Environmental stress tolerance in maize (Zea mays): role of polyamine metabolism.

Maize (Zea mays L.), a major multipurpose crop for food, feed and energy is extremely susceptible to environmental perturbations and setting off the major factors for limiting maize yield. Generally, plant yields are reduced and significantly lost to adverse environments and biotic strains. To ensure the safety of living cells under unfavourable circumstances, polyamines (PAs) play an important role in regulating the response under both abiotic and biotic stresses. It is the relative abundance of higher PAs (spermidine, Spd; spermine, Spm) vis-à-vis the diamine putrescine (Put) and PA catabolism that determines the stress tolerance in plants. Climate changes and increasing demands for production of maize have made it pressing to improve the stress tolerance strategies in this plant and it is imperative to understand the role of PAs in response to various environmental perturbations. Here, we critically review and summarise the recent literature on role of PAs in conferring stress tolerance in the golden crop. The responses in terms of PA accumulation, their mechanism of action and all the recent genetic manipulation studies carried out in PA metabolism pathway, ameliorating range of abiotic and biotic stresses have been discussed. As PA metabolism under stress conditions does not operate singly within cells and is always linked to other metabolic pathways in maize, its complex connections and role as a signalling molecule have also been discussed in this review.

Etiological Profile of Lower Gastrointestinal Bleeding in Children and Adolescents from Kashmir; A Tale of 5 Years.

Background: Lower gut bleeding is an alarming sign among caregivers. Determining the etiology is of utmost importance for further management. This is the first study conducted in northernmost India. Methods: This cross-sectional study was conducted at the Department of Pediatrics, Government Medical College, Srinagar. This study aimed to describe the etiology of lower gastrointestinal bleeding in the age group of 1-18 years over the past 5 years from June 2017 to June 2022. Results: A total of 310 children presented with hematochezia (53.5%), blood mixed with loose stools for > 2 weeks (39.3%), melena (1.9%), and occult blood in stools (0.3%). The mean age was 5.12 years. The age group of 1-6 years was 73.5 %. The most common findings were rectosigmoid polyps n=104 (33.5%), anal fissure n=47 (15.1%), lymphoid nodular hyperplasia (LNH) n=38 (12.2%), trichuris dysentery syndrome n=30(9.7%), cow's milk protein allergy n=27(8.7%), non-specific colitis n=18(5.8%), solitary rectal ulcer syndrome n=14(4.5%), inflammatory bowel disease n=6 (1.9%),intestinal tuberculosis n=3(0.9%), duodenal dieulafoy lesion 1(0.3%), and blue bleb nevus rubber syndrome n=1(0.3%). 21 patients had a normal colonoscopy. The colonoscopy yield was 93.3 %. Among the colonoscopy-negative patients, 6(1.6%) had Meckel's diverticulum, and 1(0.3%) had a duodenal dieulafoy lesion. Conclusion: Lower GI bleeding most commonly presents as hematochezia, and the most common cause is a rectosigmoid polyp. Colonoscopy is the procedure of choice to evaluate the etiology of lower GI bleeding. Anal fissures, LNH, Trichuris trichiura, and cow's milk protein allergy are other common causes of lower gut bleeding in Kashmir, northernmost India.