Heat tolerance in Brassica rapa:
developing an efficient screening method
Annisa
Supervisors :
W/ Prof Wallace Cowling
Dr. Sheng Chen
W/Prof Neil Turner
Acknowledgements
Funding
Australian Development Scholarships
The School of Plant Biology, UWA
ARC Linkage Project LP110100341
Seed sources
Australian Temperate Field Crops Collection (ATFCC)
Norddeutsche Pflanzenzucht Lembke AG (NPZ)
The Leibniz Institute of Plant Genetics and Crop Plant Research (IPK)
Help, teaching and technical assistance
Prof. John Kuo and Mr. John Murphy (Centre for Microscopy, Characterization
and Analysis)
Assoc/ Prof. Guijun Yan
Mr. Rob Creasy and Mr. Bill Piasini (Plant Growth Facilities)
Ms. Helen Bowler and Ms. Yiming Guo
The University of Western Australia
The global warming problem
Intergovernmental Panel on Climate Change, 2001
The University of Western Australia
Why choose Brassica rapa ?
B. napus (canola) suffered a genetic bottleneck, so
canola needs a new genetic source to broaden
genetic background
B. rapa is a diploid ancestor of tetraploid Brassica
napus
B. rapa has wide geographical distribution and
broad genetic diversity
The University of Western Australia
Different type of Brassica rapa
The University of Western Australia
Biogeography of the origin of B. rapa compared to
other Brassica species
United Nations Food and Agriculture Organization, Rome, cited in Dixon 2007
The University of Western Australia
Large
geographical
distribution
+
Broad
genetic
background
Tolerance to heat
How do I screen
for heat tolerance?
The University of Western Australia
How do I choose my accessions?
Self compatible
Spring type
Some selected from “hot” (tropical) region
Early flowering
One B. juncea and six B. rapa
The University of Western Australia
Two treatments:
Normal
Heat with supplemental water to avoid drought stress
Screening methods:
Leaf temperature
Bud temperature
Stomatal conductance
Bud tagging, observation continues until seed harvesting
Pollen viability
Pollen tube growth
The University of Western Australia
Heat treatment applied during the early stages of
flowering
o
( C)
Control
40
Heat
35
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
16 hours day light 8 hours night
Controlled environment room (CER)
Seven days of heat treatment
The University of Western Australia
What have I observed so far?
Leaf and bud temperature were similar to the control
No water stress, as demonstrated by leaf temperature, bud
temperature and stomatal conductance
A marked reduction in seed number and seed weight
Observed morphological difference in flowers from heat
treated plants, but no difference in bud and pod number
Little variation in pollen viability and pollen tube growth
The University of Western Australia
Summary
Heat stress without water stress
Total seed number and seed weight for the main stem were
affected by the heat for almost all accessions
Limited affect on pollen viability
Pollen tube growth in heat appeared to be no different to the
control
The University of Western Australia