Biotechnology to Improve Shelf Life and Quality Traits of Foods - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 348

which generally contribute a single independent marker to the study of hybridization.
Isozymes are also limited in terms of the total number of loci available for analysis
(30 to 50). In contrast, nuclear restriction fragment length polymorphisms (RFLPs)
and random amplified polymorphic DNAs (RAPDs) can theoretically yield an almost
unlimited number of independent molecular markers for the analysis of hybrids. 130
It is important to take into consideration the patterns of inheritance. Markers with
biparental codominant inheritance (e.g., isozymes or nuclear RFLPs) provide twice
the information of either uniparentally inherited cytoplasmic markers or markers
with predominantly dominant inheritance patterns, such as RAPDs or secondary
compounds. The use of nuclear RFLP markers requires the construction of a genomic
library for the hybridizing taxa or a close relative prior to the development of markers.
In contrast, RAPD primers tend to be consistent among different flowering plant
genera in terms of amplification strength. 131 A final consideration regarding the use
of molecular markers concerns the heritability of the molecular variation scored in
the parental populations and their hybrids. For example, intragenic recombination,
concerted evolution, and sometimes non-Mendelian inheritance patterns make rDNA
patterns in hybrids difficult to interpret at times and sometimes misleading. 132,133

FUTURE TRENDS

P LANT F OODSFORTHE F UTURE

The most important impact of biotechnology on the food chain will be in the
agriculture sector. The efficiency and profitability of producing raw agricultural
commodities could be dramatically improved by increasing crop yields and decreas-
ing agricultural inputs such as fertilizer, herbicides, pesticides, and fuel. Table 10.9

TABLE 10.9
Prospects in Biotechnology to Improve Shelf Life and Quality Traits of Foods

Product Prospect Future Benefit Ref.

Strawberries The gene cloned for ellagic acid is

planned for insertion

An increased level of ellagic acid, a
cancer protective agent that inhibits
polycyclic aromatic hydrocarbons,
nitrosamines, aflatoxins, and
aromatic amines

4

Wheat Working toward insertion of antisense

ale-bound starch synthetase gene

A high content of amylopectin (waxy)
starch

134

Wheat flour Modification of gene that encodes the

high molecular weight glutenin
protein subunit 10

Improvement of dough elasticity 75

Oilseeds Incorporation of three genes from a

bacteria into Arabidopsis to produce
polyhydroxybutyrate (PHB)

Reducing the lipid content of seed
crops and replacing it by
biodegradable polymers

54