No abstract

Bioassays and binding tests between Cry toxins (CrylAa, CrylAb, CrylAc, and Cry2Ab) and brush-border membrane vesicles (BBMVs) from larvae of a Bacillus thurningiensis (Bt)-susceptible (96S) and two CrylAc-resistant strains (BtR and LFR10) were conducted for investigating cross-resistance of CrylAc-resistant strains to Cry2Ab in Helicoverpa armigera (Hiibner) (Lepidoptera: Noctuidae). The resistance ratio (RR) values of the BtR and LFR10 strains to CrylAc and Cry2Ab were 2,971- and 1.1-fold and 253- and 1.0-fold, respectively, indicating that there was no cross-resistance to Cry2Ab. The binding experiments between Cry toxins and BBMVs from BtR, LFR10, and 96S larvae showed that all of the toxins could bind with these BBMVs, but the Cry2Ab could not displace 125I labeled CrylAc and CrylAb. The same results were observed in reciprocal binding tests, demonstrating that CrylA and Cry2Ab had different binding sites in H. armigera and providing a potential mechanism for the lack of cross-resistance between CrylA and Cry2Ab toxins. These results suggest that the transgenic cotton, Gossypium hirsutum L., expressing CrylAc and Cry2Ab genes may be deployed for management of CrylAc resistant H. armigera.

The genetic diversity of mango (Mangifera indica L.) was determined among 188 mango accessions using 40 SSR markers. A total of 303 alleles were discovered, with a mean value of 7.58 and an average PIC of 0.583, showing that the SSR markers utilized in this investigation was quite informative. High Shannon’s index (1.304) and He (0.624) reflected the high genetic diversity of Chinese mango genetic resources. PCoA analysis and phenogram analysis divided the accessions broadly into groups representing their geographical origins and suggested a clear separation between M. indica and M. persiciformis. This expanded awareness of the genetic diversity of mango germplasm would aid breeders in choosing better parents, hence accelerating the delivery of improved cultivars to industry in order to satisfy consumer demand.