Contribution of osmotic adjustment to the dehydration tolerance of water-stressed pigeon pea (Cajanus cajan (L.) millsp.) leaves

Abstract Water-stressed pigeonpea leaves have high levels of osmotic adjustment at low leaf water potentials. The possible contribution of this adjustment of dehydration tolerance of leaves was examined in plants grown in a controlled environment. Osmotic adjustment was varied by withholding water from plants growing in differing amounts of soil, which resulted in different rates of decline of leaf water potential. The level of osmotic adjustment was inversely related to leaf water potential in all treatments. In addition, at any particular water potential, plants that had experienced a rapid development of stress exhibited less osmotic adjustment than plants that experienced a slower development of stress. Leaves with different levels of osmotic adjustment died at water potentials between –3.4 and –6.3 MPa, but all leaves died at a similar relative water content (32%). Consequently, leaves died when relative water content reached a lethal value, rather than when a lethal leaf water potential was reached. Osmotic adjustment delayed the time and lowered the leaf water potential when the lethal relative water content occurred, because it helped maintain higher relative water contents at low leaf water potentials. The consequences of osmotic adjustment for leaf survival in water-stressed pigeonpea are discussed.     

Genotype-Dependent morphogenetic potentiality of various explants of a food legume,the pigeon pea (Cajanus cajan L.)

Summary The morphogenetic response of various explants of seven different cultivars of a food legume, the pigeon pea (Cajanus cajan L.), has been studied. The stimulation and elongation of shoot buds into shoots derived from the mature embryo axis and intact seed on Murashige and Skoog’s medium supplemented with 2.32µM kinetin and 22.2µM benzyladenine was found to be optimum in Murashige and Skoog’s medium supplemented with 0.46µM kinetin, 0.53µM naphthalene acetic acid, and 0.29µM gibberellic acid. Even though the response of these two explants for formation of shoot buds in all the genotypes is 30–100% depending on media composition, subsequent growth and elongation of these shoot buds into plants is genotype dependent and is restricted to two genotypes. Cotyledon and epicotyl explants of pigeon pea cultivars on the other hand differentiated directly into four to eight and two to four shoots, respectively, depending on the media composition and genotype. In vitro rhizogenesis of regenerated shoots was 80% and the survival of these plantlets in the field was 70–80%. NCL Communication no.: 5667.     

Plant regeneration via somatic embryogenesis in pigeonpea (Cajanus cajan L. Millsp)

Efficient plant regeneration via somatic embryogenesis has been developed in pigeonpea. Cotyledon and leaf explants from 10-day-old seedlings produced embryogenic callus and somatic embryos when cultured on Murashige and Skoog (MS) medium supplemented with 10 μm thidiazuron (TDZ). Subsequent withdrawal of TDZ from the induction medium resulted in the maturation and growth of the embryos into plantlets on MS basal medium. The rooted plantlets were transferred and acclimatized on vermiculite where they showed normal morphological characters. Received: 23 December 1996 / Revision received: 22 July 1997 / Accepted: 2 August 1997     

Phosphorus absorption and utilization efficiency of pigeon pea (Cajanus cajan (L) Millsp.) in relation to dry matter production and dinitrogen fixation

The effect of P supply on absorption and utilization efficiency of P in relation to dry matter production and dinitrogen fixation was examined in 8 pigeon pea cultivars with different growth duration and a soybean cultivar under field conditions. In all the pigeon pea cultivars, the maximum whole plant dry weight was obtained in a P-deficient soil at 100 kg P ha⁻¹ application. The short duration cultivars had smaller whole plant dry weights at low P rates (5 and 25 kg P ha⁻¹) and poor response to P application compared with the medium and long duration cultivars. Increasing the P application rate significantly increased dinitrogen fixation in all the cultivars. At the low P rates, the total nodule activity (TNA) was lower in the short than in the medium and the long duration cultivars. However, at 200 kg P ha⁻¹ application, dinitrogen fixation did not vary among these cultivars except for one short duration cultivar whichregistered very low values. Dry matter production and dinitrogen fixation are strongly controlled by P absorption ability rather than P utilization efficiency. The low absorption ability of the short duration cultivars is mainly due to poor root development. The high P concentrations in the nodules of all the cultivars suggest that nodules have advantage over host plant interms of P distribution under P deficient conditions. Our results suggest that P plays an important role in dinitrogen fixation through an effective translocation of P to the leaf. Thus when P supply is limited, efficient cultivars obtained reasonably high yield through an effective translocation of the absorbed P to the leaf.     

