Agriculture Reference
In-Depth Information
2009
). Cold stress mainly causes mechanical damage to the cell membrane, where-
as salinity and drought disrupt the ionic and osmotic equilibria of cells. Cytosolic
free Ca
2+
concentration ([Ca
2+
]cyt) increases in response to abiotic stress. The stress
signal is first perceived at the membrane level by the receptors and then transduced
in the cell to switch on various stress-responsive genes for mediating tolerance.
The products of stress-inducible genes function both in the initial stress response
and in establishing plant stress tolerance. Some genes have been reported to be up-
regulated in response to more than one stress, indicating the presence of cross-talk
between the different stress signaling pathways. The generation of reactive oxygen
species represents a universal mechanism in cellular responses to environmental
stresses (Bauwe et al
2010
). Plants also accumulate several osmo-protectants that
improve their ability to combat abiotic stresses.
Unraveling the opportunities for increased photosynthetic efficiency and the
mechanisms underlying stress disorders are two examples of the manner by which
genetic studies and their application through plant breeding offer substantial av-
enues for the advancement of horticulture. Each increases the efficiency and effec-
tiveness of biological processes thereby raising yield and product quality.
Resources and Befitting from Benign Microbes
The study and application of plant pathology has been and continues to be hugely
beneficial to horticulture. The unraveling of pathogen and pest biologies and life cy-
cles, host-pathogen interactions, epidemiology and methods of control were some
of the earliest benefits which science provided. The importance of such studies
remains because regrettably pests and pathogens still cause substantial losses and
control is costly. Environmentally induced stress disorders are now included with
pests and pathogens since they cause considerable crop losses and have similar
basic biological and biochemical pathways. The United Kingdom Horticultural De-
velopment Company (HDC), supported from an industrial levy, spends more on this
aspect of husbandry than any other of its priorities and this distribution of funding
seems unlikely to change radically in the immediate future.
Finely tuned diagnostics offers considerable opportunities for improving the pre-
diction, the speed and efficacy of control of pests and pathogens. The discovery of
the enzyme-linked immunosorbent assay (ELIZA) and the polymerase chain reac-
tion (PCR) have, amongst other developments, greatly enhanced opportunities for
the diagnosis of plant diseases and for charting epidemics of pathogens (Lauerman
2004
). The mechanization of various aspects of the PCR assay, such as robotics,
microfluidics and nanotechnology, has made it possible for the rapid advancement of
new procedures. Real-time PCR, DNA microarray and DNA chips utilize these new-
er techniques in conjunction with specialized computer programs. Instruments for
hand-held PCR assays are being developed. The PCR and reverse transcription-PCR
(RT-PCR) assays have greatly accelerated the speed and accuracy of disease and
pathogen diagnosis, making it possible to characterize genetically a microbial isolate
inexpensively and rapidly for identification, typing and epidemiological comparison.
