Morphological and physio-biochemical characterization of Brassica juncea L. Czern. & Coss. genotypes under salt stress

Abstract

Soil salinity is one of the major factors responsible for the low productivity of crop plants and has become an increasing threat for agriculture. In this context, the selection of tolerant genotype/s may be one of the remedies. Keeping this in view, the effect of NaCl (0–120 mM) stress on shoot length (SL) plant^?1, area (A) leaf^?1, leaf area index (LAI), fresh weight (FW) and dry weight (DW) plant^?1, stomatal conductance (g_s), net photosynthetic rate (P _N), total chlorophyll (Chl) content, malondialdehyde (MDA) content, sensitivity rate index (SRI), leaf- nitrogen (N), potassium (K) and sodium (Na) content, leaf-K/Na ratio, nitrate reductase (NR: EC.1.6.6.1) and ATP-sulphurylase (ATP-S: EC.2.7.7.4) activities and proline (Pro) and glycinebetaine (GB) content of ten genotypes of Brassica juncea L. was studied at 55 and 65 days after sowing (DAS). NaCl treatments decreased all the above parameters, except Pro, GB, MDA, Na and SRI at both stages. Salt stress resulted in accumulation of Pro and GB, in all genotypes. The magnitude of increase in both osmolytes (Pro and GB) was higher in genotype G₈ than the other genotypes. Salt stress increased MDA and Na content while it decreased Chl, N and K content and K/Na ratio, Chl content, NR and ATP-S activities in all genotypes. But the magnitude of increase in MDA and Na content and decrease in SL plant^?1, A leaf^?1, LAI, P _N, g_s, Chl content and NR and ATP-S activities in genotype G₈ was more than that of other genotypes. These results suggest that the salt-tolerant genotype may have better osmotic adjustment and protection from free radicals by increasing the accumulation of Pro and GB content with overproduction of N and K and higher K/Na, NR and ATP-S activities under salinity stress.     

A RFLP-based linkage map of mustard [Brassica juncea (L.) Czern. and Coss.]

 A genetic linkage map of Brassica juncea was constructed based on restriction fragment length polymorphism (RFLP) detected by anonymous cDNA markers from B. napus, using a segregating F₁-derived doubled haploid (DH) progeny from a cross between a canola-quality mustard line (J90-4317) and a high-oil-content mustard line (J90-2733). The RFLP probes consisted of 229 cDNA probes from B. napus and a B. napus tandem repeat sequence, RDA2. The map consisted of 343 marker loci arranged in 18 major linkage groups plus five small segments with two to five marker loci, covering a total map distance of 2073 cM. Twenty-four percent of the markers were dominant in nature. Sixty-two percent of the marker loci were duplicated, and the majority were involved in inter-linkage group duplications, illustrating that complex duplications and subsequent rearrangements occurred after allopolyploidy. Deviation from the Mendelian segregation ratio for a DH population was observed for 27% of the markers. Two-thirds of these markers with a skewed segregation were clustered in 6 linkage groups and two unassigned segments. The overall average marker interval of the B. juncea map reported here was 6.6 cM, which would provide a marker density satisfactory for efficient use of the map in breeding applications, such as tagging of important agronomic traits and marker-assisted selection. Received: 14 May 1996 / Accepted: 11 October 1996     

Influence of paclobutrazol on growth and development of fruit in Brassica juncea (L.) Czern and Coss

Foliar spraying of paclobutrazol(5, 10 and 20 g mL^–1) on Brassica juncea (cv. RLM 514) plants, at the green floral bud stage of the terminal inflorescence, exerted a profound effect on growth and metabolism of fruits (siliquae). Paclobutrazol caused a decrease in siliqua length but enhanced significantly siliqua width, seed size (diameter) and seed number per siliqua. Paclobutrazol increased dry matter production and also hastened the relative growth rate of the siliqua wall and seed. In paclobutrazol-treated plants the siliquae were darker green, and during active phases of growth both siliqua wall and seed exhibited higher total chlorophyll (Chl) content, decreased chl a/b ratios, greater hill reaction activity of chloroplasts and increased activities of -amylase, -amylase and invertase than controls. Paclobutrazol enhanced the levels of total soluble sugars, starch, protein and free amino acids in mature seeds. The seed oil content increased by 2 to 3 per cent with a treatment of 10 g mL^–1 pacolobutrazol.     

Genetic architecture of yield and components of yield in mustard (Brassica juncea (L.) Czern & Coss.)

