Physiological mechanism of light-induced seminal root waving in rice seedlings
Date Issued
2010
Date
2010
Author(s)
Ho, Chia-Hsun
Abstract
Light is an important environmental factor controlling plant growth and development. In this study, it was observed that continuous white light can induce the wavy growth pattern of seminal roots in germinating rice (Oryza sativa L. cv. Taichung Native 1; TCN1) seeds. However, the phenotype of light-induced wavy root was genetic diverse among rice cultivars; for example, the light-induced wavy root could be presented in seedlings of indica type rice (such as TCN1), but could not be presented in that of japonica type cultivars (such as Tainung 67; TNG67). According to the experiment with plants partially exposed to light, it was suggested that the light signal for inducing the wavy roots were directly sensed by root tissues. Analysis of longitudinal sections of wavy seminal roots indicated that light-induced root waving was caused by the asymmetric cell growth on both side of vascular cylinder cells in the root tips. In addition to white light, red light (90 μmol m-2s-1) could also induce root curling phenotype on seminal roots. However; the blue light with high intensity (90 μmol m-2s-1) presented no effect on inducing root waving/curling. On the other hand, other results in our laboratory showed that low intensity (30 μmol m-2s-1) of blue light could induce root waving. Using Aspirin to inhibit endogenous jasmonic acid (JA) biosynthesis in TCN1 seedlings conducted the light-induced curling/wavy root phenotypes were absent. Furthermore, light effects on expressions of the genes involved in JA biosynthesis, i.e., allene oxide synthase (OsAOS) gene family and 12-oxophytodienoic acid reductase (OsOPR1), and a root specific JA-responsive gene, root specific rice PR10 (RSOsPR10) were observed. The data showed that transcript levels of most JA biosynthesis-related and JA-responsive genes were increased in white- and red-light conditions. Moreover, N-1-naphthylphthalamic acid (NPA), an inhibitor of auxin efflux carriers, was used to interrupt auxin polar transport in roots, and then the morphology of light-induced wavy root was eliminated. Thus, the results suggested that JA biosynthesis and auxin polar transport were essential for light-induced seminal root waving in seedlings of indica type rice.
Subjects
light-induced wavy root
File(s)![Thumbnail Image]()
Loading...
Name
ntu-99-R96621115-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):3d01206ccf296fdf014fa571038a7cf3