Molecular markers enable the detection and classification of fungi isolated from their natural environments. To develop species-specific markers for detecting Trichoderma koningiopsis and T. longibrachiatum, the sequence-characterized amplified region technique, using 20 inter-simple sequence repeat-polymerase chain reaction primers, was performed. The two specific markers for amplifying a single unique band consistent with T. koningiopsis and T. longibrachiatum, which were absent with other Trichoderma strains, were successfully identified. These fragments had no meaningful sequence homology with known sequences available in the National Center for Biotechnology Information and TrichOKEY databases. Compared with traditional identification techniques, these markers can facilitate more rapid and less complicated studies of Trichoderma population dynamics and evaluate their establishment after release into agricultural environments.

High temperature is a major environmental stress that devastatingly affects wheat production. Thenceforth, developing heat-tolerant and high-yielding wheat genotypes has become more critical to sustaining wheat production particularly under abrupt climate change and fast-growing global population. The present study aimed to evaluate parental genotypes and their cross combinations under normal and heat stress conditions, exploring their diversity based on dehydration-responsive element-binding 2 gene (DREB, stress tolerance gene in response to abiotic stress) in parental genotypes, and determining gene action controlling yield traits through half-diallel analysis. Six diverse bread wheat genotypes (local and exotic) and their 15 F1 hybrids were evaluated at two different locations under timely and late sowing dates. Sowing date, location, genotype, and their interactions significantly impacted the studied traits; days to heading, chlorophyll content, plant height, grain yield, and its attributes. Cluster analysis classified the parents and their crosses into four groups varying from heat-tolerant to heat-sensitive based on heat tolerance indices. The parental genotypes P2 and P4 were identified as an excellent source of beneficial alleles for earliness and high yielding under heat stress. This was corroborated by DNA sequence analysis of DREB transcription factors. They were the highest homologies for dehydrin gene sequence with heat-tolerant wheat species. The hybrid combinations of P1 × P5, P1 × P6, P2 × P4, and P3 × P5 were detected to be good specific combiners for grain yield and its attributes under heat stress conditions. These designated genotypes could be used in wheat breeding for developing heat-tolerant and climate-resilient cultivars. The non-additive genetic variances were preponderant over additive genetic variances for grain yield and most traits under both sowing dates. The narrow-sense heritability ranged from low to moderate for most traits. Strong positive associations were detected between grain yield and each of chlorophyll content, plant height, number of grains/spike, and thousand-grain weights, which suggest their importance for indirect selection under heat stress, especially in early generations, due to the effortlessness of their measurement.

Microbial contamination is a common problem that causes significant losses in plant micropropagation systems. The present study reports on the identification and control of bacterial contaminants in banana in vitro cultures. Twelve isolates belonging to Bacillus pumilus (S2), Bacillus subtilis (R2 and M4), Geobacillus stearothermophilus (S1, S3, S4, P2, M3 and R3) and Paenibacillus spp. (P1, R1 and M2) were identified by sequencing of 16S rRNA, gyrA or gyrB genes. Antibiotic susceptibility testing was performed with the disk diffusion method on bacterial isolates using 36 antimicrobial agents. Some antibiotics, notably Ticarcillin, Penicillin, Ampicillin, Cefazolin and Imipenem, had a broader range of bactericidal activity than others did. When contaminated axillary shoot cultures of banana were treated with 100 or 200 mg·L−1 of ticarcillin, ampicillin or penicillin the bacteria were eliminated, but a reduction in shoot multiplication and growth was observed. These findings contribute to minimizing the losses in the commercial micropropagation of banana.

A b s t r a c t A r t i c l e I n f oThe present investigation was designed to study the genetic component in 23 entries of sorghum (eight parents and 15 their cross) using line × tester design under water stress. Moreover, to assess genetic diversity and find marker(s) that could be related to drought tolerance. Genotypes (PI534175), (CD550190), (CPI456765 × PI534175), (CP1987656 × PI534175), (Dorado × PI534175) (CPI456765 × CD550190), (CP1987656 × CD550190) and (Hybrid Shadwell 2 × CD550190) were the best under water deficit conditions compared with the control for most evaluated genetic parameters for important traits. Genetic diversity among selected 11 sorghum entries (8 parents and the best three crosses) were evaluated using eleven primers (six for RAPD and six for SRAP). Fifty and thirty two total bands were detected for SRAP and RAPD whereas, 27 and 29 were polymorphic respectively. Unfortunately, from RAPD primers the banding patterns could not be able to generate any marker linked to water stress among the parents and their hybrids. Moreover, SRAP primers generated polymorphic bands, ranged between 20.60% (primer me1+em3), with the lowest band number (five bands only) to 80.0% for (primer me2+em3), generated the highest band number (11 bands), which generate specific band with size 470 bp in parental genotypes (CPI456765) and (CD550190) which could be transmuted to the hybrids (CPI456765 × CD550190) and (Hybrid Shadwell2 × CD550190). This band could be considered as linked to hybrid vigor and drought stress tolerance. Phylogenetic tree using SRAP divided the tolerant parents and their hybrid in closed clusters.

No abstract