MORPHOLOGICAL CHARACTERIZATION OF BROWN SARSON (BRASSICA RAPA L. ) GENOTYPES FOR DUS TRAITS

Rapeseed and mustard , the two important oleriferous Brassicae grown in India play a magnanimous role in the national market of edible oils and meals. But the production of the crop is low due to a narrow genetic base. Much effort has been put to diversifying the oilseed breeding. The morphological characterization is the first step towards diversity analysis and conservation of plant genetic resources. A major challenge facing those involved in the testing of new plant varieties for Distinctness, Uniformity, and Stability (DUS) is the need to compare them against all those of ‘common knowledge. Protection of Plant varieties and Farmer’s Right Act insists on Distinctness, Uniformity, and Stability (DUS) characterization of new varieties and recommends the registration of varieties for any one specific novel character. On this backdrop, the present experiment was carried out to evaluate 54 Brassica rapa L. genotypes for DUS characterization under randomized complete block design ( RCBD) with three replication at the experimental farm of GPB, FoA SKUAST-K, Wadura during rabi 2019-2020. The results of the study revealed wide variation in various traits among different Brassica rapa genotypes L. The assessment of 54 genotypes for 09 traits revealed that all the traits were informative with respect to trait expression cum characterization. The different characters studied were having great impact for selection of superior genotypes for further breeding programmes. Hence, the diversity observed among the genotypes could be utilized for cultivar improvement and germplasm conservation programs aimed at improving productivity in Brassica rapaL

Characterization of the BnA10.tfl1 Gene Controls Determinate Inflorescence Trait in Brassica napus L.

Determinate inflorescences have a significant effect on the genetic improvement of rapeseed, so understanding the molecular function underlying the inflorescence trait may be beneficial to oilseed breeding. A previous study found candidate gene BnTFL1 (Terminal Flower 1) for control of the inflorescence trait on Brassica napus chromosome A10 (16,627–16,847 kb). However, little is known about the function of the BnTFL1 gene in B. napus. In this study, we firstly studied the formation of the shoot apical meristem and gene expression in indeterminate and determinate inflorescences; the results showed that the inflorescence architecture and BnA10.TFL1 expression showed significant differences in the shoot apex at the budding stage. Then, two alleles (named BnA10.TFL1 gene from indeterminate and BnA10.tfl1 gene from determinate) were cloned and sequence-analyzed; the results suggest that the open reading frame of the alleles comprises 537 bp, encodes 178 amino acids containing a conserved phosphatidylethanolamine-binding protein (PEBP) domain, and shares high similarity with Arabidopsis thaliana TFL1. To analyze the function of BnA10.TFL1, the BnA10.TFL1 gene was introduced into the determinate A. thaliana tfl1 mutant and B. napus 571 line by complementation experiment. The determinate traits were restored to indeterminate, and expression of BnA10.TFL1 was increased in the indeterminate shoot apex. These results reveal that BnA10.tfl1 is a gene controlling the determinate inflorescence trait. Moreover, the BnA10.TFL1 protein was localized to the nucleus, cytoplasm, and plasma membrane. Collectively, the results of this study help us to understand the molecular mechanism of determinate inflorescences and will provide a reliable research basis for the application of determinate inflorescences in B. napus.

Genetic variability of Canadian elite cultivars of summer turnip rape (Brassica rapa L.) revealed by simple sequence repeat markers

Canadian public oilseed breeding programs have played a leading role in the development of canola-quality Brassica rapa oilseed cultivars, but the genetic variability of the cultivars developed over the past 60 yr is poorly understood. Simple sequence repeat (SSR) markers were applied to assess the genetic variability of 294 plants representing one landrace introduced from Poland ca. 1940 and nine Canadian elite B. rapa cultivars released by Agriculture and Agri-Food Canada since 1964. Application of 18 SSR primer pairs detected 27 likely loci on five or more linkage groups and 123 polymorphic alleles. The allelic frequencies ranged from 0.003 to 0.997 and averaged 0.262. The estimates of mean heterozygosity for these cultivars ranged from 0.126 to 0.197 and averaged 0.165. Significant decreases of SSR alleles and average dissimilarities were observed over the 60 yr of breeding effort. The proportion of total SSR variation residing among the cultivars was 10.4%; between high vs. low erucic acid cultivars 5% and between high- vs. low-glucosinate cultivars 5%. Pairwise genetic differentiation ranged from 0.025 to 0.184 and averaged 0.104. Genetic clustering of these cultivars revealed AC Sunbeam to be a genetically unique cultivar, and two distinct groups of the other nine cultivars were separated by high- vs. low-glucosinate content. Several distinct genotypes, largely derived from the landrace Polish, were identified. These findings are useful for broadening the genetic base of elite B. rapa germplasm, selecting genetically diverse genotypes for synthetic and hybrid combinations, and conserving this germplasm.Key words: Simple sequence repeat, turnip rape (summer), Brassica rapa, genetic diversity, genetic relationship, genetic structure

GENETICS OF PROTEIN AND OIL CONTENT IN SUMMER RAPE: HERITABILITY, NUMBER OF EFFECTIVE FACTORS, AND CORRELATIONS

The estimates of broad sense heritability in the F2 generation derived from a cross involving two summer rape (Brassica napus L.) cultivars were approximately 0.26 for each of percent protein and percent oil, and 0.33 for the "sum" of protein and oil as a percentage of the seed. The number of effective factors conditioning parental differences in percent protein, percent oil, and sum were estimated as five to seven, one, and two, respectively. Average phenotypic and genotypic correlations between protein and oil content were −0.81 and −0.71, respectively. These strong negative correlations, often considered undesirable, can be utilized in oilseed breeding programs by selecting for the sum of protein and oil rather than for either component.