Summary The relative ability of cross- and self-pollen to achieve fertilisation in Brassica was studied by making double pollinations using cross-pollen carrying a dominant seedling marker gene. With simultaneous self- and crosspollination 12–40% self-seed was set, but when cross-pollen was applied to the stigma four hours before self-pollen, only 2–4% self-seed was obtained. In two plants to which cross-pollen was applied at various time intervals after self-pollen there was a tendency for the percentage of self-seed to increase as the time interval increased. In a third plant this trend was not apparent, probably because of a greater degree of self-incompatibility. The competitive advantage of the first pollen to arrive on the stigma is discussed in relation to the strength of the self-incompatibility and the sib problem in F₁ hybrid brassicas.     

Linked epistasis for six quantitative traits in Indian mustard (Brassica juncea (L.) Czern & Coss)

Summary Gene effects, and interactions, and associations between days-to-flower initiation and maturity, number of secondary branches and siliquae per plant, and 1,000-seed weight and yield per plant were studied in a cross of Indian mustard (Brassica juncea (L.) Czern & Coss) using the parents and F₁, F₂, F₃, B₁, B₂, B₁₁, B₁₂, B₂₁, B₂₂, B_1S, B_2S, B₁F₁, B₂F₁, B_1bip, B_2bip, F₂P₁, F₂F₁, and F_2bip generations. A linked digenic model was adequate for all characters studied. According to this model, the main effects, additive and interactions between linked pairs of genes, were present in varying proportions for days-to-flower initiation and maturity and number of siliquae per plant. The contribution of linked epistatic effects, however, was much greater than that of additive effects. Dominance effects contributed significantly to the inheritance of days-to-flower initiation. Duplicate epistasis was observed for all traits except 1,000-seed weight where epistasis was of the complementary type. A complete association among the genes of similar effect (increasing or decreasing) was observed for number of secondary branches and siliquae, and yield per plant. Coupling phase linkage was observed for days-to-flower initiation whereas repulsion phase linkage was observed for daysto-maturity and 1,000-seed weight.     

C-genome chromosome substitution lines in Brassica juncea (L.) Coss

Spontaneously developed C genome substitution lines of Brassica juncea (L.) Coss were identified in the F₇ generation of an interspecific cross between B. juncea (AABB; 2n=36) and B. napus (AACC; 2n=38). These lines were meiotically stable (2n=36) and had normal male and female fertility. They were characterized by certain specific traits like bolting habit, leaf aberrations and variation for erucic acid content. Cytological evidence indicated that at least three lines has substitution for different chromosomes. The substitution stocks characterized in this study are important for their use in practical crop breeding and certain basic genetic studies.     

卡那霉素在转基因芥菜中的应用

为了找出芥菜 (Brassica juncea Coss.) 遗传转化中最佳的卡那霉素(Kan)筛选浓度, 将芥菜的子叶接种于含有不同浓度Kan的分化培养基中, 当Kan浓度达到 30 mg/L时, 外植体的分化完全受到抑制。将芥菜种子播种于含有不同浓度Kan的培养基中, 当Kan浓度达到200 mg/L时, 长出的幼苗完全白化; 利用叶片涂抹方法, 将不同浓度的Kan涂抹于田间生长的植株叶片上, 当Kan浓度达到200 mg/L时, 被处理的叶片完全变白。为了对转基因芥菜后代中外源基因的分离情况进行遗传学分析, 分别用200 mg/L的Kan处理以npt-Ⅱ基因为选择标记基因的转基因芥菜的种子和转基因芥菜后代植株的叶片, 利用χ2测验分析试验结果, 4个含有单拷贝外源基因的转基因株系后代, 对Kan的抗感分离都符合3︰1的分离规律; 而2个含有双拷贝外源基因的转基因株系, 其中一个对Kan的抗感分离符合3︰1而不符合15︰1, 另一个对Kan的抗感分离既符合3︰1也符合 15︰1, 双拷贝外源基因在转基因芥菜中的整合方式有待进一步的研究。最后, 用PCR分析证实了该方法的准确性, 因此, 利用Kan对转基因芥菜后代进行筛选是可行的。     

Isolation and characterisation of satellite DNA from Brassica juncea (L.) Czern

Nuclear DNA isolated from hypocotyls (H), proliferating callus (PC) and differentiating callus (DC) of Brassica juncea contains a satellite DNA which can be resolved in actinomycin-D/CsCl gradients. The satellite DNA undergoes changes, when an in vitro culture is raised from hypocotyl tissue and forms a higher percentage of the genome in PC and DC than in mature differentiated tissue (hypocotyl). All the three satellite DNAs are GC-rich compared to main band DNAs. Satellite DNA of H has higher Tm and GC content than that of the PC and DC satellites. A 200 bp basic repeat unit from hypocotyl nuclear DNA has been cloned and characterised.     

