SUMMARY |
Endophytic
bacteria and fungi are defined as organisms that live in association
with plants for most if not all of their life cycles. They live
within the intercellular spaces of plants, where they live off apoplastic
nutrients. Some fungi and bacteria can be isolated from a great
variety of host plant families while growing under different ecological
and geographical conditions. Other endophytes are apparently restricted
to host species that occur within a particular plant family.
Endophytic
microorganisms may confer benefits to the plant, and the benefits
may be reciprocal, resulting in an enhanced symbiotic system for
specific plant characteristics. Therefore, the use of endophytic
bacteria and fungi opens up new areas of biothechnological exploitations,
which leads to the necessity to isolate and cultivate these organisms.
Endophytes are used for biological control of various plant diseases,
for enhanced agronomic plant characteristic such as increased
drought tolerances and nitrogen efficiency, for bioherbicides,
and for pharmaceutical agents. Because these microorganisms are
usually obligated biotrophic parasites, their culture, especially
for fungi, if ever achieved, may be difficult and slow.
The
biochemical versatility and diversity of endophytes represent
an enormous variety of genes that are still unknown. More and
more useful gene functions are being discovered, particularly
for environmental remediation and industrial processes. Endophytics
also provide numerous antimicrobial compounds; for instance, the
fungus Pestalotiopsis microspora, and endophytic of Hymalayan
yew, Taxus walkchiana produces taxol. This compound is
now marketed as an anticancer drug (Strobel et al., Microbiology,
v.142, p. 435-440, 1996).
This
project proposes to study the biological diversity of endophytic
microorganisms (considering both number of species and the partition
of abundance) from important plant species growing in São
Paulo State, such as: maize, soybeans, citrus, coffee, cassava,
Brachiaria and Dicksonia (xaxim); to study the molecular
diversity (molecular systematics) present within a specie or genus
based on comparative sequencing of the rRNAs of endophytic microorganisms;
to determine the chemical diversity, mainly of secondary metabolites
- "antibiotics"; to assess the potential of endophytes in the
biological control of most important pathogens of the host plants
(rust in coffee, Xyllela in citrus, Phytophthora
in cassava, damping-off in soybeans, Pythium aphanidermatum
in maize). Also, it is objective of this project to study best
methods of preserving representative genera and specific groups
and to organize a culture collection of all identified endophytics.
Culture collections represent valuable resources of microbial
germoplasm. Our objective is to make this collection available
for distribution and utilization.
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