木豆毛状根的诱导及其培养条件的研究

利用发根农杆菌LBA9402对木豆叶片直接进行诱导产生毛状根。本实验研究出诱导木豆毛状根的最佳条件是,以木豆叶片为外植体,于1/2MS固体培养基上预培养2~4 d,菌液浓度OD₆₀₀=0.6~0.8,浸染20 min,共培养3 d,诱导率为60.00%。在分子水平用PCR检测表明,发根农杆菌9402Ri质粒上的T-DNA成功整合进木豆毛状根的基因组中。     

微波辅助提取木豆根中染料木素工艺

以木豆根为原料,利用微波辅助提取技术进行提取,在单因素实验的基础上对提取条件进行了考察,根据BBD(Box-Behnken design)实验设计原理,采用3因素3水平的响应面分析法,以木豆根中主要异黄酮染料木素(genistein)为指标,对提取过程进行优化,得到最佳工艺参数为：提取温度为68℃,固液比为32∶1 mL·g^-1,乙醇浓度为78%,提取功率700 W,提取时间15 min。在最佳提取条件下染料木素的提取率可达到0.465±0.032 mg·g^-1。本研究对于微波提取技术的应用及木豆根的开发和利用都具有显著的意义。     

Competition for phosphorus among plant parts in early and medium-duration cultivars of pigeon pea (Cajanus cajan L.)

Differences in absorption and distribution of phosphorus (P) between early and medium-duration cultivars of pigeon pea grown on nutrient solution at two P concentrations were investigated. Low-P treatment (0.03 ppm) significantly reduced shoot weight, root length and root surface area in both cultivars compared to the control (1.0 ppm), but the reduction was more pronounced in the early than the medium-duration cultivar. Dry-matter accumulation in shoots was slightly higher in the medium-duration than in the early cultivar.³²P-labelled P in the whole plant, P uptake rate and P-absorption ability were higher in the medium than in the early cultivar. At the low-P, however, no differences in these parameters were observed for control plants. In shoots,³²P-labelled P tended to accumulate in the stem of the early cultivar whereas more P was distributed to the leaves and petioles in the medium cultivar. The results suggest that when P supply is limited, medium-duration cultivars accumulate more dry matter through high efficiency of P absorption and distribution P to leaves and petioles.     

In vitro regeneration through organogenesis and somatic embryogenesis in pigeon pea [Cajanus cajan (L.) Millsp.] cv. JKR105

In vitro regeneration of pigeon pea through organogenesis and somatic embryogenesis was demonstrated with pigeon pea cv. JKR105. Embryonic axes explants of pigeon pea showed greater regeneration of shoot buds on 2.5 mg L⁻¹ 6-benzylaminopurine (BAP) in the medium, followed by further elongation at lower concentrations. Rooting of shoots was observed on half-strength Murashige and Skoog (MS) medium with 2 % sucrose and 0.5 mg L⁻¹ 3-indolebutyric acid (IBA). On the other hand, the regeneration of globular embryos from cotyledon explant was faster and greater with thidiazuron (TDZ) than BAP with sucrose as carbohydrate source. These globular embryos were maturated on MS medium with abscisic acid (ABA) and finally germinated on half-strength MS medium at lower concentrations of BAP. Comparison of regeneration pathways in pigeon pea cv. JKR105 showed that the turnover of successful establishment of plants achieved through organogenesis was more compared to somatic embryogenesis, despite the production of more embryos than shoot buds.     

Improved growth of Cajanus cajan (L.) Millsp. in an unsterile tropical soil by three mycorrhizal fungi

Under glasshouse conditions Cajanus cajan plants grown in a dark red latosol were fertilized with soluble simple superphosphate and hardly soluble rock phosphate and inoculated with three VA mycorrhizal fungi (M₁, Gigaspora margarita; M₂, Scutellospora verrucosa; M₃, Acaulospora rehmii) from the Cerrado ecosystem, Brazil. Only with rock phosphate plant growth was significantly increased by all fungi. Enhanced P uptake corresponded with higher yields and proved to be a characteristic of the VA myccorhizae. A definite relationship between infection intensity and efficiency of VA mycorrhizae was not detected. Spore production was generally more pronounced in the treatment with rock phosphate, especially with M₁ and M₂. Nodulation of Cajanus cajan was greatly improved by all fungi in the treatment with rock phosphate. It is suggested that the increased plant development and nodulation was due to improved uptake of P by mycorrhiza.     