Mapping of QTLs for oil content and fatty acid composition in Indian mustard [Brassica juncea (L.) Czern. and Coss.]

An AFLP linkage map of Brassica juncea (L.) Czern and Coss was constructed using 88 recombinant inbred lines (RILs) from a cross between an Indian cultivar ‘Varuna’ and an accession from Poland ‘BEC-144’. The map included 91 AFLP markers organized on 19 linkage groups covering a total map distance of 1679.1 cM. A total of 14 QTLs were detected for oil content (2 QTLs), erucic acid (2 QTLs), eicosenoic acid (2 QTLs), linolenic acid (3 QTLs), linoleic acid (3 QTLs) and palmitic acid (2 QTLs). A specific genomic region on LG2 was associated with contents of three fatty acids: erucic acid, eicosenoic acid and linoleic acid. Some of the markers showed absolute linkage with the QTLs associated with the levels of linolenic acid, linoleic acid and oil content. These markers may be used for improvement of fatty acid profile of B. juncea.     

Role of Ca2+ on Growth of Brassica campestris L. and B.juncea (L.) Czern & Coss under Na+ Stress

Root and shoot growth of Brassica campestris L.and B.juncea increased significantly(P0.01) with enhanced Ca2+ treatment along with 60 mM NaCl in the root medium.The maximum fresh mass of shoot and root in B.juncea was recorded at 10 mM Ca2+ concentration.The relative growth rate of shoot of both species reached its maximum at 8 mM of Ca2+ concentration.Average rate of Ca2+ intake(Ca) was higher in B.juncea than B.campestris.In B.juncea,the average transport of Ca2+ to shoot increased by 19%,38%,119%,125% and 169% compared with the control.Furthermore specific utilization rate of Ca2+ was higher in B.juncea than B.campestris.In B.campestris it increased by 9%,32%,41% and 59% at 4,6,8,and 10 mM of calcium in comparison to 2 mM Ca2+ treatment.At 4,6,8 and 10 mM of Ca2+ application,the increase in the leaf area ratio was 10,17,23 and 30%,respectively.In the shoot and root portions of B.campestris and B.juncea,Ca2+ had a linear relationship with potassium and sulfur,whereas it was in antagonism with sodium ion.     

Regeneration of plantlets from mesophyll protoplasts of Brassica juncea (L.) Czern

Isolated mesophyll protoplasts of Brassica juncea (L.) Czern., cv. RLM 514 upon culture in suitable growth medium, regenerated cell wall, underwent cell division and formed cellular colonies. Subsequent induction of embryoid (embryogenesis) and shoot bud (organogenesis) formations in such cell masses resulted in regeneration of 186 and 42 plantlets respectively.Abbreviations NT Nagata and Takebe, 1971 - B5 Gamborg et al. 1968 - KM Kao and Michayluk, 1975 - GK₂ Schenck and Hoffmann, 1978 - MS Murashige and Skoog, 1962 - BAP 6-benzyladenine - 2, 4-D 2, 4-dichlorophenoxyacetic acid - NAA napthaleneacetic acid - GA₃ gibberellic acid     

Molecular cloning and characterization of five annexin genes from Indian mustard (Brassica juncea L. Czern and Coss)

Plant annexins constitute a multigene family having suggested roles in a variety of cellular processes including stress responses. We have isolated and characterized five different cDNAs of mustard, Brassica juncea (AnnBj1, AnnBj2, AnnBj3, AnnBj6 and AnnBj7) encoding annexin proteins using a RT-PCR/RACE-PCR based strategy. The predicted molecular masses of these annexins are ～36.0 kDa with acidic pIs. At the amino acid level, they share high sequence similarity with each other and with annexins from higher plants. Phylogenetic analysis revealed their evolutionary relationship with corresponding orthologous sequences in Arabidopsis and deduced proteins in various plant species. Expression analysis by semi-quantitative RT-PCR revealed that these genes are differentially expressed in various tissues. The expression patterns of these genes also showed regulation by various stress conditions such as exposure to signaling molecules, salinity and oxidative stress and wounding. Additionally, the in silico promoter analysis (of AnnBj1, AnnBj2 and AnnBj3) showed the presence of different cis-responsive elements that could respond to various stress conditions. These results indicate that AnnBj genes may play important roles in adaptation of plants to various environmental stresses.     

A Study on the Volatile Flavor Constituents of Sichuan Preserved Vegetable (Brassica juncea Czern et Coss.)

