Three FLOWERING LOCUS T-like genes function as potential florigens and mediate photoperiod response in sorghum

Sorghum is a typical short-day (SD) plant and its use in grain or biomass production in temperate regions depends on its flowering time control, but the underlying molecular mechanism of floral transition in sorghum is poorly understood. Here we characterized sorghum FLOWERING LOCUS T (SbFT) genes to establish a molecular road map for mechanistic understanding. Out of 19 PEBP genes, SbFT1, SbFT8 and SbFT10 were identified as potential candidates for encoding florigens using multiple approaches. Phylogenetic analysis revealed that SbFT1 clusters with the rice Hd3a subclade, while SbFT8 and SbFT10 cluster with the maize ZCN8 subclade. These three genes are expressed in the leaf at the floral transition initiation stage, expressed early in grain sorghum genotypes but late in sweet and forage sorghum genotypes, induced by SD treatment in photoperiod-sensitive genotypes, cooperatively repressed by the classical sorghum maturity loci, interact with sorghum 14-3-3 proteins and activate flowering in transgenic Arabidopsis plants, suggesting florigenic potential in sorghum. SD induction of these three genes in sensitive genotypes is fully reversed by 1 wk of long-day treatment, and yet, some aspects of the SD treatment may still make a small contribution to flowering in long days, indicating a complex photoperiod response mediated by SbFT genes

Phytoremediation of heavy metal-contaminated sites: Eco-environmental concerns, field studies, sustainability issues and future prospects

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physico-chemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metals-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches, evaluate their efficacy to remove toxic metals from our natural environment, explore current scientific progresses, field experiences and sustainability issues and revise world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in 21st century

Leaf development: a cellular perspective

Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny) from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins, and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana

Transgenic plants for phytoremediation of Arsenic and Chromium to enhance tolerance and hyperaccumulation

Phytoremediation of metals and other environmental pollutants is gaining importance as a cost-effective method for pollution mitigation and envisages sustainable development. This paper envisages prospects of phytoremediation for mitigation of heavy metal pollutants from the environment, with particular reference to arsenic (As) and chromium (Cr). Genetically engineered tailor-made plants have much potential for selective uptake, accumulation and sequestration of heavy metals. Recent developments in this area and state-of-the-art technology foresee genetically engineered plants with an ability to prevent accumulation of As in aerial parts of experimental plant systems, which could be extrapolated to edible plants such as rice, wheat and others. Similarly, hypereaccumulation in plant biomass is another important approach for removal of these toxic metals from the land and water ecosystems and mitigation of As and Cr pollution. The mechanisms of As hyperaccumulation by the hyperaccumulator plants has opened up scope for genetic engineering other prospective plant species to enhance hyperaccumulation of toxic metals in their aerial biomass. This review enumerates the mechanisms of hyperaccumulation in the plant systems, the potential genes that could be engineered to develop tailor made genetically engineered plants aimed for phytoremediation of As and Cr and other metals in general

Compost from sugar mill pressmud and distillery spent wash for sustainable agriculture

This paper describes the process for rapid composting of sugar mill pressmud and distillery spentwash by using microbial culture. These waste materials are processed to organic manure, a value added produce, which can be used to replenish soil nutrients. Replenishment of soil nutrients is essential since plants utilize them to generate a large amount of crop produce, year after year. Physico-chemical characteristics and the nutritive value of compost generated out of pressmud and distillery effluent have been found to support good plant growth. The product has gained wide utility as an ameliorating agent and as a soil conditioner to replenish soil nutrients for sustainable agriculture. Besides, composting is a suitable method for stabilization of organic wastes which avoids discharge of industrial wastes to land and water ecosystems that may cause pollution. Activated composting through microbial culture and appropriate conditions converts the organic matter of pressmud and spentwash into value added compost. The cumbersome bio-nondegradable portion of these wastes such as lignins, melanoidins and humic acid get converted to humus which is an essential component of soil and further enriches the soil for sustainable crop productivity