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RISS 인기검색어
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- 저자 : ( T. R. Ganapathi ) (검색결과 4 건)
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Overexpression of MusaNAC68 reduces secondary wall thickness of xylem tissue in banana
Sanjana Negi,Himanshu Tak,T. R. Ganapathi 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.2
Secondary wall is an important component of xylem tissue, as it maintains the integrity of the vessel elements and provides mechanical strength for upward growth of plants. Enough prior evidence has linked secondary wall thickening with auxinsignaling pathway. Hence, plants showing auxin-mediated effects might demonstrate alteration of secondary wall depositions. GUS expression from promoter of NAC68 (pMusaNAC68) was observed in many organs with strong expression in vascular tissues. Transgenic banana plants overexpressing NAC68 transcription factor were analyzed for lignin and secondary wall depositions. Strong reduction of lignin in cross-sections of transgenic lines was observed by phloroglucinol-HCl and toluidine blue-O staining. The reduction of secondary wall thickness observed after calcofluor white staining was substantiated by data from scanning electron microscopy indicating reproducibly lower secondary wall depositions. A strong reduction in transcript levels of PAL, 4CL, C4H, COMT and CcOAMT was observed due to the overexpression of NAC68. Furthermore, substantial elevation of MYB transcription factors such as MYB4a-like and MYB4b-like which are probable repressors of phenylpropanoid biosynthesis pathway was also observed. Expression of MYB transcription factors, MYB85-like and MYB58-like which are probable activators of secondary wall depositions, was remarkably downregulated after NAC68 overexpression. Transgenic lines also showed altered expression of genes coding for cellulose synthase subunits with remarkable elevation in expression of a close homologue of Arabidopsis CesA8, which functions in cellulose deposition during secondary wall development. The study indicated a novel function of NAC68 transcription factor in regulating secondary wall thickening and will enhance our knowledge about crosstalk between auxin-signaling and secondary wall depositions.
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Sanjana Negi,Himanshu Tak,T. R. Ganapathi 한국식물생명공학회 2015 Plant biotechnology reports Vol.9 No.2
Tracheary elements formation was observed in banana embryogenic cells cultured in brassinolide-supplemented medium after a period of 10 days. The highest frequency of tracheary elements observed after 10 days was up to 31.88 %. The auxin, 2,4-D was found to be inhibitor of tracheary elements formation in brassinolidesupplemented medium and at a concentration of 1.5 lM of 2,4-D, the frequency of tracheary elements formation was reduced to zero. The appearance of secondary wall in these xylem vessel elements was observed by toluidine blue staining and lignin autofluorescence under fluorescence as well as laser confocal microscopy. Similar to lignin autofluorescence imaging, the calcofluor white staining also revealed development of characteristic secondary wall in these xylem vessel elements indicating deposition of cellulose along with lignin during secondary wall formation. The xylem vessel elements induced comprised of fiber-like elements (FLEs) and tracheary elements with deposition of secondary wall. Expression analysis of lignin biosynthesis pathway genes indicated that important genes like CCR, CCoAOMT and COMT were induced as early as fifth day of brassinolide (BL) treatment. Changes in transcript level of key master regulators of xylogenesis during tracheary elements formation showed that expression of vascularrelated NAC domain containing transcription factors (VND) were up-regulated with induction of VND1–3 and VND6–7 expression as early as third day of brassinolide treatment. This study of in vitro tracheary elements formation in embryogenic cell suspension cultures is useful in understanding the genes involved in secondary wall thickening in banana.
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( Ashok Badigannavar ),( Ashok Kumar ),( G. Girish ),( T. R. Ganapathi ) 한국육종학회 2017 Plant Breeding and Biotechnology Vol.5 No.2
Sorghum is a major staple crop and vital for the marginal farmers in Asian and African countries. Landraces or germplasm lines adapted to biotic and abiotic stresses are the prime source of adaptive traits in the crop breeding programs. In order to assess the genetic variability, 141 exotic germplasm lines and 36 popular varieties were evaluated for eight agro-morphological traits. Wide range of values were observed for grain yield (6.6-124.4 g/plant), seed index (1.5-7.1 g/100 seeds), panicle length (8-44 cm) and panicle width (7.25 cm). High genotypic and phenotypic coefficient of variation was observed for grain yield per plant. The values of broad sense heritability in the sorghum core population ranged from 0.75 to 0.99. Seed weight, days to flowering, panicle width and leaf area were significantly correlated with grain yield (P ≤ 0.01). Seed weight was positively correlated with panicle width (correlation coefficient 0.31), while negatively correlated with panicle length (correlation coefficient -0.15). Cluster analysis resolved all the genotypes into four major clusters. Among germplasm lines, TSG-313 had high seed weight of 7.05 g/100 seeds, while TSG-325 had highest grain yield of 124.4 g/plant as against control variety. Germplasm lines with high heritability scores would help us to utilise them in recombination breeding.
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