The date palm is one of the most important economic species of the palm family, grown mainly for its fruits (dates). Nowadays there is increased demand for date palm fruits around the world. To meet this demand, several propagation methods have been utilized, among them micropropagation which has been used in Iraq and many other countries for large-scale multiplication of date palm. Micropropagation faces several constraints; one is microbial contamination which represents a major challenge to the initiation and maintenance of date palm micropropagation laboratories. In recent years, two major groups of contaminants have been identified and isolated from different date palm tissue culture laboratories in Iraq. The first group is fungi. Several fungal species have been isolated and identified as contaminants; most predominant are: Aspergillus niger, Alternaria alternata and Penicillium spp. The second group is bacteria; predominantly of the genera Bacillus, Staphylococcus and Proteus.
Genetic stability and uniformity of in vitro-derived date palm plants has a major importance to ascertain true-to-typeness of produced plants. The goal of present study was to evaluate the genetic toxicity of different plant growth regulators on date palm callus at initiation stages using protein patterns and RAPD analysis. Date palm offshoots of Hillawii cultivar were dissected, apical meristems were divided into four segments and cultured on callus induction medium containing the plant growth regulators as 2,4-D at 50 and 100 mg/L; NAA at 30 mg/L and Dicamba at 10 mg/L. The changes occurred in protein profile of callus when treated with high concentration of 2,4-D (100 mg/L), including loss of normal fragments (19 and 66 KDa polypeptides in control), as well as, appearance of new fragments, while at low concentration of 2,4-D (50 mg/L) and Dicamba treatment, the protein patterns showed no changes compared to control profile. Similar trends of polymorphisms were obtained with RAPD marker. The high concentration of 2,4-D produced more polymorphic fragments in comparison to control treatment. The DNA profile was identical between 2,4-D at low concentration and control. Dendrograms were generated using similarity indices of protein and RAPD results, and revealed that genetic similarity index was high between 2,4-D treatment at low concentration and control, as separated in one subcluster, followed by Dicamba and NAA, while, the highest genetic distance was obtained between 2,4-D at high concentration and control treatment and separated alone in one cluster.
Background
Wheat is the most consumed cereal crops in the world infected by several pathogens and pests causing significant losses. The most threatening pathogens are fungi which cause serious diseases on roots, leaves and heads as one of the most threatening pathogens in specific wheat-growing countries. This study aimed to identify and evaluate the prevalence of damping-off fungal pathogens in different wheat fields at Basra and Maysan provinces.
Results
Disease incidence determination and fungal isolation were carried out from two sites at Basra province (Al-Qurna and Al-Madinah) and three sites at Maysan province (Al-Amarah, Kumit, Ali Al Sharqi and Ali Al Gharbi). Al-Qurna fields had the highest disease incidence (32%), while Ali-Alsharqi fields had the lowest one (11%). Fourteen fungal genera were identified. Rhizoctonia solani had the highest appearance (21.6) and frequency (20.20%) percentages followed by Fusarium solani (16.11,14.01) percentages and Macrophomina phaseolina (12.2,11.1) percentages. Seed treatment with R. solani (Rs1 isolate) showed significant decrease in germination (56.6%) compared to F. solani and M. phaseolina treatments. Seed treatment with R. solani (Rs1 isolate) showed significant decrease in germination (56.6%) compared to F. solani and M. phaseolina treatments.
Conclusions
These results revealed the prevalence of wheat damping-off disease in all examined fields at both Basra and Maysan province; the highest disease incidence was seen in Basra wheat fields (Al-Qurna fields); the identification of fungal pathogens showed that the most isolated fungus was R. solani followed by F. solani and M. phaseolina. Laboratory experiments showed the pathogenicity of isolated fungi which varied according to the isolate type.
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