A vigorous mutant sugarcane (Saccharum sp.) clone Co 527

Summary A vigorous fast growing mutant which ends vegetative growth sixty days earlier than the parent variety Co 527 was isolated from gamma irradiated vegetative buds. The mutant initially segregated but stabilized in the vM₄ generation. Its growth rate was almost fifty per cent higher than Co 527 beginning in the early stages of growth. It produced a significantly higher early shoot population which enabled it to yield a higher number of millable canes at maturity. Economic characters like sucrose content and juice purity remained unaffected. This mutant had a chromosomal basis in that the number was 2 to 3 lower than in the parent variety.Research carried out under the FAO/IAEA Co-ordinated Research Programme on the Improvement of Vegetatively Propagated Plants and Tree Crops through Induced mutations (Research Contract No. 1680)     

Selection of callus cultures of sugarcane (Saccharum sp.) tolerant to NaCl and their response to salt stress

Stable callus cultures tolerant to NaCl (68 mM) were developed from salt-sensitive sugarcane cultivar CP65-357 by in vitro selection process. The accumulation of both inorganic (Na⁺, Cl⁻ and K⁺) and organic (proline and soluble sugars) solutes was determined in selected and non-selected calli after a NaCl shock in order to evaluate their implication in in vitro salt tolerance of the selected lines. Both salt-tolerant and non-selected calli showed similar relative fresh weight growth in the absence of NaCl. No growth reduction was observed in salt-tolerant calli while a significant reduction about 32% was observed in nonselected ones when both were cultivated on 68 mM NaCl. Accumulation of Na⁺ was similar in both salt-tolerant and non-selected calli in the presence of NaCl. Accumulation of Cl⁻ was lower in NaCl-tolerant than in non-selected calli while proline and soluble sugars were more accumulated in salt-tolerant than in non-selected calli when both were exposed to salt. K⁺ level decreased more severely in non-selected calli than in NaCl-tolerant ones after NaCl shock. The results indicated that K⁺ and Cl⁻ may play a key role in in vitro salt-tolerance in sugarcance cell lines obtained by in vitro selection and that organic solutes could contribute mainly to counteract the negative water potential of the outside medium.     

Micropropagation of sugarcane (Saccharum spp.)

A method for callus induction, adventitious bud regeneration, shoot multiplication and rooting of in vitro formed shoots of Helianthus annuus L. var. Argentario is described. Hypocotyl and cotyledon explants formed callus on medium containing 2 mgl^–1 naphthalene acetic acid and 0.5 mgl^–1 benzyladenine. Adventitious buds were formed on hypocotyl segments on medium containing 0.5–2 mgl^–1 benzyladenine. The optimal level of sucrose concentration for shoot regeneration from hypocotyls was 1.5%. Multiplication from shoot apices was promoted by kinetin (2 mgl^–1) plus gibberellic acid (5 mgl^–1), benzyladenine (2 mgl^–1) plus gibberellic acid (10 mgl^–1) or at lower frequency by benzyladenine (1 mgl^–1). A general feature of the plantlets formed in vitro was the precocious flowering.     

In vitro response of promising mulberry (Morus sp.) genotypes for tolerance to salt and osmotic stresses

An in vitro technique for screening mulberry genotypes tolerant to salt and osmotic stress has been standardized.Five mulberry genotypes, namely G2, G3, G4 along with control varieties i.e., S34 and S13, were tested on salt and osmotic stress media. Out of 14 media combinations tested, the optimum responses were observed on Kn 1 mg/l, in the case of G3 genotype, on Kn 2 mg/l with G2 genotype, on BAP 1 mg/l with G4 genotype and on BAP 2 mg/l with S34 and S13 genotypes.With regard to their performance on salt-stress media fortified with NaCl (0.1--2.0%), Na₂CO₃ + NaHCO₃ (pH 8.5--10.0), the data revealed that the genotype G4 ranked the highest in terms of sprouting percentage and shoot length, in comparison to the control variety (S34) at each concentration of NaCl up to 1.0% and pH up to 9.5. However, in the case of osmotic stress condition (media supplemented with 1.0--10.0% PEG),the control variety i.e. S13 itself exhibited the highest sprouting percentage and shoot growth compared to the other test genotypes. The genotype G4 has been screened as a salt tolerant genotype which can be tested under respective in vivo condition.     

