Studies on sodium bypass flow in lateral rootless mutants lrt1 and lrt2, and crown rootless mutant crl1 of rice (Oryza sativa L.).
An apoplastic pathway, the so-called bypass flow, is important for Na+ uptake in rice (Oryza sativa L.) under saline conditions; however, the precise site of entry is not yet known. We report the results of our test of the hypothesis that bypass flow of Na+ in rice occurs at the site where lateral roots emerge from the main roots. We investigated Na+ uptake and bypass flow in lateral rootless mutants (lrt1, lrt2), a crown rootless mutant (crl1), their wild types (Oochikara, Nipponbare and Taichung 65, respectively) and in seedlings of rice cv. IR36. The results showed that shoot Na+ concentration in lrt1, lrt2 and crl1 was lower (by 20-23%) than that of their wild types. In contrast, the bypass flow quantified using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) was significantly increased in the mutants, from an average of 1.1% in the wild types to 3.2% in the mutants. Similarly, bypass flow in shoots of IR36 where the number of lateral and crown roots had been reduced through physical and hormonal manipulations was dramatically increased (from 5.6 to 12.5%) as compared to the controls. The results suggest that the path of bypass flow in rice is not at the sites of lateral root emergence.
Faiyue
Bualuang
B
Department of Biology and Environmental Science, School of Life Sciences, University of Sussex, Brighton BN19QG, UK. B.Faiyue@sussex.ac.uk
Vijayalakshmi
Chenniappan
C
Nawaz
Shafqat
S
Nagato
Yasuo
Y
Taketa
Shin
S
Ichii
Masahiko
M
Al-Azzawi
Mohammed J
MJ
Flowers
Timothy J
TJ
D001692:Biological Transport; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D052585:Phloem / Q000737:chemistry; D018517:Plant Roots / Q000033:anatomy & histology*; D018520:Plant Shoots / Q000378:metabolism / Q000502:physiology; D018526:Plant Transpiration; D011721:Pyrenes / Q000378:metabolism; D036226:Seedlings / Q000033:anatomy & histology / Q000502:physiology; D012964:Sodium / Q000378:metabolism* / Q000502:physiology; D013451:Sulfonic Acids / Q000378:metabolism
C538892:8-hydroxy-1,3,6-pyrenetrisulfonic acid; D011721:Pyrenes; D013451:Sulfonic Acids; D012964:Sodium