Browsing by Author "Sane, Aniruddha P."

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Differential and reciprocal regulation of ethylene pathway genes regulates petal abscission in fragrant and non-fragrant roses
(Elsevier B.V., 2019) Singh, Priya; Singh, Amar Pal; Sane, Aniruddha P.
The fragrant rose, Rosa bourboniana, is highly sensitive to ethylene and shows rapid petal abscission (within 16-18 h) while the non-fragrant hybrid rose, R. hybrida, shows delayed abscission (50-52 h) due to reduced ethylene sensitivity. To understand the molecular basis governing these differences, all components of the ethylene pathway (biosynthesis/receptor/signalling) were studied for expression during abscission. Transcript accumulation of most ethylene biosynthesis genes (ACS/ACO families) increased rapidly in petal abscission zones of R. bourboniana within 4-8 h of ethylene treatment. The expression of most receptor and signalling genes encoding CTRs, EIN2 and EIN3/EIL homologues also followed similar kinetics. Under natural field conditions where abscission takes longer, there was a temporal delay in transcript accumulation of most ethylene pathway genes while some biosynthesis genes (showing reduced ethylene sensitivity) were more strongly up-regulated by abscission cues. In contrast, in R. hybrida where even ethylene-induced abscission is considerably delayed, transcript accumulation of most ethylene biosynthesis and signalling genes was, surprisingly, reduced by ethylene and showed an opposite regulation compared to R. bourboniana. The results suggest that differential and reciprocal regulation of ethylene pathway is one of the major reasons for differences in petal abscission and vase-life between Rosa bourboniana and R. hybrida.
Petal abscission in fragrant roses is associated with large scale diferential regulation of the abscission zone transcriptome
(Springer Nature Publishing AG, 2020) Singh, Priya; Bharti, Neeraj; Singh, Amar Pal; Tripathi, Siddharth Kaushal; Pandey, Saurabh Prakash; Chauhan, Abhishek Singh; Kulkarni, Abhijeet; Sane, Aniruddha P.
Flowers of fragrant roses such as Rosa bourboniana are ethylene-sensitive and undergo rapid petal abscission while hybrid roses show reduced ethylene sensitivity and delayed abscission. To understand the molecular mechanism underlying these diferences, a comparative transcriptome of petal abscission zones (AZ) of 0 h and 8 h ethylene-treated fowers from R. bourboniana was performed. Diferential regulation of 3700 genes (1518 up, 2182 down) representing 8.5% of the AZ transcriptome was observed between 0 and 8 h ethylene-treated R. bourboniana petal AZ. Abscission was associated with large scale up-regulation of the ethylene pathway but prominent suppression of the JA, auxin and light-regulated pathways. Regulatory genes encoding kinases/phosphatases/F-box proteins and transcription factors formed the major group undergoing diferential regulation besides genes for transporters, wall modifcation, defense and phenylpropanoid pathways. Further comparisons with ethylene-treated petals of R. bourboniana and 8 h ethylene-treated AZ (R. hybrida) identifed a core set of 255 genes uniquely regulated by ethylene in R. bourboniana AZ. Almost 23% of these encoded regulatory proteins largely conserved with Arabidopsis AZ components. Most of these were up-regulated while an entire set of photosystem genes was prominently down-regulated. The studies provide important information on regulation of petal abscission in roses.
Petal abscission in roses is associated with the activation of a truncated version of the animal PDCD4 homologue, RbPCD1
(Elsevier B.V., 2019) Singh, Priya; Singh, Amar Pal; Tripathi, Siddharth Kaushal; Kumar, Vinod; Sane, Aniruddha P.
Abscission is a developmental process that leads to shedding of organs not needed by the plant. Apart from wallhydrolysis, the cells of the abscission zone (AZ) are also believed to undergo programmed cell death (PCD). Weshow that ethylene-induced petal abscission inRosa bourbonianais accompanied with the activation ofRbPCD1(PROGRAMMED CELL DEATH LIKE 1) encoding a protein of 78 amino acids. Its expression increases duringnatural and ethylene-induced petal abscission. Its transcription in most tissues is up-regulated by ethylene.RbPCD1 shows similarity to the N-terminal domain of animal PDCD4 (PROGRAMMED CELL DEATH PROTEIN 4)proteins that are activated during apoptosis and function as transcriptional and translational repressors. RbPCD1resides in the nucleus and cytoplasm and acts as a transcriptional repressor. Constitutive expression ofRbPCD1intransgenic Arabidopsis is seedling lethal. Heat-induced expression ofRbPCD1under the soybean heat-shockpromoter affects leaf function, inflorescence development, silique formation, seed yield and reduces survival.Nuclear localization of RbPCD1 is necessary for manifestation of its effects. RbPCD1 may be necessary to mediatesome of the ethylene-induced changes during abscission and senescence in specific tissues.
A strong early acting wound-inducible promoter, RbPCD1pro, activates cryIAc expression within minutes of wounding to impart efficient protection against insects
(John Wiley & Sons, 2019) Pandey, Saurabh Prakash; Singh, Amar Pal; Srivastava, Shruti; Chandrashekar, Krishnappa; Sane, Aniruddha P.
The expression of insecticidal proteins under constitutive promoters in transgenic plants is fraught with problems like developmental abnormalities, yield drag, expression in unwanted tissues, and seasonal changes in expression. RbPCD1pro, a rapid, early acting wound-inducible promoter from rose that is activated within 5 min of wounding, was isolated and characterized. Wounding increased transcript levels up to 150 and 500 folds within 5 and 20 min coupled with high translation as seen by histochemical GUS enzyme activity within 5–20 min. RbPCD1pro was activated by both sucking and chewing insects and showed wound-inducible expression in various aerial tissues of plants representing commercially important dicot and monocot families. The promoter showed no expression in any vegetative tissue except upon wounding. Functionality of RbPCD1pro was tested by its ability to drive expression of the insecticidal protein gene cryIAc in transgenic Arabidopsis and tomato. Strong wound-inducible CryIAc expression was observed in both plants that increased 100–350 fold (Arabidopsis) and 280–600 fold (tomato) over the unwounded background within 5 min and over 1000–1600 fold within 20 min. The unwounded background level was just 3–6% of the CaMV35S promoter while wound-induced expression was 5–27 folds higher than the best CaMV35S line in just 5 min and 80-fold higher in 20 min. Transgenic plants showed strong resistance even to larger fourth instar larvae of H. armigera and no abnormalities in development and general plant growth. This is one of the earliest acting promoters with wide biotechnological application across monocot and dicot plants.