Leaf vasculature in sugarcane (Saccharum officinarum L.)

The vascular system of the leaves of Saccharum officinarum L. is composed in part of a system of longitudinal strands that in any given transverse section may be divided into three types of bundle according to size and structure: small, intermediate, and large. Virtually all of the longitudinal strands intergrade, however, from one type bundle to another. For example, virutually all of the strands having large bundle anatomy appear distally in the blade as small bundles, which intergrade into intermediates and then large bundles as they descend the leaf. These large bundles, together with the intermediates that arise midway between them, extend basipetally into the sheath and stem. Most of the remaining longitudinal strands of the blade do not enter the sheath but fuse with other strands above and in the region of the blade joint. Despite the marked decrease in number of bundles at the base of the blade, both the total and mean cross-sectional areas (measured with a digitizer from electron micrographs) of sieve tubes and tracheary elements increase as the bundles continuing into the sheath increase in size. Linear relationships exist between leaf width and total bundle number, and between cross-sectional area of vascular bundles and both total and mean cross-sectional areas of sieve tubes and tracheary elements.     

Proteins related with embryogenic potential in callus and cell suspensions of sugarcane (Saccharum sp.)

Summary Previous results have shown that some proteins secreted in the culture medium are involved with the formation of embryogenic cells and can modify somatic embryo differentiation. Undifferentiated cell suspensions grown in the presence of 13 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and obtained from embryogenic and non-embryogenic callus were used to study these events in sugarcane plants (cv.PR-62258). The cell suspension growth curves were determined and soluble proteins were extracted from embryogenic and non-embryogenic callus and culture medium from cell suspensions. In embryogenic callus we detected 1.43 times more protein than in non-embryogenic callus and the electrophoretic protein patterns show specific polypeptides for both callus types. In embryogenic callus we detected a cluster of four polypeptides in the range of 38–44 kDa and another polypeptide of 23 kDa that were not observed in non-embryogenic callus. In nonembryogenic callus there is a 35-kDa polypeptide that was not detected in embryogenic callus. In the case of extracellular proteins, the medium from embryogenic cell suspensions contained four polypeptides of 41, 38, 34 and 28 kDa that were slightly detected in the medium from non-embryogenic cell cultures; we also detected a band at 15 kDa that could not be observed in the medium from non-embryogenic cell suspensions. These results suggest that the development of embryogenic callus and cell suspensions is related to the type and amount of intracellular proteins in the callus cells and to the secreted proteins from these cells into the medium.     

Selection studies in sugarcane (Saccharum sp. hybrids)

Summary An approximate method to determine sample size for the estimation of population variance, ², is given. The estimate of ² is denoted as s² . Based on the assumption of a normal distribution for (s²/²–1), the sample size is approximately equal to 20,000 z² _p,/k²; where z is a standard normal deviate, p is the probability that s² ( 100¦s² – ²¦/²) is less than, or equal to, a critical value k, and k (measured as gDs²) is the desired precision of s² .The expected value of s², with respect to sample size, and the expected cumulative frequencies of s² over sample size for various k values are given. Their goodness of fit to the observed results was satisfactory except for populations that were different from normal. The observed values were taken from a study on four yield components in five sugarcane polycross progenies, grown in two contrasting environments over 2 years in three selection stages.The expected s² was found to be independent of the population coefficient of variance.Research suppoted in part by USDA, ARS, grant #12-14-5001-34. Published with the approval of the Director as Paper No. 412 in the Journal Series of the Experiment Station, Hawaiian Sugar Planters' Association.     

