Expression Patterns of OsPIL11,a Phytochrome-Interacting Factor in Rice,and Preliminary Analysis of Its Roles in Light Signal Transduction

The expression patterns of OsPILll, one of six putative phytochrome-interacting factors, were analyzed in different organs of transgenic tobacco （Nicotiana tabacum）. The expression of OsPIL 11 was organ-specific and was regulated by leaf development, abscisic acid （ABA）, jasmonic acid （JA） and salicylic acid （SA）. To further explore the role of OsPIL 11 in plant light signal transduction, a plant expression vector of OsPILll was constructed and introduced into tobacco. When grown under continuous red light, OsPILll-overexpressed transgenic tobacco exhibited shorter hypocotyls and larger cotyledons and leaves compared to wild-type seedlings. When grown under continuous far-red light, however, transgenic and wild-type seedlings showed similar phenotypes. These results indicate that OsPILll is involved in red light induced de-etiolation, but not in far-red light induced de-etiolation in transgenic tobacco, which lays the foundation for dissecting the function of OsPIL11 in phytochrome-mediated light signal transduction in rice.

Coordinated Shoot and Root Responses to Light Signaling in Arabidopsis

Light is one of the most important environmental signals and regulates many biological processes in plants.Studies on light-regulated development have mainly focused on aspects of shoot growth,such as deetiolation,cotyledon opening,inhibition of hypocotyl elongation,flowering,and anthocyanin accumulation.However,recent studies have demonstrated that light is also involved in regulating root growth and development in Arabidopsis.In this review,we summarize the progress in understanding how shoots and roots coordinate their responses to light through different light-signaling components and pathways,including the COP1(CONSTITUTIVELY PHOTOMORPHOGENIC 1),HY5(ELONGATED HYPOCOTYL 5),and MYB73/MYB77(MYB DOMAIN PROTEIN 73/77)pathways.

Temporal control of the Aux/IAA genes BnIAA32 and BnIAA34 mediates Brassica napus dual shade responses

Precise responses to changes in light quality are crucial for plant growth and development.For example,hypocotyls of shade-avoiding plants typically elongate under shade conditions.Although this typical shade-avoidance response(TSR)has been studied in Arabidopsis(Arabidopsis thaliana),the molecular mechanisms underlying shade tolerance are poorly understood.Here we report that B.napus(Brassica napus)seedlings exhibit dual shade responses.In addition to the TSR,B.napus seedlings also display an atypical shade response(ASR),with shorter hypocotyls upon perception of early-shade cues.Genome-wide selective sweep analysis indicated that ASR is associated with light and auxin signaling.Moreover,genetic studies demonstrated that phytochrome A(BnphyA)promotes ASR,whereas BnphyB inhibits it.During ASR,YUCCA8 expression is activated by early-shade cues,leading to increased auxin biosynthesis.This inhibits hypocotyl elongation,as young B.napus seedlings are highly sensitive to auxin.Notably,two non-canonical AUXIN/INDOLE-3-ACETIC ACID(Aux/IAA)repressor genes,BnIAA32 and BnIAA34,are expressed during this early stage.BnIAA32 and BnIAA34 inhibit hypocotyl elongation under shade conditions,and mutations in BnIAA32 and BnIAA34 suppress ASR.Collectively,our study demonstrates that the temporal expression of BnIAA32 and BnIAA34 determines the behavior of B.napus seedlings following shade-induced auxin biosynthesis.