieve the plantlet commercial standard using this three waste mixture and the moderate irrigation level.

Draft Genome Sequence of Bacillus velezensis 3A-25B, a Strain with Biocontrol Activity against Fungal and Oomycete Root Plant Phytopathogens, Isolated from Grassland Soil.

ABSTRACTHere, we present the draft genome of Bacillus velezensis 3A-25B, which totaled 4.01 Mb with 36 contigs, 3,948 genes, and a GC content of 46.34%. This strain, which demonstrates biocontrol activity against root rot causal phytopathogens in horticultural crops and friendly interactions in roots of pepper plantlets, was obtained from grassland soil in Zacatecas Province, Mexico.

Effects of ammonium nitrate, cesium chloride and tetraethylammonium on high-affinity potassium uptake in habanero pepper plantlets (Capsicum chinense Jacq.)

Potassium (K + ) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K + acquisition that catalyze K + uptake across a wide spectrum of external K + concentrations and mediate K + movement within the plant, as well as its release into the environment. The KUP/HAK/KT transporter family plays a key role in K + homeostasis in plant cells. The present study demonstrates that habanero pepper plantlets have a clear pattern of K + uptake when resupplemented with K + after K + starvation. Habanero pepper plantlets, re-supplemented with a solution containing low concentrations of K + after 72, 96 or 120 h of K + starvation were able to decrease the amount of K + in the solution at different time points. To study the effect of NH 4 + , we added different concentrations of NH 4 NO 3 to the medium solution and demonstrated that NH 4 + inhibited K + uptake in a dose-dependent manner. When the plantlets were subjected to K + starvation for 72 h and then resupplemented with 50 or 100 μM K + , exposure to K + channel blockers (10 mM CsCl and 20 mM TEA) decreased their K + uptake compared with the control treatment. A model demonstrating the process of K + uptake through an NH 4 + -insensitive component was proposed. Key words : Potassium, high affinity transporters, channel blockers, ammonium.

Compatibility of Piriformospora indica and Trichoderma harzianum as dual inoculants in black pepper (Piper nigrum L.)

The compatibility of two biological inoculants, Trichoderma harzianum, a mycoparasitic biological control fungus and Piriformospora indica, a root colonizing plant-growth promoting endophytic fungus was evaluated using tissue cultured black pepper plantlets. We report, for the first time, the ability of P. indica to colonize black pepper, a perennial climber. T. harzianum inhibited the growth of P. indica in an in vitro dual culture plate assay. Simultaneous inoculation with both biological inoculants of tissue cultured black pepper plantlets negatively influenced root colonization by P. indica. However, when P. indica was applied initially followed 30 days later by T. harzianum, there was increased root colonization by the root endophyte P. indica and beneficial effects were found on the growth of the black pepper plants. The present study also showed that the efficacy of inoculation of the two fungal biological agents can be increased by sequential application of P. indica at the hardening stage followed by T. harzianum during transplanting into a soil-sand mixture.

Short-term watering-distance and symmetry effects on root and shoot growth of bell pepper plantlets

► The effects of watering distance and symmetry on shoot and root development were studied. ► Initially faster shoot growth was observed with the one-side system at short distances. ► Later this changed to faster growth with the two-side system and longer, 30–40, cm watering distances. ► A steady water flow and uptake model predicts the observed trends. Drip lines were located at distances ranging from 0 to 60 cm from one or both sides of a row of pepper plantlets, and we monitored the effects on their shoot development during 76 days from transplanting to full-size first fruits, on the final root system, and on the areal water and salt distributions in the upper 15-cm soil layer. The experiment was conducted in a greenhouse with a sandy soil, and excess fresh water (1.9 L d −1 per plant) was applied via short daily irrigations. In addition, the effects of watering distance and symmetry on the potential water uptake rate were analyzed with a coupled-source–sink steady flow and uptake model. Initial faster shoot growth with the one-side system and short distances progressively changed to faster growth with the two-side system and longer watering distances, with the optimum at 30–40 cm. These temporal changes are attributed to temporal changes in the root uptake of irrigation water: small plants with small root systems benefit from the larger water supply to a smaller soil volume provided by the one-side system, whereas larger plants with greater water needs could extract more irrigation water when they developed larger, split root systems in the two-side irrigation. Balanced root systems and maximal shoot growth can be obtained by starting the irrigation with a line on each side, near the plants, and moving the lines after a short time.

Mycelium homogenates from a virulent strain of Phytophthora capsici promote a defence-related response in cell suspensions from Capsicum chinense

We analysed changes in the transcript population produced in habanero pepper (Capsicum chinense) cell suspensions by the addition of whole mycelium homogenates from a pathogenic isolate of Phytophthora capsici, to identify plant cellular processes modified by the oomycete effectors. The elicitation produced several defence-like cellular responses: alkalinisation of the medium, a two-step oxidative burst, induction of β-1,3-glucanases, and activation of mitogen-activated protein kinases. The elicitation modified the accumulation of transcripts representative of diverse metabolic pathways, including ethylene biosynthetic enzymes, MAP kinases and defence-related products, like PR proteins, but did not affect the expression of C. chinense NPR1 and WRKY orthologue genes, which are important modulators of plant defence responses. Interestingly, apart from some defence-related genes, inoculation of six-leaf-stage habanero pepper plantlets with the pathogenic isolate revealed few systemic modifications in the transcript patterns. All plantlets ultimately died, even though the in planta inoculation induced the strong accumulation of two MAPK transcripts. As few resistance-related genes were expressed in susceptible habanero pepper plantlets that died, either the extent or the timing of the defence response could be insufficient to establish a proper response against Phytophthora blight.