Nitrogen gains and losses in sugarcane (Saccharum sp.) agroecosystems on the coast of Peru

Irrigated sugarcane crops on the Peruvian coastal desert require 300 kg N-fertilizer ha^?1 for economically-optimum yields. About 24 kg N ha^?1 is added to the systemvia irrigation water from rivers and deep wells. 1.2% of the total N in the soil is in available form during the growing season. N extracted by the aerial part of the plants ranges from 210–246 kg N ha^?1 crop^?1;ca. 70% of this is removed in the harvest, and most of the remainder is lostvia pre-harvest burning.     

Plant regeneration from a cryopreserved embryogenic cell suspension of a commercial sugarcane hybrid (Saccharum sp.)

Efficient plant regeneration was obtained from a cryopreserved embryogenic cell suspension of sugarcane established from leaf derived callus. Pregrowing the cells for three days in MS basal medium supplemented with 0.33 M sorbitol was essential to the process. The cells were cooled at a rate of 0.5°C/min to –40°C and then stored in liquid nitrogen. Thawing was carried out rapidly in water at +40°C, and the cells were then plated without washing onto filter paper discs placed on a semi-solid regeneration medium (MS basal + 3% sucrose + 0.13 mg/1 2,4-D +0.25 mg/1 BAP + 0.25 mg/1 kinetin + 0.25 mg/1 zeatin). The filter paper discs, along with the cells, were transferred to the same, fresh medium after five hours. After 24 hours the cells were scraped off, placed on fresh semi-solid medium and incubated at 28°C in the dark for two weeks before transfer to light. A regeneration efficiency of 92% was obtained (regenerated plants, expressed as a percent of unfrozen control). Plants regenerated from cryopreserved cells, and grown to maturity in the greenhouse, were morphologically identical to regenerated control plants.Abbreviations DMSO dimethyl sulfoxide - PEG polyethylene glycol - 2,4-D 2,4-dichlorophenoxyacetic acid - BAP benzyl aminopurine - TTC 2,3,5-triphenyl tetrazolium chloride     

Sequestration of Mn into the cell wall contributes to Mn tolerance in sugarcane (Saccharum officinarum L.)

Plant and Soil - The selection and breeding of low grain-cadmium (Cd)-accumulating rices is a promising approach for reducing the Cd concentration in grains. A cadmium-safe rice line designated...     

Herbicide-resistant sugarcane (Saccharum officinarum L.) plants by Agrobacterium-mediated transformation

The presence of undesirable plants in sugarcane (Saccharum officinarum L.) plantations reduces crop yields. Using genetic engineering as a complement for traditional breeding methods it is possible to introduce herbicide-resistant traits into Saccharum germplasm. Transgenic sugarcane plants resistant to phosphinothricine (PPT), the active compound of the commercial herbicide BASTA were generated by Agrobacterium tumefaciens-mediated transformation. Meristematic sections of sugarcane were treated with anti-necrotic compounds to minimize oxidative bursts and used as explants. Four transformation protocols were assessed and the transformation frequencies reached 10–35%. The regeneration rate was high and did not appear to be affected by the transformation procedure. Southern blot analysis of several transformed plants indicated the integration per genome of one or two intact copies of the bar gene which encodes PPT acetyltransferase and confers resistance to BASTA. The levels of BASTA resistance were evaluated under greenhouse and small-plot conditions. Received: 8 November 1997 / Accepted: 22 November 1997     

Photosynthesis, antioxidant activities and transcriptional responses in two sugarcane (Saccharum officinarum L.) cultivars under salt stress

