Engineering cotton with ASAL and MYB genes confer dual benefits of pest resistance and fiber improvement.

The MYB-ASAL strategy is a promising integrated approach for developing cotton cultivars with enhanced fiber quality and reduced pesticide resistance, strengthening the textile security. The quality of cotton fiber is a critical determinant in the textile industry, significantly influencing the overall quality of textile products. Environmental stressors, particularly extreme climatic conditions, adversely affect fiber quality. This study aims to investigate the enhancement of fiber traits by expressing the transcription factor MYB involved in fiber quality along with the implementation of crop protection strategies and by expressing the plant lectin gene ASAL, which provides resistance against sap-sucking insects. The MYB-ASAL gene cassette was ligated into plant expression vector pCAMBIA1302 which was confirmed through restriction digestion. The Agrobacterium-mediated transformation of pCAMBIA1302_MYB-ASAL cassette in cotton plants was performed through the shoot apex cut method with 1.61% transformation efficiency. The putative transgenic cotton plants were screened through PCR and amplification of 400 bp and 551 bp confirmed the presence of pCAMBIA1302_MYB-ASAL in cotton plants (AI 01-AI 10), which were then tested for mRNA expression. Out of ten transgenic plants, AI 01, AI 03, AI 07, AI 09 and AI 10 showed higher expression (7 and 8 folds) of the MYB gene in boll and leaf, respectively. The mRNA expression level of the MYB gene in T1 generation was higher in early developmental fiber stages, i.e., at 0, 3 and 6 post-anthesis (DPA). The relative MYB expression was high in sepals followed by petals, leaf, boll and seeds, while the mRNA expression of ASAL was significantly high in leaves of AI 03 and AI 09 transgenic cotton lines as compared to control. The whitefly mortality was calculated to be 78% and 80% in T0 and T1, respectively, while 10-15% in control plants. Maximum improvement in fiber length was 20.01%, in the fiber strength up to 17.1% and in the micronaire value up to 16.2% in AI 03 and AI 09 transgenic cotton lines. Scanning electron microscopy (SEM) revealed that the fibers of the transgenic cotton plants have greater number of twists per unit length than the fibers of the non-transgenic control plants. Improved morphological, physiological and biochemical characteristics revealed that MYB-ASAL has a positive impact on these characteristics. Furthermore, single gene copy number was found at chromosome number 4. These findings support the concept of utilizing these transgenic plants to integrate additional desirable traits through breeding strategies, thereby optimizing cotton fiber enhancement.