Overexpression of phytochrome A and its hyperactive mutant improves shade tolerance and turf quality in creeping bentgrass and zoysiagrass.
Phytochrome A (phyA) in higher plants is known to function as a far-red/shade light-sensing photoreceptor in suppressing shade avoidance responses (SARs) to shade stress. In this paper, the Avena PHYA gene was introduced into creeping bentgrass (Agrostis stolonifera L.) and zoysiagrass (Zoysia japonica Steud.) to improve turf quality by suppressing the SARs. In addition to wild-type PHYA, a hyperactive mutant gene (S599A-PHYA), in which a phosphorylation site involved in light-signal attenuation was removed, was also transformed into the turfgrasses. Phenotypic traits of the transgenic plants were compared to assess the suppression of SARs under a simulated shade condition and outdoor field conditions after three growth seasons. Under the shade condition, the S599A-PhyA transgenic creeping bentgrass plants showed shade avoidance-suppressing phenotypes with a 45 % shorter leaf lengths, 24 % shorter internode lengths, and twofold increases in chlorophyll concentrations when compared with control plants. Transgenic zoysiagrass plants overexpressing S599A-PHYA also showed shade-tolerant phenotypes under the shade condition with reductions in leaf length (15 %), internode length (30 %), leaf length/width ratio (19 %) and leaf area (22 %), as well as increases in chlorophyll contents (19 %) and runner lengths (30 %) compared to control plants. The phenotypes of transgenic zoysiagrass were also investigated in dense field habitats, and the transgenic turfgrass exhibited shade-tolerant phenotypes similar to those observed under laboratory shade conditions. Therefore, the present study suggests that the hyperactive phyA is effective for the development of shade-tolerant plants, and that the shade tolerance nature is sustained under field conditions.
Faculty of Biotechnology and Subtropical Horticulture Research Institute, Jeju National University, Jeju 690-756, Korea.
Markkandan
M
Ganesan
Yun-Jeong
YJ
Han
Tae-Woong
TW
Bae
Ok-Jin
OJ
Hwang
Thummala
T
Chandrasekhar
Thummala
T
Chandrasekkhar
Ah-Young
AY
Shin
Chang-Hyo
CH
Goh
Satoshi
S
Nishiguchi
In-Ja
IJ
Song
Hyo-Yeon
HY
Lee
Jeong-Il
JI
Kim
Pill-Soon
PS
Song
D031703:Agrostis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D015139:Blotting, Southern; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D004579:Electron Transport; D005453:Fluorescence; D015870:Gene Expression; D008027:Light; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D051942:Phytochrome A / Q000235:genetics* / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D058526:Plant Vascular Bundle / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D006109:Poaceae / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects
D051942:Phytochrome A; D002734:Chlorophyll