Identifying reliable screening tools and characterizing tolerant germplasm sources are essential for developing wheat (Triticum aestivum L.) varieties suited for the hot areas of the world. Our objective was to evaluate heat tolerance of promising wild tetraploid wheat (Triticum turgidum L.) accessions that could be used as sources of heat tolerance in common- and durum-wheat (Triticum durum) breeding programs. We screened 16 wild tetraploid wheat accessions and two common wheat checks for their response to heat stress by measuring damage to the thylakoid membranes, flag leaf temperature depression (FLTD), and spike temperature depression (STD) during exposure to heat stress for 16 days post-anthesis (DPA). Measurements were taken on the day of anthesis then 4, 8, 12, 16 DPA under controlled optimum and heat-stress conditions. Individual kernel weight (IKW) and heat susceptibility index (HSI) measurements were also obtained. Prolonged exposure to heat stress was associated with increased damage to thylakoid membranes, as indicated by the high ratio of constant fluorescence (O) to peak variable fluorescence (P). Some wild tetraploid wheat accessions exhibited a better HSI than the common heat-tolerant wheat cultivar 'Kauz.' A positive and significant correlation was found between O/P ratio and each of FLTD and STD under heat-stress conditions. A negative and significant correlation was found between FLTD and HSI and between STD and HSI based on the second and third measurements (4 and 8 DPA). Correlations obtained after the third measurement were not significant because of heat-induced, accelerated maturity and a lack of green leaf tissue. This study identified potential heat-tolerant wild tetraploid wheat germplasm that can be incorporated into wheat breeding programs to improve heat tolerance in cultivated common and durum wheat.

Regenerated plants derived from somatic embryogenesis, using immature male flower technique of two banana Cavendish cultivars namely 'Grand Naine' and 'Williams', were used for somaclonal variation analysis. Thirty primer combinations of the amplified fragment length polymorphism marker system (AFLP) were used. A total of 1293 and 1302 bands were generated, of which 1275 (98.6%) and 1281 (98.4%) were monomorphic, and 18 (1.4%) and 21 (1.6%) bands were polymorphic in Grand Naine and Williams, respectively. Both cluster analysis of unweighted pair-grouping method with arithmetic averages (UPGMA) and principal coordinate (PCO) analysis separated the two cultivars, and grouped each cultivar with its regenerated plants. AFLP analysis showed 8 and 16 bands specific to the regenerated plants of Grand Naine and Williams, respectively, these were absent in their parents, in addition, we found evidence of the absence of 10 and 5 bands in the regenerated plants, respectively, which were presented exclusively in their parental plants. Such specific bands presented in the regenerated plants could be useful for further investigation on the genetic identification of somaclonal variation in banana. On the other hand, regenerated plants of both cultivars were transferred to the field; no gross phenotypic alteration, e.g. mosaics, variegation, dropping leaves and dwarfs, etc., has been detected until now with the beginning of the flowering period. However, further field evaluation of individual plants is required for the observation of possible phenotypic somaclonal variants that may show useful characters, e.g. resistance to biotic or abiotic stress as well as high yield production and fruit quality.