Sugarcane (Saccharum spp.) is a special crop plant that underwent anthropogenic evolution from a wild grass species to an important food, fodder, and energy crop. Unlike any other grass species which were selected for their kernels, sugarcane was selected for its high stem sucrose accumulation. Flowering in sugarcane is not favored since flowering diverts the stored sugar resources for the reproductive and developmental energy needs. Cultivars are vegetatively propagated and sugarcane breeding is still essentially focused on conventional methods, since the knowledge of sugarcane genetics has lagged that of other major crops. Cultivar improvement has been extremely challenging due to its polyploidy and aneuploidy nature derived from a few interspecific hybridizations between Saccharum officinarum and Saccharum spontaneum, revealing the coexistence of two distinct genome organization modes in the modern variety. Alongside implementation of modern agricultural techniques, generation of hybrid clones, transgenics and genome edited events will help to meet the ever-growing bioenergy needs. Additionally, there are two common biotechnological approaches to improve plant stress tolerance, which includes marker-assisted selection (MAS) and genetic transformation. During the past two decades, the use of molecular approaches has contributed greatly to a better understanding of the genetic and biochemical basis of plant stress-tolerance and in some cases, it led to the development of plants with enhanced tolerance to abiotic stress. Hence, this review mainly intends on the events that shaped the sugarcane as what it is now and what challenges ahead and measures taken to further improve its yield, production and maximize utilization to beat the growing demands.
Purslane is a nutritious vegetable crop rich in the polyunsaturated essential fatty acids (PUEFA) alpha-linolenic acid (LNA) and linoleic acid (LA), which are essential for normal human growth, health promotion, and disease prevention. Total lipids and fatty acid concentrations at three stages of harvest (6-, 10-, and 14-true-leaf stages) were examined in a cultivated variety of purslane (Portulaca oleraceae L. var. sativa). The 14-true-leaf stage of growth was found to be ideal for harvest because at this stage the leaf area, shoot fresh weight, shoot dry weight, and PUEFA concentrations per gram of leaf fresh weight were higher (P < or = 0.05) than at the 6- and 10-true-leaf stages of growth. The LNA to LA ratio was also highest at the 14-true-leaf stage. 相似文献
Watercress (Nasturtium officinale R.Br.) is the richest source of glucosinolate nasturtiin, which on hydrolysis produces phenethyl isothiocyante (PEITC). Interest in growing watercress is stimulated since demonstration of the role of PEITC in protection against cancers associated with tobacco specific carcinogens. Twenty-one days old watercress seedlings were transplanted into growth chambers (16-h days/8-h nights of 25/22 degrees C and photosynthetic photon flux (PPF) of approximately 265 micromol m(-2) s(-)(1)). The study was replicated three times. Leaves were analyzed for PEITC and ascorbic acid concentrations at transplant, and harvested at 10-days intervals until 60 days after transplant. The PEITC and ascorbic acid concentrations were the highest in leaves harvested at 40 days and the lowest at transplant. Leaves harvested at 40 days produced about 150% higher PEITC concentrations compared to the leaves at transplant. Both PEITC and ascorbic acid concentrations of leaves increased linearly with age until 40 days after transplant after which there was no significant increase. Seedlings at transplant had the lowest dry mass and leaf area, while plants harvested at 60 days had the highest dry mass and leaf area. 相似文献
Acidic deposition has caused a depletion of calcium (Ca) in the northeastern forest soils. Wollastonite (Ca silicate) was added to watershed 1 (WS1) at the Hubbard Brook Experimental Forest (HBEF) in 1999 to evaluate its effects on various functions of the HBEF ecosystem. The effects of Ca addition on foliar soluble (extractable in 5% HClO4) ions, chlorophyll, polyamines, and amino acids were studied in three hardwood species, namely sugar maple, yellow birch, and American beech. We further analyzed these effects in relation to elevation at Ca-supplemented WS1 and reference WS3 watersheds. Foliar soluble Ca increased significantly in all species at mid and high elevations at Ca-supplemented WS1. This was accompanied by increases in soluble P, chlorophyll, and two amino acids, glutamate and glycine. A decrease in known metabolic indicators of physiological stress (i.e., the amino acids, arginine and γ-aminobutyric acid (GABA), and the diamine, putrescine) was also observed. In general, these changes were species-specific and occurred in an elevation dependent manner. Despite an observed increase in Ca at high elevation for all three species, only sugar maple exhibited a decrease in foliar putrescine at this elevation indicating possible remediation from Ca deficiency. At higher elevations of the reference WS3 site, foliar concentrations of Ca and Mg, as well as Ca:Mn ratios were lower, whereas Al, putrescine, spermidine, and GABA were generally higher. Comparison of metabolic data from these three species reinforces the earlier findings that sugar maple is the most sensitive and American beech the least sensitive species to soil Ca limitation. Furthermore, there was an increase in sensitivity with an increase in elevation. 相似文献