Browsing by Author "Tyagi, Anshika"

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Genetics of flowering time in bread wheat Triticum aestivum: complementary interaction between vernalization-insensitive and photoperiod-insensitive mutations imparts very early flowering habit to spring wheat
(Indian Academy of Sciences, 2012) Kumar, Sushil; Sharma, Vishakha; Chaudhary, Swati; Tyagi, Anshika; Mishra, Poonam
Time to flowering in the winter growth habit bread wheat is dependent on vernalization (exposure to cold conditions) and exposure to long days (photoperiod). Dominant Vrn-1 (Vrn-A1, Vrn-B1 and Vrn-D1) alleles are associated with vernalization independent spring growth habit. The semidominant Ppd-D1a mutation confers photoperiod-insensitivity or rapid flowering in wheat under short day and long day conditions. The objective of this study was to reveal the nature of interaction between Vrn-1 and Ppd-D1a mutations (active alleles of the respective genes vrn-1 and Ppd-D1b). Twelve Indian spring wheat cultivars and the spring wheat landrace Chinese Spring were characterized for their flowering times by seeding them every month for five years under natural field conditions in New Delhi. Near isogenic Vrn-1 Ppd-D1 and Vrn-1 Ppd-D1a lines constructed in two genetic backgrounds were also phenotyped for flowering time by seeding in two different seasons. The wheat lines of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1a, Vrn-A1a Vrn-B1 Ppd-D1a and Vrn-A1a Vrn-D1 Ppd-D1a (or Vrn-1 Ppd-D1a) genotypes flowered several weeks earlier than that of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1b, Vrn-A1b Ppd-D1b and Vrn-D1 Ppd-D1b (or Vrn-1 Ppd-D1b) genotypes. The flowering time phenotypes of the isogenic vernalization-insensitive lines confirmed that Ppd-D1a hastened flowering by several weeks. It was concluded that complementary interaction between Vrn-1 and Ppd-D1a active alleles imparted super/very-early flowering habit to spring wheats. The early and late flowering wheat varieties showed differences in flowering time between short day and long day conditions. The flowering time in Vrn-1 Ppd-D1a genotypes was hastened by higher temperatures under long day conditions. The ambient air temperature and photoperiod parameters for flowering in spring wheat were estimated at 25°C and 12 h, respectively.
Variability in the accessions from aravali range assessed for domestication of the Cleomaceae biodiesel plant Cleome viscosa Linn
(NISCAIR, 2012) Kumari, Rashmi; Tyagi, Anshika; Sharma, Vishakha; Jain, Vinod Kumar; Kumar, Sushil
In an earlier study at our laboratory showed that the biodiesel derived from the seed oil of the annual herbaceous medicinal weed plant Cleome viscosa Linn. possesses properties similar to the commercial biodiesel produced from Jatropha seed oil. Here, the possibilities of domestication of C. viscosa were examined. With this objective, 15 accessions from Aravali range in North-West India and two from North-East India were evaluated for phenotypic and genetic variability. The accessions were cultivated in four seasons from May to November 2009 at New Delhi by growing them in randomized block design replicated four times. The accessions were studied for 6 qualitative and 13 agronomic characters and significant genetic variability in all the agronomic traits was observed. On the basis of morphological features, the accessions fell into two groups: a small leaved group and a large leaved group. While the small leaved group comprised of accessions from Rajasthan, the large leaved group included accessions from different locations in North-west and North-East India. One of the small leaved accessions called CVR14 was identified as a putative high yielding accession. The July-October (or monsoon-autumn) season of about 13-15 weeks was observed to be the most suitable period for obtaining rainfed crop of C. viscosa CVR14. The DNA fingerprinting based analysis of hierarchical relationships between accessions demonstrated that large leaved and small leaved accessions were inter-related. The results indicated that C. viscosa accessions from diverse locations perhaps comprised a single complex.