Plant biotechnology is helping to maintain healthy
plants, increase crop yields, and reduce pesticide treatment for the improved way
to manage plant diseases. Biotechnology
is aiming to feed increasing world population as in last 40 years the
population of world has been increased 90% and food production increased only
by 25% per person. By 2020, 39% more grain has to be increased by farmers
worldwide to feed world. Genetic engineering is among the potential tools to enhance
beneficial plant traits, particularly to enable plants to resist pathogen
attack, as existing tools are not enough equipped to manage plant
diseases. These pathogens along with
weeds and insect pests are causing 42% crop losses worldwide ($500 billion in
money) while only plant diseases cause 12% crop losses worldwide (Oerke et al.,1994).
Genetically engineered plants prevent crop
losses and reduce pesticide usage by resisting virulent pathogens. Plants have
their own system of resistance against pathogens, not all plant pathogens can
infect all plants and a single plant is not susceptible to all fungi,
nematodes, bacteria and viruses. Biotechnology tools enable to enhance plant intrinsic
responses (Hypersensitivity Response and Systemic Acquired Resistance) against
pathogens by using single dominant resistance genes or triggering plant defense
mechanisms (Rommens and Kishore, 2000) and to understand the plant-pathogen
interactions on molecular basis which enable scientists to organize resistance
genes from almost any plant.
Pathogen Derived Resistance, Plants are protected from diseases with the
genes that are engineered into plants derived from pathogens that attack them,
this model is called pathogen derived resistance. The genetic engineering in
case of plant viruses is difficult as plant resistant virus genes are not available frequently. However,
this concept worked in case of virus (TMV), the expressed coat protein of TMV was
resistant to tobacco mosaic virus (Powell-Abel et al.,1986).
protein genes have proved to be effective in reducing viral diseases in plants.
Some examples of coat protein mediated resistance are TMV, PLCV, CMV, PVX, PVY.
from coat protein some other sequences are also been engineered into plants
which include satellite virus RNA, virus antisense, ribozymes to gain
resistance. As genetic engineering is compared with conventional breeding
methods, genetic engineering enables plants to gain resistance to viruses, more
quickly and precisely.
Transgenic plants, a gene from one organism
is inserted in plants to make that plant resistant to a certain pest or
disease. There are a lot of examples of transgenic plants like papaya is
genetically engineered against papaya ring spot virus, in 1995 papaya was grown
in Hawaii over 95% of state land and papaya was infected with papaya ring spot
virus, crisis situation was looming and then transgenic papaya was developed
which showed excellent resistance against said virus and contained excellent
horticulture qualities and that papaya was called “Transgenic Virus Resistant
Plantibodies, An unconventional technique to control plant pathogens, plantibodies interact with intended target to inoperate its biological
function. This technique has been
used to control only two plant important
pathogens so far, Tomato spotted wilt
root-knot nematodes Meloidogyne spp.