Evaluation of Cajanus cajan (pigeon pea) for phytoremediation of landfill leachate containing chromium and lead

Landfill leachates containing heavy metals are important contaminants and a matter of great concern due to the effect that they might have on ecosystems. We evaluated the use of Cajanus cajan to remove chromium and lead from landfill leachates. Eight-week-old plants were submitted to varied tests to select the experimental conditions. Water assays with a solution (pH 6) containing leachate (25% v/v) were selected; the metals were added as potassium dichromate and lead (II) nitrate salts. Soil matrices that contained leachate (30% v/v) up to field capacity were used. For both water and soil assays, the metal concentrations were 10 mg kg^?1. C. cajan proved able to remove 49% of chromium and 36% of lead, both from dilute leachate. The plants also removed 34.7% of chromium from irrigated soil, but were unable to decrease the lead content. Removal of nitrogen from landfill leachate was also tested, resulting in elimination of 85% of ammonia and 70% of combined nitrite/nitrate species. The results indicate that C. cajan might be an effective candidate for the rhizofiltration of leachates containing chromium and lead, and nitrogen in large concentrations.     

Characterization of Kenyan Isolates of Fusarium udum from Pigeonpea [Cajanus cajan (L.) Millsp.] by Cultural Characteristics, Aggressiveness and AFLP Analysis

Isolates of Fusarium udum from pigeonpea (Cajanus cajan) plants with wilt symptoms were collected from various districts in Kenya and were characterized using cultural characteristics, aggressiveness and amplified fragment length polymorphism (AFLP). The 56 isolates of F. udum showed a high level of variability in aerial mycelia growth, pigmentation and radial mycelia growth (colony diameter) on potato dextrose agar. The aggressiveness of 17 isolates of F. udum on seven pigeonpea varieties varied and five aggressive groups were observed in the present study. There were no relationships among cultural characteristics and aggressiveness. AFLP analysis of the 56 isolates was tested for genetic variability using seven primer combinations. A total of 326 fragments was generated of which 121 were polymorphic. Ten AFLP groups were identified among the Kenyan isolates and, although they were not genetically distinct, six AFLP subgroups were genetically distinct. AFLP had no relationship with cultural characteristics, aggressiveness and geographical origin of the isolates. This is the first report on the study of genetic variability of F. udum using DNA analysis.     

Short Communication: Immobilization of urease from pigeonpea (Cajanus cajan L.) on flannel cloth using polyethyleneimine

Urease of pigeonpea has been immobilized on polyethyleneimine-activated cotton cloth followed by cross-linking with dimethyl suberimidate. Optimum immobilization (56%) was obtained at a protein loading of 1.2mg/5×5cm2 cloth piece. The immobilized enzyme stored in 0.1M Tris/acetate buffer, pH6.5, at 4°C had a t1/2 of 70 days. There was practically no leaching of the enzyme from the immobilization matrix in 15 days. The immobilized enzyme was used 7 times at an interval of 24h between each use with 75% residual activity at the end of the period. Blood urea analysis was carried out with immobilized urease for some clinical samples.     

Inheritance of dwarfness in pigeon pea (Cajanus cajan (L.) millsp.)

Summary A mutant pigeon pea, showing dwarf and bushy growth, very late maturity, poor yield and abnormal flowers was isolated from the tall variety, Brazil P/2. It is proposed that the mutant be called dwarf.A single recessive gene appears to be responsible for dwarfness and seems to have pleiotropic effect on maturation. The symbol proposed for the dwarfness gene is d.

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Zusammenfassung Aus einer hochwüchsigen Straucherbse (Cajanus cajan (L.) Millsp.) der Sorte Brazil P/2 wurde eine Mutante mit verzwergtem und buschigem Wuchstyp, sehr später Reife, geringer Ertragsfähigkeit und abweichender Blütenform isoliert, für die der Name dwarf vorgeschlagen wird.Nur ein rezessives Gen scheint für den Zwergwuchs verantwortlich zu sein, das einen pleiotropen Effekt auf die Reife ausübt. Für dieses Gen wird das Symbol d vorgeschlagen.

     

Progress of tissue culture and genetic transformation research in pigeon pea [Cajanus cajan (L.) Millsp.]

