Strigolactone Profile of Selected Legumes and their Potential for Use as Trap Crops for Striga
Loading...
Date
2021
Authors
Kiprotich, Kibet Willy
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Striga hermonthica’s non-hosts stimulate parasite seed to germinate without getting
infected because the non-hosts produce unique germination stimulants (strigolactones).
This phenomenon – called suicidal seed germination is greatly used in S. hermonthica
control. For improved efficiency of the suicidal seed germination method in S. hermonthica
control, detailed analysis of comparative ability of potential trap crops to stimulate
germination is critical. An additional and often ignored determinant of suitability of nonhost
intercrops is the extent to which the parasite can penetrate various non hosts and if
such interaction can adversely affect the trap crop. This is critical because although the
parasite is not able to effectively infect a non-host, it may still cause injuries that can expose
the crop to other pathogens such as bacteria and fungi. In this study, suitability of Kenya’s
commonly used legumes (cowpea, pigeon pea, common bean, and garden pea) as potential
intercrops in the control of S. hermonthica was determined. Firstly, their efficiency to
induce germination of S. hermonthica seeds using germination assays was determined.
Then, the amounts and types of strigolactones in their root exudates was assayed using a
high performance liquid chromatography coupled with tandem mass spectrometer (LCMS/
MS). Finally, the extent of interaction between the legumes and S. hermonthica was
determined using histological analysis. There were significant differences in the induction
of S. hermonthica germination by the legume root exudates, synthetic GR24, and water
(p=0.0001). Analysis of strigolactones in root exudates of legumes revealed that the most
abundant strigolactones were 2-epi-5-deoxystrigol and orobanchol with trace amounts of
2-epi-orobanchol and strigol. Expectedly, none of the legumes fully supported growth and
development of S. hermonthica to enable the parasite complete its lifecycle. However, the
extent of parasite penetration varied greatly in the different legumes. Cowpea and garden
pea formed vascular connections with S. hermonthica parasite. However, the parasite did
not grow beyond pigeon pea’s endodermis, and in the common bean, the parasite barely
attached on the host cortex. These findings suggest that all legumes tested are appropriate
for use as intercrops because they induced high S. hermonthica seed germination.
Additionally, confounding effects (mixed) on successful penetration of S. hermonthica in
non-hosts will require further investigation. Knowledge from this study has provided
fundamental insights on the importance of trap crops in induction of suicidal germination
of Striga hermonthica seeds, which depletes the parasite’s seedbank in soil.
Description
A Thesis Submitted in Partial Fulfilment of the Requirements for Award of the Degree of Master of Science (Biotechnology) in the School of Pure and Applied Sciences of Kenyatta University, May, 2021
Keywords
Strigolactone Profile, Selected Legumes, Potential, Use as Trap Crops, Striga