15th International Conference on Arabidopsis Research - TAIR

T12-009
Cold-induced pollen sterility in rice is associated with
a disruption in sugar metabolism and increase in
ABA levels
Sandra N. Oliver(1, 2), Joost Van Dongen(3), Peter Geigenberger(3), Hargurdeep
S. Saini(4), Chris L. Blanchard(2), Paul E. Roffey(2), Elizabeth S. Dennis(1), Rudy
Dolferus(1)
1-CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia and Cooperative Research
Centre for Sustainable Rice Production, c/- New South Wales Agriculture, Private Mail Bag, Yanco,
NSW 2703, Australia
2-Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
3-Max Planck Institute of Molecular Plant Physiology, 14476 Golm, Germany
4-Institut de Recherche en Biologie Vegetale, Universite de Montreal, 4101 Rue Sherbrooke est,
Montreal Qc, Canada H1X 2B2
Cold-induced pollen sterility is a problem that greatly affects the rice crops
grown in Australia and other temperate-climate regions of the world. Male
gametophyte development in rice is highly sensitive to abiotic stresses such
as drought, cold, heat, and salinity. Cold temperatures at the young microspore
stage of pollen development cause a reduction in pollen fertility, which
ultimately results in large reductions in grain yield. We are studying the effect
of cold temperature on sugar metabolism in rice anthers. We have found that
pollen sterility induced by cold is associated with an accumulation of sucrose
and decreased cell wall invertase activity in anthers at the young microspore
stage, and cold-affected pollen lacks starch at maturity. We have identified
a cell wall invertase gene (OSINV4) that is expressed in rice anthers and is
down-regulated by cold treatment. Expression analysis of monosaccharide
transporter genes in rice anthers indicates that a sugar transport pathway
involving OSINV4 could be blocked by cold. These results suggest that cold
temperatures may induce a re-direction of sugars away from the developing
microspores. Cold-induced pollen sterility is also associated with an increase
in the hormone ABA within 5 hours of cold treatment at the young microspore
stage of pollen development. These results indicate that ABA might be
involved in signalling events that cause pollen sterility, possibly interacting
with sugar signalling pathways.
15 th <strong>International</strong> <strong>Conference</strong> on Arabidopsis Research 2004 · Berlin
T12-010
Molecular and Genetic Analysis of rough endosperm
Mutants in Maize
Diego Fajardo(1), Susan Latshaw(1), Donald R. McCarty(1), A. Mark Settles(1)
1-University of Florida
The Arabidopsis endosperm is largely subsumed in the mature seed with only
a persistent single cell layer that is comparable to a cereal aleurone. Due to
the reduced size of the Arabidopsis endosperm, it is difficult to identify genes
required for cereal grain development from Arabidopsis mutants. In contrast,
the maize endosperm is an expanded and differentiated organ in mature
kernels, and thus, is an accessible genetic model for plant development. As
a direct product of fertilization, the endosperm does not require a functional
meristem for organ formation or cell type differentiation. A molecular
understanding of endosperm development mutants should provide a basis for
targeted seed improvement and will answer basic questions about organ formation
in maize. The rough endosperm (rgh) class of seed mutants disrupts
normal endosperm and embryo development and is characterized by seeds
with a pitted or etched surface. We have identified 140 rgh mutant isolates
from the UniformMu population. UniformMu is a Robertson’s Mutator, transposon-active
population that is introgressed into the W22 color-converted
inbred. We used SSR and B-A translocation mapping to locate 17 of these
rgh isolates to the long arm of chromosome 5. Mature kernel sections of the
5L rghs showed several distinct endosperm and embryo defects suggesting
possible allelic groups. Preliminary complementation tests based on these
phenotypic groups indicate at least 4 loci. Furthermore, the complementation
tests identified multiple alleles for 3 of the 5L rgh loci To clone the rgh
genes, we are utilizing MuTAIL-PCR to amplify Mu-flanking sequences from
selected mutants.
T12 Non-Arabidopsis (Limitations of the Arabidopsis Model)