This study analyzes changes in gene expression and the biochemical and physiological properties of the antioxidant system in the leaves of two sugarcane cultivars under salt stress. In both salt-stressed cultivars, no alteration in the foliar nitrogen content was observed; however, there was a reduction in the phosphorus and potassium levels and an increase in the sodium and chloride concentrations. There was also a reduction in gas exchange on the third day under salt stress. Although the content of soluble sugars remained stable in both species, there was a decrease in free amino acids. However, only the RB872552 cultivar displayed a lower leaf protein content compared to the control. The salt stress resulted in higher superoxide dismutase and l-ascorbate peroxidase activities, but only for the RB92579 cultivar. On the other hand, both cultivars were able to maintain lower malondialdehyde contents than the control plants. The gene expression analysis revealed down-regulated expression levels, including the levels of those enzymes linked to higher activities under salt stress. Our results showed that gene induction and leaf antioxidative cycle enzyme activity do not occur at the same time. The variations in gene expression and physiological responses are also discussed.     

Molecular analysis of plants regenerated from embryogenic cultures of hybrid sugarcane cultivars (Saccharum spp.)

Summary The genomic stability of tissue culture regenerants of sugarcane (Saccharum spp. hybrids, cvs CP721210, CP68-1067 and B43-62) was analyzed by DNA restriction fragment length polymorphism (RFLP). Plants regenerated from calli, cell suspensions, cryopreserved cell suspensions and protoplasts were used. Total DNA isolated from 19 different sources was digested with EcoRI, HindIII, BamHI, BamHI, EcoRI and PstI and probed with six known maize mitochondrial genes (coxI, coxII, atpA, atp6, atp9 and rrn18-rrn5), three random maize mitochondrial cosmid clones, two random maize chloroplast cosmid clones and a wheat Nor locus clone. Hybridization patterns indicated that the variation observed was minor and appeared only in the secondcycle regenerants. No differences were observed among the three cultivars and the regenerants from calli, suspension culture, cryopreserved suspension culture and protoplasts. Mitochondrial DNA (mtDNA) isolated from CP72-1210 plants and its embryogenic cell suspensions, and bulk samples from all CP72-1210 regenerants pooled together were digested with EcoRI, HindIII, PstI, BamHI and SalI and probed with three recombinationally active wheat mtDNA clones, K, K3 and X2. No variation in the mtDNA restriction patterns was observed between the CP72-1210 plants and its regenerants. However, restriction pattern variation was observed only from EcoRI digestion, and hybridization patterns of K3, K and X2 revealed minor variations in the mtDNA of cell suspensions when compared with the DNA of the CP72-1210 plant. Except for a qualitative variation detected by the X2 probe and minor stoichiometric variations detected by the K3 probe, sugarcane DNAs were found to be stable after plant regeneration.Florida Agriculture Experiment Station Journal Series No. R-02703     

Alleviation of detrimental effects of NaCl by silicon nutrition in salt-sensitive and salt-tolerant genotypes of sugarcane (Saccharum officinarum L.)

Salt stress is a major environmental factor which adversely affects the crop yield and quality. However, adequate regulation of mineral nutrients may ameliorate the deleterious effects of salts and help to sustain crop productivity under salt stress. Salt-sensitive (SPF 213) and salt-tolerant (HSF 240) sugarcane genotypes were grown in gravel at 0 and 100 mM NaCl by supplying 0, 1.4 mM, 2.1 mM and 2.8 mM of Si as calcium silicate. Results revealed that plants treated with NaCl alone showed a significant (P?≤?0.05) reduction in dry matter production, K⁺ concentration, cane yield and juice quality in both genotypes but the magnitude of reduction was relatively more in salt-sensitive genotype than salt-tolerant. Addition of Si significantly (P?≤?0.05) reduced the uptake and translocation of Na⁺ but increased K⁺ concentrations particularly in shoots of both sugarcane genotypes. Cane yield and yield attributes were significantly (P?≤?0.05) higher where Si was added. Juice quality characteristics were significantly (P?≤?0.05) improved in salt-sensitive and salt-tolerant sugarcane genotypes with the application of Si. The results suggested that added Si interacted with Na⁺, reduced its uptake and transport to shoots and consequently improved cane yield and juice quality in salt-sensitive and salt-tolerant sugarcane genotypes under salt stress.     

