Jong-Goo Kang

Interactions between temperature and fertilizer concentration affect growth of subirrigated petunias

To evaluate effects of fertilizer concentration and temperature on growth of petunia (Petunia × hybrida Hort. Vilm-Andr.), we grew petunias under three different day/night temperature regimes (35/27°C, 25/17°C, and 15/7°C) and with five different concentrations of fertilizers [electrical conductivity (EC) of 0.15, 1.0, 2.0, 3.0, and 4.0 dS m−1]. There was an interactive effect of temperature and fertilizer EC on the growth of the petunias. Optimal fertilizer EC decreased as temperature increased. Growth was better correlated with the EC of the growing medium than with the EC of the fertilizer solution. Irrespective of growing temperature, plant growth was best in treatments with a final growing medium EC of 3–4 dS m−1. The time to flowering was decreased, but flowers senesced more rapidly at higher temperature. Flower diameter decreased with increasing temperature. At the highest temperature (35/27°C), flower diameter also decreased with increasing EC of the fertilizer solution. The EC of the growing medium increased with increasing EC of the fertilizer solution and with increasing temperature. Effects on shoot nutrient concentrations were inconsistent among the three temperature treatments. At 25/17°C, a fertilizer EC of 2 dS m−1 resulted in the highest shoot N concentrations, while shoot N was not affected by fertilizer EC at 35/27°C or 15/7°C. Shoot P concentration increased with increasing fertilizer EC at a temperature of 15/7°C, but not at higher temperatures. These results indicate that fertilization guidelines for greenhouse growers should be based on maintaining the EC of the growing medium within an optimal range, instead of the more traditional recommendations based on the concentration of the fertilizer solution.

Identification and expression analysis of glucosinolate biosynthetic genes and estimation of glucosinolate contents in edible organs of Brassica oleracea subspecies.

Glucosinolates are anti-carcinogenic, anti-oxidative biochemical compounds that defend plants from insect and microbial attack. Glucosinolates are abundant in all cruciferous crops, including all vegetable and oilseed Brassica species. Here, we studied the expression of glucosinolate biosynthesis genes and determined glucosinolate contents in the edible organs of a total of 12 genotypes of Brassica oleracea: three genotypes each from cabbage, kale, kohlrabi and cauliflower subspecies. Among the 81 genes analyzed by RT-PCR, 19 are transcription factor-related, two different sets of 25 genes are involved in aliphatic and indolic biosynthesis pathways and the rest are breakdown-related. The expression of glucosinolate-related genes in the stems of kohlrabi was remarkably different compared to leaves of cabbage and kale and florets of cauliflower as only eight genes out of 81 were expressed in the stem tissues of kohlrabi. In the stem tissue of kohlrabi, only one aliphatic transcription factor-related gene, Bol036286 (MYB28) and one indolic transcription factor-related gene, Bol030761 (MYB51), were expressed. The results indicated the expression of all genes is not essential for glucosinolate biosynthesis. Using HPLC analysis, a total of 16 different types of glucosinolates were identified in four subspecies, nine of them were aliphatic, four of them were indolic and one was aromatic. Cauliflower florets measured the highest number of 14 glucosinolates. Among the aliphatic glucosinolates, only gluconapin was found in the florets of cauliflower. Glucoiberverin and glucobrassicanapin contents were the highest in the stems of kohlrabi. The indolic methoxyglucobrassicin and aromatic gluconasturtiin accounted for the highest content in the florets of cauliflower. A further detailed investigation and analyses is required to discern the precise roles of each of the genes for aliphatic and indolic glucosinolate biosynthesis in the edible organs.

Fertilizer Concentration and Irrigation Method Affect Growth and Fruiting of Ornamental Pepper

Abstract To evaluate the effects of fertilizer concentration and irrigation method on growth of ornamental pepper (Capsicum annuum L. “Treasures Red”), a water-soluble fertilizer solution containing 0, 100, 200, 300, or 400 mg L−1 nitrogen (N) was applied, using subirrigation and hand-watering. Fertilizer concentrations of 200–400 mg L−1 N resulted in an electrical conductivity (EC) gradient from the bottom (lowest EC) to the top (highest EC) of the growing medium in subirrigated, but not in hand-watered pots. The EC in the bottom layer of the medium was affected by irrigation method only at a fertilizer concentration of 400 mg L−1 N. The pH of the growing medium decreased with increasing fertilizer concentration. Shoot dry mass was highest at 200 mg L−1 N in both irrigation treatments and was consistently higher with hand-watering than with subirrigation. Leaf area also was highest at 200 mg L−1 N, but was not affected by irrigation method. In contrast, plant height was greater with subirrigation than with hand-watering, and also peaked at 200 mg L−1 N. Hand-watering increased stem diameter compared to subirrigation and was maximal with 200–400 mg L−1 N. Chlorophyll content of the leaves was much lower at 0 than at 100–400 mg L−1 N, and not affected by irrigation method. Fruit fresh mass was higher with hand-watering than with subirrigation, but shoot dry mass was not affected by irrigation method. Fruiting was poor at 0 mg L−1 N, but did not vary much among fertilizer concentrations ranging from 100–400 mg L−1 N. Subirrigation resulted in earlier flowering and fruit ripening than hand-watering, suggesting that the production period may be a few days shorter with subirrigation. Although N, iron (Fe), and molybdenum (Mo) all increased with increasing fertilizer concentrations, N most likely limited growth at low fertilizer concentrations. In contrast to previous research, these results do not indicate that subirrigated plants should be fertilized with lower concentrations than hand-watered plants.

