Populus: A plant genus of the family SALICACEAE. Balm of Gilead is a common name used for P. candicans, or P. gileadensis, or P. jackii, and sometimes also used for ABIES BALSAMEA or for COMMIPHORA.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Desert Climate: A type of climate characterized by insufficient moisture to support appreciable plant life. It is a climate of extreme aridity, usually of extreme heat, and of negligible rainfall. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Salicaceae: A plant family of the order Salicales, subclass Dilleniidae, class Magnoliopsida. The leaves are alternate and simple. Staminate (male) flowers consist of from one to many stamens. Pistillate (female) flowers consist of a one-chambered ovary with several to many ovules (potential silky seeds).Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.Genome, Plant: The genetic complement of a plant (PLANTS) as represented in its DNA.Expressed Sequence Tags: Partial cDNA (DNA, COMPLEMENTARY) sequences that are unique to the cDNAs from which they were derived.Xylem: Plant tissue that carries water up the root and stem. Xylem cell walls derive most of their strength from LIGNIN. The vessels are similar to PHLOEM sieve tubes but lack companion cells and do not have perforated sides and pores.Genes, Plant: The functional hereditary units of PLANTS.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Sodium Chloride: A ubiquitous sodium salt that is commonly used to season food.Laccaria: A genus of white-spored mushrooms in the family Tricholomataceae. They form symbiotic partnerships (MYCORRHIZAE) with trees.Lignin: The most abundant natural aromatic organic polymer found in all vascular plants. Lignin together with cellulose and hemicellulose are the major cell wall components of the fibers of all wood and grass species. Lignin is composed of coniferyl, p-coumaryl, and sinapyl alcohols in varying ratios in different plant species. (From Merck Index, 11th ed)Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Wood: A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.RNA, Plant: Ribonucleic acid in plants having regulatory and catalytic roles as well as involvement in protein synthesis.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Multigene Family: A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.China: A country spanning from central Asia to the Pacific Ocean.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Oryza sativa: Annual cereal grass of the family POACEAE and its edible starchy grain, rice, which is the staple food of roughly one-half of the world's population.Chromosomes, Plant: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.Ovule: The element in plants that contains the female GAMETOPHYTES.DNA, Plant: Deoxyribonucleic acid that makes up the genetic material of plants.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Gene Duplication: Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.Vitis: A plant genus in the family VITACEAE, order Rhamnales, subclass Rosidae. It is a woody vine cultivated worldwide. It is best known for grapes, the edible fruit and used to make WINE and raisins.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.