Soil Study

Dramatically Dynamic Genomic Evolution of a Mighty Mite As a major natural enemy of several damaging agricultural pests, the predatory mite Metaseiulus occidentalis is used in many agricultural settings as an effective biological control agent. Some of its favorite prey include spider mites that feed on and destroy various fruits including strawberries, apples, peaches and grapes. "I have been studying the behavior, ecology, and molecular biology of these mites for more than 40 years," said Prof. Marjorie Hoy lead author from the University of Florida USA, "so I was very keen to sequence the entire genome to reveal the full catalogue of genes." To explore the unique biology of this agriculturally important predator the researchers focused their studies on genes putatively involved in processes linked to paralysis and pre-oral digestion of prey species and its rather rare par haploid sex determination system, as well as how it senses chemical cues from its surro...

Modern Corn Hybrids More Resilient to Nitrogen Stress In an analysis of 86 field experiments, agronomists found that corn hybrids released after 1990 prove more resilient than their predecessors in multiple ways. Modern hybrids maintain per-plant yield in environments with low nitrogen, can bounce back from mid-season stress and have an improved ability to take up nitrogen after silking, even if they suffered from nitrogen deficiency during flowering. The study suggests reserving a portion of nitrogen fertilizer to apply later in the season could be a good bet for growers, said Tony Vyn, professor of agronomy. "This is like insurance," he said. "Previously, withholding some of your nitrogen for later could be perceived as a risky venture -- you don't want to inadvertently cause nitrogen deficiency. But this paper suggests that with modern hybrids, that risk is lower." Nitrogen is an essential building block of plant proteins and plays a vital role...

Genetic Transfer to Prevent Self-Pollination Self-pollination or 'selfing' can be bad for a plant resulting in inbreeding and less healthy offspring. This breakthrough could be used to breed stronger more resilient crops faster and at lower cost; a new approach in the quest for a secure and plentiful food supply. The team took the self-fertile plant thale cress -- Arabidopsis thaliana -- a relative of cabbages, cauliflowers and oilseed rape, and made it self-incompatible by the transfer of just two genes from poppies that enable the recipient plant to recognize and reject its own pollen whilst permitting cross-pollination. Such conversion of a selfing plant to a self-incompatible one has been a long term goal of self-incompatibility research. The basic anatomy of most flowers means the male pollen is produced next to the female reproductive organs running the real risk of self-pollination, rather than receiving pollen from a different flower transported by the wind...

Wild Plants Call to Carnivores to Get Rid of Pests While this strategy may work in someone's backyard, it's not an option on a large farm. In an October 4 Trends in Plant Science Opinion paper, agricultural researchers in Sweden and Mexico argue that one way around the scalability problem is to bring back the odors and nectars found in wild plants that attract pest-eating predators. This could be done either through breeding programs or by using artificial devices. "Wild plants commonly emit natural odors when they are damaged that attract natural enemies of pest insects--even as humans we smell it when our neighbour is mowing the lawn -- odors can carry very precise information," says co-author Martin Heil of CINVESTAV-Irapuato in Mexico. "Agriculture has bred such defenses out of crops, and since these odors have no negative effects on human consumers, we want to replace what the plant would already be doing." It's also not unusual for w...

Plant Breeding Plant breeding in a simple language is genetic improvement of plants for the best economic productivity. It could also be defined in terms of art and the Science of changing and improving the heredity of plants. Plant breeding was practiced first when people learned to look for superior plants to harvest for seed; thus selection became the earliest method of plant breeding. Primitive efforts in plant selection contributed much to the evolutionary development of each of the cultivated crops. These all efforts were done unintentionally. As human knowledge about plants increased, people were able to select more intelligently with the discovery of sex in plants, hybridization was added to breeding techniques. Although hybridization was practiced before the time of Mendel’s experiments provided a basis for understanding the mechanism of heredity and how it may be manipulated in the development of improved varieties. A more precise explanation of the heredity mecha...

Pleiotropy Sometime a gene may have more than one effect, i.e. it influences more than one character simultaneously. It has long been noted that blue-eyed white cats are always deaf; blue eye gene also causes deafness. In wheat the presence of awn usually has a pleiotropic effect on grain yield. Awned wheat is better yielder than those without awns.

Structural Changes in Chromosome Deletion                 When a chromosome somehow loses a part of itself, deficiency of genes contained in deleted part occurs. The loss may be at the end of chromosome causing terminal deficiency and it may be central due to two breaks in the chromosome and the reunion at wrong places causing intercalary deficiency. Loss of a chromosomal segment may be so small that it includes only a single gene or part of a gene. In this case the phenotypic effects may resemble those of a mutant allele at that locus. Deletion never back mutate to the normal condition, because a lost piece of chromosome cannot be replaced in this way, a deletion can be distinguished from a gene mutation. A loss of any considerable portion of a chromosome is usually lethal to a diploid organism because of genetic unbalance. When an organism heterozygous for a pair of alleles (Aa) loses a small portion of th...