Light regulation and differential tissue-specific expression of phototropin homologues from rice (Oryza sativa ssp. indica)

Jain, Mukesh; Sharma, Pooja; Tyagi, S.; Tyagi, Akhilesh K.; Khurana, Jitendra P.

doi:10.1016/j.plantsci.2006.08.003

Cited by 20 publications

(19 citation statements)

References 33 publications

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“…In rice (Oryza sativa), PHOTs consist of a small gene family with a duplication of PHOT1 and a single PHOT2 gene (Kanegae et al, 2000;Jain et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

A Role for Barley CRYPTOCHROME1 in Light Regulation of Grain Dormancy and Germination

et al. 2014

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It is well known that abscisic acid (ABA) plays a central role in the regulation of seed dormancy and that transcriptional regulation of genes encoding ABA biosynthetic and degradation enzymes is responsible for determining ABA content. However, little is known about the upstream signaling pathways impinging on transcription to ultimately regulate ABA content or how environmental signals (e.g., light and cold) might direct such expression in grains. Our previous studies indicated that light is a key environmental signal inhibiting germination in dormant grains of barley (Hordeum vulgare), wheat (Triticum aestivum), and Brachypodium distachyon and that this effect attenuates as after-ripening progresses further. We found that the blue component of the light spectrum inhibits completion of germination in barley by inducing the expression of the ABA biosynthetic gene 9-cis-epoxycarotenoid dioxygenase and dampening expression of ABA 8'-hydroxylase, thus increasing ABA content in the grain. We have now created barley transgenic lines downregulating the genes encoding the blue light receptors CRYTOCHROME (CRY1) and CRY2. Our results demonstrate that CRY1 is the key receptor perceiving and transducing the blue light signal in dormant grains.

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“…In rice (Oryza sativa), PHOTs consist of a small gene family with a duplication of PHOT1 and a single PHOT2 gene (Kanegae et al, 2000;Jain et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

A Role for Barley CRYPTOCHROME1 in Light Regulation of Grain Dormancy and Germination

et al. 2014

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“…18 In rice, both phot1 and phot2 have also been predicted to function as BL receptors, 19,20 and investigation of the rice genome database has indicated the presence of two copies of phot1 (phot1a and phot1b), as well as one copy of phot2. 19,21,22 Interestingly, mutation of phot1a causes growth defects in rice. 23 Although Arabidopsis phot1/phot2 double mutant plants exhibit significantly decreased growth, loss of growth is not observed in phot1 Arabidopsis mutants.…”

Section: Discussionmentioning

confidence: 99%

Phototropins and chloroplast activity in plant blue light signaling

Goh

2009

Plant Signaling & Behavior

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In plants, phototropins 1 (phot1) and 2 (phot2) mediate chloroplast movement to blue light (BL). A recent report showed that phototropins (phot) are required for the expression of chloroplast genes in rice. The light-induced responses of phot1a rice mutants result in H 2 O 2 -mediated damage to chloroplast photosystems, indicating that phot-regulated responses might be associated with the other photoreceptor, such as cryptochrome (cry) BL receptor. This suggests diversification and specialization of photoreceptor signaling in plants.In order to counteract the adverse effects of environmental ight, plants have evolved sensory mechanisms that monitor their surroundings and adapt their growth and development through the use of a complex signaling network. 1 Plants sense their environmental light conditions by using three principal families of signal-transducing photoreceptors; the red/far-red (R/FR) light-absorbing phytochromes (phy) and the UV-A/blue light (BL)-absorbing cryptochromes (cry) and phototropins (phot). 2 The phys are reversibly photochromic biliproteins that absorb maximally in the R and FR light regions of the spectrum. Cry and phot possess a pair of flavin derivates. Two cry and two phot family members have been identified and well characterized in Arabidopsis. Photoreceptors regulate development throughout the plant lifecycle, from seed germination through to plant maturation and the onset of reproduction. BL regulates a wide variety of photoresponses in higher plants, including chloroplast movement, inhibition of hypocotyls elongation, circadian timing, regulation of gene expression and stomatal opening. [3][4][5] The roles of individual photoreceptors in mediating plant development have, however, often been confounded by redundant, synergistic and in some cases mutually antagonistic mechanisms of action. The mechanisms of photoreceptor signal transduction are far from being completely elucidated, but are believed to involve both cytosolic and nuclear components. The presence of putative kinase domains within photoreceptor proteins has suggested a role for phosphorylation in light signaling. The action of cry1 and cry2 has been demonstrated to involve BL-mediated autophosphorylation. 6,7 Phot1 was originally identified as a 120 kDa-membrane associated protein displaying BL-mediated autophosphorylation. 8 It is now well accepted that phot mediates chloroplast movement, phototropism and stomatal opening in plants in response to BL. Phototropin BL ReceptorsRecent genetic studies using mutant Arabidopsis revealed that at least two distinct types of BL receptors are responsible for BL-induced responses. Microarray analysis suggested that cryptochromes (cry1 and cry2) independently function as key regulators of early BL-induced genes, whereas phototropins (phot1 and phot2, formerly known as NPH1 and NPL1) play subsidiary roles in transcriptional regulation by BL. 9 Cry functions mainly in photomorphogenic responses involving the regulation of photoinduced movement. The cry signaling mechanism in Arabido...

