Plant breeding for abiotic & biotic stresses
Fariba Morsali Aghajari; Reza Darvishzadeh; Mitra Razi
Abstract
Salinity is one of the most important non-biological stresses that affect plant growth and development. Effect of different levels of NaCl (0, 2, 4, 6 and 8 dS/m) were investigated on enzymatic and non-enzymatic activities in C64 and C68 oilseed sunflower genotypes at two times; 3 and 12 days after salinity ...
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Salinity is one of the most important non-biological stresses that affect plant growth and development. Effect of different levels of NaCl (0, 2, 4, 6 and 8 dS/m) were investigated on enzymatic and non-enzymatic activities in C64 and C68 oilseed sunflower genotypes at two times; 3 and 12 days after salinity stress application. Net photosynthesis rate, chlorophyll content and soluble proteins amount decreased by increasing salinity level but proline and malondialdehyde (MDA) contents increased. However, the changes in net photosynthesis in the two studied genotypes was different across time and do not follow statistically the same trend line. In genotype C86, the reduction of photosynthesis rate at all studied salinity levels was very high compared to normal condition (0 dS/m) after 3 days; especially at salinity levels of 2, 4 and 6 dS/m, while 12 days later, the decrease of photosynthesis rate was moderate at salinity levels of 2 and 4 dS/m but severe at 6 and 8 dS/m salinity levels. The highest amount of proline (31.36%) related to tolerant genotype and the lowest amount (7.72%) related to susceptible one was measured 12 days after 2 dS/m salt stress treatment. Considerable MDA was observed in both tolerant and sensitive genotypes 12 days post salt stress application; the highest amount (83%) was observed at 8 dS/m treatment. Catalase and ascorbate peroxidase activity increased with increasing salt intensity. The rate of increase in guaiacol peroxidase activity was higher in C86 genotype than C64. Chlorophyll a and total chlorophyll contents decreased in both sunflower genotypes under salinity stress. The lowest amount of total chlorophyll (8.6%) was observed in the salinity level of 8 dS/m in the sensitive line (C64). Results revealed the C64 and C68 selected genotypes from two our identified sunflower heterotic groups have different physiological response to salinity stress and C68 is more tolerant to salt stress than C64. So, they can be potentially used as parents in sunflower breeding programs to produce salt stress tolerant hybrids.
Molecular markers & plant breeding
Nader Eyvaznejad; Reza Darvishzadeh
Abstract
Many agriculturally important traits are complex, affected by many genes and the environment. Quantitative trait loci (QTL) mapping is a key tool for studying the genetic structure of complex traits in plants. In the present study QTLs associated with yield and agronomical traits such as leaf number, ...
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Many agriculturally important traits are complex, affected by many genes and the environment. Quantitative trait loci (QTL) mapping is a key tool for studying the genetic structure of complex traits in plants. In the present study QTLs associated with yield and agronomical traits such as leaf number, leaf length, leaf width, plant height, stem and head diameter were identified by using 70 recombinant inbred lines (RILs) from the cross (♀) PAC2 × RHA266(♂). RILs and their parents were evaluated in a rectangular 8´9 lattice design with two replications. High genetic variability and transgressive segregation were observed in all studied traits. Genetic gain representing the difference between 10% of selected RILs and their parents was significant for most of the studied traits. Positive and significant genotypic and phenotypic correlations were observed among the studied traits. QTL analysis was performed using a recently developed SSR and SNP sunflower linkage map. The map consists of 210 SSRs and 11 SNP markers placed in 17 linkage groups (LGs). The total map length is 1,653.1 cM with a mean density of 1 marker per 7.44 cM. Composite interval mapping (CIM) procedure detected 21 QTLs involved in genetic control of studied traits. The phenotypic variance explained by the identified QTLs varied from 1.13 to 73.70%. QTLs such as HMBPP associated with the expression of more than one trait could increase the efficiency of marker-assisted selection (MAS) and genetic progress in sunflower.