Improvement of In Vitro Culturing of Habanero Pepper by Inhibition of Ethylene Effects

The in vitro production of ethylene and its effects on the development of Habanero pepper (Capsicum chinense Jacq.) plantlets were evaluated using nonventilated containers (NVCs) and ventilated containers (VCs). Shoots of Habanero pepper between 0.5 and 1.0 cm of height were cultivated in Magenta culture boxes and samples of the headspace atmosphere were taken every four days during the previously established culturing time of 40 days. The presence of ethylene was detected in the NVCs and produced a negative effect on the development of plantlets. In a second phase of this work, the effect of silver nitrate (AgNO3) and cobalt chloride (CoCl2) on ethylene production was evaluated during in vitro development of Habanero pepper plantlets. Concentrations of 50, 300, and 500 μm of each ethylene inhibitor were used in the culture medium. Although cobalt chloride partially inhibited the production of ethylene during in vitro culture of this species, at low concentrations the plantlets presented some degree of vitrification and the highest concentration proved to be toxic for the plantlets. Silver nitrate added to the culture medium did not inhibit ethylene production, however, it did inhibit the effect of this hormone on the plantlets. In fact, when high concentrations of silver nitrate were used (300 μm), high amounts of ethylene were detected in the headspace of the vessels and plantlets were actually healthier.

Physiological changes and growth of micropropagated chile ancho pepper plantlets during acclimatization and post-acclimatization

Little is known about physiological changes that occur with micropropagated chile ancho pepper (Capsicum annuum L. cv. San Luis) plantlets during acclimatization. Plantlets were transferred to ex vitro conditions to study selected physiological changes and growth performance during acclimatization and post-acclimatization. The physiology of the plantlets was characterized by measuring leaf gas exchange and water status. Plant growth was determined by assessing plant height, leaf number, total leaf area, relative growth rate (RGR), and leaf, root, and stem dry matter (DM). Chile pepper plantlets became acclimatized within 6 days after transplantation. During this period, physiological adjustments occurred, which were critical for plantlet survival. After initial ex vitro transplanting, plantlets experienced water deficit [leaf wilting and reduced relative water content (RWC)], which corresponded with reduced stomatal conductance (gs) and transpiration (E), and an increase in stomatal resistance (rs). Thus, leaf stomata that developed in vitro were functional ex vitro. Because of this stomatal control, plantlets minimized transplant shock, recovered and survived. Prior to transplanting, plantlets were photomixotrophic, as indicated by low photosynthetic rates (A). During acclimatization, RWC, gs, E, and A were significantly lower two days after transplanting. However, within 6 days after transplanting, plantlets recovered and became photoautotrophic – attaining high A, gs, and E. Water use efficiency was initially low during the first days after transplanting, but increased dramatically at the end of the acclimatization period in part due to increased A. The stabilization and improvement of plantlet water status and gas exchange during acclimatization and post-acclimatization closely correlated with increased plantlet growth.

207 Mycorrhizal Enhancement of the Physiology and Growth of Micropropagated Chile Ancho Pepper (Capsicum annuum L. cv. San Luis) Plantlets during Acclimatization and Post-acclimatization

The role of mycorrhiza fungi during acclimatization and post-acclimatization of micropropagated chile ancho plantlets was characterized through physiological and plantlet development changes. Regardless of mycorrhizal colonization, the pepper plantlets had initially low photosynthetic rates and poor growth following transplanting ex vitro. During the first days of acclimatization, water deficits occurred as evidenced by drastic reductions in relative water content. Consequently, transpiration rates and stomatal conductance (gs) declined, confirming that in vitro formed stomata were functional, thus avoiding excessive leaf dehydration and plant death. Mycorrhiza had a positive effect on gas exchange as early as day 7 and 8, as indicated by increasing photosynthesis (A) and gs. Mycorrhizal plantlets had reduced levels of abscisic acid (ABA) during peak stress (6 days after transplanting ex vitro), which corresponded with subsequent increases in gs and A. During acclimatization, A increased in both non-colonized and colonized plantlets, with greater rates observed in mycorrhizal plantlets. During post-acclimatization, mycorrhiza colonized 45% of the roots of pepper plantlets and enhanced plant growth by increasing leaf area, leaf dry mass, and fruit number. Mycorrhiza also enhanced total leaf chlorophyll content, A, and nutrient uptake of pepper plantlets, particularly N, P, and K. Early mycorrhizal colonization produced important benefits, which helped ex vitro transplanted plantlets recover during acclimatization and enhance physiological performance and growth during post-acclimatization.

Chloroplast number in guard cells as ploidy indicator of in vitro-grown androgenic pepper plantlets

The number of chloroplasts per guard cell pair and the stomatal length of seventeen anther-derived plants obtained from three pepper donor genotypes were recorded. The haploid plants showed significantly fewer chloroplasts and shorter stomatal length than the diploid plants. Although both characters were positively correlated with the ploidy level, chloroplast number resulted a more reliable method compared to stomatal length to distinguish haploid from diploid in vitro-grown plantlets. The stomatal length values showed either significant variation among androgenic plants with the same ploidy or overlapping values between haploid and diploid individuals. On the contrary, the values for chloroplast number were more stable permitting discrimination of haploid from diploid plantlets regardless of their genetic background. Early ploidy estimation based on chloroplast counts of in vitro-grown plantlets may hasten pepper breeding programs utilizing anther-derived doubled haploids.