The volatile constituents of Sichuan Preserved vegetable (Brassica juncea) were separated by a distillation-extraction device, and 41 compounds were identified by tile GC-MS-DS, and with the retention index of GC. The samples were obtained by N2 blast adsorption with the Porapak Q as adsorbent. They were then eluted with ether and separated by the column chromatography of silica gel. The concentrate fractions obtained were again eluted with benzene and ether. It was identified that the con- centrate fractions possessed the characteristic odor of Preserved vegetable (Brassica juncea), and that the characteristic odor compounds were: 3-butenonitrile, phenyla- cetonitrile, 3-phenypropiononitrile, allyl isothiocyanate, 2-phenylethyl isothiocyanate, di- methyl trisulfide, 1-allyl-4-methoxybenzene, 1-methoxy-4-(1-propenyl)-benzene, 7-methoxybenzofuran. The result of this study may be helpful to improve the aroma quality of preserved vegetable, to develop its new varieties, and to research the aroma of food stuffs.     

Calcium supplementation modulates arsenic-induced alterations and augments arsenic accumulation in callus cultures of Indian mustard (Brassica juncea (L.) Czern.)

In the present study, the effect of arsenate (AsV) exposure either alone or in combination with calcium (Ca) was investigated in callus cultures of Brassica juncea (L.) Czern. cv. Pusa Bold grown for a period up to 24 h. The AsV?(250 μM) + Ca (10 mM) treatment resulted in a significantly higher level of As (464 μg g^?1 dry weight (DW)) than AsV without Ca (167 μg g^?1 DW) treatment at 24 h. Furthermore, AsV + Ca-treated calli had a higher percent of AsIII (24–47%) than calli subjected to AsV treatment (12–14%). Despite this, AsV + Ca-treated calli did not show any signs of hydrogen peroxide (H₂O₂) accumulation or cell death upon in vivo staining, while AsV-exposed calli had increased H₂O₂, shrinkage of cytoplasmic contents, and cell death. Thus, AsV treatment induced oxidative stress, which in turn elicited a response of antioxidant enzymes and metabolites as compared with control and AsV + Ca treatment. The positive effects of Ca supplementation were also correlated to an increase in thiolic constituents', viz., cysteine, reduced glutathione, and glutathione reductase in AsV + Ca than in AsV treatment. An analysis of selected signaling related genes, e.g., mitogen-activated protein kinases (MAPK3 and MAPK6) and jasmonate ZIM-domain (JAZ3) suggested that AsV and AsV + Ca followed variable pathways to sense and signal the As stress. In AsV-alone treatment, jasmonate signaling was seemingly activated, while MAPK3 was not involved. In contrast, AsV + Ca treatment appeared to specifically inhibit jasmonate signaling and activate MAPK3. In conclusion, Ca supplementation may hold promise for achieving increased As accumulation in plants without compromising their tolerance.     

Microspore embryogenesis in anther cultures of two Indian cultivars of Brassica juncea (L.) Czern.

Direct microspore-derived embryo formation in anther cultures of two cultivars of Brassica juncea was obtained. Preliminary culture of anthers at 35°C for 1–5 days prior to maintenance at 25°C stimulated embryogenesis. Embryogenesis was also stimulated by an initial culture at 5°C for 3 days. Analysis of squashed anthers revealed that approximately 10% of the microspores began dividing, but less than 1% developed into macroscopic embryos. All embryos transferred to embryo culture medium survived, but only 30% of these developed directly into normal plantlets. The androgenic plants were haploid (2n=18).     

Alternaria incidence in some alloplasmic lines of Indian mustard (Brassica juncea (L.) Coss.)

Summary The cytoplasmic substitution lines of Brassica juncea (L.) Coss were evaluated for their field resistance to Alternaria blight (Alternaria brassicae). The euplasmic B. juncea cv. RLM 198 had a mesothetic reaction while alloplasmic B. juncea lines with cytoplasms of B. campestris, B. chinensis, and B. japonica were highly susceptible. B. nigra cytoplasm did not have any effect on the disease reaction of the B. juncea genome. However, the alloplasmic lines with the cytoplasm of B. napus and B. carinata revealed a comparatively higher degree of resistance. The study underlined the utility of cytoplasmic manipulations in modifying the phenotypic expression of nuclear genes.     

Supplementation of Salicylic Acid and Citric Acid for Alleviation of Cadmium Toxicity to Brassica juncea

Journal of Plant Growth Regulation - The reported study investigated the interaction between salicylic acid (SA) and citric acid (CA) in cadmium (Cd)-stressed Brassica juncea plants. Seedling...