Genome-Wide Identification and Characterization of bZIP Transcription Factors in Brassica oleracea under Cold Stress

Cabbages (Brassica oleracea L.) are an important vegetable crop around world, and cold temperature is among the most significant abiotic stresses causing agricultural losses, especially in cabbage crops. Plant bZIP transcription factors play diverse roles in biotic/abiotic stress responses. In this study, 119 putative BolbZIP transcription factors were identified using amino acid sequences from several bZIP domain consensus sequences. The BolbZIP members were classified into 63 categories based on amino acid sequence similarity and were also compared with BrbZIP and AtbZIP transcription factors. Based on this BolbZIP identification and classification, cold stress-responsive BolbZIP genes were screened in inbred lines, BN106 and BN107, using RNA sequencing data and qRT-PCR. The expression level of the 3 genes, Bol008071, Bol033132, and Bol042729, was significantly increased in BN107 under cold conditions and was unchanged in BN106. The upregulation of these genes in BN107, a cold-susceptible inbred line, suggests that they might be significant components in the cold response. Among three identified genes, Bol033132 has 97% sequence similarity to Bra020735, which was identified in a screen for cold-related genes in B. rapa and a protein containing N-rich regions in LCRs. The results obtained in this study provide valuable information for understanding the potential function of BolbZIP transcription factors in cold stress responses.

Characterization and stress-induced expression analysis of Alfin-like transcription factors in Brassica rapa

AbstractThe Alfin-like (AL) transcription factors (TFs) family is involved in many developmental processes, including the growth and development of roots, root hair elongation, meristem development, etc. However, stress resistance-related function and the regulatory mechanism of these TFs have yet to be elucidated. This study identified 15 Brassica rapa AL (BrAL) TFs from BRAD database, analyzed the sequences and profiled their expression first time in response to Fusarium oxysporum f. sp. conglutinans and Pectobacterium carotovorum subsp. carotovorum in fection, cold, salt and drought stresses in B. rapa. Structural and phylogenetic analyses of 15 BrAL TFs revealed four distinct groups (groups I–IV) with AL TFs of Arabidopsis thaliana. In the expression analyses, ten BrAL TFs showed responsive expression after F. oxysporum f. sp. conglutinans infection, while all BrAL TFs showed responses under cold, salt and drought stresses in B. rapa. Interestingly, ten BrAL TFs showed responses to both biotic and abiotic stress factors tested here. The differentially expressed BrAL TFs thus represent potential resources for molecular breeding of Brassica crops resistant against abiotic and biotic stresses. Our findings will also help to elucidate the complex regulatory mechanism of AL TFs in stress resistance and provide a foundation for further functional genomics studies and applications.

Exploration and Exploitation of Novel SSR Markers for Candidate Transcription Factor Genes in Lilium Species

Lilies (Lilium sp.) are commercially important horticultural crops widely cultivated for their flowers and bulbs. Here, we conducted large-scale data mining of the lily transcriptome to develop transcription factor (TF)-associated microsatellite markers (TFSSRs). Among 216,768 unigenes extracted from our sequence data, 6966 unigenes harbored simple sequence repeats (SSRs). Seventy-one SSRs were associated with TF genes, and these were used to design primers and validate their potential as markers. These 71 SSRs were accomplished with 31 transcription factor families; including bHLH, MYB, C2H2, ERF, C3H, NAC, bZIP, and so on. Fourteen highly polymorphic SSRs were selected based on Polymorphic Information Content (PIC) values and used to study genetic diversity and population structure in lily accessions. Higher genetic diversity was observed in Longiflorum compared to Oriental and Asiatic populations. Lily accessions were divided into three sub-populations based in our structure analysis, and an un-rooted neighbor-joining tree effectively separated the accessions according to Asiatic, Oriental, and Longiflorum subgroups. Finally, we showed that 46 of the SSR-associated genes were differentially expressed in response to Botrytis elliptica infection. Thus, our newly developed TFSSR markers represent a powerful tool for large-scale genotyping, high-density and comparative mapping, marker-aided backcrossing, and molecular diversity analysis of Lilium sp.

Increased Fertilizer Levels Do Not Prevent Abscisic Acid–Induced Chlorosis in Pansy

Abscisic acid (ABA) is a plant hormone involved in regulating stomatal responses to environmental stress. By inducing stomatal closure, applications of exogenous ABA can reduce plant water use and delay the onset of drought stress when plants are not watered. However, ABA can also cause unwanted side effects, including chlorosis. Pansy (Viola ·wittrockiana) has been shown to be particularly susceptible to ABA-induced chlorosis. The objective of this study was to determine if fertilization rate affects the severity of ABA-induced chlorosis in this species. ‘Delta PremiumPure Yellow’ pansy seedlings were fertilizedwith controlled-release fertilizer incorporated at rates from 0 to 8 g L of substrate. When plants had reached a salable size, half the plants were sprayed with a solution containing 1 g L ABA, whereas the other plants were sprayed with water. Leaf chlorophyll content was monitored for 2 weeks following ABA application. Leaf chlorophyll content increased greatly as fertilizer rate increased from 0 to 2 g L, with little increase in leaf chlorophyll at even higher fertilizer rates. ABA induced chlorosis, irrespective of the fertilizer rate. Plant dry weight was lowest when no controlledrelease fertilizer was incorporated, but similar in all fertilized treatments. ABA treatment reduced shoot dry weight by 24%, regardless of fertilization rate. This may be due to ABA-induced stomatal closure, which limits carbon dioxide (CO2) diffusion into the leaves. We conclude that ABA sprays induce chlorosis, regardless of which fertilizer rate is used. However, because leaf chlorophyll concentration increases with increasing fertilizer rates, higher fertilizer rates can mask ABAinduced chlorosis.