With growing concerns over the sustainability of conventional farming systems, perennial crops offer an environmentally friendly and resilient alternative for long-term agricultural production. Perennial grain crops provide numerous benefits, such as low input investment, reduced tillage, soil conservation, better carbon sequestration, sustainable yields, and enhanced biodiversity support. Sorghum (Sorghum bicolor) is the fifth most-grown cereal crop grown for food, fuel, and food grain in the world. The development of perennial sorghum offers a substitute for traditional annual sorghum crops by providing long-term environmental, economic, and agronomic benefits. Sugarcane aphid (SCA; Melanaphis sacchari), a phloem-feeder, is considered a major threat to sorghum production. Since its first report in 2013, it caused $40.95 million in losses in South Texas alone by 2015, accounting for about 19% of the total value of sorghum production in the region. In this study, we screened diverse perennial sorghum genotypes using no-choice and choice assays to determine their innate antibiosis and antixenosis resistance levels to SCAs. Based on aphid reproduction and plant damage rating, no-choice bioassay classified the 43 perennial sorghum genotypes into four clusters: highly susceptible, moderately susceptible, moderately resistant, and highly resistant. To further investigate the resistance mechanisms, we selected two genotypes, X999 > R485 (SCA-resistant) and PR376 similar to Tift241 (SCA-susceptible) that showed the greatest variation in resistance to SCA, for subsequent experiments. Choice bioassay results indicated that aphids chose PR376 similar to Tift241 for settlement, whereas no significant preference was observed for X999 > R485 compared to the control genotype. Electrical penetration graph (EPG) results demonstrated that aphids feeding on the SCA-resistant genotype spent significantly less time in the phloem phase than the susceptible genotype and control plants. The identification of SCA-resistant perennial sorghum genotypes will be valuable for future sorghum breeding programs in managing this economically important pest.

Endophytic and rhizosphere-competent entomopathogenic fungi (EF) are important plant bodyguards, although the mechanisms underlying this phenomenon are poorly understood. Therefore, we aimed to elucidate the roles of antibiosis (lethal and sublethal effects), and potential growth compensation (in response to leaf injury) in melon plants exposed to cotton leafworm. Plants were inoculated with one of three EF strains (EAMa 0158-Su Metarhizium brunneum strain or EABb 04/01-Tip and EABb 01/33-Su Beauveria bassiana strains) by either foliar spray, seed dressing or soil drenching and then challenged with either multiple short-term, or single long-term Spodoptera littoralis larval infestation. Endophytic colonization and relative expression of plant defense genes were tracked using molecular techniques alongside evaluation of antibiosis effects on S. littoralis and plant tolerance to larval-induced leaf injuries. Inoculated plants exhibited antibiosis and potential growth compensation in responses to various S. littoralis challenges, which resulted in increased fresh and dry weight, chlorophyll content, number of secondary branches and stem diameter. Furthermore, up-regulation in the relative expression of ethylene (ACO1, ACO3, EIN2, EIN3) and jasmonic acid (LOX2)-related genes were observed, with the endophytic B. bassiana- induction of ethylene and jasmonic acid production being higher in S. littoralis infested plants. Our findings strongly confirm the EF multifunctionality and the involvement of the Endophytic EF triggered melon defensive system induction in the antibiosis and compensatory growth to protect melon plants from pest damage.