Pigeon pea [Cajanus cajan (L.) Millsp.] (Family: Fabaceae) is an important legume crop cultivated across 50 countries in Asia, Africa, and the Americas; and ranks fifth in area among pulses after soybean, common bean, peanut, and chickpea. It is consumed as a major source of protein (21%) to the human population in many developing countries. In India, it is the second important food legume contributing to 80% of the global production. Several biotic and abiotic stresses are posing a big threat to its production and productivity. Attempts to address these problems through conventional breeding methods have met with partial success. This paper reviews the chronological progress made in tissue culture through organogenesis and somatic embryogenesis, including the influence of factors such as genotypes, explant sources, and culture media including the supplementation of plant growth regulators. Comprehensive lists of morphogenetic pathways involved in in vitro regeneration through organogenesis and somatic embryogenesis using different explant tissues of diverse pigeon pea genotypes are presented. Similarly, the establishment of protocols for the production of transgenics via particle bombardment and Agrobacterium-mediated transformation using different explant tissues, Agrobacterium strains, Ti plasmids, and plant selectable markers, as well as their interactions on transformation efficiency have been discussed. Future research thrusts on the use of different promoters and stacking of genes for various biotic and abiotic stresses in pigeon pea are suggested.     

Characterization of five fungal endophytes producing Cajaninstilbene acid isolated from pigeon pea [Cajanus cajan (L.) Millsp

Five fungal endophytes (K4, K5, K6, K9, K14) producing Cajaninstilbene acid (CSA, 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid) were isolated from the roots of pigeon pea [Cajanus cajan (L.) Millsp.]. CSA is responsible for the prominent pharmacological activities in pigeon pea. The amount of CSA in culture solution varied among the five fungal endophytes. K4 produced the highest levels of CSA (1037.13 μg/L) among the endophytes tested after incubation for five days. Both morphological characteristics and molecular methods were used for species identification of fungal endophytes. The five endophytic isolates were characterized by analyzing the internal transcribed spacer (ITS) rRNA and β-tubulin genes. The K4, K5, K9 and K14 strains isolated from pigeon pea roots were found to be closely related to the species Fusarium oxysporum. K6 was identified as Neonectria macrodidym. The present study is the first report on the isolation and identification of fungal endophytes producing CSA in pigeon pea. The study also provides a scientific base for large scale production of CSA.     

碳源、生长素及诱导子对木豆不定根生长和次生代谢产物合成的影响

以1/2MS为基本培养基,研究了蔗糖、IBA、茉莉酸甲酯（MJ）及水杨酸（SA）对木豆不定根生物量和次生代谢产物合成的影响。研究结果表明,蔗糖浓度对木豆不定根的生物量和次生代谢产物合成有显著影响,蔗糖浓度为30 g·L^-1时,木豆不定根的生物量和次生代谢产物的含量均达到最大值。低浓度的IBA有利于木豆不定根的生长和次生代谢产物的积累,高浓度的IBA表现出抑制作用。IBA浓度为0.1 mg·L^-1时,生物量、染料木素及芹菜素含量均为最大值,分别为对照组的1.1、1.1和2.8倍。在0~200 μmol·L^-1浓度范围内,MJ对不定根的生长几乎无影响（P>0.05）,但对次生代谢产物的合成有重要影响。MJ浓度为100 μmol·L^-1时,染料木素和芹菜素的含量均达到最大值,分别为对照组的1.9和2.1倍。SA抑制木豆不定根的生长和染料木素的合成,但对芹菜素的合成有一定促进作用,SA浓度为100 μmol·L^-1时,芹菜素的含量最高,为对照组的1.5倍。木豆不定根的悬浮培养是获得次生代谢产物的一条有效途径,为大规模生产染料木素和芹菜素提供了很好的思路。     

Enhanced extraction genistein from pigeon pea [Cajanus cajan (L.) Millsp.] roots with the biotransformation of immobilized edible Aspergillus oryzae and Monacus anka and antioxidant activity evaluation

A new method of enhanced extraction genistein from pigeon pea [Cajanus cajan (L.) Millsp.] roots with the biotransformation of immobilized edible Aspergillus oryzae and Monacus anka, was investigated. It showed that immobilized Aspergillus oryzae and Monacus anka on sodium alginate effectively supported the highest genistein extraction yield by screening microorganism tests. After biotransformation process with immobilized Aspergillus oryzae and Monacus anka under 30 °C, pH 6.0, 2 days, liquid-solid ratio 12: 1 (mL/g), the extraction yield of genistein reached 1.877 mg/g, which was 2.65-fold to that of normal extraction yield. Moreover, IC₅₀ values of the extracts measured by DPPH-radical scavenging test and β-Carotene-linoleic acid bleaching test were 0.737 mg/mL and 0.173 mg/mL (control sample 1.117 mg/mL and 0.216 mg/mL), respectively. SOD (Super Oxygen Dehydrogenises) activity of the extracts treated with immobilized microorganism which was stronger than that of the untreated pigon pea roots (1.44 U/mg) at the concentration of protein (0.9375 μg/mL) was 1.83 U/mg. The developed method could be an alternative method for the enhanced extraction of genistein from plants and could be potentially applied in the food industry