Improvement of qualitative and quantitative traits in cotton under normal and stressed environments using genomics and biotechnological tools: A review.

Due to the increasing demand for high-quality and high fiber-yielding cotton (Gossypium spp.), research into the development of stress-resilient cotton cultivars has acquired greater significance. Various biotic and abiotic stressors greatly affect cotton production and productivity, posing challenges to the future of the textile industry. Moreover, the content and quality of cottonseed oil can also potentially be influenced by future environmental conditions. Apart from conventional methods, genetic engineering has emerged as a potential tool to improve cotton fiber quality and productivity. Identification and modification of genome sequences and the expression levels of yield-related genes using genetic engineering approaches have enabled to increase both the quality and yields of cotton fiber and cottonseed oil. Herein, we evaluate the significance and molecular mechanisms associated with the regulation of cotton agronomic traits under both normal and stressful environmental conditions. In addition, the importance of gossypol, a toxic phenolic compound in cottonseed that can limit consumption by animals and humans, is reviewed and discussed.

First report of Curvularia penniseti causing leaf blight of Bajra Napier hybrid grass in India.

Bajra Napier hybrid (Pennisetum glaucum x Pennisetum purpureum) is a perennial, high yielding grass and is widely grown for fodder in India. During August-2021, Bajra Napier hybrid germplasm line (NBN 15-2) showed severe leaf blight symptoms at ICAR-Indian Grassland and fodder research institute, Jhansi (25.527890 N, 78.5451400 E). Symptoms were initial irregular yellow spots on the leaf lamina, which later became brownish, coalesced and gave blighted appearance to the leaf surface. Disease severity recorded was 55 to 60 percent. To isolate the pathogen, 10 symptomatic leaf samples were cut into small pieces (~4 mm2), surface-sterilized with 70% ethanol for 30 seconds and rinsed with sterile water. Sterilized leaf pieces were transferred to potato dextrose agar (PDA) and incubated at 28°C for 7 days. Four similar fungal isolates (BNHCP-1 to BNHCP-4) were obtained from the affected portions. The colonies were grayish-brown with dark brown margins. Conidia were mostly clavate, elongated, straight or bent at the terminal cell, with 2-3 septa with dimensions of 17.5 to 30 µm × 10 to 12.5 µm (avg. 24 µm × 12 µm; n=40). The third cell from the base was broader and darker. These morphological characteristics were consistent with previous descriptions of Curvularia penniseti (Mitra) Boedijn (Ellis, 1971). To confirm the species, BNHCP-1 was chosen as representative isolate for further studies. Internal transcribed spacer (ITS) region and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene of isolate BNHCP-1 was amplified with primers ITS1F/ITS4R (White et al. 1990) and GDF/GDR (Templeton et al. 1992), and sequenced. The sequences were deposited in GenBank (ITS: OM073980; GAPDH: OM103702.2). BLASTn analysis showed 99.6% and 98% similarity of ITS and GAPDH gene respectively with GenBank accession numbers MH859833.1 (548 bp/550 bp) and MN688838.1 (130 bp/133 bp) of C. penniseti. A maximum-likelihood phylogenetic analysis based on concatenated sequences of ITS and GAPDH gene using MEGA X placed the isolate BNHCP-1 within a clade comprising C. penniseti. Pure culture of BNHCP-1 was deposited in National Agriculturally Important Microbial Culture Collection (NAIMCC), Maunath Bhanjan (Uttar Pradesh) with accession number NAIMCC-F-04251. For pathogenicity, root slips of Bajra Napier hybrid germplasm line NBN 15-2 were transplanted in pots (6 pots; 2 root slips per pot) and kept for fresh growth in a growth chamber at 25 0C for 21 days. Bajra-Napier hybrid plants were sprayed until runoff with conidial suspension (5 × 105 conidia/ml) made from 2-week old fungal colony grown on PDA petri dish. The pots were covered with plastic bag for 48 h to maintain humidity. Inoculated plants displayed small, brown, oval-shaped lesions within seven days on the lamina and edges of the leaf which later enlarged and gave blighted appearance to the leaf. Control plants were asymptomatic. The pathogen was re-isolated from the inoculated leaves and confirmed morphologically, fulfilling Koch's postulates. C. penniseti has been reported earlier from Pennisetum americanum, P. clandestinum, Sorghum and Triticum sp. from different parts of the world (Sivanesan, 1987). However, there is no report of C. penniseti in Bajra Napier hybrid. Thus, to the best of our knowledge, this is the first report of C. penniseti from Bajra-Napier hybrid grass in India. Further studies on economic impact of this disease on Bajra-Napier hybrid production and its presence on commercial cultivars are needed.

Silencing of HaAce1 gene by host-delivered artificial microRNA disrupts growth and development of Helicoverpa armigera.

The polyphagous insect-pest, Helicoverpa armigera, is a serious threat to a number of economically important crops. Chemical application and/or cultivation of Bt transgenic crops are the two strategies available now for insect-pest management. However, environmental pollution and long-term sustainability are major concerns against these two options. RNAi is now considered as a promising technology to complement Bt to tackle insect-pests menace. In this study, we report host-delivered silencing of HaAce1 gene, encoding the predominant isoform of H. armigera acetylcholinesterase, by an artificial microRNA, HaAce1-amiR1. Arabidopsis pre-miRNA164b was modified by replacing miR164b/miR164b* sequences with HaAce1-amiR1/HaAce1-amiR1* sequences. The recombinant HaAce1-preamiRNA1 was put under the control of CaMV 35S promoter and NOS terminator of plant binary vector pBI121, and the resultant vector cassette was used for tobacco transformation. Two transgenic tobacco lines expressing HaAce1-amiR1 was used for detached leaf insect feeding bioassays. Larval mortality of 25% and adult deformity of 20% were observed in transgenic treated insect group over that control tobacco treated insect group. The reduction in the steady-state level of HaAce1 mRNA was 70-80% in the defective adults compared to control. Our results demonstrate promise for host-delivered amiRNA-mediated silencing of HaAce1 gene for H. armigera management.