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“…Both phot1 and phot2 were expected to function as photoreceptors in rice Kanegae et al 2000) and investigation of the rice genome database indicated the presence of two copies of PHOT1 (Os Phot1a or Os Nph1a and Os Phot1b), as well as one copy of PHOT2 (Os Nph1b or Os Phot2; Kanegae et al 2000;Iino and Haga 2005;Jain et al 2007). We isolated two mutant alleles in Os NPH1a/Os PHOT1a (Os Phot1a-1 and Os Phot1a-2), using T-DNA and Tos17 insertions, respectively (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Phototropin homologues have been predicted in monocot species such as oat (Zacherl and Huala 1997) and rice (Kanegae et al 2000;Iino and Haga 2005;Jain et al 2007), as well as dicots such as Arabidopsis Jarillo et al 2001) and green pea (Khanna et al 1999). Recent database searches of the rice genome have identified two copies of PHOT1 (Os Nph1a or Os Phot1a and Os Phot1b, which are located on chromosomes 11 and 12, respectively) in which the deduced protein sequences differ by only four amino acids, and a PHOT2 homologue (Os Nph1b or Os Phot2; Kanegae et al 2000;Iino and Haga 2005).…”

Section: Introductionmentioning

confidence: 99%

Rice phot1a mutation reduces plant growth by affecting photosynthetic responses to light during early seedling growth

et al. 2008

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The aim of this work was to characterize the phot1 mutant of rice during early seedling growth in various light conditions. We isolated the rice T-DNA insertion mutant phot1a-1 and compared it to the Tos17 insertion mutant phot1a-2. When phot1a mutants were grown under WL (100) and BL (40 miccromol m(-2) s(-1)), they demonstrated a considerable reduction in photosynthetic capacity, which included decreased leaf CO(2) uptake and plant growth. Pigment analysis showed no significant difference between wild-type and mutants in the Chl a:b ratios, whereas in the latter, total concentration was reduced (a 2-fold decrease). Carotenoid contents of the mutants were also decreased considerably, implying the involvement of phot1a in pigment degradation. Deletion of phot1a showed higher contents of H(2)O(2) in leaves. Chloroplastic APX and SOD activities were lower in the mutants whereas the activities of cytosolic enzymes were increased. Immunoblotting indicated reduced accumulation of photosystem proteins (D1, D2, CP43, Lhca2, and PsaC) relative to the other light-harvesting complexes in the mutant. We conclude that the defect of Os Phot1a affects degradation of chlorophylls and carotenoids, and under photosynthetically active photon fluxes, mutation of phot1a results in loss of photosynthetic capacity owing to the damage of photosystems caused by elevated H(2)O(2) accumulation, leading to a reduction in plant growth.

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Light regulation and differential tissue-specific expression of phototropin homologues from rice (Oryza sativa ssp. indica)

Cited by 20 publications

References 33 publications

A Role for Barley CRYPTOCHROME1 in Light Regulation of Grain Dormancy and Germination

A Role for Barley CRYPTOCHROME1 in Light Regulation of Grain Dormancy and Germination

Phototropins and chloroplast activity in plant blue light signaling

Rice phot1a mutation reduces plant growth by affecting photosynthetic responses to light during early seedling growth

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