Molecular breeding of healthy vegetables

Abstract

Breeders and plant scientists are increasing their efforts to raise the health benefits of fruits and vegetables. Yet, the positive impact of this on public health, it is not a substitute for a healthy diet.

Figure 1

Two molecular approaches for modifying the concentration of organosulphur compounds in onion. The approaches are shown in blue boxes. Antisense lachrymatory factor synthase blocks the formation of propanethial sulphoxide and eliminates tearing when chopping onions, but allows 1-propanesulphenic acid to form thiosulphinates. This, in turn, produces normal flavours and bioactivity. Heating of thiosulphinates inactivates their health-functional properties such as inhibition of platelet aggregation, but these are unaffected when onion is consumed raw. Marker-facilitated selection of low pungency onions helps in the development of new cultivars that can be consumed raw. LF, lachrymatory factor.

Figure 2

Three molecular approaches for modifying carotenoid levels in vegetable crops. The approaches are shown in blue boxes. Overexpression of the PSY allele, which converts geranylgeranyl pyrophosphate into phytoene, has shown promise as a mechanism by which to enhance native carotenoid levels (Fraser et al, 2009). This approach has also demonstrated corresponding increases in tocopherols, which are responsible for pro-vitamin E activity. Antisense silencing of the lycopene cyclase enzyme LCY-e has similarly increased β-carotene levels. Molecular markers linked to key quantitative trait loci in the carotenoid pathway are being used to enhance carotenoid levels in vegetable crops.

Figure 3

Four molecular approaches for modifying phytic acid accumulation in seeds. The approaches are shown in blue boxes. Silencing of a key phytate transporter and engineering of increased phytase activity in seeds will reduce phytic acid levels, but it compromises germination and plant performance. Identification of naturally occurring low-phytic-acid mutants and development of low-phytic-acid genotypes through induced mutagenesis have resulted in very low phytic acid levels in seeds. All four of these methods have the potential to lead to low phytic acid crops.