ABSTRACT
BACKGROUND: Sweet corn is gaining tremendous demand worldwide due to urbanization and changing consumer preferences. However, genetic improvement in this crop is being limited by narrow genetic base and other undesirable agronomic traits that hinder the development of superior cultivars. The main requirement in this direction is the development of potentially promising parental lines. One of the most important strategies in this direction is to develop such lines from hybrid-oriented source germplasm which may provide diverse base material with desirable biochemical and agro-morphological attributes. METHODS AND RESULTS: The study was undertaken to carry out morphological and biochemical evaluation of 80 early generation inbred lines (S2) of sweet corn that were developed from a cross between two single cross sweet corn hybrids (Mithas and Sugar-75). Moreover, validation of favourable recessive alleles for sugar content was carried out using SSR markers. The 80 sweet corn inbreds evaluated for phenotypic characterization showed wide range of variability with respect to different traits studied. The highest content of total carotenoids was found in the inbred S27 (34 µg g-1) followed by the inbred S65 (31.1 µg g-1). The highest content for total sugars was found in S60 (8.54%) followed by S14 (8.34%). Molecular characterization of 80 inbred lines led to the identification of seven inbreds viz., S21, S28, S47, S48, S49, S53, and S54, carrying the alleles specific to the sugary gene (su1) with respect to the markers umc2061 and bnlg1937. Comparing the results of scatter plot for biochemical and morphological traits, it was revealed that inbreds S9, S23, S27 and S36 contain high levels of total sugars and total carotenoids along with moderate values for amylose and yield attributing traits. CONCLUSION: The inbred lines identified with desirable biochemical and agro-morphological attributes in the study could be utilized as source of favourable alleles in sweet corn breeding programmes after further validation for disease resistance and other agronomic traits. Consequently, the study will not only enhance the genetic base of sweet corn germplasm but also has the potential to develop high-yielding hybrids with improved quality. The inbreds possessing su1 gene on the basis of umc2061 and bnlg1937 markers were also found to possess high sugar content. This indicates the potential of these lines as desirable candidates for breeding programs aimed at improving sweet corn yield and quality. These findings also demonstrate the effectiveness of the molecular markers in facilitating marker-assisted selection for important traits in sweet corn breeding.
Subject(s)
Plant Breeding , Zea mays , Zea mays/genetics , Phenotype , Vegetables , Sugars , CarotenoidsABSTRACT
BACKGROUND: Kashmir valley, India is a homeland to rice landraces like Zag, Nunbeoul, Qadirbeigh, Kawkadur, Kamad, Mushk Budji, etc., generally characterized by short grains, aroma, earliness and cold tolerance. Mushk Budji is a commercially important speciality rice known for its taste and aroma, nonetheless, is extremely vulnerable to blast disease. Through the use of the marker-assisted backcrossing (MABC) approach, a set of 24 Near-isogenic lines (NILs) was created, and the lines with the highest background genome recovery were chosen. The expression analysis was carried out for the component genes and other eight pathway genes related to blast resistance. RESULTS: The major blast resistance genes Pi9 (from IRBL-9W) and Pi54 (from DHMAS 70Q 164-1b) were incorporated following simultaneous-but-step-wise MABC. The NILs harbouring genes Pi9 + Pi54, Pi9 and Pi54 expressed resistance to isolate (Mo-nwi-kash-32) under controlled and natural field conditions. The loci controlling ETI (effector triggered immunity) included the gene Pi9 and showed 61.18 and 60.27 fold change in relative gene expression in Pi54 + Pi9 and Pi9 carrying NILs against RP Mushk Budji. Pi54 was up regulated and showed 41 and 21 fold change in relative gene expression for NIL-Pi54 + Pi9 and NIL-Pi54, respectively. Among the pathway genes, LOC_Os01g60600 (WRKY 108) recorded 8 and 7.5 fold up regulation in Pi9 and Pi54 NILs. CONCLUSION: The NILs showed recurrent parent genome recovery (RPG) per cent of 81.67 to 92.54 and were on par in performance to recurrent parent Mushk Budji. The lines were utilized to study the expression of the loci controlling WRKYs, peroxidases and chitinases that confer overall ETI response.