Biodiversity of rice (Oryza sativa L.) and sugarcane (Saccharum officinarum L.) rhizosphere pseudomonads

Fluorescent pseudomonads were isolated from the rhizosphere of rice and sugarcane and examined for their biodiversity. All fifty strains of the fluorescent pseudomonads produced indole acetic acid. Among these pseudomonads, halves of sugarcane rhizosphere isolates and one isolate from the rice rhizosphere exhibited phosphate solubilization activity. On the contrary, majority of the rice rhizosphere pseudomonads, and one isolate from sugarcane rhizosphere exhibited antifungal activity. These fluorescent pseudomonads were further classified based on their growth and biochemical characteristics. Those isolates that had same biochemical characteristics were distinguished by random amplification of polymorphic DNA (RAPD). These biochemical and molecular biological methods clearly differentiated fluorescent Pseudomonads of rice and sugarcane rhizosphere.     

甘蔗抗旱性生理生化鉴定指标

利用因子分析和灰色关联度分析方法研究了甘蔗叶片相对含水量、膜脂过氧化代谢、活性氧代谢、光合参数及蔗茎产量性状等指标与抗旱性的关系.结果表明,干旱胁迫下甘蔗叶片的MDA含量和PMP明显提高,而RWC、SOD活性、Chl含量、F_v/F_m、F_v/F_o、△F_v/F_t、△F_v/F_o和蔗茎单茎重(SSW)8个抗旱性指标均显著降低.SSW与其它9个生理生化指标的相关性大小依次为PMP＞SOD活性＞MDA含量＞RWC＞F_v/F_o＞F_v/F_m＞Chl含量＞F_v/F_o＞F_v/F_t,其中,SSW与F_v/F_o和ΔF_v/F_t相关性不显著.通过因子分析将10个甘蔗抗旱性指标用4个公共因子表示,累加方差贡献率达到92.08%.因子l主要是反映光合作用特性指标对甘蔗品种抗旱性起支配作用,因子2主要是反映叶片相对含水量及活性氧代谢指标对甘蔗品种抗旱性起支配作用,因子3和因子4分别只有SSW和Chl含量有较大载荷.灰色关联度分析表明,各抗旱性生理生化指标与SSW关联密切程度依次为F_v/F_m＞PMP＞F_v/F_o＞RWC＞MDA含量＞SOD活性＞ΔF_v/F_t＞Chl含量＞F_v/F_o.     

Assessment of terminal heat tolerance ability of wheat genotypes based on physiological traits using multivariate analysis

Terminal heat stress is one of the limiting factors in wheat production and it is expected to rise under present scenario of climate change. The present study was conducted to evaluate the performance of 40 wheat genotypes under terminal heat stress conditions based on eight physiological traits. The plants were sown late (i.e. on 5th January) to expose them terminal heat stress. The genotypes were evaluated using multivariate analysis viz. Ward’s method of hierarchical clusters analysis, discriminant analysis and principle component analysis. The genotypes were categorized into three groups namely tolerant, intermediate and sensitive. Tolerant genotypes like DBW 14, RAJ 3765, HD 2643 and HALNA performed physiologically better in terms of higher membrane stability index (MSI), chlorophyll content, photosynthesis rate (Pn), harvest index under heat stress conditions. Genotypes HD 2987, SHANGHAI, HD 2402 and WH 730 were found to be heat sensitive. Physiological traits like MSI, SPAD value, Fv/Fm ratio and Pn were found to be most important contributor in grouping of genotypes and showed positive correlations (r) of 0.73, 0.47, 0.41 and 0.39 with grain yield, respectively, which is significant at p < 0.05. The large genetic diversity was found among the genotypes based on physiological traits. These genotypes can be utilized in wheat improvement programme for heat tolerance.